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  • richardmitnick 7:06 am on March 29, 2016 Permalink | Reply
    Tags: , , , ESA Rosetta, Landing on a comet   

    From Discovery: “Documentary 2015 Landing On A Comet Rosetta Mission 2014 New Details” 

    Discovery News
    Discovery News

    Published on Nov 13, 2014

    Documentary Landing On A Comet Rosetta Mission 2014 New

    Watch, enjoy, learn.

    See the full article here .

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  • richardmitnick 8:09 am on November 12, 2015 Permalink | Reply
    Tags: , , ESA Rosetta,   

    From ESA: “Rosetta and Philae: one year since landing on a comet” 

    ESASpaceForEuropeBanner
    European Space Agency

    12 November 2015
    Markus Bauer








    ESA Science and Robotic Exploration Communication Officer









    Tel: +31 71 565 6799









    Mob: +31 61 594 3 954









    Email: markus.bauer@esa.int

    Patrick Martin
    Rosetta Mission Manager
    Email: patrick.martin@esa.int

    Sylvain Lodiot
    Rosetta Spacecraft Operations Manager
    Email: sylvain.lodiot@esa.int

    Matt Taylor
    ESA Rosetta Project Scientist
    Email: matt.taylor@esa.int

    Koen Geurts
    Philae Lander Technical Manager, DLR
    Email: Koen.Geurts@dlr.de

    Stephan Ulamec
    Philae Lander Manager, DLR
    Email: Stephan.Ulamec@dlr.de


    Reconstructing Philae’s flight
    download mp4 video here.

    One year since Philae made its historic landing on a comet, mission teams remain hopeful for renewed contact with the lander, while also looking ahead to next year’s grand finale: making a controlled impact of the Rosetta orbiter on the comet.

    Rosetta arrived at Comet 67P/Churyumov–Gerasimenko on 6 August 2014, and after an initial survey and selection of a landing site, Philae was delivered to the surface on 12 November.

    After touching down in the Agilkia region as planned, Philae did not secure itself to the comet, and it bounced to a new location in Abydos. Its flight across the surface is depicted in a new animation, using data collected by Rosetta and Philae to reconstruct the lander’s rotation and attitude.

    In the year since landing, a thorough analysis has also now been performed on why Philae bounced.

    1
    Agilkia mosaic, labelled

    There were three methods to secure it after landing: ice screws, harpoons and a small thruster. The ice screws were designed with relatively soft material in mind, but Agilkia turned out to be very hard and they did not penetrate the surface.

    The harpoons were capable of working in both softer and harder material. They were supposed to fire on contact and lock Philae to the surface, while a thruster on top of the lander was meant to push it down to counteract the recoil from the harpoon.

    Attempts to arm the thruster the night before failed: it is thought that a seal did not open, although a sensor failure cannot be excluded.

    Then, on landing, the harpoons themselves did not fire. “It seems that the problem was either with the four ‘bridge wires’ taking current to ignite the explosive that triggers the harpoons, or the explosive itself, which may have degraded over time,” explains Stephan Ulamec, Philae lander manager at the DLR German Aerospace Center.

    “In any case, if we can regain contact with Philae, we might consider an attempt to retry the firing.”

    The reason is scientific: the harpoons contain sensors that could measure the temperature below the surface.

    Despite the unplanned bouncing, Philae completed 80% of its planned first science sequence before falling into hibernation in the early hours of 15 November when the primary battery was exhausted. There was not enough sunlight in Philae’s final location at Abydos to charge the secondary batteries and continue science measurements.

    The hope was that as the comet moved nearer to the Sun, heading towards closest approach in August, there would be enough energy to reactivate Philae. Indeed, contact was made with the lander on 13 June but only eight intermittent contacts were made up to 9 July.

    The problem was that the increasing sunlight also led to increased activity on the comet, forcing Rosetta to retreat to several hundred kilometres for safety, well out of range with Philae.

    However, over the past few weeks, with the comet’s activity now subsiding, Rosetta has started to approach again. This week it reached 200 km, the limit for making good contact with Philae, and today it dips to within 170 km.


    Philae’s descent: The director’s cut
    download the mp4 video here.

    In the meantime, the lander teams have continued their analysis of the data returned during the contacts in June and July, hoping to understand the status of Philae when it first woke up from hibernation.

    “We had already determined that one of Philae’s two receivers and one of the two transmitters were likely no longer working,” says Koen Geurts, Philae’s technical manager at DLR’s Lander Control Centre in Cologne, Germany, “and it now seems that the other transmitter is suffering problems. Sometimes it did not switch on as expected, or it switched off too early, meaning that we likely missed possible contacts.”

    The team is taking this new information into account to determine the most promising strategy to regain regular contact.

    But it’s a race against time: with the comet now heading out beyond the orbit of Mars, temperatures are falling.

    “We think we have until the end of January before the lander’s internal temperature gets too cold to operate: it cannot work below –51ºC,” adds Koen.

    Meanwhile, Rosetta continues to return unique data with its suite of instruments, analysing changes to the comet’s surface, atmosphere and plasma environment in incredible detail.

    “We recently celebrated our first year at the comet and we are looking forward to the scientific discoveries the next year will bring,” says Matt Taylor, ESA’s Rosetta project scientist.

    “Next year, we plan to do another far excursion, this time through the comet’s tail and out to 2000 km. To complement that, we hope to make some very close flybys towards the end of the mission, as we prepare to put the orbiter down on the comet.”

    The plan is to end the mission with a ‘controlled impact’ of Rosetta on the surface. This idea emerged around six months ago, when an extension of operations from December 2015 to September 2016 was announced.

    The solar-powered Rosetta will no longer receive enough sunlight to operate as the comet recedes from the Sun, out beyond the orbit of Jupiter on its 6.5-year circuit. It will travel even further out than during the previous 31 months of deep-space hibernation that ended in January 2014.

    In addition, as seen from Earth next September, Rosetta and the comet will look very close to the Sun, making the relay of both scientific data and operational commands very difficult.

    The Rosetta teams are now investigating the manoeuvres needed for operating close to the comet in the weeks leading up to the dramatic mission finale.

    “We are still discussing exactly what the final end of mission scenario will involve,” says Sylvain Lodiot, ESA’s Rosetta spacecraft operations manager. “It is very complex and challenging, even more so even than the lander delivery trajectory our flight dynamics teams had to plan for delivering Philae.

    “The schedule we’re looking at would first involve a move into highly elliptical orbits – perhaps as low as 1 km – in August, before moving out to a more distant point for a final approach that will set Rosetta on a slow collision course with the comet at the end of September.”

    It is expected that science observations would continue throughout and up to almost the end of mission, allowing Rosetta’s instruments to gather unique data at unprecedentedly close distances.

    “We’ll control Rosetta all the way down to the end, but once on the surface it will be highly improbable that we’ll be able to ‘speak’ to it anymore,” adds Sylvain.

    “Landing Rosetta on a comet will be a fitting ending to this incredible mission,” says Patrick Martin, ESA’s Rosetta mission manager.

    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 3:44 pm on October 28, 2015 Permalink | Reply
    Tags: , , Comet 67P/Churyumov–Gerasimenko, ESA Rosetta, O2   

    From ESA: “First detection of molecular oxygen at a comet” 

    ESASpaceForEuropeBanner
    European Space Agency

    28 October 2015
    Markus Bauer








    ESA Science and Robotic Exploration Communication Officer









    Tel: +31 71 565 6799









    Mob: +31 61 594 3 954









    Email: markus.bauer@esa.int

    Kathrin Altwegg

    Principal investigator for ROSINA

    University of Bern, Switzerland

    Email: kathrin.altwegg@space.unibe.ch

    Andre Bieler
    University of Michigan
    Email: abieler@umich.edu

    Ewine van Dishoeck
    Leiden Observatory, University of Leiden, the Netherlands
    Email: ewine@strw.leidenuniv.nl

    Matt Taylor
    ESA Rosetta Project Scientist
    Email: matt.taylor@esa.int

    1
    Rosetta’s detection of molecular oxygen Released 28/10/2015

    ESA’s Rosetta spacecraft has made the first in situ detection of oxygen molecules outgassing from a comet, a surprising observation that suggests they were incorporated into the comet during its formation.

    Rosetta has been studying Comet 67P/Churyumov–Gerasimenko for over a year and has detected an abundance of different gases pouring from its nucleus. Water vapour, carbon monoxide and carbon dioxide are the most prolific, with a rich array of other nitrogen-, sulphur- and carbon-bearing species, and even noble gases also recorded.

    2
    Comet 67P/Churyumov–Gerasimenko

    ESA Rosetta spacecraft
    Rosetta

    4
    Rosetta’s Philae Lander

    Oxygen is the third most abundant element in the Universe, but the simplest molecular version of the gas, O2, has proven surprisingly hard to track down, even in star-forming clouds, because it is highly reactive and readily breaks apart to bind with other atoms and molecules.

    For example, oxygen atoms can combine with hydrogen atoms on cold dust grains to form water, or a free oxygen split from O2 by ultraviolet radiation can recombine with an O2 molecule to form ozone (O3).

    Despite its detection on the icy moons of Jupiter and Saturn, O2 had been missing in the inventory of volatile species associated with comets until now.

    “We weren’t really expecting to detect O2 at the comet – and in such high abundance – because it is so chemically reactive, so it was quite a surprise,” says Kathrin Altwegg of the University of Bern, and principal investigator of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument, ROSINA.

    ESA Rosetta ROSINA
    ROSINA

    “It’s also unanticipated because there aren’t very many examples of the detection of interstellar O2. And thus, even though it must have been incorporated into the comet during its formation, this is not so easily explained by current Solar System formation models.”

    The team analysed more than 3000 samples collected around the comet between September 2014 and March 2015 to identify the O2. They determined an abundance of 1–10% relative to H2O, with an average value of 3.80 ± 0.85%, an order of magnitude higher than predicted by models describing the chemistry in molecular clouds.

    The amount of molecular oxygen detected showed a strong relationship to the amount of water measured at any given time, suggesting that their origin on the nucleus and release mechanism are linked. By contrast, the amount of O2 seen was poorly correlated with carbon monoxide and molecular nitrogen, even though they have a similar volatility to O2. In addition, no ozone was detected.

    Over the six-month study period, Rosetta was inbound towards the Sun along its orbit, and orbiting as close as 10–30 km from the nucleus. Despite the decreasing distance to the Sun, the O2/H2O ratio remained constant over time, and it also did not change with Rosetta’s longitude or latitude over the comet.

    In more detail, the O2/H2O ratio was seen to decrease for high H2O abundances, an observation that might be influenced by surface water ice produced in the observed daily sublimation–condensation process.

    The team explored the possibilities to explain the presence and consistently high abundance of O2 and its relationship to water, as well as the lack of ozone, by first considering photolysis and radiolysis of water ice over a range of timescales.

    In photolysis, photons break bonds between molecules, whereas radiolysis involves more energetic photons or fast electrons and ions depositing energy into ice and ionising molecules – a process observed on icy moons in the outer Solar System, and in Saturn’s rings. Either process can, in principle, lead to the formation and liberation of molecular oxygen.

    Radiolysis will have operated over the billions of years that the comet spent in the Kuiper Belt and led to the build-up of O2 to a few metres depth.

    5
    Known objects in the Kuiper belt beyond the orbit of Neptune. (Scale in AU; epoch as of January 2015.)

    But these top layers must all have been removed in the time since the comet moved into its inner Solar System orbit, ruling this out as the source of the O2 seen today.

    More recent generation of O2 via radiolysis and photolysis by solar wind particles and UV photons should only have occurred in the top few micrometres of the comet.

    “But if this was the primary source of the O2 then we would have expected to see a decrease in the O2/H2O ratio as this layer was removed during the six-month timespan of our observations,” says Andre Bieler of the University of Michigan and lead author of the paper describing the new results in the journal Nature this week.

    “The instantaneous generation of O2 also seems unlikely, as that should lead to variable O2 ratios under different illumination conditions. Instead, it seems more likely that primordial O2 was somehow incorporated into the comet’s ices during its formation, and is being released with the water vapour today.”

    In one scenario, gaseous O2 would first be incorporated into water ice in the early protosolar nebula stage of our Solar System. Chemical models of protoplanetary discs predict that high abundances of gaseous O2 could be available in the comet forming zone, but rapid cooling from temperatures above –173ºC to less than –243ºC would be required to form water ice with O2 trapped on dust grains. The grains would then have to be incorporated into the comet without being chemically altered.

    “Other possibilities include the Solar System being formed in an unusually warm part of a dense molecular cloud, at temperatures of 10–20ºC above the –263ºC or so typically expected for such clouds,” says Ewine van Dishoeck of Leiden Observatory in the Netherlands, co-author of the paper.

    “This is still consistent with estimates for the comet formation conditions in the outer solar nebula, and also with previous findings at Rosetta’s comet regarding the low abundance of N2.”

    Alternatively, radiolysis of icy dust grains could have taken place prior to the comet’s accretion into a larger body. In this case, the O2 would remain trapped in the voids of the water ice on the grains while the hydrogen diffused out, preventing the reformation of O2 to water, and resulting in an increased and stable level of O2 in the solid ice.

    Incorporation of such icy grains into the nucleus could explain the observed strong correlation with H2O observed at the comet today.

    “Regardless of how it was made, the O2 was also somehow protected during the accretion stage of the comet: this must have happened gently to avoid the O2 being destroyed by further chemical reactions,” adds Kathrin.

    “This is an intriguing result for studies both within and beyond the comet community, with possible implications for our models of Solar System evolution,” says Matt Taylor, ESA’s Rosetta project scientist.

    Abundant molecular oxygen in the coma of 67P/Churyumov–Gerasimenko, by A. Bieler et al is published in the 29 October 2015 issue of the journal Nature.

    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 10:09 am on August 13, 2015 Permalink | Reply
    Tags: , , , ESA Rosetta   

    From SPACE.com: “Comet and Rosetta Spacecraft Make Closest Approach to the Sun” 

    space-dot-com logo

    SPACE.com

    August 13, 2015
    Elizabeth Howell

    Temp 1

    After more than a year in orbit around a comet, the European Rosetta spacecraft and its icy dance partner are hitting a huge milestone: their closest approach to the sun.

    ESA Rosetta spacecraft
    Rosetta

    The Rosetta and its target, Comet 67P/Churyumov–Gerasimenko, reach perihelion today (Aug. 13), when the comet’s 6.5-year orbit brings it within 114.9 million miles (185 million kilometers) of the sun.

    Activity is already exploding on Comet 67P. In late July, Rosetta’s camera caught a jet erupting in the space of less than half an hour. And because it takes about a month for the comet to get its warmest, this means that activity is expected to peak in a few short weeks.

    2

    “The key to the Rosetta mission is that it is there for the long haul. It is there to watch and observe changes in the comet over time, with the same suite of instruments, as opposed to a flyby — or maybe different missions having flybys at different times with different instruments,” said Joel Parker, an interdisciplinary scientist on the mission. He is a research astronomer and director at the Southwest Research Institute in San Antonio, Texas.

    Rosetta arrived in orbit around Comet 67P on Aug. 6, 2014, nearly 10 years after launching into space. In November of last year, the orbiter’s small Philae lander touched down on the comet to study the object’s surface.

    “This is creating the baselines for all future study of comet activity for us to understand what is going on at the small scale, that cannot be observed from Earth or near-Earth observations,” Parker told Space.com.

    Among other things, researchers will learn about how the brightness of a comet increases, which could lead to better predictions for amateur astronomers, he said. Researchers will also look at how the composition of the comet’s emissions (dust and gas) change, which will provide clues about what the early universe looked like.

    How the solar system was

    Comets such as 67P are considered chunks of what the solar system appeared to be early in its formation, before the planets and moons were formed. Studying comets and asteroids therefore helps researchers understand the makeup of the young solar system shortly after its formation 4.5 billion years ago.

    Rosetta is the first spacecraft to orbit a comet and also the first to drop a small probe, the Philae comet lander, on a comet’s surface. Among other findings, the Rosetta mission revealed that the type of water on the comet is different than that of Earth, meaning that comets like 67P could not have delivered water to this planet. The spacecraft also detected organics, a building block to life on Earth, and possibly across the universe.

    There has been some discussion (and dispute) among the Rosetta researchers as to whether the comet’s outgassing will change as the object gets closer to the sun, said Paul Weissman, another Rosetta interdisciplinary scientist who recently retired from NASA’s Jet Propulsion Laboratory in California.

    Solar heating could unveil deeper regions of the comet that were untouched for millions or billions of years, depending on how much bled away when 67P passed by the sun previously.

    “This comet has this unusual … ratio” of the constituents of hydrogen in water, specifically the ratio of a rarer type of hydrogen, called deuterium, to hydrogen, Weissman said. “We’re curious to see if that changes as it goes around the sun and as it gets more active.

    Comet brightness

    It is notoriously difficult for even professional astronomers to predict how bright a comet will appear when it swings by Earth. This is because it’s difficult to see the nucleus (heart) of the comet, Parker said, so measurements are made from observing the comet or atmosphere.

    As Rosetta observes 67P from up close, the spacecraft will see how much gas is coming out, what dust the gas is dragging out and how big the gas particles are, Parker said. Weissman added that these particles could be a centimeter (0.4 inches) across or larger, which is big enough for the comet’s imaging instruments to resolve the individual particles and potentially, track their movements.

    The team will also be observing how the solar wind, the constant stream of gas from the sun, interacts with the comet’s surface and causes changes, Weissman said. The researchers will additionally watch how the coma of the comet – the dusty envelope around its nucleus – flexes when the solar wind hits it.

    Rosetta’s current mission ends on Sept. 30, 2016, when the mission will be operating at about four astronomical units or AU from Earth. (One astronomical unit is the Earth-sun distance, about 93 million miles or 150 million km.) At that point, the spacecraft will be so far from the sun that it will be difficult for its solar panels to collect the energy required to continue operating, so further work after that is unlikely, Weissman said.

    See the full article here.

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  • richardmitnick 3:19 pm on July 13, 2015 Permalink | Reply
    Tags: , , , ESA Rosetta   

    From ESA: “Rosetta: preparing for perihelion” 

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    European Space Agency

    13 July 2015
    No Writer Credit

    ESA Rosetta spacecraft
    Rosetta with Philae

    1
    Comet around perihelion

    Rosetta’s investigations of its comet are continuing as the mission teams count down the last month to perihelion – the closest point to the Sun along the comet’s orbit – when the comet’s activity is expected to be at its highest.

    Rosetta has been studying Comet 67P/Churyumov–Gerasimenko for over a year now, with observations beginning during the approach to the comet in March 2014. This included witnessing an outburst in late April 2014 and the revelation of the comet’s curious shape in early July.

    After arriving at a distance of 100 km from the double-lobed comet on 6 August, Rosetta has spent an intense year analysing the properties of this intriguing body – the interior, surface and surrounding dust, gas and plasma.

    Comets are known to be made of dust and frozen ices. As these ices are warmed by the Sun, they turn directly to vapour, with the gases dragging the comet’s dust along with it. Together, the gas and dust create a fuzzy atmosphere, or coma, and often-spectacular tails extend tens or hundreds of thousands of kilometres into space.

    2
    Comet on 25 June 2015 – NavCam

    While ground-based observations can monitor the development of the coma and tail from afar, Rosetta has a ringside seat for studying the source of this activity directly from the nucleus. One important aspect of Rosetta’s long-term study is watching how the activity waxes and wanes along the comet’s orbit.

    The comet has a 6.5 year commute around the Sun from just beyond the orbit of Jupiter at its furthest, to between the orbits of Earth and Mars at it closest.

    Rosetta rendezvoused with the comet around 540 million km from the Sun. Today, 13 July, a month from perihelion, this distance is much smaller: 195 million km. Currently travelling at around 120 000 km/h around their orbit, Rosetta and the comet will be 186 million km from the Sun by 13 August.

    “Perihelion is an important milestone in any comet’s calendar, and even more so for the Rosetta mission because this will be the first time a spacecraft has been following a comet from close quarters as it moves through this phase of its journey around the Solar System,” notes Matt Taylor, ESA’s Rosetta project scientist.

    “We’re looking forward to reaching perihelion, after which we’ll be continuing to monitor how the comet’s nucleus, activity and plasma environment changes in the year after, as part of our long-term studies.”

    See our FAQ below for more on what can you expect from perihelion and the activities planned around it.

    ————————————————————————-

    Perihelion basics

    4
    Comet’s orbit

    What is perihelion exactly?
    Perihelion is the closest point a Solar System object gets to the Sun along its orbit (aphelion is the term given to the most distant point). The term derives from ancient Greek, where ‘peri’ means near and ‘helios’ means Sun.

    How close to the Sun will the comet be at perihelion?
    Comet 67P/Churyumov–Gerasimenko is on a 6.5 year elliptical orbit around the Sun which takes it between 850 million km (5.68 AU) from the Sun at its most distant, just beyond the orbit of Jupiter, and 186 million km (1.24 AU) at its nearest, between the orbits of Earth and Mars. As a comparison, Earth orbits the Sun at an average distance of 149 million km (1 Astronomical Unit, or AU). .

    At what moment does perihelion occur?
    For this comet, the upcoming perihelion occurs at 02:03 GMT on 13 August 2015. The previous perihelion took place on 28 February 2009.

    The comet during perihelion

    5
    Comet activity 31 January – 25 March 2015

    What happens to the comet during perihelion? Will there be a big difference in activity in the coming weeks?
    The comet’s activity has been growing over the last year that Rosetta has been at the comet. This is an incremental process brought about by the increase in solar energy incident on the comet, warming up its frozen ices that subsequently sublimate. Rosetta has been witnessing this gradual rise, and scientists expect that this activity will reach a peak during August and September. Outbursts are possible, but unpredictable.

    Other comets plunge into the Sun at perihelion, what about this one?
    Comet 67P/Churyumov–Gerasimenko does not get close enough to the Sun to be destroyed by it; its closest point is actually further than Earth ever gets to the Sun and, furthermore, the comet has survived many previous orbits. It is not, for example, classed as a ‘sungrazer’ like Comet C/2012 S1 ISON, which broke apart during its perihelion passage in November 2013.

    Will Comet 67P/C-G break apart during perihelion?
    The comet has not broken apart during its many previous orbits, so it is not expected to do so this time, but it cannot be ruled out. Scientists are keen to watch the possible evolution of a 500 m-long fracture that runs along the surface of the neck on the comet during the peak activity.

    What happens to the comet after perihelion?
    As with the last observed perihelia, we expect the comet to continue on its orbit as normal, away from the Sun and back towards the outer Solar System again. Thanks to the heat absorbed during perihelion, the activity is expected to remain high for a couple of months before gently decreasing towards the moderate activity levels seen earlier in the mission, allowing Rosetta to get closer to the nucleus again.

    Rosetta and Philae during perihelion

    6
    Rosetta approaching comet

    Does Rosetta have to do any special manoeuvres for perihelion?
    Perihelion is a very different milestone to the other events such as waking up from hibernation, arriving at or landing on the comet where critical operations had to be carried out. Perihelion is simply a moment in time, and in terms of operations, it is business as usual – no special manoeuvres are required. The mission team hopes to have Rosetta as close as possible to the comet during perihelion to perform science observations without jeopardising the safety of the spacecraft, but this distance is currently decided on a twice-weekly basis for the week ahead, so the exact distance for perihelion is not currently known. During the last few months, it has not been possible to operate closer than 150 km without running into difficulties caused by the vast amounts of dust around the comet at the present time.

    Are there any special science observations that will be done at the time of perihelion?
    As with operations, it is also business as usual for science observations – monitoring of the comet and its dust, gas and plasma environment will continue during perihelion. Scientists are particularly keen to study the southern hemisphere of the comet, which has been in full sunlight only since May.

    How long will it take Rosetta to communicate with Earth on 13 August?
    The one-way signal travel time on 13 August is 14 min 44 sec.

    When will we see an image from the moment of perihelion?
    Rosetta’s Navigation Camera takes images several times during each 24 hour Earth day for navigation purposes, while the science camera OSIRIS has dedicated imaging slots. While the imaging schedule is not currently known for perihelion, we are hoping to be able to share both NavCam and OSIRIS image(s) with you from around the time of perihelion, during the afternoon of 13 August. Note that for OSIRIS this will depend on the data prioritisation on that day and the time it takes to downlink so this cannot be guaranteed. Time is also needed to check and process the images for release (for both NavCam and OSIRIS). We will update this section if/when more information about the timing of the image release(s) is known.

    Will Rosetta and Philae be safe during perihelion?
    Owing to the large amounts of dust, Rosetta will continue to operate at a safe distance from the comet throughout perihelion. We cannot predict any sudden increases in activity of the comet in advance, but the spacecraft safety remains – as always – a priority.

    Philae is on the surface of the comet, although its exact location remains unknown. Having regained communications with Rosetta on 13 June the link has been unpredictable and intermittent. The mission teams are carefully analysing the situation and hope that Philae will be operational during perihelion (separate updates on Philae’s condition will be made via the Rosetta Blog).

    What will happen to the mission after perihelion?
    Rosetta will continue to follow the comet as it moves back towards the outer Solar System, watching how the activity decreases over time and monitoring any post-perihelion changes that may occur. The Rosetta mission is scheduled to continue until September 2016, when the nominal planning would see Rosetta spiral down to the surface of the comet, where operations would likely end.

    8
    Comet from Earth – 22 May 2015

    Observing the comet from Earth during perihelion

    Why is perihelion interesting for astronomers?
    Near perihelion, comets reach their highest level of brightness, releasing large amounts of gas and dust. Possible outbursts and other unpredictable events might also take place around perihelion, so it is extremely important to obtain as many observations as possible during this period. While ground-based observations provide large-scale context for Rosetta’s measurements, Rosetta’s close-up data provide in turn the possibility to calibrate many of the observations made from the ground. This unique opportunity will also improve the study and interpretation of ground-based observations of other comets.

    How close to Earth will the comet be at perihelion? Is this the closest it gets to Earth?
    While the distance between the comet and the Sun decreases steadily until perihelion, before increasing again afterwards up to aphelion, the distance between Earth and the comet depends on their relative positions in the Solar System. At perihelion, the comet is 265 million km from Earth, but it will be closer (222 million km) during January–February 2016. Follow the positions of Rosetta and the comet through the Solar System using our Where is Rosetta? tool.

    Will astronomers be observing the comet at perihelion?
    Yes, a large network of professional and amateur astronomers has been observing the comet from across the globe in the past months. Observations with professional telescopes are planned every night around perihelion, relying on several robotic telescopes in many locations, and spectroscopic observations will be performed once a week. More details of the professional campaign are available here.

    How can I observe the comet at perihelion?
    Unfortunately, even at perihelion, the comet is too faint to be seen with the naked eye. To observe the comet, you will need a good telescope: a minimum of a 20 cm-aperture telescope is recommended. Guidance on how amateur astronomers can observe the comet is available here How can I observe the comet at perihelion?
    Unfortunately, even at perihelion, the comet is too faint to be seen with the naked eye. To observe the comet, you will need a good telescope: a minimum of a 20 cm-aperture telescope is recommended. Guidance on how amateur astronomers can observe the comet is available here.

    Until when is it possible to observe the comet from Earth?
    The comet is currently passing from the southern sky to the northern sky, so its visibility depends on where you live. Around the time of perihelion, it can be observed from Earth in the early morning hours, just before sunrise. It will remain relatively close to the Sun in the sky, and thus observable in the early morning, for several months. Then, the comet will be in the night sky between December 2015 and March 2016, which will be the prime time for ground-based observations. By the middle of 2016 it will likely be too faint to see except by large telescopes owing to its distance from the Sun and Earth, and it will also start moving behind the Sun as seen from Earth.

    Media

    Will there be any special events to mark the occasion of perihelion?
    Members of the public and media are invited to join an online Google+ Hangout on 13 August, during which we hope to have one or more images on the ground from around the time of perihelion. Time and guests to be announced nearer the time.

    How can I follow online?
    You can follow the mission in a number of ways (see esa.int/rosetta for an overview). On Twitter, official updates will be made by @ESA_Rosetta using the hashtag #perihelion2015. Information will also be provided by the Rosetta blog and on the Rosetta Mission Facebook page. The image(s) from perihelion will be published on our main ESA web portal, esa.int, in an official press release. The Google+ Hangout will also be advertised on esa.int and will be available to watch live via ESA’s G+ page and later as a replay on G+ and ESA’s YouTube channel.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    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 9:58 am on June 23, 2015 Permalink | Reply
    Tags: , , ESA Rosetta   

    From ESA: “Rosetta Mission Extended” 

    ESASpaceForEuropeBanner
    European Space Agency

    23 June 2015
    Markus Bauer







    ESA Science and Robotic Exploration Communication Officer








    Tel: +31 71 565 6799








    Mob: +31 61 594 3 954








    Email: markus.bauer@esa.int

    Patrick Martin
    ESA Rosetta Mission Manager
    Email: Patrick.martin@esa.int

    Matt Taylor






    ESA Rosetta project scientist






    Email: matthew.taylor@esa.int

    1
    Rosetta approaching comet

    The adventure continues: ESA today confirmed that its Rosetta mission will be extended until the end of September 2016, at which point the spacecraft will most likely be landed on the surface of Comet 67P/Churyumov-Gerasimenko.

    Rosetta was launched in 2004 and arrived at the comet in August 2014, where it has been studying the nucleus and its environment as the comet moves along its 6.5-year orbit closer to the Sun. After a detailed survey, Rosetta deployed the lander, Philae, to the surface on 12 November. Philae fell into hibernation after 57 hours of initial scientific operations, but recently awoke and made contact with Rosetta again.

    Rosetta’s nominal mission was originally funded until the end of December 2015, but at a meeting today, ESA’s Science Programme Committee has given formal approval to continue the mission for an additional nine months. At that point, as the comet moves far away from the Sun again, there will no longer be enough solar power to run Rosetta’s set of scientific instrumentation efficiently.

    “This is fantastic news for science,” says Matt Taylor, ESA’s Rosetta Project Scientist. “We’ll be able to monitor the decline in the comet’s activity as we move away from the Sun again, and we’ll have the opportunity to fly closer to the comet to continue collecting more unique data. By comparing detailed ‘before and after’ data, we’ll have a much better understanding of how comets evolve during their lifetimes.”

    Comet 67P/Churyumov-Gerasimenko will make its closest approach to the Sun on 13 August and Rosetta has been watching its activity increase over the last year. Continuing its study of the comet in the year following perihelion will give scientists a fuller picture of how a comet’s activity waxes and wanes along its orbit.

    The extra observations collected by Rosetta will also provide additional context for complementary Earth-based observations of the comet. At present, the comet is close to the line-of-sight to the Sun, making ground-based observations difficult.

    As the activity diminishes post-perihelion, it should be possible to move the orbiter much closer to the comet’s nucleus again, to make a detailed survey of changes in the comet’s properties during its brief ‘summer’.

    In addition, there may be an opportunity to make a definitive visual identification of Philae. Although candidates have been seen in images acquired from a distance of 20 km, images taken from 10 km or less after perihelion could provide the most compelling confirmation.

    During the extended mission, the team will use the experience gained in operating Rosetta in the challenging cometary environment to carry out some new and potentially slightly riskier investigations, including flights across the night-side of the comet to observe the plasma, dust, and gas interactions in this region, and to collect dust samples ejected close to the nucleus.

    As the comet recedes from the Sun, the solar-powered spacecraft will no longer receive enough sunlight to operate efficiently and safely, equivalent to the situation in June 2011 when the spacecraft was put into hibernation for 31 months for the most distant leg of its journey out towards the orbit of Jupiter.

    In addition, Rosetta and the comet will again be close to the Sun as seen from the Earth in October 2016, making operations difficult by then.

    However, with Rosetta’s propellant largely depleted by that time, it makes little sense to place the spacecraft in hibernation again.

    “This time, as we’re riding along next to the comet, the most logical way to end the mission is to set Rosetta down on the surface,” says Patrick Martin, Rosetta Mission Manager.

    “But there is still a lot to do to confirm that this end-of-mission scenario is possible. We’ll first have to see what the status of the spacecraft is after perihelion and how well it is performing close to the comet, and later we will have to try and determine where on the surface we can have a touchdown.”

    If this proposed scenario were played out, then the spacecraft would be commanded to spiral down to the comet over a period of about three months.

    It is expected that science operations would continue throughout this period and be feasible up to very close to the end of mission, allowing Rosetta’s instruments to gather unique data at unprecedentedly close distances.

    Once the orbiter lands on the surface, however, it is highly unlikely to be able to continue operations and relay data back to Earth, bringing to an end one of the most successful space exploration missions of all time.

    About Rosetta
    Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander was provided by a consortium led by DLR, MPS, CNES and ASI. Rosetta is the first mission in history to rendezvous with a comet. It is escorting the comet as they orbit the Sun together. Philae landed on the comet on 12 November 2014. Comets are time capsules containing primitive material left over from the epoch when the Sun and its planets formed. By studying the gas, dust and structure of the nucleus and organic materials associated with the comet, via both remote and in situ observations, the Rosetta mission should become the key to unlocking the history and evolution of our Solar System.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    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 7:41 am on June 20, 2015 Permalink | Reply
    Tags: , , ESA Rosetta,   

    From DLR: “Lander Control Center in contact with Philae once again” 

    DLR Bloc

    German Aerospace Center

    1
    Lander Control Center at DLR – Control Center for Philae

    The team at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) received data from the Philae lander for the third time on 19 June 2015.

    ESA Rosetta Philae Lander
    Philae

    Between 15:20 and 15:39 CEST, Philae sent 185 data packets. “Among other things, we have received updated status information,” says Michael Maibaum, a systems engineer at the DLR Lander Control Center (LCC) in Cologne and Deputy Operations Manager. “At present, the lander is operating at a temperature of zero degrees Celsius, which means that the battery is now warm enough to store energy. This means that Philae will also be able to work during the comet’s night, regardless of solar illumination.” In the 19 minutes of transmission, the lander sent data recorded last week; from this, the engineers determined that the amount of sunlight has increased: “More solar panels were illuminated; at the end of contact, four of Philae’s panels were receiving energy”. There were a number of interruptions in the connection, but it was otherwise stable over a longer period for the first time. “The contact has confirmed that Philae is doing very well.”

    The lander had already reported from the comet twice after its seven-month hibernation; it sent data on 13 and 14 June 2015. The analysis by the DLR team at the LCC was clear – Philae has managed to survive the icy temperatures on Comet 67P/Churyumov-Gerasimenko – temperature and energy values show that the lander is now operational. In the first two contacts, it sent stored data from early May. “Philae was already awake at this time, but could not contact us,” explains DLR’s Philae Project Manager, Stephan Ulamec. Now, the trajectory of the Rosetta orbiter around the comet is being modified to optimise the possibility for renewed contact, to allow the orbiter to act as a relay between Philae and Earth.

    ESA Rosetta spacecraft
    ESA/Rosetta

    “However, we need a long and stable contact time to conduct research with Philae again as planned,” says Maibaum. If these conditions are met, the 10 instruments on board Philae could once again be operated from the LCC.

    See the full article here.

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    DLR Center

    DLR is the national aeronautics and space research centre of the Federal Republic of Germany. Its extensive research and development work in aeronautics, space, energy, transport and security is integrated into national and international cooperative ventures. In addition to its own research, as Germany’s space agency, DLR has been given responsibility by the federal government for the planning and implementation of the German space programme. DLR is also the umbrella organisation for the nation’s largest project management agency.

    DLR has approximately 8000 employees at 16 locations in Germany: Cologne (headquarters), Augsburg, Berlin, Bonn, Braunschweig, Bremen, Goettingen, Hamburg, Juelich, Lampoldshausen, Neustrelitz, Oberpfaffenhofen, Stade, Stuttgart, Trauen, and Weilheim. DLR also has offices in Brussels, Paris, Tokyo and Washington D.C.

     
  • richardmitnick 10:33 am on June 2, 2015 Permalink | Reply
    Tags: , , , ESA Rosetta   

    From ESA: “Ultraviolet study reveals surprises in comet coma” 

    ESASpaceForEuropeBanner
    European Space Agency

    For more information, please contact:

    Markus Bauer







    ESA Science and Robotic Exploration Communication Officer








    Tel: +31 71 565 6799








    Mob: +31 61 594 3 954








    Email: markus.bauer@esa.int

    Paul Feldman
    Johns Hopkins University, Baltimore
    Email: pfeldman@jhu.edu

    Matt Taylor






    ESA Rosetta project scientist






    Email: matthew.taylor@esa.int

    Rosetta’s continued close study of Comet 67P/Churyumov–Gerasimenko has revealed an unexpected process at work, causing the rapid breakup of water and carbon dioxide molecules spewing from the comet’s surface.

    ESA Rosetta spacecraft
    Rosetta

    ESA’s Rosetta mission arrived at the comet in August last year. Since then, it has been orbiting or flying past the comet at distances from as far as several hundred kilometres down to as little as 8 km. While doing so, it has been collecting data on every aspect of the comet’s environment with its suite of 11 science instruments.

    One instrument, the Alice spectrograph provided by NASA, has been examining the chemical composition of the comet’s atmosphere, or coma, at far-ultraviolet wavelengths.

    At these wavelengths, Alice allows scientists to detect some of the most abundant elements in the Universe such as hydrogen, oxygen, carbon and nitrogen. The spectrograph splits the comet’s light into its various colours – its spectrum – from which scientists can identify the chemical composition of the coma gases.


    Rosetta’s imaging and spectroscopy instruments

    In a paper accepted for publication in the journal Astronomy and Astrophysics, scientists report the detections made by Alice from Rosetta’s first four months at the comet, when the spacecraft was between 10 km and 80 km from the centre of the comet nucleus.

    For this study, the team focused on the nature of ‘plumes’ of water and carbon dioxide gas erupting from the comet’s surface, triggered by the warmth of the Sun. To do so, they looked at the emission from hydrogen and oxygen atoms resulting from broken water molecules, and similarly carbon atoms from carbon dioxide molecules, close to the comet nucleus.

    They discovered that the molecules seem to be broken up in a two-step process.

    First, an ultraviolet photon from the Sun hits a water molecule in the comet’s coma and ionises it, knocking out an energetic electron. This electron then hits another water molecule in the coma, breaking it apart into two hydrogen atoms and one oxygen, and energising them in the process. These atoms then emit ultraviolet light that is detected at characteristic wavelengths by Alice.

    Similarly, it is the impact of an electron with a carbon dioxide molecule that results in its break-up into atoms and the observed carbon emissions.

    “Analysis of the relative intensities of observed atomic emissions allows us to determine that we are directly observing the ‘parent’ molecules that are being broken up by electrons in the immediate vicinity, about 1 km, of the comet’s nucleus where they are being produced,” says Paul Feldman, professor of physics and astronomy at the Johns Hopkins University in Baltimore, and lead author of the paper discussing the results.

    By comparison, from Earth or from Earth-orbiting space observatories such as the Hubble Space Telescope, the atomic constituents of comets can only be seen after their parent molecules, such as water and carbon dioxide, have been broken up by sunlight, hundreds to thousands of kilometres away from the nucleus of the comet.

    2
    Comet on 20 May 2015 – NavCam

    “The discovery we’re reporting is quite unexpected,” says Alice Principal Investigator Alan Stern, an associate vice president in the Space Science and Engineering Division of the Southwest Research Institute (SwRI).

    “It shows us the value of going to comets to observe them up close, since this discovery simply could not have been made from Earth or Earth orbit with any existing or planned observatory. And, it is fundamentally transforming our knowledge of comets.”

    “By looking at the emission from hydrogen and oxygen atoms broken from the water molecules, we also can actually trace the location and structure of water plumes from the surface of the comet,” adds co-author Joel Parker, an assistant director in SwRI’s Space Science and Engineering Division in Boulder, Colorado.

    The team likens the break-up of the molecules to the process that has been proposed for the plumes on Jupiter’s icy moon Europa, except that the electrons at the comet are produced by solar photons, while the electrons at Europa come from Jupiter’s magnetosphere.

    The results from Alice are supported by data obtained by other Rosetta instruments, in particular MIRO, ROSINA and VIRTIS, which are able to study the abundance of different coma constituents and their variation over time, and particle detecting instruments like RPC-IES.

    “These early results from Alice demonstrate how important it is to study a comet at different wavelengths and with different techniques, in order to probe various aspects of the comet environment,” says ESA’s Rosetta project scientist Matt Taylor.

    “We’re actively watching how the comet evolves as it moves closer to the Sun along its orbit towards perihelion in August, seeing how the plumes become more active due to solar heating, and studying the effects of the comet’s interaction with the solar wind.”

    More information

    Measurements of the near-nucleus coma of Comet 67P/Churyumov-Gerasimenko with the Alice far-ultraviolet spectrograph on Rosetta, by P Feldman et al is accepted for publication in Astronomy and Astrophysics.

    About Rosetta
    Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander was provided by a consortium led by DLR, MPS, CNES and ASI.

    ESA Rosetta Philae Lander
    Rosetta’s Philae lander

    Rosetta is the first mission in history to rendezvous with a comet. It is escorting the comet as they orbit the Sun together. Philae landed on the comet on 12 November 2014. Comets are time capsules containing primitive material left over from the epoch when the Sun and its planets formed. By studying the gas, dust and structure of the nucleus and organic materials associated with the comet, via both remote and in situ observations, the Rosetta mission should become the key to unlocking the history and evolution of our Solar System.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    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 11:27 am on March 21, 2015 Permalink | Reply
    Tags: , , ESA Rosetta   

    From ESA: “Rosetta makes first detection of molecular nitrogen at a comet” 

    ESASpaceForEuropeBanner
    European Space Agency

    19 March 2015

    Markus Bauer





    ESA Science and Robotic Exploration Communication Officer






    Tel: +31 71 565 6799






    Mob: +31 61 594 3 954






    Email: markus.bauer@esa.int

    Martin Rubin
    University of Bern, Switzerland
    Email: martin.rubin@space.unibe.ch

    Kathrin Altwegg

    Principal investigator for ROSINA

    University of Bern, Switzerland

    Email: kathrin.altwegg@space.unibe.ch

    Matt Taylor




    ESA Rosetta project scientist




    Email: matthew.taylor@esa.int

    1
    First detection of molecular nitrogen at a comet

    ESA’s Rosetta spacecraft has made the first measurement of molecular nitrogen at a comet, providing clues about the temperature environment in which Comet 67P/Churyumov–Gerasimenko formed.

    ESA Rosetta spacecraft
    Rosetta

    Rosetta arrived last August, and has since been collecting extensive data on the comet and its environment with its suite of 11 science instruments.

    The in situ detection of molecular nitrogen has long been sought at a comet. Nitrogen had only previously been detected bound up in other compounds, including hydrogen cyanide and ammonia, for example.

    Its detection is particularly important since molecular nitrogen is thought to have been the most common type of nitrogen available when the Solar System was forming. In the colder outer regions, it likely provided the main source of nitrogen that was incorporated into the gas planets. It also dominates the dense atmosphere of Saturn’s moon, Titan, and is present in the atmospheres and surface ices on Pluto and Neptune’s moon Triton.

    It is in these cold outer reaches of our Solar System in which the family of comets that includes Rosetta’s comet is believed to have formed.

    2
    Comet on 14 March 2015 – NavCam

    The new results are based on 138 measurements collected by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument, ROSINA, during 17–23 October 2014, when Rosetta was about 10 km from the centre of the comet.

    “Identifying molecular nitrogen places important constraints on the conditions in which the comet formed, because it requires very low temperatures to become trapped in ice,” says Martin Rubin of the University of Bern, lead author of the paper presenting the results published today in the journal Science.

    The trapping of molecular nitrogen in ice in the protosolar nebula is thought to take place at temperatures similar to those required to trap carbon monoxide. So in order to put constraints on comet formation models, the scientists compared the ratio of molecular nitrogen to carbon monoxide measured at the comet to that of the protosolar nebula, as calculated from the measured nitrogen to carbon ratio in Jupiter and the solar wind.

    That ratio for Comet 67P/Churyumov–Gerasimenko turns out to be about 25 times less than that of the expected protosolar value. The scientists think that this depletion may be a consequence of the ice forming at very low temperatures in the protosolar nebula.

    One scenario involves temperatures of between roughly –250ºC and perhaps –220ºC, with relatively inefficient trapping of molecular nitrogen in either amorphous water ice or cage-like water ice known as a clathrate, in both cases yielding a low ratio directly.

    3
    Comet’s orbit

    Alternatively, the molecular nitrogen could have been trapped more efficiently at even lower temperatures of around –253ºC in the same region as Pluto and Triton, resulting in relatively nitrogen-rich ices as seen on them.

    Subsequent heating of the comet through the decay of radioactive nuclides, or as Rosetta’s comet moved into orbits closer to the Sun, could have been sufficient to trigger outgassing of the nitrogen and thus a reduction of the ratio over time.

    “This very low-temperature process is similar to how we think Pluto and Triton have developed their nitrogen-rich ice and is consistent with the comet originating from the Kuiper Belt,” says Martin.

    The only other body in the Solar System with a nitrogen-dominated atmosphere is Earth. The current best guess at its origin is via plate tectonics, with volcanoes releasing nitrogen locked in silicate rocks in the mantle.

    However, the question remains as to the role played by comets in delivering this important ingredient.

    “Just as we wanted to learn more about the role of comets in bringing water to Earth, we would also like to place constraints on the delivery of other ingredients, especially those that are needed for the building blocks of life, like nitrogen,” says Kathrin Altwegg, also at the University of Bern, and principal investigator for ROSINA.

    To assess the possible contribution of comets like Rosetta’s to the nitrogen in Earth’s atmosphere, the scientists assumed that the isotopic ratio of 14N to 15N in the comet is the same as that measured for Jupiter and solar wind, which reflects the composition of the protosolar nebula.

    However, this isotopic ratio is much higher than measured for other nitrogen-bearing species present in comets, such as hydrogen cyanide and ammonia.

    Earth’s 14N/15N ratio lies roughly between these two values, and thus if there was an equal mix of the molecular form on the one hand, and in hydrogen cyanide and ammonia on the other in comets, it would be at least conceivable that Earth’s nitrogen could have come from comets.

    “However, the amount of nitrogen found in 67P/Churyumov–Gerasimenko is not an equal mix between molecular nitrogen and the other nitrogen-bearing molecules. Rather, there is 15 times too little molecular nitrogen, and therefore Earth’s 14N/15N ratio cannot be reproduced through delivery of Jupiter family comets like Rosetta’s,” says Martin.

    “It’s another piece of the puzzle in terms of the role of Jupiter family comets in the evolution of the Solar System, but the puzzle is by no means finished yet,” says ESA’s Rosetta project scientist, Matt Taylor

    “Rosetta is about five months away from perihelion now, and we’ll be watching how the composition of the gases changes over this period, and trying to decipher what that tells us about the past life of this comet.”

    Molecular nitrogen in comet 67P/Churyumov-Gerasimenko indicates a low formation temperature, by M. Rubin et al is published in the 20 March issue of the journal Science. 10.1126/science.aaa6100

    ROSINA is the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument and comprises two mass spectrometers: the Double Focusing Mass Spectrometer (DFMS) and the Reflectron Time of Flight mass spectrometer (RTOF) – and the COmetary Pressure Sensor (COPS). The measurements reported here were conducted with DFMS. The ROSINA team is led by Kathrin Altwegg of the University of Bern, Switzerland.

    An average ratio of N2/CO = (5.70 +/- 0.66) x 10–3 was determined for the period 17–23 October 2014. The minimum and maximum values measured were 1.7 x 10–3 and 1.6 x 10–2, respectively. Because the amount and composition of the gases change with comet rotation and position of the spacecraft with respect to the comet’s surface, an average value is used.

    The 14N/15N ratio for the N2 in Comet 67P/Churyumov–Gerasimenko is assumed to be 441, the value for the protosolar nebula as measured from Jupiter and the solar wind, while the corresponding value for nitrogen in hydrogen cyanide and ammonia is 130, as measured at other comets. The value for the Earth’s nitrogen is 272.

    Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander was provided by a consortium led by DLR, MPS, CNES and ASI.

    ESA Rosetta Philae Lander
    Philae lander

    Rosetta is the first mission in history to rendezvous with a comet. It is escorting the comet as they orbit the Sun together. Philae landed on the comet on 12 November 2014. Comets are time capsules containing primitive material left over from the epoch when the Sun and its planets formed. By studying the gas, dust and structure of the nucleus and organic materials associated with the comet, via both remote and in situ observations, the Rosetta mission should become the key to unlocking the history and evolution of our Solar System.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    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 5:21 pm on January 22, 2015 Permalink | Reply
    Tags: , , , ESA Rosetta,   

    From Nature: “Science pours in from Rosetta comet mission” 

    Nature Mag
    Nature

    22 January 2015
    Elizabeth Gibney

    The first major haul of research from the European Space Agency’s Rosetta mission, published in seven papers in Science on 22 January, reveals a rich and diverse landscape on 67P/Churyumov–Gerasimenko, the most studied comet in history. The best images from the haul are pictured below.

    1
    Charting gravity
    Using data from the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) and the Radio Science Investigation instrument, the Rosetta mission team calculated the comet’s gravitational field1. The gravitational potential (pictured) also takes into account a pull caused by the comet’s rotation. The resulting force is greatest on top of the lobes, but it is about six times weaker in the neck region, where dust can lift off more easily. The team also used the data to calculate the comet’s density, finding that the body is relatively fluffy and porous — with a density of around half that of water, giving clues as to its structure and strength.

    2
    Different terrains
    Images taken by the OSIRIS camera reveal vastly different kinds of terrain, including dunes, ripples and fractures2. Rosetta scientists have split the comet into regions defined by surface structure (see false-colour image), with each named after an Egyptian god. Hatmehit, for example, is a smooth depression on the ‘head’ of the duck-shaped comet that could be a dust-filled impact crater. Other areas, such as Seth and Hathor, are rough with steep cliff-like structures. However, the porosity of the comet means that rock-like structures are in fact compacted dust. Many structures look as though they are formed by gas moving dust around the surface, say the authors, in the same way that wind shapes sand in a desert

    3
    Clues to the origins
    Detailed pictures, at their best with a resolution of 15 centimetres per pixel, show structures that could hint at the comet’s history1. Three-metre-wide features nicknamed “goosebumps”, pictured here running down the inside of a pit in the Seth region, are found all over the comet. Holger Sierks of the Max Planck Institute for Solar System Research in Göttingen, Germany, who is principal investigator on the OSIRIS camera instrument, says that the pebble-like shapes could hint at the scale on which grains of dust and ice first clumped together in the early Solar System. “The hypothesis is these might be the building blocks of comets,” he says.

    4
    The neck riddle
    Data from several instruments show that the comet’s neck is the source of most of its streaming gas and dust. To understand why the region is so active, the Rosetta team looked at how much thermal energy hits the surface per 12.4-hour rotation (left) and per 6.5-year solar orbit (right). The neck receives less energy from the Sun than the rest of the comet because it is shaded, but they found that a suntrap effect from radiation bouncing between opposite cliff walls goes some way towards compensating for that. Other possible reasons for the region’s high activity include its low gravitational pull, which means that little force is needed to blow dust away, and that the region might have a different composition than other regions, or have more ready access to water beneath the surface1. The team has still to answer whether the neck denotes a join between two comets or has been carved out of a single comet by erosion. Evidence of differences between the two lobes would indicate the former, but so far the two lobes seem to have very similar structures, says Sierks.

    6
    Coming from afar
    This visible and infrared portrait of 67P’s surface, obtained by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS), shows an abundance of opaque, organic compounds, but very little water ice. This would be consistent with an origin for the comet in the distant Kuiper belt — beyond the orbit of Neptune — rather than closer to Jupiter, as its current orbit would suggest.

    References
    1.Sierks, H. et al. Science http://dx.doi.org/10.1126/science.aaa1044 (2015)
    2.Thomas, N. et al. Science http://dx.doi.org/10.1126/science.aaa0440 (2015)
    3.Hässig, M. et al. Science http://dx.doi.org/10.1126/science.aaa0276 (2015)
    4.Capaccioni, F. et al. Science http://dx.doi.org/10.1126/science.aaa0628 (2015)
    6.Gulkis, S. et al. Science http://dx.doi.org/10.1126/science.aaa0709 (2015)

    Additional reporting by Davide Castelvecchi

    See the full article here.

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