Page 5 of 6 FirstFirst 123456 LastLast
Results 61 to 75 of 90

Thread: Rosetta and 67P/Churyumov-Gerasimenko

  1. #61
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    COSIMA:
    • A lot of particles were collected by COSIMA during two "dust storms" in last two weeks, total "harvest" so far is 100 times of expectation
    • Larger dust grains collected by Cosima seem themselves to be small "rubble piles" collapsing into a small pile of smaller particles after impacting the collector at slow speed
    • Dust grains are mostly irregular shaped and are covered in "pits" on their surface
    • One of the grains - nicknamed "Nick", all surveyed grains are named get people names - actually moved after it had been collected. They don't know what force moved them, one proposal is that some larger piles might be venting gas like "mini comets" themselves.


    Seriously, this is the kind of science that gives us more understanding how our solar system formed. From the smallest particle in the solar nebula upwards to rocks, to planetesimals, to planets. Just awesome.

    Presentation for Rosetta's RPC instrument complex should be next.

  2. #62
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    Modeled terrain at Philae's final landing site:

    Philae Lander's Setting on Comet, with Cliff-Image Inset | NASA

    Moderately current picture (Dec 17th, 5 am UTC) - only 12 hours old when they posted it:

    December 2014 View of Rosetta's Destination Comet | NASA

  3. #63
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    Orbital operations:

    • since delivery of Philae, Rosetta has been at a circular 20 km orbit over the terminator plane of the comet again
    • on saturday and wednesday two burns will lift Rosetta into a Hohmann transfer orbit to a circular 30 km orbit
    • Rosetta will remain at this altitude until mid-February
    • Rosetta will then perform a number of eccentric orbits, close and distant flybys of the comet etc
    • this is due to the coma getting more turbulous and hence harder to navigate (see "snowstorm" in science results); Rosetta effectively has to evade into deeper space
    • during the early phase, Rosetta will perform a number of flybys taking her as close as possible to the comet, in order to produce high-res pictures of the surface and to sample the inner coma directly
    • the closest flyby will be the first; Rosetta will move itself out of the 30 km orbit into a position 140 km away from the comet, and will then - on Valentine's Day - plunge back towards the comet in a hyperbolic orbit taking it to by the surface at the minimum safety distance of about 5-6 km. This is similar to how Rosetta moved for Philae's delivery, just with an even sharper inflight angle.
    • Rosetta will continue doing such flybys at larger distances for the next six months
    • During August 2015, at perihelion, Rosetta will fly directly into a jet above a venting pit in order to sample the jet's gas and dust itself.
    • All orbital movements beginning in February will be planned with dual paths; one "optimal for science" and one "safe for passage" based upon the environment (coma, dust clouds, jets...) which always takes first place.


    Philae's possible reawakening and potential survival way beyond the original planned maximum (March) may see some adaptions of the above. Around this time (probably March/April) there'll also be a decision on whether to fund Rosetta's mission to continue past its own planned end end of 2015. The mission extension would see Rosetta monitoring the comet as it becomes dormant again while it moves back out away from the sun, passing through the asteroid belt in 2016 and moving towards Jupiter.
    Last edited by kato; 19 Dec 14, at 00:36.

  4. #64
    Military Professional
    Join Date
    06 Aug 03
    Posts
    29,353
    Wow
    Chimo

  5. #65
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    Science magazine and the American Association for the Advancement of Science (AAAS) named the European Space Agency’s Rosetta mission as the scientific breakthrough of the year on Thursday.

    “It was a genuine first in planetary science, and that doesn’t happen very often,” says Science’s deputy news editor Robert Coontz, who is responsible for putting together the breakthroughs of the year feature. “This is the first time anybody’s landed on a comet.”
    Newsweek: Top Science Breakthroughs of 2014: Rosetta Tops Science Magazine’s List

    Whatever data Philae did manage to return will be significant, not least because 67P is just the seventh place beyond Earth explored by a lander. (Venus, Mars, the moon, Saturn's moon Titan, and two asteroids are the others.) Yet the importance of the landing was largely emotional and symbolic. Mission managers have suggested that 80% of the overall science return would come from Philae's mother ship, Rosetta, which reached the comet in August and has been orbiting it ever since, scrutinizing it from as close as 10 kilometers away. That broader achievement, and the cornucopia of information it is yielding, are what Science is celebrating as 2014's Breakthrough of the Year.
    Science: Comet Breakthrough of the Year + People's choice


    (1-minute Rosetta mission summary at 03:55)
    Last edited by kato; 19 Dec 14, at 16:34.

  6. #66
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    This is what the comet looked like for NAVCAM a week ago on the 16th, complete with jets all over. Taken from 28.4 km at 2.4 m/pixel resolution. For reference, the Cheops boulder is in the "sandy" field on the left side.

    Attachment 38996
    Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

    ---

    Full-resolution OSIRIS picture taken from 8 km distance, at 15 cm/pixel resolution:

    http://www.esa.int/var/esa/storage/i..._from_8_km.jpg

    Science actually has that on its cover.

    A number of (quite awesome!) OSIRIS pictures have been released, available through the following two links:

    Getting to know Rosetta
    Getting to know Rosetta

    These include:


    (warning: some of the high-res pictures are rather large - up to 10 MB; in general not directly linked therefore; i think some of the larger uploaded pictures may also not be complete)

    The following two Science articles from the current issue have even more (!) OSIRIS pictures:

    http://www.sciencemag.org/content/347/6220/aaa1044.full
    http://www.sciencemag.org/content/347/6220/aaa0440.full

    These also includes regions previously seen with explanations regarding surface features.

    In case anyone wonders about those round, shallow pits seen occasionally for example:

    The Maftet region has several irregular-shaped pits, 10 to 20 m deep and 100 to 150 m in scale. On the surrounding terrain, there are blocks of similar size (fig. S8). A possible interpretation of these observations is that gas pressure, building in a subsurface pocket (30), overcomes the overburden and the cohesive strength of the material. A block or chunk is then ejected by the expanding gas. In the case of Fig. 7, left, and Aten, sufficient energy was apparently available to eject the material from the area completely. For Maftet, insufficient energy was available, and the block was therefore deposited on adjacent terrains.

    As in "watch out, there's a 50-meter boulder flying towards you". Ejected by a CO2 bubble.

    This article on GIADA's results, posted yesterday, also has one interesting line on that near the bottom: GIADA

    When the comet starts to eject bigger clumps (metre-sized clumps at next perihelion, as already observed in the bound cloud as being remnants from the last perihelion), ...

    Some of the first science papers have been published regarding things Rosetta has found. This includes e.g. a treatise on comet comas with this quite interesting graphic showing that the outgassing - unlike what's been seen from Earth before - at closer range and better resolution is anything but uniform. The graphic shows the ratio between CO2 and H2O emitted, which as already posted a while ago, shows crass differences depending on the area of the comet. There's speculation that 67P/C-G may have formed from multiple small objects originated in entirely different parts of the solar system, which would revolutionize comet science.

    The comet is also now growing a decent atmosphere and is in the process of developing a magnetosphere soon: Watching the birth of a comet magnetosphere | Rosetta - ESA's comet chaser
    Last edited by kato; 22 Jan 15, at 22:40.

  7. #67
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    Quote Originally Posted by kato View Post
    When the comet starts to eject bigger clumps (metre-sized clumps at next perihelion, as already observed in the bound cloud as being remnants from the last perihelion), ...
    A bit more exactly:

    • OSIRIS was used on August 4th in a concerted campaign to image the surroundings of the comet.
    • 25 pictures in 5 sets were taken, with Rosetta at 275 km from the comet.
    • some 353 micro-asteroids were found, orbiting in a cloud at up to 145 km distance from the comet.
    • calculated by mean albedo, these micro-asteroids have been estimated to be between 0.2cm and 2 meters in diameter
    • one of the images taken can be found here, with the numbers labelling the individual objects. The comet nucleas is visible at the top center of the image.
    • these bound objects will be re-examined when Rosetta is further away from the comet again, which it is moving for now.


    • some 48 outbound considerably smaller objects were imaged in the same campaign.
    • this was essentially small pebbles that had been ejected the previous day from the comet, and that were at less than 20 km distance within the cone of vision of OSIRIS.
    • these pebbles were up to 1.7cm in diameter
    • these were streaking away from the comet at higher speeds (up to around 3 m/s?)
    • the tracks of the three brightest of these are labeled in the above linked pictures (a, b, c)


    They have also released a "Where's Waldo" picture for their search for Philae.

    http://www.esa.int/spaceinimages/Ima...er_search_area

    Philae is suspected to be somewhere in the red ellipse, and at the resolution of this 16 megapixel composite would be about 3 pixels wide. Agilkia, the original planned landing site, is visible at the top left - basically the high plain at the horizon, which is the border region between the crater "Hatmehit" and the high plain "Maftet". The rougher terrain "below" the crater in which the lander ellipse is located is called "Bastet". They have also released a picture in which they think they spotted Philae mid-bounce over the rim of Hatmehit towards Bastet:

    http://www.esa.int/spaceinimages/Ima...bove_the_comet
    Last edited by kato; 30 Jan 15, at 19:49.

  8. #68
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    Dr Ulamec said consideration was given to bringing in military imaging experts to help with the analysis, but it was concluded that looking for probes on comets was a very different task to hunting for camouflaged tanks.
    BBC News - Controllers now banking on Philae wake-up call

  9. #69
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    This one is the latest NAVCAM picture showing Hatmehit, from January 18th. I've circled the rough area where Philae should be; probably in the shadow right next to that knob. Compared to earlier pictures of the area, we're already seeing a change in seasons - in that the final landing area is already far better lit than it used to be two months ago, when that area was entirely cast in shadows.

    Attachment 39083

    Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

    P.S.: Resolution is about 2.4 meters per pixel.
    Last edited by kato; 31 Jan 15, at 22:43.

  10. #70
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    Rosetta ended its bound orbit phase yesterday, and has dropped out of orbit of 67P/C-G.

    For the rest of the year Rosetta will, instead of orbiting the comet, move alongside it on its heliocentric path. After perihelion - that's Aug 13th - the team will decide whether to return to bound orbits of the comet nucleus, partly dependent on whether the mission gets extended into 2016 - decision for that is in May.

    Rosetta is currently enroute to a point 140 km from the surface, with arrival there planned for the 7th. From there and similar distant points it will then perform flybys through the coma. The first flyby will take Rosetta to within 4 km from the surface, cruising across Imhotep regio, i.e. the region with the Cheops boulder. At this distance Osiris will be capable of a resolution of under 8 cm/pixel; the flyby is also timed such that Rosetta will be able to take photos completely without shadows, especially without its own. Later flybys will occur at distances of about 13 to 100 km from the surface. Some will be planned to be in lockstep with the comet's rotation, giving Rosetta the opportunity to monitor a single point for multiple days. The more distant flybys will be used for wide-angle shots of the coma - including the cloud of micro-asteroids in orbit - as well as researching the coma on a larger scale. During late July or early August, a flyby directly through a comet jet is also planned.

    These flybys constitute the main science mission phase of Rosetta, which only starts now.

    The comet on January 22nd:

    Attachment 39125
    ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

  11. #71
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    Probably the last Navcam picture from the 28 km orbit - taken on January 31st and showing the entire comet in a picture spanning 4.6x4.3 km :

    Attachment 39151

    ESA/Rosetta/NAVCAM CC BY-SA IGO 3.0

    Rosetta left orbit four days later, and should be arriving at the 140 km point today.

  12. #72
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    Quote Originally Posted by kato View Post
    Probably the last Navcam picture from the 28 km orbit
    Well, they snapped another one just before leaving.

    This one, also from 28 km and looking like it's high time to leave:

    Attachment 39186
    ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

    The above is a mosaic of four pictures.


    Three days later, Rosetta took this picture of the comet from 124 km distance:

    Attachment 39187
    ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

    This one is the first single NAVCAM picture Rosetta has taken that fit the entire comet, i.e. in comparison to the one above this one is 2x enlarged.

    Both pictures above have been processed somewhat to emphasize comet activity, which in the second picture also brings out the objects in its surroundings - the image isn't really grainy with artefacts, many of those are the one- to eight-feet pieces orbiting the comet after being ejected from it.

    Rosetta is on the way back in for its close flyby, currently at about 100 km distance. The flyby will occur on saturday around noon GMT. NAVCAM is preprogrammed to take pictures before and after closest flyby, which will be downloaded from Rosetta on sunday or monday (NAVCAM has relatively low priority in the datastream, being only an engineering add-on and not scientific).
    Last edited by kato; 11 Feb 15, at 20:31.

  13. #73
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    February 9th, from 105 km:

    Attachment 39199
    ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

    The flyby will go over the large lobe, i.e. in this picture over the "top" of the comet. After the flyby Rosetta will move even farther out, up to 250 km from the comet, and then return for more flybys.

    Data return from Rosetta currently is relatively low due to the position of the comet and Rosetta - they're on almost exactly the opposite side of the sun from us, roughly on the inner side of the asteroid belt. About 1.3 AU outwards from SEL3. The sun interferes with communications, much like it does with e.g. STEREO which is currently near SEL3.

    You can find the exact position here:
    Where is Rosetta?

  14. #74
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    Realtime simulation of Rosetta's view:

    http://comsim.esac.esa.int/rossim/bgrieger/ROSETTANOW/

  15. #75
    Senior Contributor
    Join Date
    05 Sep 06
    Posts
    4,010
    Flyby special: Four different NAVCAM pictures

    CometWatch 14 February

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Darwinism's Rosetta stone
    By Parihaka in forum Science & Technology
    Replies: 4
    Last Post: 24 Nov 09,, 19:34

Share this thread with friends:

Share this thread with friends:

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •