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  • richardmitnick 12:37 pm on June 29, 2019 Permalink | Reply
    Tags: , Asteroids, , , , , , , ,   

    From European Space Agency: “When CubeSats meet asteroid” 

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    From European Space Agency

    28 June 2019

    ESA’s Hera mission for planetary defence, being designed to survey the smallest asteroid ever explored, is really three spacecraft in one. The main mothership will carry two briefcase-sized CubeSats, which will touch down on the target body. A French team has been investigating what might happen at that initial instant of alien contact.

    ESA’s proposed Hera spaceraft

    “We’ve customised an existing drop tower and rigged it up with a system of pulleys and counterweights in order to simulate a low gravity environment,” explains researcher Naomi Murdoch of the Institut Supérieur de l’Aéronautique et de l’Espace (ISAE-Supaero), part of the University of Toulouse.

    “We can go down to a few percent of Earth’s gravity within the test box that we place within the drop tower, containing a model lander and simulated asteroid terrain.

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    APEX and Juventas CubeSats

    “Our team started out with a spherical lander touching down on a sandy surface, but we’ve progressed to cubic shapes more representative of the actual CubeSats. We’ve also been studying the influence of different surface materials, and sought to understand how the landing process varies with different material properties, gravity levels and velocities.

    “This is necessary because each time we go to a different asteroid we end up surprised by what we find. For instance, Japan’s Hayabusa2, currently exploring the Ryugu asteroid, has found much scarcer ‘regolith’ dust and more boulders than researchers had expected.”

    JAXA/Hayabusa 2 Credit: JAXA/Akihiro Ikeshita

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    Lander models inside drop box

    Hera’s Juventas CubeSat will perform the first radar probe of an asteroid, while the APEX CubeSat will perform a multispectral mineral survey of its makeup.

    These two nanosatellites will fly closer to their target asteroid and take more risks than the main Hera spacecraft, and will both end up landing on the surface once their main mission goals are achieved.

    The pull of gravity involved is less than one hundred thousandth of Earth’s, far lower than can be reproduced by the ISAE-Supaero team. This means the touchdown itself will be more like a spacecraft docking than a traditional planetary landing.

    “Imagine, for instance, if the CubeSats are released 200 m from the asteroid surface, then they will take over an hour to cover that brief distance to the surface,” adds Naomi. “Everything moves in a kind of slow motion. Then there is also the possibility of bouncing off again.

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    APEX CubeSat above Didymoon

    “The Rosetta comet-chaser’s Philae lander bounced off the surface of comet 67P/Churyumov–Gerasimenko repeatedly before finally coming to rest. Certainly if you were an astronaut on the surface you would have to walk with incredibly gentle steps to avoid leaving the surface and never coming back.”

    The hope is that both CubeSats survive their descent to return some observations, including close-up views of the surface material. But the main purpose of the ISAE-Supaero testing is to squeeze as much valuable data out of that initial moment of contact.

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    Juventas CubeSat coming in for asteroid landing

    “We’ve fitted our test lander with accelerometers similar to those that one of the Hera CubeSats will be carrying,” says Naomi. “We can see for example how the impact dynamics vary based on the material properties, from sand to large gravel, influencing how much we penetrate into the surface and how long the collision lasts.

    “And we are learning how results differ based on how the CubeSats land, whether they come down corner or face first – a face-down landing would give a higher peak acceleration. At the end of our testing we hope to have a set of data to better interpret the actual landings – and prove useful for understanding other missions’ interactions with asteroids as well.”

    Back in 2005 researchers were similarly able to acquire precious knowledge of the frozen methane crust of Saturn’s Moon Titan by the way ESA’s Huygens lander wobbled as it came to rest. The lander’s motion suggests a surface consistency of damp sand, covered with a fluffy dust layer, with dampness just below the surface – and the presence of at least one 1-2 cm sized pebble.

    ISAE-Supaero’s tests so far underline how Hera’s target 160-m diameter, extremely low gravity target asteroid is shaping up to be a truly alien environment. “The surface material is bound to behave differently, because reducing gravity reduces the normal force between particles and therefore also the friction – so it should take less force to penetrate the same sandy material.

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    Hera deploying CubeSats

    “The low gravity also means other phenomenon such as van der Waals force, which causes things like flour to stick together, will play a much larger role. The asteroid surface might have a collection of large rocks which end up behaving more like particles of flour. Or electrostatic charging could encourage dust to be levitated and transported across the surface.”

    These landing data should also help reveal scaling laws inherent to collision dynamics, extending all the way up the scale to the impact of NASA’s DART spacecraft with the same asteroid, to test planetary defence techniques.

    The Hera mission will be presented to ESA’s Space19+ meeting this November, where Europe’s space ministers will take a final decision on flying the mission.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    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 8:58 am on June 27, 2019 Permalink | Reply
    Tags: Asteroids, , , , , , , , Planetary defence   

    From European Space Agency: “Video: ESA defending Earth” 

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    From European Space Agency

    25/06/2019
    ESA’s planetary defence mission

    Hera will show us things we’ve never seen before.

    ESA’s proposed Hera spaceraft

    Astrophysicist and and Queen guitarist Brian May tells the story of the ESA mission that would be humanity’s first-ever spacecraft to visit a double asteroid.

    The asteroid system – named Didymos – is typical of the thousands that pose an impact risk to our planet, and even the smaller of the two would be big enough to destroy an entire city if it were to collide with Earth.

    Hera will help ESA to find out if it would be possible to deflect such an asteroid on a collision course with Earth. The mission will revolutionise our understanding of asteroids and how to protect ourselves from them, and therefore could be crucial for saving our planet.

    First, NASA will crash its DART spacecraft into the smaller asteroid – known as Didymoon – before ESA’s Hera comes in to map the resulting impact crater and measure the asteroid’s mass.

    NASA DART Double Impact Redirection Test vehicle depiction schematic

    Hera will carry two CubeSats on board, which will be able to fly much closer to the asteroid’s surface, carrying out crucial scientific studies, before touching down.

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    ESA APEX CubeSat

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    Juventas CubeSat

    Hera’s up-close observations will turn asteroid deflection into a well-understood planetary defence technique.

    The Hera mission will be presented to ESA’s Space19+ meeting this November, where Europe’s space ministers will take a final decision on flying the mission, as part of the Agency’s broader planetary defence initiatives that aim to protect European and world citizens.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    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 9:14 am on June 3, 2019 Permalink | Reply
    Tags: Asteroids, , , , ,   

    From European Southern Observatory: “ESO contributes to protecting Earth from dangerous asteroids” 

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    From European Southern Observatory

    3 June 2019
    Calum Turner
    ESO Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6670
    Email: pio@eso.org

    VLT observes a passing double asteroid hurtling by Earth at 70 000 km/h.

    1
    The unique capabilities of the SPHERE instrument on ESO’s Very Large Telescope have enabled it to obtain the sharpest images of a double asteroid as it flew by Earth on 25 May. While this double asteroid was not itself a threatening object, scientists used the opportunity to rehearse the response to a hazardous Near-Earth Object (NEO), proving that ESO’s front-line technology could be critical in planetary defence.

    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

    The International Asteroid Warning Network (IAWN) coordinated a cross-organisational observing campaign of the asteroid 1999 KW4 as it flew by Earth, reaching a minimum distance of 5.2 million km [1] on 25 May 2019. 1999 KW4 is about 1.3 km wide, and does not pose any risk to Earth. Since its orbit is well known, scientists were able to predict this fly-by and prepare the observing campaign.

    ESO joined the campaign with its flagship facility, the Very Large Telescope (VLT). The VLT is equipped with SPHERE [above] — one of the very few instruments in the world capable of obtaining images sharp enough to distinguish the two components of the asteroid, which are separated by around 2.6 km.

    SPHERE was designed to observe exoplanets; its state-of-the-art adaptive optics (AO) system corrects for the turbulence of the atmosphere, delivering images as sharp as if the telescope were in space. It is also equipped with coronagraphs to dim the glare of bright stars, exposing faint orbiting exoplanets.

    Taking a break from its usual night job hunting exoplanets, SPHERE data helped astronomers characterise the double asteroid. In particular, it is now possible to measure whether the smaller satellite has the same composition as the larger object.

    “These data, combined with all those that are obtained on other telescopes through the IAWN campaign, will be essential for evaluating effective deflection strategies in the event that an asteroid was found to be on a collision course with Earth,” explained ESO astronomer Olivier Hainaut. “In the worst possible case, this knowledge is also essential to predict how an asteroid could interact with the atmosphere and Earth’s surface, allowing us to mitigate damage in the event of a collision.”

    “The double asteroid was hurtling by the Earth at more than 70 000 km/h, making observing it with the VLT challenging,” said Diego Parraguez, who was piloting the telescope. He had to use all his expertise to lock on to the fast asteroid and capture it with SPHERE.

    Bin Yang, VLT astronomer, declared “When we saw the satellite in the AO-corrected images, we were extremely thrilled. At that moment, we felt that all the pain, all the efforts were worth it.” Mathias Jones, another VLT astronomer involved in these observations, elaborated on the difficulties. “During the observations the atmospheric conditions were a bit unstable. In addition, the asteroid was relatively faint and moving very fast in the sky, making these observations particularly challenging, and causing the AO system to crash several times. It was great to see our hard work pay off despite the difficulties!”

    While 1999 KW4 is not an impact threat, it bears a striking resemblance to another binary asteroid system called Didymos which could pose a threat to Earth sometime in the distant future.

    Didymos and its companion called “Didymoon” are the target of a future pioneering planetary defence experiment. NASA’s DART spacecraft will impact Didymoon in an attempt to change its orbit around its larger twin, in a test of the feasibility of deflecting asteroids.

    NASA DART Double Impact Redirection Test vehicle depiction schematic

    After the impact, ESA’s Hera mission will survey the Didymos asteroids in 2026 to gather key information, including Didymoon’s mass, its surface properties and the shape of the DART crater.

    ESA’s proposed Hera spaceraft

    The success of such missions depends on collaborations between organisations, and tracking Near-Earth Objects is a major focus for the collaboration between ESO and ESA. This cooperative effort has been ongoing since their first successful tracking of a potentially hazardous NEO in early 2014.

    “We are delighted to be playing a role in keeping Earth safe from asteroids,” said Xavier Barcons, ESO’s Director General. “As well as employing the sophisticated capabilities of the VLT, we are working with ESA to create prototypes for a large network to take asteroid detection, tracking and characterization to the next level.”

    This recent close encounter with 1999 KW4 comes just a month before Asteroid Day, an official United Nations day of education and awareness about asteroids, to be celebrated on 30 June. Events will be held on five continents, and ESO will be among the major astronomical organisations taking part. The ESO Supernova Planetarium & Visitor Centre will host a range of activities on the theme of asteroids on the day, and members of the public are invited to join in the celebrations.
    Notes

    [1] This distance is about 14 times the distance to the Moon — close enough to study, but not close enough to be threatening! Many small asteroids fly past the Earth much closer than 1999 KW4, occasionally closer than the Moon. Earth’s most recent encounter with an asteroid took place on 15 February 2013, when a previously unknown asteroid 18 metres across exploded as it entered Earth’s atmosphere over the Russian city of Chelyabinsk. The damage produced by the subsequent shockwave caused injuries to about 1,500 people.

    Links

    ESO/ESA observations of Didymos
    Photos of the VLT
    DART mission
    Hera Mission
    ESOblog on ESA-ESO collaboration
    ESA’s technical web portal for near-Earth objects

    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 EEuropean Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO La Silla HELIOS (HARPS Experiment for Light Integrated Over the Sun)

    ESO/HARPS at La Silla

    ESO 3.6m telescope & HARPS at Cerro LaSilla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    MPG/ESO 2.2 meter telescope at Cerro La Silla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres


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

    ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ),
    •KUEYEN (UT2; The Moon ),
    •MELIPAL (UT3; The Southern Cross ), and
    •YEPUN (UT4; Venus – as evening star).
    elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo,

    2009 ESO VLTI Interferometer image, Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level, •ANTU (UT1; The Sun ),
    •KUEYEN (UT2; The Moon ),
    •MELIPAL (UT3; The Southern Cross ), and
    •YEPUN (UT4; Venus – as evening star).

    ESO VLT 4 lasers on Yepun

    Glistening against the awesome backdrop of the night sky above ESO_s Paranal Observatory, four laser beams project out into the darkness from Unit Telescope 4 UT4 of the VLT.

    ESO/NTT at Cerro La Silla, Chile, at an altitude of 2400 metres



    Part of ESO’s Paranal Observatory, the VLT Survey Telescope (VISTA) observes the brilliantly clear skies above the Atacama Desert of Chile. It is the largest survey telescope in the world in visible light.
    Credit: ESO/Y. Beletsky, with an elevation of 2,635 metres (8,645 ft) above sea level


    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at 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 high on the Chajnantor plateau in Chile’s Atacama region, at an altitude of over 4,800 m (15,700 ft)

    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


    ESO Speculoos telescopes four 1m-diameter robotic telescopes at ESO Paranal Observatory 2635 metres 8645 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

    A novel gamma ray telescope under construction on Mount Hopkins, Arizona. a large project known as the Cherenkov Telescope Array, composed of hundreds of similar telescopes to be situated in the Canary Islands and Chile. The telescope on Mount Hopkins will be fitted with a prototype high-speed camera, assembled at the University of Wisconsin–Madison, and capable of taking pictures at a billion frames per second. Credit: Vladimir Vassiliev

     
  • richardmitnick 8:45 am on May 1, 2019 Permalink | Reply
    Tags: Asteroids,   

    From European Space Agency: “Asteroid detected” 

    ESA Space For Europe Banner

    From European Space Agency

    27/04/2019

    1

    Some day in the future, an asteroid might be detected heading toward our home planet. What on Earth happens next?

    This infographic shows the flow of actions that would take place between global agencies and organisations, should a risky asteroid be detected.

    Observations from around the globe, including from ESA’s Optical Ground Station, European observatories and observers – both professional and ‘back-yard’ – and, soon, from ESA’s Flyeye telescope and Test-Bed Telescopes, are fed into the US-based Minor Planet Center – the international ‘asteroid sorting hat’.

    ESA Optical Ground Station, on the premises of the Instituto Astro- física de Canarias (IAC) at the Observatorio del Teide, Tenerife

    ESA Flyeye telescope

    2
    ESA Test-Bed Telescope

    Using the data aggregated by the Minor Planet Center, ESA’s Near-Earth Object Coordination Centre and NASA’s Centre for Near-Earth Object Studies determine the orbits of hazardous asteroids, and assess the risk they pose.

    Finally, if an asteroid is deemed to be potentially dangerous, national civil authorities, the UN and other bodies are informed, and given support and guidance from ESA, NASA and other agencies.

    Watch ‘Asteroid Impact 2028: Protecting our planet’, a dramatisation of how ESA might react if a threatening asteroid is ever discovered.

    Space safety at ESA

    Solar activity, asteroids and artificial space debris all pose threats to our planet and our use of space.

    ESA’s Space Safety activities aim to safeguard society and the critical satellites on which we depend, identifying and mitigating threats from space through projects such as the Flyeye telescopes, the Lagrange space weather mission and the Hera asteroid mission.

    As asteroid experts meet for the international Planetary Defense Conference, ESA is focusing on the threat we face from space rocks. How likely is an asteroid impact? What is ESA doing to mitigate impact risks? Follow the hashtag #PlanetaryDefense to find out more.

    Space Safety & Security at ESA: http://www.esa.int/spacesafety

    Planetary Defence: http://www.esa.int/planetarydefence

    Download the posters: http://www.esa.int/paleblue

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    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 8:05 am on April 30, 2019 Permalink | Reply
    Tags: Asteroids, , , , ,   

    From European Space Agency: “Gaia’s first asteroid discoveries” 

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    From European Space Agency

    29/04/2019

    1

    While scanning the sky to chart a billion stars in our Milky Way galaxy, ESA’s Gaia satellite is also sensitive to celestial bodies closer to home, and regularly observes asteroids in our Solar System.

    ESA/GAIA satellite

    This view shows the orbits of more than 14 000 known asteroids (with the Sun at the centre of the image) based on information from Gaia’s second data release, which was made public in 2018.

    The majority of asteroids depicted in this image, shown in bright red and orange hues, are main-belt asteroids, located between the orbits of Mars and Jupiter; Trojan asteroids, found around the orbit of Jupiter, are shown in dark red.

    In yellow, towards the image centre, are the orbits of several tens of near-Earth asteroids observed by Gaia: these are asteroids that come to within 1.3 astronomical units (AU) to the Sun at the closest approach along their orbit. The Earth circles the Sun at a distance of 1 AU (around 150 million km) so near-Earth asteroids have the potential to come into proximity with our planet.

    Most asteroids that Gaia detects are already known, but every now and then, the asteroids seen by ESA’s Milky Way surveyor do not match any existing observations. This is the case for the three orbits shown in grey in this view: these are Gaia’s first asteroid discoveries.

    The three new asteroids were first spotted by Gaia in December 2018, and later confirmed by follow-up observations performed with the Haute-Provence Observatory in France, which enabled scientists to determine their orbits.

    Haute-Provence Observatory 1.93 meter telescope interior

    L’Observatoire de Haute-Provence, in the southeast of France,, about 90 km east of Avignon and 100 km north of Marseille Altitude 650 m (2,130 ft)

    Comparing these informations with existing observations indicated the objects had not been detected earlier.

    While they are part of the main belt of asteroids, all three move around the Sun on orbits that have a greater tilt (15 degrees or more) with respect to the orbital plane of planets than most main-belt asteroids.

    The population of such high-inclination asteroids is not as well studied as those with less tilted orbits, since most surveys tend to focus on the plane where the majority of asteroids reside. But Gaia can readily observe them as it scans the entire sky from its vantage point in space, so it is possible that the satellite will find more such objects in the future and contribute new information to study their properties.

    Alongside the extensive processing and analysis of Gaia’s data in preparation for subsequent data releases, preliminary information about Gaia’s asteroid detections are regularly shared via an online alert system so that astronomers across the world can perform follow-up observations. To observe these asteroids, a 1-m or larger telescope is needed.

    Once an asteroid detected by Gaia has been identified also in ground-based observations, the scientists in charge of the alert system analyse the data to determine the object’s orbit. In case the ground observations match the orbit based on Gaia’s data, they provide the information to the Minor Planet Center, which is the official worldwide organization collecting observational data for small Solar System bodies like asteroids and comets.

    This process may lead to new discoveries, like the three asteroids with orbits depicted in this image, or to improvements in the determination of the orbits of known asteroids, which are sometimes very poorly known. So far, several tens of asteroids detected by Gaia have been observed from the ground in response to the alert system, all of them belonging to the main belt, but it is possible that also near-Earth asteroids will be spotted in the future.

    A number of observatories across the world are already involved in these activities, including the Haute-Provence Observatory, Kyiv Comet station, Odessa-Mayaki, Terskol, C2PU at Observatoire de la Côte d’Azur and Las Cumbres Observatory Global Telescope Network. The more that join, the more we will learn about asteroids – known and new ones alike.

    C2PU (Centre Pédagogique Planète et Univers),at Observatoire de la Côte d’Azur

    LCOGT Las Cumbres Observatory Global Telescope Network, Haleakala Hawaii, USA, Elevation 10,023 ft (3,055 m)

    Acknowledgement: Gaia Data Processing and Analysis Consortium (DPAC); Gaia Coordinating Unit 4; B. Carry, F. Spoto, P. Tanga (Observatoire de la Côte d’Azur, France) & W. Thuillot (IMCCE, Observatoire de Paris, France); Gaia Data Processing Center at CNES, Toulouse, France

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    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 8:04 am on April 23, 2019 Permalink | Reply
    Tags: , Asteroids, , , , , , ESA's proposed Hera spaceraft, , NASA's Deep Impact spacecraft 2004, US Double Asteroid Redirect Test or DART spacecraft   

    From European Space Agency: “Earth vs. asteroids: humans strike back” 

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    From European Space Agency

    22 April 2019

    Incoming asteroids have been scarring our home planet for billions of years. This month humankind left our own mark on an asteroid for the first time: Japan’s Hayabusa2 spacecraft dropped a copper projectile at very high speed in an attempt to form a crater on asteroid Ryugu. A much bigger asteroid impact is planned for the coming decade, involving an international double-spacecraft mission.

    JAXA/Hayabusa 2 Credit: JAXA/Akihiro Ikeshita

    On 5 April, Hayabusa2 released an experiment called the ‘Small Carry-on Impactor’ or SCI for short, carrying a plastic explosive charge that shot a 2.5-kg copper projectile at the surface of the 900-m diameter Ryugu asteroid at a velocity of around 2 km per second. The objective is to uncover subsurface material to be brought back to Earth for detailed analysis.

    “We are expecting it to form a distinctive crater,” comments Patrick Michel, CNRS Director of Research of France’s Côte d’Azur Observatory, serving as co-investigator and interdisciplinary scientist on the Japanese mission. “But we don’t know for sure yet, because Hayabusa2 was moved around to the other side of Ryugu, for maximum safety.

    “The asteroid’s low gravity means it has an escape velocity of a few tens of centimetres per second, so most of the material ejected by the impact would have gone straight out to space. But at the same time it is possible that lower-velocity ejecta might have gone into orbit around Ryugu and might pose a danger to the Hayabusa2 spacecraft.

    “So the plan is to wait until this Thursday, 25 April, to go back and image the crater. We expect that very small fragments will meanwhile have their orbits disrupted by solar radiation pressure – the slow but persistent push of sunlight itself. In the meantime we’ve also been downloading images from a camera called DCAM3 that accompanied the SCI payload to see if it caught a glimpse of the crater and the early ejecta evolution.”

    According to simulations, the crater is predicted to have a roughly 2 m diameter, although the modelling of impacts in such a low-gravity environment is extremely challenging. It should appear darker than the surrounding surface, based on a February touch-and-go sampling operation when Hayabusa2’s thrusters dislodged surface dust to expose blacker material underneath.

    “For us this is an exciting first data point to compare with simulations,” adds Patrick, “but we have a much larger impact to look forward to in future, as part of the forthcoming double-spacecraft Asteroid Impact & Deflection Assessment (AIDA) mission.

    “In late 2022 the US Double Asteroid Redirect Test or DART spacecraft will crash into the smaller of the two Didymos asteroids.

    NASA DART Double Impact Redirection Test vehicle depiction schematic

    As with Hayabusa2’s SCI test it should form a very distinct crater and expose subsurface material in an even lower gravity environment, but its main purpose is to actually divert the orbit of the 160 m diameter ‘Didymoon’ asteroid in a measurable way.”

    The DART spacecraft will have a mass of 550 kg, and will strike Didymoon at 6 km/s. Striking an asteroid five times smaller with a spacecraft more than 200 times larger and moving three times faster should deliver sufficient impact energy to achieve the first ever asteroid deflection experiment for planetary defence.

    3
    DART mission profile. APL – Johns Hopkins University Applied Physics Laboratory

    A proposed ESA mission called Hera would then visit Didymos to survey the diverted asteroid, measure its mass and perform high-resolution mapping of the crater left by the DART impact.

    DLR Asteroid Framing Camera used on NASA Dawn and ESA HERA missions

    ESA’s proposed Hera spaceraft

    “The actual relation between projectile size, speed and crater size in low gravity environments is still poorly understood,” adds Patrick, also serving as Hera’s lead scientist. “Having both SCI and Hera data on crater sizes in two different impact speed regimes will offer crucial insights.

    “These scaling laws are also crucial on a practical basis, because they underpin how our calculations estimating the efficiency of asteroid deflection are made, taking account the properties of the asteroid material as well as the impact velocity involved.

    “This is why Hera is so important; not only will we have DART’s full-scale test of asteroid deflection in space, but also Hera’s detailed follow-up survey to discover Didymoon’s composition and structure. Hera will also record the precise shape of the DART crater, right down to centimetre scale.

    “So, building on this Hayabusa2 impact experiment, DART and Hera between them will go on to close the gap in asteroid deflection techniques, bringing us to a point where such a method might be used for real.”

    Didymoon will also be by far the smallest asteroid ever explored, so will offer insights into the cohesion of material in an environment whose gravity is more than a million times weaker than our own – an alien situation extremely challenging to simulate.

    In 2004, NASA’s Deep Impact spacecraft launched an impactor into comet Tempel 1. The body was subsequently revisited, but the artificial crater was hard to pinpoint – largely because the comet had flown close to the Sun in the meantime, and its heating would have modified the surface.

    6
    NASA’s Deep Impact hitting a comet

    NASA Deep Impact spacecraft 2004

    Hera will visit Didymoon around four years after DART’s impact, but because it is an inactive asteroid in deep space, no such modification will occur. “The crater will still be ‘fresh’ for Hera,” Patrick concludes.

    See the full article here .


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    Please help promote STEM in your local schools.

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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 2:36 pm on April 22, 2019 Permalink | Reply
    Tags: Asteroids, , , , , , ,   

    From PBS NOVA: “How This NASA Telescope is Defending the Earth From Asteroids” 

    From PBS NOVA

    April 19, 2019
    Katherine J. Wu

    1
    An artist’s conception of the Wide-field Infrared Survey Explorer, or WISE spacecraft, in its orbit around Earth, which has now been repurposed into NEOWISE. NEOWISE has been scouring the skies for near-Earth objects for the past five years. Image Credit: NASA/JPL-Caltech

    With rogue asteroids and comets on the move, space can sometimes be a bit of a warzone.

    Serious impacts with Earth are few and far between. But these collisions can be catastrophic (just ask a few disgruntled dinosaurs circa 66 million years ago)—and Earthlings are often caught unaware.

    That’s why a team of NASA astronomers has spent the past five years scouring the skies for near-Earth objects (NEOs)—asteroids and comets that orbit the Sun in our vicinity—in the hopes of potentially staving off impending doom.

    “If we find an object only a few days from impact, it greatly limits our choices,” NASA astronomer Amy Mainzer said in a statement. “We’ve focused on finding NEOs when they are further away from Earth, providing the maximum amount of time and opening up a wider range of mitigation possibilities.”

    The endeavor is a part of NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission, an Earth-orbiting satellite equipped with cameras and an infrared-sensitive telescope. And the spacecraft, which isn’t limited to tracking the trajectories of asteroids, has kept itself busy: In the past half decade, it has recorded more than 95 billion measurements of asteroids, comets, stars, and galaxies, with data collection ongoing.

    These measurements have revealed more than 1,000 wayfaring asteroids near our planet in the past half decade. None of these NEOs currently pose any threat to us here on Earth. But according to NASA estimates, about 20,000 near-Earth objects have flitted in and out of our neighborhood in recent decades—almost 900 of which were more than 3,200 feet across. And it was only six years ago that a meteor just 66 feet in diameter injured over 1,500 people when it exploded over the Russian region of Chelyabinsk.

    Detecting rocky interlopers, however, is no easy task. Because NEOs are often so small and far away, they’re frustratingly hard to spot under even the best of circumstances. What’s more, under visible light, these objects can look as dark as coal or printer toner, making them hard to pick out against the black backdrop of space.

    But the NEOWISE telescope has found a clever workaround—one that essentially involves it donning a set of cosmic night vision goggles. Heated by the warmth of the Sun, rocky bodies near Earth emit an infrared glow. By working in infrared, the telescope can pick up on any objects that are comin’ in hot, providing Mainzer’s team with images that reveal properties like a NEO’s size, mass, and composition. These measurements could someday help engineers calculate the amount of energy needed for a spacecraft to “nudge” (or detonate) a looming asteroid off an Earthbound path.

    The NEOWISE spacecraft, which was initially launched for a separate mission in 2009, will eventually reach the end of its tenure when its changing orbit prevents it from acquiring high-quality data. But a plan is already in the works to succeed it with another telescope called NEOCam—a new and improved addition to the NEO suite that will purposefully be designed to peer into space for asteroids.

    NASA NEOCam depiction

    If funded, NEOCam will “do a much more comprehensive job of mapping asteroid locations and measuring their sizes,” Mainzer said in the statement.

    NEOCam’s fate hasn’t yet been decided. For now, its predecessor remains on the frontlines of defense, and will still be actively collecting data. So for any asteroids, comets, or meteors headed our way, the message is clear: Earth has plans to take the heat—and it starts with taking note of it.

    See the full article here .

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    Please help promote STEM in your local schools.

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    NOVA is the highest rated science series on television and the most watched documentary series on public television. It is also one of television’s most acclaimed series, having won every major television award, most of them many times over.

     
  • richardmitnick 9:57 am on April 22, 2019 Permalink | Reply
    Tags: Asteroids, By simulating conditions in the early solar system researchers can calculate the ratio of heavy water to ordinary water when the planets were forming., , From Astronomy Magazine: "Where did Earth's water come from?", Reservoirs with a high quantity of heavy water have a high D/H ratio while deuterium-poor reservoirs show a lower ratio., What do the samples suggest is the source of Earth’s water? Hallis suspects it came from the solar nebula., When hydrogen-rich and oxygen-rich minerals melt because of the mantle’s heat the resulting water can spew from the planet’s crust., When the European Giotto spacecraft visited Halley’s Comet in 1986 researchers noticed its heavy water content was higher than the gas in Earth’s part of the early solar system.   

    From Astronomy Magazine: “Where did Earth’s water come from?” 

    Astronomy magazine

    From Astronomy Magazine

    April 01, 2019
    Nola Taylor Redd

    Most astronomers believe asteroids carried water to early Earth. But new research suggests it may have come from even closer to home.

    1
    Asteroids could have carried water, locked away in their minerals, to a young Earth, depositing it through impacts during our planet’s early years. But this isn’t the only possible explanation for our watery world. Ron Miller for Astronomy.

    Karen Meech doesn’t spend a lot of time digging through Earth’s rocks. An astronomer by trade, she is usually behind the telescope, investigating comets and looking for hints about how Earth got its water. But a field trip to Iceland in 2004 ultimately sent her scrambling through the craters of Hawaii nearly a decade later in search of clues about the liquid that helped birth life on this planet.

    On that fateful Icelandic tour, Meech saw geothermal areas with gas billowing out of the ground. The guide told the group not to worry — it was only water. “Then she said, ‘This is probably primordial water,’ and it set a lightbulb off,” Meech says.

    The flavors of water

    The source of Earth’s water has been a long-standing mystery; Meech herself has been trying to solve it for at least 20 years. Most of that search has focused on sorting out the various isotopes of hydrogen that go into making the water — or “the flavor of water,” as Lydia Hallis of the University of Glasgow calls it. One of those “flavors” is heavy water, a form of water that incorporates deuterium, an isotope of hydrogen whose nucleus contains one proton and one neutron. Normal hydrogen lacks a neutron, so water with deuterium weighs more than ordinary water.

    By simulating conditions in the early solar system, researchers can calculate the ratio of heavy water to ordinary water when the planets were forming. On Earth, the observed ratio is higher than it would have been in the young solar system, leading many astronomers to suspect that the water was imported because the ratio should remain constant over time. Today, most scientists believe asteroids carried water to the young, dry Earth.

    Meech was suspicious of this idea because measurements of Earth’s deuterium-to-hydrogen (D/H) ratio, which is connected to the ratio of heavy water to normal, is generally based on the composition of today’s oceans. Reservoirs with a high quantity of heavy water have a high D/H ratio, while deuterium-poor reservoirs show a lower ratio.

    2
    Earth formed from the dust and gas of the nebula that surrounded our infant Sun. This artist’s concept shows the protoplanetary disk of material around a young star. The disk contains the individual components of water — hydrogen and oxygen — and water in both ice and vapor forms. NASA/JPL-Caltech.

    But Earth’s ratio should have changed over time. Like most planets, Earth probably lost some of its atmosphere to space, and the lighter hydrogen would be easier to strip from the planet than its heavier counterpart. Geological processes, such as the evaporation of water from reservoirs such as lakes and oceans, can also change the ratio, as can biological reactions, because lighter isotopes are used differently than heavier ones in metabolic processes. All of these processes would give the modern Earth a higher D/H ratio compared with when the planet was newly formed.

    When Meech heard that primordial water could be spouting from the surface in Iceland, she grew excited at the chance to study the earliest flavor of water. But after chatting with a geologist, she learned that the plumes actually came from more recent activity — they weren’t primordial after all. However, the geologist revealed that some rocky material brought up from Earth’s mantle does contain small traces of water. That material may never have mixed with the stuff on the surface and could represent Earth’s early water. No one had investigated the D/H ratio in those samples because the technology to do so was new. But the University of Hawaii, where Meech is based, had just purchased a new ion microprobe that might be able to do the job.

    U Hawaii Ion microprobe

    UH Researchers Shed New Light on the Origins of Earth’s Water 12 November 2015

    “I thought, wow, here’s a way we can actually measure the original fingerprints,” Meech says. “At that point, I got very excited.”

    In search of the culprit

    Earth and the rest of the planets formed inside a nest of gas left over from the birth of the Sun. This material, known as the solar nebula, contained all the elements that built the planets, and the compositions varied with distance from the Sun. The region near the star was too warm for some material to coalesce as ices, which instead formed in the outer part of the solar system. Around Earth, hydrogen and other elements could stick around only as a gas. Because the nebula was short-lived, most scientists suspect that Earth didn’t have enough time to collect these gases before they escaped into space. That idea, along with the planet’s high D/H ratio, led many to believe that Earth’s water must have arrived after Earth had cooled.

    When the European Giotto spacecraft visited Halley’s Comet in 1986, researchers noticed its heavy water content was higher than the gas in Earth’s part of the early solar system.

    3
    ESA Giotto spacecraft

    A new theory emerged: Comets could have carried water to early Earth. After the planets formed, the enormous bodies would continue to stir things up, with giant planets like Jupiter hurling some material toward the inner solar system. Icy objects that formed in the outer solar system could have been tossed at Earth to rain down as giant water-laden impacts.

    4
    Heavy water, or D2O, contains deuterium in place of hydrogen. Deuterium is an isotope of hydrogen whose nucleus contains one proton and one neutron, whereas normal hydrogen contains only a proton. The ratio of heavy water to normal water in a sample gives scientists information about how it formed — information researchers are now using to try to unravel the origin of Earth’s water. Astronomy: Roen Kelly.

    But as other missions probed more comets, it became clear that the amount of heavy water wasn’t consistent among them. In fact, most of the comets’ heavy water ratios were far too high to be responsible for dropping water on Earth. Another culprit must be responsible.

    Comets weren’t the only thing that the gas giants tossed around. As Jupiter plowed through the asteroid belt early in our solar system’s history, it scattered the rocky debris in all directions. Like comets, some of the material rained down on Earth. Unlike comets, asteroids don’t lock up water as ice. Instead, they trap its components — hydrogen and oxygen — inside minerals. Also, the heavy water content in asteroids falls much closer to Earth’s current ratio. That’s why asteroids are the leading suspect for the source of our planet’s water.

    “Really, we’re not talking about water; we’re talking about hydrogen,” says Anne Peslier, a geochemist at NASA’s Johnson Space Center. Peslier studies the geochemistry of Earth’s mantle and the other terrestrial planets, including the hydrogen trapped within minerals.

    When Earth formed, the hydrogen surrounding the growing planet was captured in its rocks and minerals. When hydrogen-rich and oxygen-rich minerals melt because of the mantle’s heat, the resulting water can spew from the planet’s crust.

    Most of the mantle is rocky, and enormous quantities of hydrogen and oxygen could be trapped inside. Researchers estimate that as much as 10 oceans of water may exist within the mantle.

    Erupting volcanoes usually bring up magma from the upper part of Earth’s mantle, the region closer to the surface. This material is more likely to be polluted by hydrogen from the crust, which contains the same higher D/H ratios measured in the oceans today. More pristine samples lie much farther down in the mantle. Although it’s hot there, less than 20 percent of the mantle rock has melted, Peslier says. When the melted material erupts, it can have a violent effect on the solid rock.

    “If [the lavas] go fast enough and brutally enough, they sometimes break off pieces of what they are traversing along the way,” Peslier says. She describes the result — called mantle xenolith, after the Greek word for “foreign rock” — as crystals of bright green olivine and black pyroxene embedded in the black lava.

    If the hydrogen-rich olivine crystals were captured early enough during Earth’s formation and remained undisturbed for the planet’s 4.5 billion-year lifetime, they could reveal how much the ancient ratios of heavy and normal water shifted, if they changed at all. The tiny time capsules could provide answers to the long-standing questions regarding the source of Earth’s water.

    But first, they had to be found.

    Hunting primordial water

    While Meech knows a great deal about water in the solar system, she wasn’t as familiar with rocks on Earth. She pulled in Hallis, then a postdoctoral student, to lead geological excavations in a hunt for those early fingerprints of normal and heavy water. Hallis was intrigued by the chance to scramble across craters in Hawaii and along the shores of Baffin Island in Canada in search of clues. Baffin is one of the few places where Earth’s deep mantle is accessible. The chain of eruptions that formed the island also created Greenland and Iceland. “The Baffin Island samples are the most pristine examples that we have of the deep mantle,” Hallis says.

    Hallis also received samples collected by Don Francis, now an emeritus professor at McGill University in Montreal, from a tiny uninhabited island called Padloping, off the eastern coast of Canada and northwest of Baffin Island. According to Hallis, Francis collected the first of his samples in 1985. The isolation of Padloping Island meant that researchers had to travel there by boat and set up camp. The sheer cliffs made falling rocks plentiful, and Francis picked up the best-looking minerals from the beach. A return trip in 2004 netted even more samples. “Something I would really like to do is go back [to Padloping Island],” Hallis says. The imposing cliffs make it challenging to collect samples, but if she could obtain some from the steep overhangs, she would be able to pinpoint where and when the material rose to the surface.

    5
    Green olivine crystals in lava can contain and protect hydrogen collected during Earth’s formation, allowing researchers to determine its ratio of deuterium to hydrogen.
    S. Rae/Flickr.

    With the well-preserved samples in hand, Hallis and her colleagues began to systematically destroy them. The rocks were ground up into sandlike powder. Using the microprobe, the scientists sorted the enclosed crystals by color.

    Meech helped to categorize the crystals. “I found it hard to manipulate the tiny little bits of sand without spilling them on the floor,” she admits ruefully.

    Part of the process involved ensuring the samples were stripped from the mantle rather than the crust as the volcanic plume burst upward. Previous studies of the Baffin Island minerals suggested that they came from the mantle’s depths, and mineralogical evidence revealed that the samples Hallis had in the lab were most likely pristine. The tiny glass beads were protected in part by olivine crystals, which act as a barrier to prevent weathering once the rocks are on the surface. Even so, they weren’t entirely perfect.

    “Even with the most pristine samples that we have, it’s not 100 percent exactly deep mantle,” Hallis says. “It’s always going to have some incorporation of the [upper] mantle in there, just because it has to travel through so much of the mantle to get to the surface.”

    While the Baffin Island samples were free of crust pollution, the team wasn’t so fortunate with the rocks gathered near their university. The Hawaiian minerals had suffered from weathering and had been heavily affected by surface water, most likely rain. The pollution kept these samples from revealing the flavors of pristine water.

    With the first fingerprints of Earth’s water finally taken, Meech and Hallis began to compare them with other samples. Hallis expected to observe a heavy water content closer to the meteorites thought to have delivered water to the young planet. Instead, the samples weighed in with about 25 percent less heavy water compared with normal water — far less than expected.

    “That was a bit of a surprise,” Hallis says. “It suggests that carbonaceous chondrites [a class of meteorites] are not a good fit for the source of Earth’s water.” While meteorites may have provided some of Earth’s water, she doesn’t think that they delivered all of it.

    The source of Earth’s water

    What do the samples suggest is the source of Earth’s water? Hallis suspects it came from the solar nebula. While many scientists argue that the nebula would have dissipated within 6 million years — long before our planet could have grown large enough to capture it — she points out that several young stars have been found with gas around them for as long as 10 million years. That would give the tiny rocks that ultimately built Earth enough time to incorporate elements like hydrogen and nitrogen into their structure. Hallis says nitrogen and hydrogen in the solar system tend to follow one another — “If you have a certain flavor of hydrogen, you have a certain flavor of nitrogen,” she says.

    “Perhaps you still have pockets in the Earth that have preserved this initial hydrogen source,” says Zachary Sharp, a researcher at the University of New Mexico who also suspects that Earth’s D/H ratio has shifted over time.

    7
    Geysers such as Strokkur in Iceland inspired Karen Meech to hunt for Earth’s primordial water. Although such geysers do not spew the unaltered early water needed to pursue this line of study, other geological processes, such as volcanic plumes, do. Ivan Sabljak/Wikimedia Commons.

    Hallis’ results aren’t the only ones to suggest that Earth may have picked up the bulk of its water from the start. While the Moon was once thought to be completely dry, recent re-examinations of Apollo Moon rocks have revealed traces of water. The leading theory for the Moon’s formation is that it was created when a Mars-sized object slammed into the young Earth. Liquid water on the surface would have been vaporized, leading many to conclude that Earth had to pick up more water from elsewhere. But the low D/H ratios from the lunar samples suggest that the Moon could have collected the water in minerals locked in its interior, a region neither comets nor asteroids could have polluted. Later volcanic eruptions hurled that material to the surface, to be returned to Earth by astronauts.

    Why is this important? The high temperatures post-collision would have been similar to those found in the solar nebula, Hallis says. That helps to make the case that even in the hot early solar system, volatiles and water could be accreted.

    But hydrogen comes in heavy and light flavors, so doesn’t that mean the ratio could change in either direction? Not really, according to Sharp, who has revisited the idea that most of Earth’s water may have been collected from the nebula rather than later collisions. “It’s easy to increase the isotopic ratio of the samples, but it’s difficult to lower them,” he says. That’s because the lighter hydrogen is easier to remove. For instance, hydrogen rises more easily to the top of the atmosphere, where the solar wind can strip it away. The heavier deuterium tends to stay closer to the ground.

    Asteroids are also providing hints that Earth’s water may have come from the gas that birthed the planets. Studies of meteorites from the large asteroid Vesta have revealed ratios of heavy water similar to the Baffin Island estimates.

    “Now that we are finding low values in Earth, the Moon, and Vesta, and also in the water reservoir of the asteroids, now maybe the [nebula] story is possible,” says Alice Stephant of Arizona State University, who studies Vesta. “It seems like they all share a common reservoir that is lower [in deuterium] than what we thought.”

    8
    Padloping Island is isolated, uninhabited, and home to what may be some of Earth’s oldest rock. Future expeditions to this island in Canada may confirm preliminary findings that our Sun’s protoplanetary nebula may have stuck around long enough for a forming Earth to capture hydrogen — a building block of water. Doc Searls/Flickr.

    The smoking gun

    The lower D/H ratios revealed by Hallis, Meech, and their colleagues are not yet widely accepted. Conel Alexander, a cosmo-chemist at the Carnegie Institution of Washington, says there are two reasons why other researchers didn’t immediately change their minds about the source of Earth’s water.

    One argument against the results stems from how Hallis extrapolated the isotopes and elemental abundances in her measurements; Alexander says some scientists disagree with how the final numbers play out using her method. The other issue is how Hallis explained her results. “Lydia’s interpretation was unique,” Alexander says. “There may be other ways of getting hydrogen into the melt inclusions that she was measuring.”

    Alexander’s chief concern stems from the fact that only a single source of rocks — the Baffin Island samples — was used to estimate the entire planet’s ancient ratios. “The bulk of Earth may have a completely different composition, and there may be something weird about ocean islands’ basalts,” he says. He hopes that other scientists will follow Hallis’ lead and measure the D/H ratio from a variety of deep-mantle plumes.

    Hallis is ready to take her own trip to Padloping Island to collect more samples. One thing she would like to do is investigate not just the hydrogen involved, but also the nitrogen. But analyzing the nitrogen in samples is more difficult than hunting down hydrogen, partly because there is even less nitrogen in these samples than hydrogen. Measuring nitrogen also requires instruments capable of very high precision. Hallis says it’s pushing the limit of what current technology can do.

    Alexander says that Hallis’ goal of hunting down nitrogen from future samples will also help firm up any doubts about the primordial nature of the Baffin Island samples. “If she can show that there is both light hydrogen and light nitrogen in these inclusions, I think that would be a smoking gun,” he says.
    “If the nitrogen follows the hydrogen, then we proved our theory that [the samples] are primitive,” Hallis says.

    See the full article here .


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  • richardmitnick 12:28 pm on March 19, 2019 Permalink | Reply
    Tags: Asteroids, ,   

    From BBC: “US detects huge meteor explosion” 

    BBC
    From BBC

    18 March 2019
    Paul Rincon

    A huge fireball exploded in the Earth’s atmosphere in December, according to NASA.

    1
    Artwork: The fireball was the kind of event expected to happen only two to three times per century. Getty Images

    The blast was the second largest of its kind in 30 years, and the biggest since the fireball over Chelyabinsk in Russia six years ago.

    But it went largely unnoticed until now because it blew up over the Bering Sea, off Russia’s Kamchatka Peninsula.

    The space rock exploded with 10 times the energy released by the Hiroshima atomic bomb.

    Lindley Johnson, planetary defence officer at NASA, told BBC News a fireball this big is only expected about two or three times every 100 years.

    What do we know?

    At about noon local time on 18 December, the asteroid barrelled through the atmosphere at a speed of 32km/s (20 miles per second) , on a steep trajectory of seven degrees.

    Measuring several metres in size, the space rock exploded 25.6km above the Earth’s surface, with an impact energy of 173 kilotons.

    “That was 40% the energy release of Chelyabinsk, but it was over the Bering Sea so it didn’t have the same type of effect or show up in the news,” said Kelly Fast, near-Earth objects observations programme manager at Nasa.

    “That’s another thing we have in our defence, there’s plenty of water on the planet.”

    Dr Fast was discussing the event here at the 50th Lunar and Planetary Science Conference in The Woodlands, near Houston, Texas.

    Military satellites picked up the blast last year; NASA was notified of the event by the US Air Force.

    Dr Johnson said the fireball came in over an area not too far from routes used by commercial planes flying between North America and Asia. So researchers have been checking with airlines to see if there were any reported sightings of the event.

    2

    What’s the significance?

    In 2005, Congress tasked NASA with finding 90% of near-Earth asteroids of 140m (460ft) in size or larger by 2020. Space rocks of this size are so-called “problems without passports” because they are expected to affect whole regions if they collide with Earth. But scientists estimate it will take them another 30 years to fulfill this congressional directive.

    NASA NEOCAM

    Once an incoming object is identified, NASA has had some notable success at calculating where on Earth the impact will occur, based on a precise determination of its orbit.

    In June 2018, the small 3m (10ft) asteroid 2018 LA was discovered by a ground-based observatory in Arizona eight hours before impact. The Center for Near-Earth Object Studies at Nasa’s Jet Propulsion Laboratory (JPL) then made a precision determination of its orbit, which was used to calculate a probable impact location.


    This showed the rock was likely to hit southern Africa.

    Just as the calculation suggested, a fireball was recorded over Botswana by security camera footage on a farm. Fragments of the object were later found in the area.

    4
    Japan’s Himawari satellite captures the fireball’s steep descent. Himawari/JMA/@simon_sat

    How can monitoring be improved?

    The latest event over the Bering Sea shows that larger objects can collide with us without warning, underlining the need for enhanced monitoring.

    A more robust network would be dependent not only on ground telescopes, but space-based observatories also.

    A mission concept in development would see a telescope called NeoCam launched to a gravitational balance point in space, where it would discover and characterise potentially hazardous asteroids larger than 140m.

    Dr Amy Mainzer, chief scientist on NeoCam at JPL, said: “The idea is really to get as close as possible to reaching that 90% goal of finding the 140m and larger near-Earth asteroids given to Nasa by Congress.

    She said that if the mission did not launch, projections suggested it would “take us many decades to get there with the existing suite of ground-based surveys”.

    Dr Mainzer added: “But if you have an IR-based (infrared) telescope, it goes a lot faster.”

    See the full article here .

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  • richardmitnick 9:17 am on March 19, 2019 Permalink | Reply
    Tags: Asteroids, , , , , , NASA Dawn mission   

    From European Space Agency: “ESA’s Hera asteroid mission borrows eyes of NASA’s Dawn” 

    ESA Space For Europe Banner

    From European Space Agency

    18 March 2019

    The mission to the smallest asteroid ever explored will employ the same main camera as the mission to the largest asteroids of all. ESA’s proposed Hera spacecraft to the Didymos asteroid pair has inherited its main imager from NASA’s Dawn mission to the Vesta and Ceres asteroids.

    ESA’s proposed Hera spaceraft

    NASA/DLR Dawn Spacescraft (2007-2018)

    Hera is currently the subject of detailed design work, ahead of being presented to Europe’s space ministers at the Space19+ Ministerial Council at the end of this year, for launch in late 2023. The spacecraft will survey a tiny 160-m diameter moon of the 780-m diameter Didymos asteroid, in the aftermath of a pioneering planetary defence experiment.

    But the Asteroid Framing Camera (AFC) Hera will use to navigate through space and survey its targeted double asteroids is already built and ready. Two of these cameras – Hera will carry a pair, for redundancy – are sitting in protective nitrogen gas inside a clean room in Göttingen, Germany.

    DLR Asteroid Framing Camera used on NASA Dawn and ESA HERA missions

    “The AFC was designed specifically for NASA’s Dawn mission to the two largest bodies in the Asteroid belt: Vesta, at 525 km across, and 946 km diameter Ceres,” explains Holger Sierks of the Max Planck Institute for Solar System Research.

    “There was no other camera aboard the spacecraft so the AFC had a mission-critical role, being employed both for navigation and scientific investigation.

    “The AFC worked like Swiss clockwork throughout Dawn’s 11-year lifetime. Before Dawn finally ended in November 2018 the spacecraft came as close as 30 km from the surface of Ceres, and returned spectacular views of its striking bright spots.

    “At the same time the camera, equipped with seven spectral filters from the visible to the near-infrared, was able to gather spectral information on these formations, as well as the rest of the asteroids. An eighth clear filter was used when the AFC was employed for navigation purposes and for broadband surface science.”

    MPS Spectral filters on DLR Asteroid Framing Camera used on NASA Dawn and ESA HERA missions

    Two AFC flight units were supplied to NASA by the Institute, in cooperation with the DLR German Aerospace Center and the Technical University of Braunschweig’s Institute of Computer and Network Engineering. A spare camera was built and kept at the Institute to replace a flight unit if needed.

    “We still had spare, flight quality subsystems including the optics that we could integrate into a full camera, so ended up with two flight ready spares on the shelf,” adds Holger. “We wanted to find a flight use for them, and decided we should contribute these fully mission proven cameras to Europe’s next asteroid mission free of charge.”

    The 5.5 kg AFC resembles a computer printer-sized box containing power and mass memory with a thermally insulated telescope extending out from it. Maximum image sensitivity is ensured by cooling the telescope’s CCD light detector down to -60 °C.

    One qualification model camera has already been lent to GMV in Spain as they develop autonomous navigation systems for Hera. This allows the team to test their feature-detecting algorithms with the same hardware as will actually be flown.

    While the AFC was designed specifically for Vesta and Ceres, Holger explains the camera is also a very good fit for Hera – especially with its dual science and navigation functionality: “When we designed it, those two asteroids were only known to us as little dots in the sky, just a few pixels across at best using the Hubble Space Telescope, like the Didymos system today. The camera’s optics – the work of the Kayser-Threde company in Munich, now owned by OHB – are distortion free with a sharp focus, right down to 150 m from the target surface.”

    The Max Planck Institute for Solar System Research also built the Rosetta comet chaser’s main Osiris science imager, so has plenty of experience in imaging distant planetoids close up. “These bodies would be dark like charcoal to the human eye, so it takes highly sensitive detectors and carefully judged exposure times to see what we see.”

    ESA/Rosetta spacecraft, European Space Agency’s legendary comet explorer Rosetta

    Hera’s planetary defence purpose feels personal to Holger and the rest of the Institute team. The team recently met in the German town of Nördlingen, located inside a 24-km diameter crater, formed by an impacting binary asteroid just like Didymos and its moon an estimated 14 million years ago.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    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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