Rosetta’s Grain Impact Analyser and Dust Accumulator, GIADA, has detected its first dust grains. This is the first time in cometary space exploration that dust has been collected so close to the nucleus and at such large distances from the Sun.
GIADA is one of three instruments on-board Rosetta, along with COSIMA and MIDAS, designed to provide information about dust associated with comet 67P/Churyumov-Gerasimenko (follow the links to read earlier blog posts about the roles of COSIMA and MIDAS). GIADA’s role is to measure the number, mass, momentum, and velocity distribution of dust grains in the near-comet environment, as well as supporting the characterisation of any dust emitting areas on the surface of the comet.
Comet dust grains are thought be a combination of silicates, organics and some minor constituents. These grains are encased in the various ices of the nucleus and released as the ice sublimates (changes to a gas) when warmed by the Sun. Dust grains form part of the coma around the comet and, later the dust tail.
Peer over cliffs and onto the boulder-strewn 'neck' region, marvel at the layers in the exposed cliff face, and ponder the formation of the numerous crater-like depressions in this amazing 3D view of comet 67P/C-G
The anaglyph image can be viewed using stereoscopic glasses with red–green/blue filters. The two images used ... were taken on 7 August 2014, from a distance of 104 kilometres through the orange filter of the OSIRIS narrow-angle camera. They are separated by 17 minutes and the exposure time is 138 milliseconds.
... Each day we're getting views of the nucleus from more directions. There are amazing features everywhere, but it's really hard to orient myself on this crazy-shaped world, and that makes it hard to figure out whether I'm looking at the same thing from one image to the next. I figure other observers are having the same problem, so I thought I'd put together some images that will help all of us navigate around Rosetta's new home! ...
Today: a quick recap of Rosetta orbital manoeuvres in the past fortnight since arrival at Comet 67P/C-G on 6 August. Today’s post is covers multiple manoeuvres, which means that the mission operations teams and flight dynamics experts at ESOC have been busy ensuring that everything is happening when it should!
First, before we go any further, a mandatory video! We say ‘mandatory’ because this animation explains in rather good detail what Rosetta has been doing and covers the current time frame up to the end of September. OK – lets watch:
Click to play embedded YouTube video.
(In this animation the comet is an artist’s impression and is not to scale with the spacecraft. The comet rotation is not representative (67P rotates once per 12.4 hours). Dates may be subject to change.)
...
• It’s important to note Rosetta has not been captured by 67P/C-G gravity, and the continuing series of thruster burns are necessary to keep the spacecraft at the comet.
• The craft will execute two of these triangular orbits, referred to by the mission team at ESOC as ‘Close Approach Trajectory’ (CAT); there will be one large, at about 100km closest pass-by distance (‘Big CAT’) and the second will be done at about 50km (‘Little CAT’). This means that the thruster burns are not only changing Rosetta’s direction on each arc, but are also lowering the pass-by distance (i.e. altitude) as well.
There's a lot more detail on the blog post and some very useful further information in the comments section.
Re: ESA: Rosetta: 100 days to wake-up
Posted: Mon Aug 25, 2014 9:17 pm
by MargaritaMc
ESA:ROSETTA LANDING SITE SEARCH NARROWS
Using detailed information collected by ESA’s Rosetta spacecraft during its first two weeks at Comet 67P/Churyumov-Gerasimenko, five locations have been identified as candidate sites to set down the Philae lander in November – the first time a landing on a comet has ever been attempted.
Before arrival, Comet 67P/Churyumov-Gerasimenko had never been seen close up and so the race to find a suitable landing site for the 100 kg lander could only begin when Rosetta rendezvoused with the comet on 6 August.
The landing is expected to take place in mid-November when the comet is about 450 million km from the Sun, before activity on the comet reaches levels that might jeopardise the safe and accurate deployment of Philae to the comet’s surface, and before surface material is modified by this activity.
...[there is considerably more info at the news release on the website, including examination of each of the potential landing sites .]
The surface of comet 67P/Churyumov-Gerasimenko can be divided into several morphologically different regions.
High-resolution images of comet 67P/Churyumov-Gerasimenko reveal a unique, multifaceted world. ESA's Rosetta spacecraft arrived at its destination about a month ago and is currently accompanying the comet as it progresses on its route toward the inner solar system. Scientists have now analyzed images of the comet's surface taken by OSIRIS, Rosetta's scientific imaging system, and allocated several distinct regions, each of which is defined by special morphological characteristics. This analysis provides the basis for a detailed scientific description of 67P's surface. It was presented today at the European Planetary Science Congress 2014.
"Never before have we seen a cometary surface in such detail", says OSIRIS Principal Investigator Holger Sierks from the Max Planck Institute for Solar System Research (MPS) in Germany. In some of the images, one pixel corresponds to 75 centimeters scale on the nucleus. "It is a historic moment, we have an unprecedented resolution to map a comet", he adds.
With areas dominated by cliffs, depressions, craters, boulders or even parallel grooves, 67P displays a multitude of different terrains. While some of these areas appear to be quiet, others seem to be shaped by the comet's activity. As OSIRIS images of the comet's coma indicate, the dust that 67P casts into space is emitted there. ...
Re: ESA: Rosetta: 100 days to wake-up
Posted: Mon Sep 08, 2014 9:46 pm
by MargaritaMc
There is an interesting guest blog at the Rosetta blog
Guest post by Colin Snodgrass from the Max Planck Institute for Solar System Research, Germany. Colin coordinates a consortium of professional astronomers observing comet 67P/Churyumov-Gerasimenko from Earth.
VLT Tracks Rosetta's Comet
This image of comet 67P/C-G was taken with ESO's Very Large Telescope on 11 August 2014. It was made by stacking 40 short exposure images (each lasting 50 seconds) and then removing the background stars. The comet's coma extends at least 19,000 km from the nucleus. The central pixel includes the Rosetta spacecraft, presently at comet 67P/C-G, which is too small to be resolved in the image. The coma is asymmetric, as the dust is swept away from the Sun – located beyond the lower right corner of the image – to form the beginnings of a tail. Credit: Colin Snodgrass/ESO/ESA
Since rendezvousing with Comet 67P/C-G in early August, Rosetta has been mapping the nucleus, the main focus being the search for suitable landing sites for Philae. There are still just over two months to go before Philae is released from Rosetta, but, in some ways, the lander has already begun its descent, as Rosetta itself is already deep inside the ‘atmosphere’ of the comet, namely its coma. If we want a view of the whole comet we need to take a step back from Rosetta, and use telescopes on Earth. ...
This sequence of images shows a crowded star field towards the centre of our Galaxy, the Milky Way. In the foreground, comet 67P/Churyumov-Gerasimenko passes through the stars. The comet is difficult to spot, even with a giant telescope like ESO's Very Large Telescope, but it can be seen here moving across the middle of the frame. Even in this image, careful inspection reveals the comet’s coma.
Credit: Colin Snodgrass/ESO/ESA
Margarita
ESA: Landing spot chosen
Posted: Mon Sep 15, 2014 3:37 pm
by MargaritaMc
ESA: 'J' marks the spot for Rosetta's lander
15 September 2014
Rosetta’s lander Philae will target Site J, an intriguing region on Comet 67P/Churyumov–Gerasimenko that offers unique scientific potential, with hints of activity nearby, and minimum risk to the lander compared to the other candidate sites.
Site J is on the ‘head’ of the comet, an irregular shaped world that is just over 4 km across at its widest point. The decision to select Site J as the primary site was unanimous. The backup, Site C, is located on the ‘body’ of the comet.
The 100 kg lander is planned to reach the surface on 11 November, where it will perform indepth measurements to characterise the nucleus in situ, in a totally unprecedented way.
... A detailed operational timeline will now be prepared to determine the precise approach trajectory of Rosetta in order to deliver Philae to Site J. The landing must take place before mid-November, as the comet is predicted to grow more active as it moves closer to the Sun.
“There’s no time to lose, but now that we’re closer to the comet, continued science and mapping operations will help us improve the analysis of the primary and backup landing sites,” says ESA Rosetta flight director Andrea Accomazzo.
“Of course, we cannot predict the activity of the comet between now and landing, and on landing day itself. A sudden increase in activity could affect the position of Rosetta in its orbit at the moment of deployment and in turn the exact location where Philae will land, and that’s what makes this a risky operation.”
...
This is the link to Emily Lakdawalla's September 11 post about the Rosetta team's presentation at the European Planetary Science Congress. She wasn't there but Pamela Gay was and there are some interesting tweets from her. http://www.planetary.org/blogs/emily-la ... first.html
This is a rather nice view of the comet taken by the cameras on Philae, whilst still a passenger on Rosetta.
Philae's passenger-side view of comet Churuymov-Gerasimenko
The Philae lander, attached to the side of Rosetta opposite its high-gain antenna, has six micro-cameras positioned around its circumference to capture panoramic views of its landing site after it touches down: the CIVA instrument. While Philae is still attached to Rosetta, two of CIVA's cameras are able to see the solar panels -- and sometimes other things, including, in this case, the comet. Churyumov-Gerasimenko was about 50 kilometers away when the spacecraft took this photo. Two images with different exposure times were merged to bring out the sunlit details on the comet in combination with the very faintly lit backside of the spacecraft's solar panels. This image has been rotated 180 degrees from the original so that solar illumination appears to be coming from the top.
I think that the comet looks like a champagne cork!
M
Planetary Society blog post about the landing site.
Posted: Wed Sep 17, 2014 1:35 pm
by MargaritaMc
Planetary society blog post about the chosen landing site. As always, Emily Lakdawalla writes in great and interesting detail. http://www.planetary.org/blogs/emily-la ... hilae.html
I particularly like this flicker gif she's made of the 3D photos which focus of the landing site (I don't have the necessary glasses to view such images.)
M
More jets from Rosetta's comet.
Posted: Fri Sep 19, 2014 9:27 pm
by MargaritaMc
ESA Rosetta blog, 19 September, 2014
This beautiful view shows off a wide range of the comet's features: from the jets emanating from the ‘neck’ region, to the steep cliffs towering over both smooth and grooved terrain, and to the hundreds of boulders scattered across the surface.
Now I think the comet looks like a Chinese lion...
Margarita
Re: ESA: Rosetta: 100 days to wake-up
Posted: Sat Sep 20, 2014 3:50 pm
by BMAONE23
In that interestingly lit view of the comet, the Left side resembles a lion head facing left with the Mane flowing toward the right but the Right lobe looks like a Monkey Facing right
The date is set! Rosetta will deploy lander Philae to the surface of comet 67P/C-G on 12 November.
For the primary landing scenario, targeting Site J, Rosetta will release Philae at 08:35 GMT/09:35 CET at a distance of 22.5 km from the centre of the comet, landing about seven hours later. The one-way signal travel time between Rosetta and Earth on 12 November is 28 minutes 20 seconds, meaning that confirmation of the landing will arrive at Earth ground stations at around 16:00 GMT/17:00 CET.
If a decision is made to use the backup Site C, separation will occur at 13:04 GMT/14:04 CET, 12.5 km from the centre of the comet. Landing will occur about four hours later, with confirmation on Earth at around 17:30 GMT/18:30 CET. The timings are subject to uncertainties of several minutes.
Final confirmation of the primary landing site and its landing scenario will be made on 14 October after a formal Lander Operations Readiness Review, which will include the results of additional high-resolution analysis of the landing sites conducted in the meantime. Should the backup site be chosen at this stage, landing can still occur on 12 November.
Montage of four images of Comet 67P/C-G taken on 26 September, from a distance of 26.3 km from the centre of the comet. The four 1024 x 1024 pixel images making up the montage are provided at the end of this post.
We have not made a proper mosaic on this occasion, because it is becoming extremely difficult at these close distances due to the combined effect of the comet rotating between the first and last images taken in the sequence (about 10 degrees over 20 minutes) and the spacecraft moving by some 1–2 km in the same time.
While the two images on the right of the montage could perhaps be joined seamlessly, the problem becomes much harder between the lower-right and lower-left images. Careful inspection makes it clear that the perspective has shifted considerably between them and that some of the shadows have changed a lot as well.
It’s not easy to bring these images into alignment and thus we leave the challenge of making a reasonable mosaic from them to you!
That aside, it goes without saying that the main talking point of this image is the spectacular region of activity at the neck of 67P/C-G. What we’re seeing is the product of ices sublimating and gases escaping from inside the comet, carrying streams of dust out into space. Zooming in close to the surface and to the source of this activity and it is apparent that it is originating from several discrete locations.
Scientists have named one of the largest boulders on Rosetta’s comet after an Egyptian pyramid.
The scientific imaging system OSIRIS on board ESA’s spacecraft Rosetta has caught a spectacular glimpse of one of the many boulders that cover the surface of comet 67P/Churyumov-Gerasimenko. With a maximum extension of approximately 45 meters it is one of the larger structures of this kind on the comet and stands out among a group of boulders located on the lower side of 67P’s larger lobe. Since this cluster of boulders reminded the scientists of the pyramids of Giza, the boulder has been named Cheops after the largest pyramid within the Giza Necropolis. The boulder-like structures that Rosetta has revealed on the surface of 67P in the past months are among the comet’s most striking and mysterious features. ...
Re: Planetary Society blog post on EPSC and Rosetta
Posted: Fri Oct 10, 2014 8:18 pm
by KiethHoyt
MargaritaMc wrote:This is the link to Emily Lakdawalla's September 11 post about the Rosetta team's presentation at the European Planetary Science Congress. She wasn't there but Pamela Gay was and there are some interesting tweets from her. http://www.planetary.org/blogs/emily-la ... first.html
This is a rather nice view of the comet taken by the cameras on Philae, whilst still a passenger on Rosetta.
Philae's passenger-side view of comet Churuymov-Gerasimenko
The Philae lander, attached to the side of Rosetta opposite its high-gain antenna, has six micro-cameras positioned around its circumference to capture panoramic views of its landing site after it touches down: the CIVA instrument. While Philae is still attached to Rosetta, two of CIVA's cameras are able to see the solar panels -- and sometimes other things, including, in this case, the comet. Churyumov-Gerasimenko was about 50 kilometers away when the spacecraft took this photo. Two images with different exposure times were merged to bring out the sunlit details on the comet in combination with the very faintly lit backside of the spacecraft's solar panels. This image has been rotated 180 degrees from the original so that solar illumination appears to be coming from the top.
I think that the comet looks like a champagne cork!
M
This really puts into perspective how far we have come as a species, as well as the massiveness of space. To think, a large, mountainous beast millions of miles away is touched by technology that was created by the smallest speck of star-stuff; humans.
Re: ESA: Rosetta: 100 days to wake-up
Posted: Fri Oct 10, 2014 9:09 pm
by MargaritaMc
Here is a NavCam wide view of the area of the comet containing Cheops.
This four-image NAVCAM montage comprises images taken on 8 October from a distance of 16.9 km from the centre of comet 67P/C-G, so roughly 15 km from the surface.
... When seen in this side-on view, Cheops appears much more like its Egyptian pyramid namesake and has a height of approximately 25 metres, compared with a width of 45 metres as seen from above in yesterday’s OSIRIS image. For reference, the real Pyramid of Cheops* at Giza is 139 metres high and 230 metres across at the base. ...
* Info about the Egyptian original at Wikipedia and here
One does wonder what the Pharoah Khufu (Cheops) would think about this use of his name, four and a half thousand years on... I suspect that he would feel that it was a fitting tribute to his greatness.
MargaritaMc wrote:
* Info about the Egyptian original at Wikipedia and here
One does wonder what the Pharoah Khufu (Cheops) would think about this use of his name, four and a half thousand years on... I suspect that he would feel that it was a fitting tribute to his greatness.
Well, the name sure is fitting when talking about a great King that roams the skies. The ironic thing is that a book by Jane C. Loudon, The Mummy! A Tale of the 22nd Century is about a society that is highly advanced on one side and completely immoral on on the other side. The only thing that could save the people was the mummy of Khufu (Cheops). The comet looks as if it could be broken up into two sides, but also her story alludes to our world's societies today.
ESA: Rosetta Philae Self portrait with Comet from 16 km
If you thought last month’s mission ‘selfie’ from a distance of 50 km from Comet 67P/C-G was impressive, then prepare to be wowed some more: this one was taken from less than half that distance, at just 18 km from the centre of the comet, or about 16 km from the surface.
...
The 7 October selfie is the last image from Philae before the lander separates from Rosetta on 12 November. The next image will be taken by CIVA shortly after separation, when the lander will look back at the orbiter to bid it a final farewell.
