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Rosetta EOM, End of mission alternatives
jasedm
post Mar 7 2015, 05:11 PM
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A little premature perhaps, but I was wondering if there were as yet any firm plans for disposing of/de-commissioning Rosetta at the end of the mission?

The Rosetta website FAQ section states in answers, that a decision on this would be made in late 2014, but I've been unable to turn up any information relating to it.

A six-month extension has been mooted and I presume this would involve some closer approaches to 67P towards the EOM, with subsequent very high resolution studies.

The propellant issue is, as ever the prime governing factor (aside from funding of course) especially in view of the existing leak in the reaction control system onboard the spacecraft.

It would be great to think that Rosetta could be landed on the comet as NEAR did at Eros, with similar images transmitted all the way down, or a short 'hover' a few tens of metres above a particularly active part of the surface long enough to directly sample jets, or image particles as they come away from the comet.

Should the mission be able to pin down Philae's location in the coming months, might there even be an opportunity to image the lander at a reasonable resolution?

Jase



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anticitizen2
post Mar 7 2015, 09:47 PM
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Matt Taylor has mentioned several times taking more risks in an extended mission, and specifically making a fourth landing on the comet with Rosetta when the propellant is almost gone.

Based on how he and others have spoken of it, I think the landing is the most likely ending. Anything can change between now and then, of course.
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Explorer1
post Mar 7 2015, 10:59 PM
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Once perihelion is past, Rosetta will be able to go back to mapping in lower orbits, so there should be plenty of opportunity to find a suitable landing site, perhaps on the portion still in darkness now.
I'm sure it would be great for the other science instruments, but would the cameras even be able to focus on a surface that close?
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Sherbert
post Mar 8 2015, 12:17 AM
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Matt Taylor also joked about the idea of flying along the Hapi Valley between the cliffs. Parking Rosetta in some stable orbit would seem unlikely as the power question raises its head again. We know now that comet activity can affect any such orbit. Even if there is a suitable Lagrange point, I doubt that would be stable enough in such an elliptical orbit to not require manoeuvres to maintain Rosetta's position during another 2 -3 year period of hibernation. The final decision may depend upon whether Philae wakes up and can do more science. If Philae is lost, an attempt at a very close flyby and attempted soft landing would seem inevitable. Were Philae to reawaken and carry out a significant program of further science, the decision may be to place Rosetta in a solar orbit in the slim hope of investigating further wanderers into the inner solar system. In this case fuel management becomes a major priority and the effects on Rosetta's current mission priorities may rule out this option as well.

An attempted landing on the comet towards the end of summer 2016 looks the most likely. The information and experience the flight operations and flight dynamics team would gain would justify it alone. Small solar system bodies are a vast, almost inexhaustible, store of resources needed for both long term Solar System exploration and to reduce the burden on Earths natural resources and environment. If Asteroid mining is going to become a reality, learning how to land on them is a number one priority. Any chance to learn more about how to do it, or not to do it, should not be missed in my view.
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Explorer1
post Mar 8 2015, 01:05 AM
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QUOTE (Sherbert @ Mar 7 2015, 04:17 PM) *
[...] the decision may be to place Rosetta in a solar orbit in the slim hope of investigating further wanderers into the inner solar system

Space is big, and by that point there will be little left in the fuel tanks to do any burns. If there's anything even remotely in the neighbourhood of 67P, I'd say we would have heard about it already.
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Gerald
post Mar 8 2015, 12:55 PM
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A soft landing would probably become kind of a cliff hanger - maybe in both senses - since after landing Rosetta probably wouldn'd be able to re-establish contact to Earth, due to reduced power from the solar panels, and wrong pointing of the antenna.
The landing may work, but we'll never be sure.
The science return (and the thrill) during the spiraling descent phase will certainly be worth carrying it out.
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katodomo
post Mar 8 2015, 03:49 PM
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QUOTE (Explorer1 @ Mar 7 2015, 11:59 PM) *
would the cameras even be able to focus on a surface that close?

Offhand, OSIRIS can focus to at least a minimum distance of 1 km, otherwise they wouldn't have given resolution for that distance in some publications.

QUOTE (Explorer1 @ Mar 8 2015, 02:05 AM) *
If there's anything even remotely in the neighbourhood of 67P, I'd say we would have heard about it already.

In the second half of 2016 67P/C-G and Rosetta will traverse the asteroid belt, and i seem to remember their course taking them towards the Jupiter L4 aphelion group of the Hilda family by early 2017 or so (although pushing off the comet's trajectory to reach any asteroid there or in the Jupiter Greek camp - or Jupiter itself - for a flyby would be far too much of a push).
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nogal
post Mar 8 2015, 04:29 PM
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Mark McCaughrean, Senior Scientific Adviser for Science and Robotic Exploration Consultant for ESA, gave a conference in Lisbon on January 29. Stressing these were ideas that are being talked about, he mentioned that towards the end of the mission a fly through the neck might be attempted "Star Wars" style, followed by a landing on the comet. But Rosetta would have to "land upside down", because of the communications' antenna position.

The conference was given in English, but there are some brief comments in Portuguese. The video can be found here Rosetta: on the trail of the comet - Mark McCaughrean, Lisbon, January 29, 2015. The comments mentioned above can be located at 1h30m14s and, on the Q&A period, at 1h40m30s, 1h45m22s, and 1h48m18s.

Fernando
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Habukaz
post Mar 8 2015, 04:35 PM
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On OSIRIS NAC's focusing capabilities:

QUOTE
To capture images in a wide variety of ranges, the NAC has focusing plates that enable it to do both far-focus (2 km to infinity) and near-focus (1 to 2 km) imaging.


http://www.planetary.org/explore/resource-...tta-osiris.html

QUOTE
near focus (2 km to 1 km, optimised at 1.3 km)


http://pdssbn.astro.umd.edu/holdings/ro-a-.../osiris_ssr.pdf


--------------------
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jasedm
post Mar 8 2015, 05:43 PM
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Thanks all for the responses, it seems that there's a good deal of latitude in the available options at this stage. I suppose the unexpected contact-binary (TBC wink.gif ) nature of 67P has altered the possibilities for EOM somewhat.

Jase
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Gerald
post Apr 18 2015, 07:32 PM
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QUOTE (jasedm @ Mar 7 2015, 06:11 PM) *
The propellant issue is, as ever the prime governing factor (aside from funding of course) ...

Propellant seems to look good due to the excellect job of the flight dynamics team, such that another hybernation through aphelion might become feasible, provided ESA approves mission extension.
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Gerald
post Jun 17 2015, 07:48 AM
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Proposal for EOM of today's presscon:
September 2016 spiraling down and land on the comet.
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