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  • richardmitnick 9:38 am on December 3, 2018 Permalink | Reply
    Tags: , Asteroids, , , , , , NASA NEOCam   

    From Science Alert: “Astronaut Warns This Neglected NASA Telescope Is Our Best Chance to Avoid Death by Asteroid” 

    ScienceAlert

    From Science Alert

    3 DEC 2018
    DAVE MOSHER

    A former NASA astronaut says the agency he used to work for has a duty to protect civilians from killer asteroids, but that it isn’t meeting that obligation.

    The threat of asteroid strikes might seem as abstract as outer space itself. But the risk, while infrequent, is real – and potentially more deadly than the threat posed by some of the most powerful nuclear weapons ever detonated.

    Risk of death from above

    In 1908, a space rock estimated to be several hundred feet in diameter screamed into Earth’s atmosphere at many thousands of miles per hour, causing the foreign body to explode over the remote Tunguska region of Russia with the force of a thermonuclear weapon.

    The resulting blast flattened trees over an area nearly twice the size of New York City.

    More recently, in 2013, a roughly 70-foot-wide meteorite shot over Chelyabinsk, Russia.

    The concussive fireball smashed windows for miles around and sent more than 1,000 people in multiple cities to hospitals, several dozen of them with serious injuries.

    We know they’re out there

    NASA is poignantly aware of such risks – and so are lawmakers.

    In 2005 Congress made one of the agency’s seven core goals to track down 90 percent of asteroids 460 feet (140 meters) and larger, which could lead to a worse-than-Tunguska-level event. The deadline for this legally mandated goal is 2020.

    So far, however, telescopes on Earth and in space have found less than one third of these near-Earth objects (NEOs) and NASA will almost certainly fail to hit its deadline.

    Practically, this means tens of thousands of NEOs big enough to wipe out a city have yet to be found, according to a June 2018 report published by the White House.

    The same report concludes that even with current and planned capabilities, less than half of such space rocks will be located by 2033.

    We have the technology to confront the problem

    Russell “Rusty” Schweickart, an aerospace engineer retired astronaut who flew on the Apollo 9 mission, says there is a solution in waiting for this problem: NASA can launch the Near-Earth Object Camera (NEOCam), which is a small infrared observatory, into space.

    NASA NEOCAM

    “It’s a critical discovery telescope to protect life on Earth, and it’s ready to go,” Schweickart told Business Insider at The Economist Space Summit on November 1.

    NEOCam’s designers have pitched the mission to NASA multiple times. The mission has received several million dollars here and there to continue its development in response to those proposals, but the agency has denied full funding in every instance on account of it not being the best purely science-focused mission.

    “For God’s sake, fund it as a mainline program. Don’t put it in yet another competition with science,” Schweickart said. “This is a public safety program.”

    How NEOCam would hunt for ‘city killer’ asteroids

    Telescopes that are looking in the right place at the right time can detect a dot of that light sneaking across the blackness of space. This allows scientists to calculate an NEO’s mass, speed, orbit, and the odds that it will eventually smack into Earth.

    Small NEOs, though, aren’t very bright. This means a telescope has to be big, see a lot of the sky, and use very advanced hardware to pick them up. These monstrous telescopes take a very long time to build and calibrate and are budget-crushingly expensive.

    Take the Large Synoptic Survey Telescope (LSST), for example, which is one of Earth’s best current hopes of finding killer asteroids.

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    The project broke ground in 2015 and is expected to cost about half a billion dollars to build.

    Based on its current construction schedule, it won’t be fully operational until late 2021, at the soonest, or able to fulfill the 90 percent detection goal set by Congress until the mid-2030s.

    LSST, like all ground-based observatories, also comes with two major limitations.

    The first: “You can’t see asteroids near the Sun. You’re blinded by the sky,” Mark Sykes, director of the Planetary Science Institute and a scientist on the NEOCam team, previously told Business Insider.

    “Right now we have to wait until those pop out in front of us.”

    Sykes said the second snag is that ground-based telescopes mainly rely on visible light for detection. “If [an asteroid] has a dark surface, it’s going to be very hard to see,” he said.

    NEOCam addresses these two problems by being in space, where Sykes says “you’re not blinded by the sky.”

    The telescope would also use an advanced, high-resolution infrared camera. Infrared is a longer wavelength of light that’s invisible to our eyes, but if a source is strong enough – say, a roaring fire – we can feel invisible light as warmth on our skin.

    Asteroids warmed by the Sun, radioactive elements, or both will emit infrared light, even when they’re too small or dark for ground-based telescopes to see. Which means NEOCam could spot them merely by their heat signatures.

    This approach is already proven to work.

    The prime example is NASA’s eight-year-old Wide-field Infrared Survey Explorer (WISE) telescope, which has found roughly 275 NEOs, including 50 potentially hazardous asteroids, or PHOs (so named because they come within 4.6 million miles of Earth at some point in their orbits).

    NASA Wise Telescope

    1
    (NASA/JPL-Caltech)

    However, it’s a less powerful telescope, has a smaller field of view, an older camera that requires cryogenic cooling that eventually runs out (NEOCam’s doesn’t need it), and wasn’t designed just to hunt asteroids.

    The telescope, now called NEOWISE, may end operations in December 2018.

    NEOCam is Earth’s best immediate hope for quick detection of asteroids

    According to a recent study in The Astronomical Journal, neither NEOCam nor LSST alone would ever achieve Congress’ 90 percent detection mandate – only by working together, the research found, could the observatories achieve that goal over a decade.

    But NEOCam offers significant upgrades to the situation under LSST.

    In its latest pitch to NASA, the NEOCam team proposed to launch in 2021 and find two-thirds of missing objects in the larger-than-460-feet (140 meters) category within four years, or about a decade ahead of LSST’s schedule.

    Less than 70 percent of all NEOs that are 460 feet (140 meters) or larger have not been found, according to a report published by the White House’s National Science and Technology Council (NSTC) in December 2016.

    This amounts to about 25,000 nearby asteroids and roughly 2,300 potentially hazardous ones.

    The NTSC report suggests that an orbiting telescope like NEOCam could also help root out asteroids that would strike with a force somewhere between a Tunguska-type event (occurring about once every 100-200 years) and a Chelyabinsk-type event (occurring about once every 10 years), of which less than 1 percent have been located.

    So if launching a more-capable replacement for NEOWISE is a top priority, why might NASA not fully fund NEOCam for a 2024 launch?

    ‘NASA has a responsibility to do it’

    The team behind NEOCam has pitched the mission to NASA three times – in 2006, 2010, and 2015 – and three times NASA has punted on fully funding the telescope.

    The last instance it was denied, sources told Business Insider the proposal had no major technical weaknesses. Instead, it was a case of trying to jam a square peg into a round bureaucratic hole.

    The NASA competition it was a part of, called Discovery, values scientific firsts – not ensuring humanity’s safety – and thus did not grant NEOCam nearly US$450 million to develop its spacecraft and a rocket with which to launch it.

    NASA instead picked two new space missions to explore the Solar System: Lucy, a probe that will visit swarms of ancient asteroids lurking near Jupiter, and Psyche, which will orbit the all-metal core of a dead planet.

    For Schweickart’s part, he doesn’t care about the distinction.

    “NASA has a responsibility to do it, and it’s not happening,” he said. “It needs to be put into the NASA budget both by NASA and by the Congress.”

    NEOCam did get US$35 million in the 2018 government funding bill to keep itself going, but proponents say this is not enough to get the telescope to a launch pad.

    “In the meantime, NEOCam is in a zombie state and all the while Earth waits inevitably in the crosshairs,” Richard Binzel, a planetary scientist and expert on the hazards posed by asteroids at Massachusetts Institute of Technology, told Business Insider in an email.

    Binzel is one of three scientists who wrote a recent op-ed in Space News in support of fully funding the project, even though they’re not on the project’s team.

    Binzel and others argue NEOCam could get launched by raising the House of Representatives’ proposed budget for NASA planetary defence by another US$40 million (up from a US$160 million to US$200 million) and by sharing a rocket ride with a spacecraft called IMAP, which the agency plans to launch in 2024.

    By working in coordination with ground-based telescopes, NEOCam could achieve nearly 70 percent detection in four years, and the agency’s target of 90 percent detection in less than 10 years.

    Finding such money is not easy though. Binzel said the infrequency of asteroid strikes makes it politically uncostly to instead fund other initiatives year after year.

    “But the consequences of being wrong are irresponsible, especially when the capability to gain the necessary knowledge is easily within our grasp,” he said.

    “We should simply act like responsible adults and ‘just do it.’ What are we waiting for?”

    It’s now up to President Trump and Congress

    Schweickart acknowledged that NASA’s budgeting and culture has, for decades, been focused on pushing top-tier scientific exploration and that deviating from this norm – Congressional mandate or not – isn’t easy.

    “You’re going upstream. You’re fighting a pretty strong headwind within NASA,” he said, adding that pulling money from science budgets to fund anything is extremely unpopular. “But government agencies are not at liberty to ask for increases in their budget.”

    Schweickart and fellow retired astronaut Ed Lu tried years ago to end-run around the problem by co-founding the B612 Foundation, which is a nonprofit dedicated to developing NEO-detecting capabilities.

    But the group tabled its longest-running (and most expensive) idea, the Sentinel space telescope, in part to improve NEOCam’s chances of getting funded. On Oct. 29, the organisation even publicized its strong support for lawmakers fully funding its rival.

    The public also appears to be on-board with NASA making asteroid detection projects like NEOCam happen.

    In a June poll by Pew Research Center, nearly two-thirds of 2,500 American adults surveyed said that asteroid monitoring should be a top priority for NASA. (Only monitoring climate change was higher.)

    It remains to be seen what the Trump administration will decide to do with NEOCam in the next NASA budget, and if Congress authorizes that funding.

    “That’s a February discussion,” Stephen Jurczyk, NASA’s associate administrator, told Business Insider at the Economist Space Summit.

    “All of that’s all embargoed until the president releases his budget to Congress.”

    Jurczyk acknowledged the tension between NASA’s duty to locate dangerous asteroids along with internal changes required to make that work happen.

    “It is to some extent a cultural issue, where we kind of have this mentality of pure science and pure competition,” he said.

    “I think we’re starting to evolve to a more diverse and more balanced approach between pure science and other things that we need to do.”

    The question is whether those changes will happen before the next Tunguska-type asteroid arrives at Earth. Given enough warning, we might fly out to such a space rock and prevent a calamity or, if there isn’t enough time for that, try to move people out of harm’s way.

    See the full article here .

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  • richardmitnick 4:08 pm on November 30, 2018 Permalink | Reply
    Tags: Asteroids, , , , ,   

    From ESOblog: “Revealing the True Nature of Asteroids” 

    ESO 50 Large

    From ESOblog

    A team of scientists are currently using ESO’s Very Large Telescope to survey the largest asteroids in the Solar System. Nicknamed HARISSA, the survey has recently gathered lots of information on asteroid Psyche, special because of its metallic nature. In this week’s blog post the team behind the project explain what Psyche can tell us about the history of the Solar System, and how their research will feed into a NASA mission to study the same asteroid.

    Q. Firstly, could you tell us a bit about the HARISSA survey.

    Pierre (P): We are finding out more about some of the largest asteroids in the Asteroid Belt using the SPHERE instrument on the Very Large Telescope (VLT).

    ESO SPHERE extreme adaptive optics system and coronagraphic facility on the extreme adaptive optics system and coronagraphic facility on the VLT MELIPAL UT3, Cerro Paranal, Chile, with an elevation of 2,635 metres (8,645 ft) above sea level

    With the VLT, we can see surface features such as craters, allowing us to carry out geology and geophysics from here on Earth for the first time ever. Craters tell us more about the age and collisional history of each asteroid, as a higher number of craters imply an older surface or more violent past. They can also hint at an asteroid’s internal structure.

    Franck (F): We have been observing asteroids for years using the W.M. Keck Observatory, so when we found out about the VLT’s next-generation adaptive optics system, we couldn’t wait to use it to image asteroids with a much better resolution — four times sharper than that of the Hubble Space Telescope! The survey is still ongoing, and more data is coming, so we hope that there will be some interesting results in the future.

    Q. So you observed Psyche as part of this HARISSA survey — could you give us a brief overview of how you observed this asteroid and what you found out?

    P: We combined our VLT observations from May this year with additional data from the last 20 years, many of which came from amateur astronomers! In total, we had 206 data sets for Psyche, and we fed them all into an algorithm to find out about its size and shape. We discovered that it is 226 kilometres wide, with two particularly interesting features — one very bright patch and one huge crater almost half the size of the asteroid itself.

    F: We named the bright patch Panthia and the crater Meroe after the twin witches in the story Metamorphosis, which Psyche’s name also comes from. We also looked for a moon, because measuring a moon’s orbit could give us a good estimate of Psyche’s mass. But we are now almost certain that Psyche hosts no moons larger than one kilometre in diameter.

    2
    Images of Psyche from the HARISSA survey, with Meroe and Panthia highlighted. Credit: ESO/LAM

    Q. Could you tell us a bit about asteroids? What are they and why should we study them?

    F: Asteroids are the remnants of the formation of the Solar System. In a way, they are the “bricks” that make up the Solar System, and it’s important to understand the bricks to understand the whole structure.

    P: Most asteroids live in the Asteroid Belt between Mars and Jupiter. But we believe that they actually formed in a wider range of locations. Some are very rocky, and probably formed closer to the Sun, and some are more icy, having probably formed further out, between Jupiter and Neptune. There are clear differences between these icy and rocky bodies — rocky asteroids are covered in craters, but the presence of ice smooths these scars on the icy asteroids. Rarer, metal-rich asteroids also exist.

    Q. Why did you decide to investigate this particular asteroid? Why is it interesting?

    P: Psyche is much richer in metals than other asteroids, which implies that it formed a very long time ago. Being part of the first generation of planetary building blocks means that it could be useful for understanding the early Solar System.

    F: Also, past radar observations implied that this asteroid is a metallic world with a metal-rich surface. These types of asteroids are rare compared to rocky and icy asteroids. We are trying to observe all types of asteroids through the HARISSA programme, and Psyche is one of the few large metallic asteroids believed to exist.

    F: But actually, we were surprised that our observations showed Psyche to be a mesosiderite asteroid, meaning it is a mixture of metal and rock. Mesosiderite meteorites make up just 0.7% of the meteorites found on Earth, making them even rarer than purely metallic meteorites. This leads us to wonder which asteroids they came from and where these parent bodies were formed. And now we consider that Psyche could be the source of these meteorites!

    P: It is possible that mesosiderite asteroids are the result of a collision between small molten objects and a large asteroid early in the history of the Solar System, or maybe they arose from the breakup and reassembly of a large asteroid. Understanding the formation of Psyche with a dedicated NASA mission will hopefully shed some light on this mystery to tell us more about the early Solar System. That’s really exciting!

    Q. So why is NASA sending a spacecraft to Psyche?

    P: Metal-rich asteroids have not been observed in much detail before. And although we have found out a lot from ground-based observations, some measurements can only be done in situ, for example analysing the composition of the rock to find out what elements are on the surface and measuring the magnetic field around Psyche. The NASA spacecraft will carry instruments that can do these things. It will also measure Psyche’s gravity to find out about its interior, possibly helping us determine whether the asteroid formed as a result of a collision.

    F: Metal-rich asteroids are like a missing piece in the puzzle of our understanding of the formation of the Solar System. And one topic that comes up quite a lot at the moment is asteroid mining. These metal-rich objects are the type that we would mine for precious metals that are becoming more difficult to collect on Earth. But first, we need to answer questions like: how much metal is in the rock? how could we go about extracting it? Moral questions surround asteroid mining, but at least if we understand the science, we can get a broader view of the situation.

    NASA Psyche spacecraft

    Q. Will your observations be useful for the NASA mission?

    F: By carrying out the first exploration of the asteroid, we observed some things that will be very useful for the Psyche mission team, for example, we now know that there is no large moon for the spacecraft to potentially collide with. We also found that the features on the surface vary by about 10% in brightness; this knowledge will help the Psyche team tune their instruments to clearly see surface features — just like when your camera has to adjust to different light levels here on Earth.

    NASA will use all this information to optimise their mission. For example, they might plan to start by studying the most interesting geophysical areas — Meroe or Panthea, perhaps — as they don’t know exactly how long the spacecraft will survive in deep space. They want to get the most interesting results right at the beginning!

    Q. What do you hope to do in the future?

    P: Psyche is moving closer to Earth, so in a few months it will be even larger than when we first observed it. If the HARISSA programme is extended, we hope to get additional observations; new images would allow us to see other sides of the asteroid that weren’t visible when we first observed it in May, meaning we could identify and map new features.

    F: We would also like to use the Extremely Large Telescope (ELT) [below] to image this asteroid. The resolution will initially be two to three times better than that of the VLT, so we would be able to see small details on the surface, and to spot if there is a tiny moon. We already have images of the surfaces of the very largest asteroid belt objects, but the ELT will allow us to clearly spot craters on the surfaces of more than 100 asteroids!

    See the full article here .


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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT 4 lasers on Yepun


    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres.

    ESO/E-ELT,to be on top of Cerro Armazones in the Atacama Desert of northern Chile. located at the summit of the mountain at an altitude of 3,060 metres (10,040 ft).


    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 11:22 am on July 31, 2018 Permalink | Reply
    Tags: Asteroids, , , , , , NASA's Center for Near-Earth Object Studies (CNEOS), Scout, Sentry   

    From JPL-Caltech: “Twenty Years of Tracking Near-Earth Objects” 

    NASA JPL Banner

    From JPL-Caltech

    July 23, 2018
    DC Agle
    Jet Propulsion Laboratory, Pasadena, Calif.
    818-393-9011
    agle@jpl.nasa.gov

    JoAnna Wendel
    Headquarters, Washington
    202-358-1003
    Joanna.r.wendel@nasa.gov

    1
    The animation depicts a mapping of the positions of known near-Earth objects (NEOs) at points in time over the past 20 years, and finishes with a map of all known asteroids as of January 2018. Asteroid search teams supported by NASA’s NEO Observations Program have found over 95 percent of near-Earth asteroids currently known. There are now over 18,000 known NEOs and the discovery rate averages about 40 per week. Image credit: NASA/JPL-Caltech.

    NASA’s Center for Near-Earth Object Studies Enters Third Decade.

    On March 11, 1998, asteroid astronomers around the world received an ominous message: new observational data on the recently discovered asteroid 1997 XF11 suggested there was a chance that the half-mile-wide (nearly one kilometer) object could hit Earth in 2028.

    The message came from the Minor Planet Center, in Cambridge, Massachusetts, the worldwide repository for such observations and initial determination of asteroid orbits. And although it was intended to alert only the very small astronomical community that hunts and tracks asteroids to call for more observations, the news spread quickly.

    Most media outlets did not know what to make of the announcement, and mistakenly highlighted the prospect that Earth was doomed.


    The animation depicts a mapping of the positions of known near-Earth objects (NEOs) at points in time over the past 20 years, and finishes with a map of all known asteroids as of January 2018. Asteroid search teams supported by NASA’s NEO Observations Program have found over 95 percent of near-Earth asteroids currently known. There are now over 18,000 known NEOs and the discovery rate averages about 40 per week. Image credit: NASA/JPL-Caltech

    Fortunately, it turned out that Earth was never in danger from 1997 XF11. After performing a more thorough orbit analysis with the available asteroid observations, Don Yeomans, then the leader of the Solar System Dynamics group at NASA’s Jet Propulsion Laboratory in Pasadena, California, along with his colleague Paul Chodas, concluded otherwise. “The 2028 impact was essentially impossible,” said Chodas, who is now director of NASA’s Center for Near-Earth Object Studies (CNEOS), located at JPL.

    “To this day we still get queries on the chances of XF11 impacting in 2028,” Chodas said. “There is simply no chance of XF11 impacting our planet that year, or for the next 200 years.”

    Chodas knows this thanks to CNEOS’ precise orbit calculations using observation data submitted to the Minor Planet Center by observatories all over the world that detect and track the motion of asteroids and comets. For the past two decades, CNEOS calculations have enabled NASA to become the world leader in these efforts, keeping close watch on all nearby asteroids and comets — especially those that can cross Earth’s orbit.

    “We compute high-precision orbits for all asteroids and comets and map their positions in the Solar System, both forward in time to detect potential impacts, and backward to see where they’ve been in the sky,” Chodas said. “We provide the best map of orbits for all known small bodies in the Solar System.”

    2
    The animated chart depicts the cumulative number of known Near-Earth asteroids (NEAs) versus time. The area in red depicts the number of known NEAs larger than 0.6 miles (1 kilometer). The area in orange depicts the quantity of known NEAs larger than 460 feet (140 meters). The area in blue depicts the number of known NEAs in all sizes. Image credit: NASA/JPL-Caltech.

    Mapping the Celestial Hazard

    Near-Earth Objects (NEOs) are asteroids and comets in orbits that bring them into the inner solar system, within 121 million miles (195 million kilometers) of the Sun, and also within roughly 30 million miles (50 million kilometers) of Earth’s orbit around the Sun.

    The media frenzy around NEO 1997 XF11 demonstrated the need for clarity and precision in communicating with the public about the close passes by Earth of these objects, as well as “the importance of peer review before public statements like these are made,” Chodas said.

    NASA’s original intent was to fulfill a 1998 Congressional request to detect and catalogue at least 90 percent of all NEOs larger than one kilometer in size (roughly two-thirds of a mile) within 10 years. To help reach the Congressional goal, NASA Headquarters requested that JPL establish a new office to work with the data provided by the International Astronomical Union-sanctioned Minor Planet Center for submission of all observations of asteroids and comets, and to coordinate with observatories operated by academic institutions around the United States, as well as U.S. Air Force space surveillance assets.

    In the summer of 1998, NASA established the Near-Earth Object Observations Program and JPL became the home for the agency’s research data and analysis on NEOs, the “Near-Earth Object Program Office.” (To view the announcement regarding the creation of the Near-Earth Object Program Office, see: https://www.jpl.nasa.gov/news/news.php?feature=5134)

    In 2016, the office was renamed the Center for Near-Earth Object Studies (CNEOS) in conjunction with the establishment of the Planetary Defense Coordination Office (PDCO) at NASA Headquarters in Washington.

    For about 20 years, CNEOS has been NASA’s central hub for accurately mapping the orbits of all the known NEOs, predicting their upcoming close approaches, reliably assessing their chances of impact to our planet, and delivering that information to both astronomers worldwide and the general public.

    Predicting Close Approaches and Impacts: Sentry and Scout

    The first and most important step in assessing the impact risk of an asteroid or comet is to determine whether any given object’s orbit will cross Earth’s orbit — and then how close it will actually get to our planet. JPL was determining high-precision orbits for a few NEOs even before NASA launched its NEO Observations Program, and has since upgraded its orbit models to provide the most accurate assessment available for asteroid positions and orbits.

    Observatories around the world take digital images of the sky to detect moving points of light (the asteroid or comet) over days, weeks, months (and even decades!), and then report the positions of these moving objects relative to the static background of stars to the Minor Planet Center. See “How a Speck of Light Becomes an Asteroid“.The CNEOS scientists then use all this observation data to more precisely calculate an NEO’s orbit and predict its motion forward in time for many years, looking for close approaches and potential impacts to the Earth, its Moon, and other planets.

    A CNEOS system called “Sentry” searches ahead for all potential future Earth impact possibilities over the next hundred years — for every known NEO. Sentry’s impact monitoring runs continually using the latest CNEOS generated orbit models, and the results are stored online.In most cases so far, the probabilities of any potential impacts are extremely small, and in other cases, the objects themselves are so small — less than 20 meters in size, or nearly 66 feet — that they would almost certainly disintegrate even if they did enter Earth’s atmosphere.

    “If Sentry finds potential impacts for an object, we add it to our online ‘impact risk’ table, and asteroid observers can then prioritize that object for further observation,” said Steve Chesley of JPL, a member of the CNEOS team who was the main developer of the Sentry system. “The more measurements made of the object’s position over time, the better we can predict its future path.”

    “In most cases, the new measurements mean the object can be removed from the risk list because the uncertainties in the orbital path are reduced and the possibility of impact is ruled out,” Chesley said.

    More recently, CNEOS also developed a system called Scout to provide more immediate and automatic trajectory analyses for the most recently discovered objects, even before independent observatories confirm their discovery. Operating around the clock, the Scout system not only notifies observers of the highest priority objects to observe at any given time, it also immediately alerts the Planetary Defense Coordination Office of any possible imminent impacts within the next few hours or days.A recent example is the Scout-predicted impact of the small asteroid 2018 LA over Botswana, Africa.

    More Hunting to Do

    With the addition of more capable NASA-funded asteroid surveys over the years, NASA’s NEO Observations Program is responsible for over 90 percent of near-Earth asteroid and comet discoveries. There are now over 18,000 known NEOs and the discovery rate averages about 40 per week.

    Although the original Congressional goal from 1998 has been exceeded and much progress has been made in asteroid discovery and tracking over the past two decades, the work isn’t over. In 2005, Congress established a new, much more ambitious goal for the NEO Observations Program — to discover 90 percent of the NEOs down to the much smaller size of 450 feet (140 meters), and to do so by the year 2020 (https://www.congress.gov/congressional-report/109th-congress/house-report/158/1).

    These smaller asteroids may not present a threat of global catastrophe if they impact Earth, but they could still cause massive regional devastation and loss of life, especially if they occur near a metropolitan area. CNEOS continues to make improvements to its orbital analysis tools, image and graphic presentation capabilities, and updates of its websites to quickly and accurately provide the very latest information on NEOs to PDCO, the astronomical community and the public.

    JPL hosts the Center for Near-Earth Object Studies for NASA’s Near-Earth Object Observations Program, an element of the Planetary Defense Coordination Office within the agency’s Science Mission Directorate.

    More information about CNEOS, asteroids and near-Earth objects can be found at:

    https://cneos.jpl.nasa.gov

    https://www.jpl.nasa.gov/asteroidwatch

    For more information about NASA’s Planetary Defense Coordination Office, visit:

    https://www.nasa.gov/planetarydefense

    For asteroid and comet news and updates, followAsteroidWatchon Twitter:

    twitter.com/AsteroidWatch

    See the full article here .


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  • richardmitnick 7:52 am on February 23, 2018 Permalink | Reply
    Tags: Asteroids, , , , , , ESA HERA spacecraft, SCITECH Europa   

    From ESA via SCITECH Europa: “Crash investigation” 

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    European Space Agency

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    SCITECH Europa

    21st February 2018
    Ian Carnelli
    Programme Manager
    General Studies Programme (GSP)
    European Space Agency (ESA)

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    ESA HERA

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    Hera will provide humanity’s first view of a binary asteroid system, proceeding to map the entire surface of ‘Didymoon’ down to a size resolution of a few meters and the tenth of the surface surrounding the DART impact to better than 10cm, through a series of daring flybys © ESA – ScienceOffice.org

    ESA’s Hera mission is designed to test deep space technology while exploring a distant asteroid and investigating a unique, man-made crater, testing a deflection method that may one day prove literally Earth-saving.

    If all goes to plan, October 2022 will mark a significant achievement in the life of our species: the first time that Homo sapiens shifts the orbit of a body in the Solar System in a measureable way. The target is an approximately 170-m diameter asteroid – about the same size as the Great Pyramid of Giza – which is in orbit around another, larger asteroid: the 780m diameter Didymos (Greek for ‘twin’) near-Earth asteroid.The method is a NASA spacecraft called the Double Asteroid Redirection Test (DART), which will autonomously fly itself into the smaller body at 6km/s, nine times faster than a bullet.

    NASA DART Double Imact Redirection Test vehicle

    The result of the collision with this refrigerator-sized DART spacecraft is expected to be an alteration in the tight 11.9-hour orbit of ‘Didymoon’ around its parent asteroid. This shift should be observable from Earth-based telescopes, because the Didymos binary pair will be on an unusually close approach to our planet at that point, coming just 11 million kilometres away at its nearest.

    Didymoon’s degree of orbital shift will give researchers essential insights into the internal structure of asteroids and the potential of deflecting them as a means of planetary defence. But monitoring this historic event from a distance will not be sufficient by itself if we are to learn all its lessons.

    By its very nature the Double Asteroid Redirection Test is a suicide mission, which has some unavoidable drawbacks. The last thing Earth will see in advance of the collision will be a close-up of Didymoon’s surface features – and then nothing. Potentially, DART might also carry a small ‘selfie-sat’ that it deploys beforehand in order to capture imagery of the moment of impact – but even so, past experience suggests nothing will be viewable directly at that point and only very limited data will be available on the surface properties of Didymoon.

    Deep impact

    On 4 July 2005, NASA’s spacecraft shot a 370kg copper impactor into comet Tempel 1.

    NASA Deep Impact spacecraft

    Shifting the orbit of this massive 7.6km × 4.9km body was never on the agenda; instead the aim was to expose the comet’s interior. However, in the impact’s aftermath millions of kilograms of dust and ice continued to outgas from the impact zone for days on end.

    Deep Impact’s follow-on flyby showed nothing; it took a new visit by a separate spacecraft, NASA’s Stardust, in 2011 to finally measure the fresh 150m diameter crater scarring the comet’s surface.

    NASA Stardust spacecraft

    Plus, the distance involved means that terrestrial observatories’ measurement of Didymoon’s altered orbit will be stuck with a 10% residual uncertainty. The only way to improve on this, and really hone our understanding of this grand-scale space experiment, and see how the Double Asteroid Redirection Test impact has affected the surface of Didymoon, is to venture much, much nearer.

    ESA’s Hera mission

    That is the task of ESA’s Hera mission, the optimised design of which benefits from multiple ESA studies of asteroid missions across the last two decades – most recently the proposed Asteroid Impact Mission (AIM), which was planned in conjunction with the Double Asteroid Redirection Test. Hera is a small-scale mission in planetary terms, a large desk-sized spacecraft weighing in at less than 800kg fully fuelled (compared, for instance, to the van-sized, three tonne Rosetta comet-chaser). But it is also a highly agile, ambitious one.

    Europe’s first deep-space CubeSat

    In addition to its primary planetary defence objectives, Hera will demonstrate the ability to operate at close proximity around a low-gravity asteroid with some on-board autonomy similar in scope to a self-driving car, going on to deploy Europe’s first deep-space CubeSat, and potentially also a micro-lander, to test out a new multi-point intersatellite link technology.

    Hera will also provide humanity’s first view of a binary asteroid system, proceeding to map the entire surface of Didymoon down to a size resolution of a few meters and the tenth of the surface surrounding the Double Asteroid Redirection Test impact to better than 10cm, through a series of daring flybys. How large a crater will Double Asteroid Redirection Test end up leaving? Will there be larger morphological effects, such as ground cracking, or stones and dust scattered widely compared to DART’s pre-impact images, implying post-collision quaking?

    Planetary defence

    Precise mapping of Didymoon’s volume will be combined with radio science experiments to assess how Didymoon’s gravity influences the spacecraft’s trajectory, to derive the asteroid’s density and constrain our models of its internal structure. Hera will also be a pioneer in the novel field of planetary defence: by pinpointing the shift in Didymoon’s orbit to a much greater precision than is achievable from Earth, the mission will give the fullest possible insight into the end result of the Double Asteroid Redirection Test collision – serving up hard data that might one day be used to safeguard Earth, demonstrating how to divert an incoming body before it becomes a threat.

    What is Hera’s Asteroid Framing Camera (AFC)?

    Hera’s baseline payload begins with an instrument called the Asteroid Framing Camera (AFC), to be used for guidance and navigation as well as scientific observation, which is an already-existing flight spare of a German contribution to NASA’s Dawn mission to the asteroid belt.

    NASA Dawn Spacescraft

    This camera has been distinguished by returning remarkable images of the largest single asteroid, Ceres, and its mysterious bright spots.

    Now, its sister camera is set to survey the smallest asteroid humankind has visited as well. The AFC is joined by a compact lidar (or ‘laser radar’) instrument to be used for measuring surface altimetry, plus one or more deployable six-unit CubeSat nanosatellites to carry a hyperspectral imager and a second instrument still to be finalised.

    At the time of writing, Hera still has another 40kg of payload capacity available, which could take the shape of a high-frequency radar for measurement of subsurface properties, a mini-impactor proposed by Japan (a twin of the version currently in flight on Japan’s Hayabusa-2 asteroid mission, see below) or a mini-lander, currently under study by Airbus and DLR, the German Aerospace Center (based on a version also in flight aboard Hayabusa-2).

    Space servicing vehicles

    ESA has a long tradition of technology-testing missions being used for ambitious science goals, exemplified since the turn of the century by the Proba series of minisatellites, variously tasked with gathering data for environmental and solar science. Hera follows the same philosophy, even though it will go one better than the Proba family by departing Earth orbit entirely.

    The single most significant technology Hera will demonstrate during its mission to the Didymos binary is intangible in nature, a software algorithm rather than physical hardware, but one seen as essential to a coming class of autonomous ‘space servicing vehicles’.

    Hera’s streamlined nature means it will perform its guidance, navigation and control (GNC) activities through an innovative data fusion strategy, combining inputs from multiple sensors to build up a detailed picture of its surroundings in space. That would mean the bringing together second-by-second of visual tracking of distinctive features on the asteroid surface with altimeter distances plus onboard inertial and star tracker measurements. Future servicing vehicles would need to perform comparable data fusion when it comes to rendezvous and docking with satellites intended to be refurbished, refuelled or potentially deorbited. Any mistake in this scenario would lead to catastrophic collision, and plentiful space debris.

    Failure is not an option

    In the case of Hera, failure will not be an option when it comes to key manoeuvres such as CubeSat (and possibly lander) deployment or close Didymoon flybys, down to a matter of metres above the surface. But what if one or more of the sensor inputs is in error or an actuator delivers the wrong correction to the spacecraft trajectory or attitude? That is where Hera’s ‘Fault Detection, Isolation and Recovery’ (FDIR) technique comes in.

    FDIR is an approach widely applied in space engineering, ranging from protecting individual electronic components to safeguarding the entire spacecraft: for example, modern space computer chips seeking to make up for memory ‘bit flips’ due to space radiation can perform calculations on a multiple, parallel basis, sometimes voting to decide the most likely truthful result. In a similar fashion, Hera’s data-fusion-based GNC FDIR is designed to identify errors in real time through ongoing sensor cross-checks, isolating them and then making up for them by triggering sensor or actuator reconfigurations or even, in case of extreme emergency, triggering an autonomous collision avoidance manoeuvre.

    The combination of GNC and FDIR using vision-based sensing was achieved by ESA for the first time in the relatively straightforward but safety-critical case of semi-autonomous docking by the Automated Transfer Vehicle cargo spacecraft to the International Space Station (ISS). Expanding the technique to more challenging rendezvouses in space and increasing its degree of autonomy has been worked on for years in the context of this mission, most recently by GMV in Spain. Success will mark a giant leap forward for mission-critical autonomy.

    What new discoveries will asteroid missions make?

    Plenty of new discoveries can be expected from Hera. Each fresh close encounter with an asteroid has led to a fresh transformation in our understanding. A decade ago Europe took its first asteroid close-up, as ESA’s Rosetta probe performed a flyby of 2867 Šteins, a Gibraltar-sized diamond-shaped asteroid in the main Asteroid Belt. Dozens of craters were seen, including a gaping hole at the south pole of Steins – a large impact crater about 2km wide and nearly 300 m deep.

    ESA Rosetta spacecraft

    A chain of several craters ran towards the north pole from this crater. The low density of Šteins suggests it is a ‘rubble pile’ asteroid, broken apart by previous impacts and held together weakly by its gravity – and probably fated to one day break apart. A second Main Belt asteroid flyby took place in 2010, as Rosetta passed the mammoth 100km 21 Lutetia. This higher-density asteroid was similarly studded with craters, confirming that collision is the main shaper of these primitive bodies.

    Europe plays a key role in a new asteroid encounter scheduled for this July, when Japan’s Hayabusa 2 reaches near-Earth asteroid 162173 Ryugu.

    JAXA/Hayabusa 2

    It will put down a micro-lander called the Mobile Asteroid Surface Scout (Mascot), developed by the German Aerospace Center [DLR] (who previously contributed the Philae lander to Rosetta) and French space agency CNES, carrying an infrared spectrometer, a magnetometer, a radiometer and camera. A follow-on version of the Mascot lander, known as Mascot+, is currently under study to be carried by Hera.

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    DLR Mobile Asteroid Surface Scout (Mascot)

    Additionally Hayabusa 2 will perform its own miniature version of an impactor experiment, called the Small Carry-on Impactor (SCI), consisting of a small 2.5kg copper projectile given added force by a high-explosive charge. SCI will strike with a velocity of 2km/s, offering a valuable bridge between the kind of simulated impact tests performed in terrestrial labs and the full-scale Double Asteroid Redirection Test collision, allowing the testing of impact scaling laws. A follow-up SCI payload is also being considered for Hera, not to attempt to change Didymoon’s trajectory any further but to produce a second crater at a different energy level than DART. This experiment will provide invaluable data to fully validate numerical impact algorithms that will be key to designing any future planetary defence missions.

    Exploration of these asteroids, and the many others surveyed so far, have highlighted their striking variety in terms of size, shape, surface characteristics and constituent materials. Similarly, asteroids rotate in various ways, from simple rotation to slow precession or rapid tumbling. It is possible that asteroid rotation is constrained by fundamental ‘spin limits’, beyond which centrifugal acceleration would lead material to escape from the surface of rubble-pile bodies. Indeed, such escapes might explain the origin of many binary asteroid systems, which make up 15% of the known total.

    New light on collisional dynamics

    The internal structure of asteroids remains a blank spot in scientific understanding. Are there large voids within their deep interior, or are they composed of loose regolith or conglomerates of monolithic rock? In particular, there is no way of knowing how an actual asteroid would respond to the specific external stimulus of an impact – short of trying it for real.

    By shedding new light on collisional dynamics, the combination of the Double Asteroid Redirection Test plus Hera will add to our understanding not just of asteroid formation and evolution but the creation and ongoing history of our entire Solar System – a story etched in impacts.

    Down at smaller scales, Hera’s surface observations will reveal the range of physical phenomena other than gravity that govern asteroid surfaces, influence their material properties and keep them bound together. What are the relative roles of electrostatic and Van der Waals forces, for instance? One proposal is that the most finely-grained asteroids might resemble ‘fairy castles’, crumbling to the touch. Such findings would hold relevance for asteroid mining as well as planetary defence, while also offering insight into the very earliest microscopic-scale processes of accretion, right back at the dawn of this and other planetary systems.

    Historic moment

    Hera is currently preparing for its Phase B1 study, along with a set of technology developments. The decision on whether the mission will progress to flight will be taken by Europe’s leaders at the end of next year. But certainly planetary defence is a global responsibility, and ESA is currently readying a new programme to be presented at the next Ministerial Council called Space Safety, that places planetary defence together with related topics such as space debris and space weather.

    DART and Hera were originally conceived as one – the origin of the two missions can be traced back to an ESA 2002 study of a double spacecraft asteroid deflection mission called Don Quijote. If approved, Hera is on track for a 2023 launch, arriving at Didymos for its ‘crime scene investigation’ a couple of years later. The experience of the Stardust crater – as well as the recently discovered crater of ESA’s Smart-1 spacecraft on the Moon – suggests DART’s impact point will be largely unchanged from the moment of collision. Or, in the event of a delay in the Double Asteroid Redirection Test mission, then the pair might reach Didymos at the same time. Either way, a historic moment is coming in the shape of the DART impact. Humankind will draw maximum benefit from it through a close-up view.

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 9:43 pm on January 26, 2018 Permalink | Reply
    Tags: Asteroids, , , , , ,   

    From ESOblog: “Protecting the Earth from Cosmic Clashes” 

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    Science in Society

    65 million years ago, the most famous asteroid in history slammed into Earth and most likely exterminated the dinosaurs. Disconcertingly, we are no less likely to be to hit by an asteroid today than our ancient reptilian counterparts were — but luckily we have helpful tools at our disposal. In 2015 ESO joined the International Asteroid Warning Network (IAWN). To find out what this entails, we talked to Andy Williams, ESO’s Institutional Relations Officer, and Olivier Hainaut, an ESO astronomer in charge of NEO follow-up at the VLT.

    Q: What are asteroids and why should we be worried about them?

    Oli: An asteroid is “just” a rock, or a pile of rocks, that orbits the Sun. Some asteroids are dead comets — those that have lost their ices so the comet is covered by a rocky crust. My work at ESO focuses on minor bodies such as asteroids, comets and trans-Neptunian objects — including those with the potential to smash into Earth. We call these Near-Earth Objects, or NEOs. Currently, we know of about 17 000 asteroids and 100 comets that are classified as NEOs.

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    Meteor Crater on the Colorado Plateau in Arizona. This crater is 1.2 kilometres in diameter and was created by a 46-metre asteroid 50 000 years ago.
    Credit: NASA Earth Observatory

    A key number to remember with NEOs is 10: if an asteroid 10 metres across hit Earth, it would release about the same amount of energy as the Hiroshima bomb. As its effect would be localised to within a few square kilometres around the impact site, it’s unlikely to do a large amount of damage. Remember that the surface area of the Earth is huge and a lot of it is taken up by the ocean, so it would be incredibly unlikely — and extremely unlucky — for an asteroid 10 metres across to severely damage a populated area. But the energy that an object releases is proportional to the cube of its size — so in comparison, a 100-metre asteroid (with the same composition and speed as the 10-metre asteroid) would release 1000 Hiroshimas. An asteroid with a diameter of one kilometre would do much greater damage, and an asteroid of 10 kilometres would be like the one that killed off the dinosaurs. It would sterilise an entire continent and cause major global damage.

    On average, one of these huge 10-km asteroids strikes Earth every 50 million years, and the last one was 65 million years ago — meaning we are now overdue. Of course, I should mention that I’m not too worried about an asteroid wiping out all of humanity. We know about most asteroids of this size in the Solar System – we’ve studied their orbits, their characteristics, and we can predict their chance of impact. But as the asteroids get smaller, the less we know of them. We estimate that about 70–80% of asteroids from 500 metres to 1 kilometre in diameter are known, but only about 10% of asteroids 100 metres in diameter are known. The International Asteroid Warning Network (IAWN) is working to improve these numbers.

    Q: So what is the IAWN?

    Andy: The International Asteroid Warning Network aims to detect, track, and physically characterise Near-Earth Objects to determine which are potentially dangerous to Earth. The network is made up of scientific institutions, observatories, and a variety of interested groups — all of which can make observations of asteroids and NEOs. Participation in the network is voluntary and partners are funded with their own resources. They also agree to a policy of free and open exchange of all data submitted to the network.

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    Credit: Dan Durda

    Q: How did the IAWN form?

    Andy: The network has its roots in the United Nations Committee on the Peaceful Uses of Outer Space (UN COPUOS), which was established in 1959 shortly after the launch of Sputnik. NEO detection happened for years by observatories around the world, including ESO, but in 2002 the UN committee decided there should be a single team to oversee the detection, risk analysis and communication of NEOs and their dangers. By 2008 two vital organisations had been set up: the International Asteroid Warning Network (IAWN) and the Space Mission Planning Advisory Group (SMPAG). The establishment of these groups marked a tangible and essential step in protecting Earth from potential asteroid impacts, and the IAWN, in particular, was crucial in collecting and sharing information about potential space hazards. Then in 2013, the Science and Technology subcommittee (STSC) gave IAWN the official role of NEO detection. By cosmic coincidence the Chelyabinsk meteorite struck the atmosphere above Russia on 15 February 2013 during the STSC meeting, giving immediate impetus to this work!

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    A photo from the first COPUOUS meeting. Credit: UN Photo

    Q: What is ESO’s role in the IAWN?

    Oli: To search for asteroids you need a survey-type instrument such as Pan-STARRS, which continuously scans the whole sky with the aim of detecting moving objects. ESO’s telescopes are very powerful, but have a narrow field of view and so are used to observe specific objects; in other words, they are not suitable for discovering NEOs. So we work as part of a team. Other huge surveys detect asteroids, some of which are considered potentially hazardous — and some of these are threatening enough get on ESO’s “to-do list”. Our role is to target the high-risk asteroids that no other observatory can observe. If an object is small or far away, only big telescopes like ESO’s Very Large Telescope get called on to hone in and measure it.

    In collaboration with ESA, we’ve run an ongoing project on the VLT since 2015. The project is awarded 24 hours of observing time per year, and while this time is modest, it’s enough to follow-up all the potentially dangerous NEOs that cannot be observed by smaller telescopes. 58 high risk or difficult NEOs have been observed by the VLT so far, 24 of which were removed from the risk list—the others are still on the list, despite the VLT observations.

    Andy: It’s really important to note that as an intergovernmental organisation, ESO has a great responsibility to the public who ultimately pay for what we do. The Director General decides on the 24 hours set aside per year for asteroid observations using the VLT.

    Q: How do we calculate the risk and the probability of an asteroid hitting Earth?

    Andy: Short answer: it’s complicated. The risk is a combination of the likelihood that an asteroid will strike, how soon it will strike, and the effects it would have on Earth. Astronomers use the Palermo Technical Impact Hazard Scale, which combines these values and also compares it to the ‘background’ level of risk. We have to consider many variables.

    Firstly, the orbit of the asteroid must be determined, along with the chance its path could intersect with Earth’s and when this would happen. Next, the size of the asteroid is vital, as it provides the main indicator of its danger — a large asteroid would slam into Earth’s surface intact, while a smaller one would burn up harmlessly in our atmosphere. The danger also depends on composition; some asteroids are basically huge chunks of iron ore, which can hold together as they pass through the atmosphere, while others are loosely-bound dust, ice and rocks, which burn up more easily. Then we must consider the angle of incidence — whether the asteroid travels straight down or at an angle, passing through much more of the atmosphere. In this case, the asteroid experiences more friction and is more likely to reduce in size (and danger) or be vaporised altogether. For most NEOs, these parameters are unknown, so we have to work with average, typical values.
    The Chelyabinsk asteroid that struck Russia in February 2013 passed through Earth’s atmosphere at a 20-degree angle and was quite small, approximately 20 metres across. It skimmed the atmosphere like a pebble over water and fortunately exploded before it reached the ground.

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    The Chelyabinsk meteoroid fell to Earth on February 15, streaking across the sky above the city of Chelyabinsk, Russia, at 9:20 am local time.
    Credit: Marat Ahmetvaleev

    Q: What happens if we find an asteroid at high risk of hitting Earth?

    Andy: Certain criteria have been set up that trigger an impact response. If the probability of impact is greater than 1% for objects over 10 metres, IAWN must alert the Space Mission Planning Advisory Group (SMPAG), of which ESO became an observer on 11 October 2017. SMPAG then have the harder job of coming up with an international action plan and deciding on the criteria for action. If the probability of impact within 20 years is greater than 10% for objects over 20 metres, SMPAG must alert authorities and the United Nations to begin terrestrial planning, which includes determining a “risk corridor” on the earth’s surface. If the probability of impact within 50 years is greater than 1% for an object of over 50 metres, SMPAG must begin mission planning. Much of the current work of SMPAG involves analysing the various mission options.

    Q: And what are those options?

    Oli: There are many possible hazard mitigation methods that are being considered, all of which sound very dramatic and sci-fi. It might seem like the best option to avoid a large predicted impact is to destroy the asteroid — but this isn’t such a good idea. We don’t want to break up the asteroid because it would dramatically increase the number of impacts and the likelihood they’d hit human populations! Not to mention the difficulty of tracking all the fragments.

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    A close-up image of asteroid (25143) Itokawa taken by the Japanese spacecraft Hayabusa during its close approach in 2005.
    Credit: JAXA

    A much better option is to deflect the asteroid. One idea is to spray paint one side of the asteroid white, making it more reflective — so when photons from the Sun bounce off, their momentum will transfer to the asteroid, pushing it off course just enough to miss Earth. This technique is based on the phenomenon of the Yarkovsky effect. Another idea is to send up a small rocket to push the object gently off course over a long period — say, 10 years. Basically, if we know about a potential impact long enough in advance, we can do something about it. We already have the technology today.

    Andy: Like Oli said, the extent of our preparedness will largely depend on the amount of time we have — obviously a 20-year warning will be different to a 2-day warning! Lots of people are thinking about mitigating the hazard of asteroids — NASA has the Asteroid Impact and Deflection Assessment (AIDA) Mission, and ESA used to have Asteroid Impact Mission (AIM) although at present its funding is unclear.

    Q: Does the recent discovery of the interstellar asteroid `Oumuamua affect our understanding of NEOs?

    Oli: Our team at Pan-STARRS first spotted the `Oumuamua asteroid.

    Pann-STARS telescope, U Hawaii, Mauna Kea, Hawaii, USA, 4,207 m (13,802 ft) above sea level

    This was an interstellar object — the first ever discovered — that briefly became a Near-Earth Object, except it was travelling much faster, meaning it would have been extremely damaging if it struck the Earth.

    We think that over its lifetime, our Sun has ejected tens of trillions of objects into interstellar space, so it’s reasonable to assume that other stars, including our neighbours, have done the same. This means there are a huge number of interstellar objects travelling through space. But when you compare this with the sheer scale of the Universe, the likelihood of even coming across one is exceedingly slim — and the chances of an interstellar asteroid striking the Earth are negligible. Furthermore, there would be not much we could do to mitigate such an impact because we’d have just a few weeks’ notice. It is better to focus our efforts on the much higher risk from our own Solar System’s NEOs.

    See the full article here .

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  • richardmitnick 5:36 pm on January 10, 2018 Permalink | Reply
    Tags: , Asteroids, , , , , , , , , STXM-scanning transmission X-ray microscope, We’re looking at the organic ingredients that can lead to the origin of life” including the amino acids needed to form proteins,   

    From LBNL: “Ingredients for Life Revealed in Meteorites That Fell to Earth” 

    Berkeley Logo

    Berkeley Lab

    January 10, 2018
    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 486-5582

    1
    A blue crystal recovered from a meteorite that fell near Morocco in 1998. The scale bar represents 200 microns (millionths of a meter). (Credit: Queenie Chan/The Open University, U.K.)

    Two wayward space rocks, which separately crashed to Earth in 1998 after circulating in our solar system’s asteroid belt for billions of years, share something else in common: the ingredients for life. They are the first meteorites found to contain both liquid water and a mix of complex organic compounds such as hydrocarbons and amino acids.

    A detailed study of the chemical makeup within tiny blue and purple salt crystals sampled from these meteorites, which included results from X-ray experiments at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), also found evidence for the pair’s past intermingling and likely parents. These include Ceres, a brown dwarf planet that is the largest object in the asteroid belt, and the asteroid Hebe, a major source of meteorites that fall on Earth.

    The study, published Jan. 10 in the journal Science Advances, provides the first comprehensive chemical exploration of organic matter and liquid water in salt crystals found in Earth-impacting meteorites. The study treads new ground in the narrative of our solar system’s early history and asteroid geology while surfacing exciting possibilities for the existence of life elsewhere in Earth’s neighborhood.

    “It’s like a fly in amber,” said David Kilcoyne, a scientist at Berkeley Lab’s Advanced Light Source (ALS), which provided X-rays that were used to scan the samples’ organic chemical components, including carbon, oxygen, and nitrogen.

    LBNL/ALS

    Kilcoyne was part of the international research team that prepared the study.

    While the rich deposits of organic remnants recovered from the meteorites don’t provide any proof of life outside of Earth, Kilcoyne said the meteorites’ encapsulation of rich chemistry is analogous to the preservation of prehistoric insects in solidified sap droplets.

    Queenie Chan, a planetary scientist and postdoctoral research associate at The Open University in the U.K. who was the study’s lead author, said, “This is really the first time we have found abundant organic matter also associated with liquid water that is really crucial to the origin of life and the origin of complex organic compounds in space.”

    She added, “We’re looking at the organic ingredients that can lead to the origin of life,” including the amino acids needed to form proteins.

    If life did exist in some form in the early solar system, the study notes that these salt crystal-containing meteorites raise the “possibility of trapping life and/or biomolecules” within their salt crystals. The crystals carried microscopic traces of water that is believed to date back to the infancy of our solar system – about 4.5 billion years ago.

    Chan said the similarity of the crystals found in the meteorites – one of which smashed into the ground near a children’s basketball game in Texas in March 1998 and the other which hit near Morocco in August 1998 – suggest that their asteroid hosts may have crossed paths and mixed materials.

    There are also structural clues of an impact – perhaps by a small asteroid fragment impacting a larger asteroid, Chan said.

    This opens up many possibilities for how organic matter may be passed from one host to another in space, and scientists may need to rethink the processes that led to the complex suite of organic compounds on these meteorites.

    “Things are not as simple as we thought they were,” Chan said.

    There are also clues, based on the organic chemistry and space observations, that the crystals may have originally been seeded by ice- or water-spewing volcanic activity on Ceres, she said.

    “Everything leads to the conclusion that the origin of life is really possible elsewhere,” Chan said. “There is a great range of organic compounds within these meteorites, including a very primitive type of organics that likely represent the early solar system’s organic composition.”

    Chan said the two meteorites that yielded the 2-millimeter-sized salt crystals were carefully preserved at NASA’s Johnson Space Center in Texas, and the tiny crystals containing organic solids and water traces measure just a fraction of the width of a human hair. Chan meticulously collected these crystals in a dust-controlled room, splitting off tiny sample fragments with metal instruments resembling dental picks.

    2
    These ALS X-ray images show organic matter (magenta, bottom) sampled from a meteorite, and carbon (top). (Credit: Berkeley Lab)

    “What makes our analysis so special is that we combined a lot of different state-of-the-art techniques to comprehensively study the organic components of these tiny salt crystals,” Chan said.

    Yoko Kebukawa, an associate professor of engineering at Yokohama National University in Japan, carried out experiments for the study at Berkeley Lab’s ALS in May 2016 with Aiko Nakato, a postdoctoral researcher at Kyoto University in Japan. Kilcoyne helped to train the researchers to use the ALS X-ray beamline and microscope.

    The beamline equipped with this X-ray microscope (a scanning transmission X-ray microscope, or STXM) is used in combination with a technique known as XANES (X-ray absorption near edge structure spectroscopy) to measure the presence of specific elements with a precision of tens of nanometers (tens of billionths of a meter).

    “We revealed that the organic matter was somewhat similar to that found in primitive meteorites, but contained more oxygen-bearing chemistry,” Kebukawa said. “Combined with other evidence, the results support the idea that the organic matter originated from a water-rich, or previously water-rich parent body – an ocean world in the early solar system, possibly Ceres.”

    Kebukawa also used the same STXM technique to study samples at the Photon Factory, a research site in Japan. And the research team enlisted a variety of other chemical experimental techniques to explore the samples’ makeup in different ways and at different scales.

    Chan noted that there are some other well-preserved crystals from the meteorites that haven’t yet been studied, and there are plans for follow-up studies to identify if any of those crystals may also contain water and complex organic molecules.

    3
    Ceres, a dwarf planet in the asteroid belt pictured here in this false-color image, may be the source of organic matter found in two meteorites that crashed to Earth in 1998. (Credit: NASA)

    Kebukawa said she looks forward to continuing studies of these samples at the ALS and other sites: “We may find more variations in organic chemistry.”

    The Advanced Light Source is a DOE Office of Science User Facility.

    Scientists at NASA Johnson Space Center, Kochi Institute for Core Sample Research in Japan, Carnegie Institution of Washington, Hiroshima University, The University of Tokyo, the High-Energy Accelerator Research Organization (KEK) in Japan, and The Graduate University for Advanced Studies (SOKENDAI) in Japan also participated in the study. The work was supported by the U.S. DOE Office of Science, the Universities Space Research Association, NASA, the National Institutes of Natural Sciences in Japan, Japan Society for the Promotion of Science, and The Mitsubishi Foundation.

    See the full article here .

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  • richardmitnick 9:53 am on August 11, 2017 Permalink | Reply
    Tags: Asteroids, , , , ,   

    From Many Worlds: “Primordial Asteroids, And The Stories They Are Telling” 

    NASA NExSS bloc

    NASA NExSS

    Many Words icon

    Many Worlds

    2017-08-07
    Marc Kaufman

    1
    The main asteroid belt of our solar system — with almost two million asteroids a kilometer in diameter orbiting in the region between Mars and Jupiter. There are billions more that are smaller. New research has identified the “family” of a primordial asteroid or planetesimal, one of the oldest ever detected.

    Asteroid, we’ve long been told, started tiny in our protoplanetary disk and only very gradually became more massive through a process of accretion. They collected dust from the gas cloud that surrounded our new star, and then grew larger through collisions with other growing asteroids.

    But in recent years, a new school of thought has proposed a different scenario: that large clumps of dust and pebbles in the disk could experience gravitational collapse, a binding together of concentrated disk material.

    This process would produce a large asteroid (which is sometimes called a planetesimal) relatively quickly, without that long process of accretion. This theory would solve some of the known problems with the gradual accretion method, though it brings some problems of its own.

    Now research just published in the journal Science offers some potentially important support to the gravitational collapse model, while also describing the computational detection of a primordial family of asteroids some 4 billion years old.

    Led by Marco Delbo’, an astrophysicist at the University of the Côte d’Azur in Nice, France, the scientists have identified a previously unknown family of darkly colored asteroids that is “the oldest known family in the main belt,” their study concluded.

    The family was identified and grouped together by the unusual darkness (low albedo) of its asteroids’ reflective powers, a signature that the object has a high concentrations of carbon-based organic compounds. This family of asteroids was also less extensively heated — having formed when the sun radiated less energy — and contains more water, making them potential goldmines for understanding the makeup and processes of the early solar system.

    2
    Artist depiction of a dusty disc surrounding a red dwarf.artist rendering of a protoplanetary dust disk, from which asteroid, planetesimals and ultimately planets are formed. NASA/JPL-Caltech/T. Pyle (SSC)

    “They are from an original planetesimal and the location of these fragments tell us they are very, very old,” Delbo’ told me. “So old that the original object is older than the epoch when our giant planets moved to their current locations.” That would make this ancient asteroid family more than 4 billion years old, formed when the solar system was but 600 million years from inception.

    By adding up the masses of the members of the asteroid family, the researchers could also come up with a size for the original planetesimal that gave birth to the asteroid family — at least 35 kilometers wide at its inception.

    Some background:

    What is termed our “solar nebula” is thought to have been a disk-shaped cloud of gas and dust that remained after the formation of the sun. Just like a dancer that spins faster as she pulls in her arms, the cloud began to spin as it collapsed. Eventually, the cloud grew hotter and more dense in the center, with a disk of gas and dust surrounding it that was hot near the center but cool at the edges.

    Since these earliest days of the solar system, a vast collection of dust and later rocks of all shapes and sizes has been circling the sun, especially in the broad expanse of space between Mars and Jupiter. This is both the material from which planets were formed, and also leftover material from the formation of the solar system.

    There are many of these asteroids, or planetesimals, but they don’t carry much mass — all of them together roughly equaling that of our moon.

    There are some 130 known “families” of asteroids. The effort to understand the processes that created the asteroids has been enormously difficult because they have been broken and then broken again and again as they crash into each other.

    But that is changing thanks to this discovery of the new family of “dark” asteroids. Unlike the brighter, highly reflective asteroid families nearby, the population of dark asteroids’ orbits are more spread out, interpreted to mean that more time has passed since the asteroids formed

    Most asteroid families are thought to have formed about 1 billion years ago. By aggregating the sizes of the modern dark asteroids, researchers suggest their original planetesimals formed about 4 billion years ago, making this one of the oldest asteroid families in the main asteroid belt.

    The scientists also determined that the dark family’s original planetesimals were no smaller than about 25 miles across.

    This provides support for the gravitational collapse hypothesis, originated at Germany’s Max Planck Institute, by suggesting the oldest asteroids started out large, and then became smaller through collisions and other destructive forces happening in the ancient solar system.

    The earlier and more conventional theory had the asteroids starting small and getting gradually bigger. This difference in hypotheses has been a hot topic among planetary scientists for nearly a decade.

    3
    This image, taken by NASA’s Near Earth Asteroid Rendezvous mission in 2000, shows a close-up view of Eros, an asteroid with an orbit that takes it somewhat close to Earth. American and Japanese and European missions to study and scoop up material from asteroids are now on their way. The European Space Agency has also undertaken an asteroid landing mission and a joint NASA-ESA asteroid-ramming mission is under consideration. NASA/JHUAPL

    These findings are not based on telescope viewing and measuring; that was all done by NASA’s Wide-field Infrared Survey Explorer in 2011. The spacecraft took images of some 750 million objects, including millions of asteroids.

    Delbo’ and his team used computer models to search for groups of related asteroids spread within a V-shaped region. This V pattern is what one would expect from a single object that fragmented into pieces, and the wider the V-shape the older the objects.

    Their asteroid family features rocks averaging 7.15 miles in diameter, and are found across the entire inner part of the main asteroid belt. The family has 108 members and counting, with the largest of which the largest being asteroid 282 Clorinde, which is about 26 wide.

    “Each family member drifts away from the center of the family in a way that depends on its size, with small guys drifting faster and further than the larger guys,” Delbo said. “If you look for correlations of size and distance, you can see the shapes of old families.”

    But that wasn’t all.

    “By identifying all the families in the main belt, we can figure out which asteroids have been formed by collisions and which might be some of the original members of the asteroid belt,” said Southwest Research Institute astronomer Kevin Walsh, a coauthor of the Science article.

    “We identified all known families and their members and discovered a gigantic void in the main belt, populated by only a handful of asteroids. These relics must be part of the original asteroid belt. That is the real prize, to know what the main belt looked like just after it formed.”

    These primordial objects had to have formed differently from those belonging to the newer families. They were the original inhabitants and were present in the inner asteroid belt before anything else.

    ranging from 21 to around 93 miles across, their size matches up with predictions from theoretical models of how large original asteroids might have been 4 billion years ago, when they initially formed.

    In other words, their age and size supports the gravitational collapse theory of asteroid formation.

    5
    An artist’s concept depicts a distant hypothetical solar system, similar in age to our own. Looking inward from the system’s outer fringes, a ring of dusty debris can be seen, and within it, planets circling a star the size of our Sun. This debris is all that remains of the planet-forming disk from which the planets evolved. Planets are formed when dusty material in a large disk surrounding a young star clumps together. (NASA)

    To put these findings into a larger context, I asked Elizabeth Tasker, astrophyscist at the Japan Space Agency and the Earth-Life Science Institute in Tokyo, to explain further. She is the author of the soon-to-be released book, “The Planet Factory,” which deals extensively with these issues. First is her take on the logic of gravitational collapse:

    “In the gravitational collapse model, the pebbles and small boulders around 1m-ish in size concentrate in one region of the protoplanetary disk. This concentration initially happens because nothing is ever perfectly homogeneous, but it grows because having a group of rocks together helps mitigate the gas drag.

    This grows until eventually its combined mass is enough that their total gravity finally becomes a big enough force to bind them together into a planetesimal. This doesn’t happen until you have a serious chunk of mass, so the result is always a big planetesimal tens to hundred of kilometers across (about the size of Ceres). A smaller group of rocks wouldn’t have enough total mass to produce the gravitational force needed to collapse.”

    And now why the Delbo’ paper is important:

    “The formation of our own solar system is the key to understanding the properties of exoplanets around other stars. For example, if we truly want to find another habitable world, we need to understand how the Earth acquired and kept its oceans, developed a protective magnetic field and a sizeable moon, while Venus and Mars did not.

    “A problem we face is that the early planet-forming action happened 4.6 billion years ago. We can build models, but how do we tell which one is correct when this all happened so long ago?

    “Marco Delbo’ and his team have identified a holy grail; an observational signature that can be used to constrain the myriad of formation ideas we are imaginative enough to create.”

    See the full article here .

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    About Many Worlds

    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 2:26 pm on July 8, 2017 Permalink | Reply
    Tags: Asteroids, , , , , HeraldNet, ,   

    From U Washington via Heraldnet: “UW scientists may save the Earth using computer algorithms” 

    U Washington

    University of Washington

    1

    HeraldNet

    Jun 29th, 2017
    Katherine Long

    1
    Andrew Connolly, left, director of DIRAC, a new institute for intensive survey astrophysics at the University of Washington, and Zeljko Ivezic, a professor of astronomy and a key player in the development of software for the LSST telescope in Chile, stand in the planetarium at the UW. They’re involved in a major project to create a map of all the asteroids in our solar system, and to figure out which ones might pose a danger to Earth. (Ellen M. Banner/The Seattle Times) [U Washington]

    Scientists at the University of Washington are writing computer algorithms that could one day save the world — and that’s no exaggeration.

    Working away in the university’s quiet Physics/Astronomy building, these scientists are teaching computers how to sift through massive amounts of data to identify asteroids on a collision course with Earth.

    Together with 60 colleagues at six other universities, the 20 UW scientists are part of a massive new data project to catalog space itself, using the largest digital camera ever made.

    Five years from now, a sky-scanning telescope under construction in Chile will begin photographing the night sky with a 3,200-megapixel camera. The telescope will have the power to peer into the solar system and beyond, and track things we have never been able to track before — including asteroids, the rubble left behind during the formation of the solar system.

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    When it is up and running, the Large Synoptic Survey Telescope (LSST) will produce 20 terabytes of images every night, and will be able to photograph half the night sky every three days, said Andrew Connolly, one of the UW astronomers working on the project.

    It will replace the Sloan Digital Sky Survey, which dates back to 1998, and which was only able to cover one-eighth the sky over 10 years.

    SDSS Telescope at Apache Point Observatory, NM, USA

    The LSST’s mission is different from NASA’s Hubble Space Telescope, which sends back detailed photos of specific regions of space, but does not take vast surveys of everything in the sky.

    NASA/ESA Hubble Telescope

    The danger asteroids pose became clear in 2013, when more than 1,000 people were reportedly injured after a meteor exploded near the Russian town of Chelyabinsk. (Meteorites are closely related to asteroids.)

    And 66 million years ago, many scientists believe, an asteroid the size of a mountain smashed into Mexico’s Yucatán Peninsula, dramatically changing Earth’s environment and wiping out the dinosaurs.

    Scientists have already plotted the orbits of more than 700,000 known asteroids in the solar system, said Željko Ivezic, a UW astronomy professor and project scientist for LSST. The LSST will help astronomers identify an estimated 5 million more.

    That’s why teaching a computer to identify asteroids is such vital work.

    See the full article here .

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    The University of Washington is one of the world’s preeminent public universities. Our impact on individuals, on our region, and on the world is profound — whether we are launching young people into a boundless future or confronting the grand challenges of our time through undaunted research and scholarship. Ranked number 10 in the world in Shanghai Jiao Tong University rankings and educating more than 54,000 students annually, our students and faculty work together to turn ideas into impact and in the process transform lives and our world. For more about our impact on the world, every day.

    So what defines us — the students, faculty and community members at the University of Washington? Above all, it’s our belief in possibility and our unshakable optimism. It’s a connection to others, both near and far. It’s a hunger that pushes us to tackle challenges and pursue progress. It’s the conviction that together we can create a world of good. Join us on the journey.

     
  • richardmitnick 11:59 am on July 8, 2017 Permalink | Reply
    Tags: , Asteroids, , , , The Martian meteorite of Tissint   

    From NS: “Why Morocco loves its meteorites” 

    NewScientist

    New Scientist

    30 June 2017
    Sandrine Ceurstemont

    1
    A hotspot for space rocks. Sandrine Ceurstemont

    In Morocco’s High Atlas mountains, the twin lakes of Isli and Tislit (nicknamed the Moroccan Romeo and Juliet) have an unusual origin. Abderrahmane Ibhi from Ibn Zohr University in Agadir found strong evidence in 2013 that they were impact craters, formed when an asteroid hurtling towards Earth split in two about 40,000 years ago. “It was over 100 metres wide,” says Ibhi. “It’s the biggest asteroid to fall in Morocco.”

    Large space rocks can cause destruction or alter the landscape if they hit Earth. Today, the world’s Asteroid Day, Ibhi gave a talk about how to protect our planet from killer asteroids. “When they are over 10 metres wide, they can be dangerous,” he says.

    Luckily, space rocks rarely hit Earth. And double impacts are even less common: there are only three other known cases worldwide. But in recent years, the already otherworldly rocky land and desert close to Tata in southern Morocco has been defying the odds. From chunks of asteroids to pieces of the moon, more space rocks have been recovered in Morocco than in other countries of a similar size, with 95 per cent of them coming from around Tata.

    Rare finds

    It has been home to several rare finds, too. The most famous – the Martian meteorite of Tissint – blasted through the night sky in July 2011, scattering pieces that were collected over the following months.

    2
    http://www.mirror.co.uk/news/technology-science/science/tissint-martian-meteorite-which-landed-in-morocco-1373528

    It’s one of five rocks from the Red Planet ever to be found on Earth, and the first to carry traces of Martian soil.

    Ibhi and his team have been trying to work out why the area is such a hotspot. One reason seems to be the landscape: meteorites are easily revealed by windswept sand, in which their dark colour also makes them stand out. And a dry climate helps preserve them far better than a humid one.

    Then there’s the well-distributed population, which gives people a greater chance of stumbling upon them. In Tata, several villages are close together and many nomads live in the desert, explains team member Fouad Khiri. In addition, Morocco’s political stability is a plus, making it safer than in other countries to wander around searching for meteorites.

    But the biggest factor is a surprise: local knowledge. Since 2006, Ibhi has been organising workshops to teach people how to identify space rocks. Many nomads are now aware, for example, that looking for a particular combination of features that may mark them out is key.

    One of the telltale signs is a black skin, or fusion crust, formed by the fiery journey through the atmosphere. But desert rocks can appear similar, given that they too can have a dark surface from the extreme heat. Looking for marks that resemble thumbprints, caused by wind sculpting the rock during its journey, is a helpful clue.

    Space rocks from asteroids – the most common type – also have circular grains across their surface composed of molten minerals. “I always bring meteorites along so that people can take a close look and feel them,” says Ibhi.

    See the full article here .

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  • richardmitnick 1:14 pm on June 19, 2017 Permalink | Reply
    Tags: 6 Hebe, Asteroids, , , , , , H-chondrites - 34% of all meteorites found on Earth, SPHERE on the VLT   

    From ESO: “Not the mother of meteorites” 

    ESO 50 Large

    European Southern Observatory

    19 June 2017
    NO writer credit found.

    The region between Mars and Jupiter is teeming with rocky worlds called asteroids. This asteroid belt is estimated to contain millions of small rocky bodies, and between 1.1 and 1.9 million larger ones spanning over one kilometre across. Small fragments of these bodies often fall to Earth as meteorites. Interestingly, 34% of all meteorites found on Earth are of one particular type: H-chondrites. These are thought to have originated from a common parent body — and one potential suspect is the asteroid 6 Hebe, shown here.

    Approximately 186 kilometres in diameter and named for the Greek goddess of youth, 6 Hebe was the sixth asteroid ever to be discovered. These images were taken during a study of the mini-world using the SPHERE instrument on ESO’s Very Large Telescope, which aimed to test the idea that 6 Hebe is the source of H-chondrites.

    ESO/SPHERE extreme adaptive optics system and coronagraphic facility on the VLT

    Astronomers modelled the spin and 3D shape of 6 Hebe as reconstructed from the observations, and used their 3D model to determine the volume of the largest depression on 6 Hebe — likely an impact crater from a collision that could have created numerous daughter meteorites. However, the volume of the depression is five times smaller than the total volume of nearby asteroid families with H-chondrite composition, which suggests that 6 Hebe is not the most likely source of H-chondrites after all.

    1
    Credit: ESO/M. Marsset

    Research paper

    See the full article here .

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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

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    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

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