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Rosetta, Philae and Comet 67P/Churyumov-Gerasimenko.

Vicomt

By Vicomt
in Science & Spaceflight

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Aningaaq

Aningaaq

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Taken from http://blogs.esa.int/rosetta/2014/09/08/virtis-maps-comet-hot-spots/

The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) has mapped out the surface temperature of the comet. Temperatures on the surface range from 180 to 220 Kelvin (-93.15 to -53.15 Celsius).

VIRTIS_EPSC_labelled-1024x500.jpg

It was already known back in July that the surface was likely not totally covered in ice as some suspected. In the photo you can see the 5 potential landing sites. This data will help narrow down more appropriate landing sites for Philae. Site A being the coldest in this set of data and Site I or C being the warmest. Naturally, the temperatures of these sites vary over time (as with any satellite or planet).

Personally, I find this data very interesting because they will be able to make some guesses about the surface material of the comet. Dry conditions are optimal for the CONSERT instrument onboard I think. Anyway, I suggest reading the article! There will be more information regarding this data at the European Planetary Science Congress (http://www.epsc2014.eu/)

What do you all think about this latest data? Do you think it will greatly influence which landing site is chosen?

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Squelch

Squelch

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I see that ESA have made a call for media interest in the landing site announcement planned for the 15th.

My personal take is that it has been not as straightforward as originally expected. The "duck" or "dumbbell" shape was totally unexpected, and brings a whole set of interesting problems. How's the gravity well going to affect a stable orbit for relay?

Temperature and sunlight exposure need to be reconciled, and those images certainly leave food for thought. That map, and the VIRTIS measurements don't make it clear how much variance those potential sites have considering Philae has minimal temp management. Will it survive?

I find it so exciting that this is happening, but with celebrity stories taking the headlines, how can the press make this utterly mind blowing event more appealing?

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Aningaaq

Aningaaq

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Temperature and sunlight exposure need to be reconciled, and those images certainly leave food for thought. That map, and the VIRTIS measurements don't make it clear how much variance those potential sites have considering Philae has minimal temp management. Will it survive?

I find it so exciting that this is happening, but with celebrity stories taking the headlines, how can the press make this utterly mind blowing event more appealing?

You are right about the reconciliation. They make note of this in the article I posted I think. I don't know about a gravity well affecting a circular orbit but I imagine it may be a problem for their CONSERT tool as far as I understand.

The press in the U.S. right now is all about abuse and the new iPhone. I imagine the Rosetta won't make headlines on major US networks until it achieves the historical landing. Maybe one article when the landing nears. One way to make this more appealing is tying it to the economy. This historical event can infer that we can land on small objects such as asteroids which = potential $$$ via mining for rare elements.

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Sky_walker

Sky_walker

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Selected landing site is J - it's on a smaller lobe. See the center image below.

Back-up landing side is C - on a larger lobe, more risky, highly structured, but in case J will be unsuitable for whatever reason (Eg. jet forming) - C will be used.

ESA_Rosetta_OSIRIS-Landing-Site-Context.jpg

Edited by Sky_walker
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Nibb31

Nibb31

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BTW: Looks like ESA loves anagrams. They made another one for the presentation and seems like they equipped all of the reporters, visitors and speakers with anagram glasses, hehehehe

Surely you mean anaglyph. An anagram is something else.

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Sky_walker

Sky_walker

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Selected landing site is J - it's on a smaller lobe. See the center image below.

Back-up landing side is C - on a larger lobe, more risky, highly structured, but in case J will be unsuitable for whatever reason (Eg. jet forming) - C will be used.

ESA_Rosetta_OSIRIS-Landing-Site-Context.jpg

Some quotes / info:

"We are on the edge of revolution for our understanding of how the solar system formed and what's driving the diversity."

"Rosetta contributes the unique ways to expand our understanding of the creation, building blocks of life, and diversity of the universe"

"Comets although are made of 90% of ice are darker than the darkest place in our moon"

"Molecules that are covering the comets might be the critical contribution to the creation of life on earth."

Rosetta will perform first ever studies of comet magnetic field

Philae will measure pretty much all of the surface properties, even it's electric resistance

Rosetta mission will give complete studies of the comet, from macroscopic properties to microscopic studies.

Site J is the best one to achieve all of the mission goals.

Another image (small lobe on a foreground, large lobe in a background)

Two major points before the landing itself.

- Decision if Rosetta can approach comet to 20km

- In late October - decision if Rosetta can descend to 10km.

Descend will take approximately 7 hours

For a few days after the descend Rosetta will have to actively maneuver to keep stable radio frequency link with Philae.

Sep 26 - announcement of Philae descend date

14 October - confirmation of GO/NOGO - if not possible then landing on site J can be delayed by up to 28 days if needed be. There are 2 landing opportunities every day.

Estimation of the successful landing was initially estimated at 70-75% assuming that comet is rounded, however complex shape made it much more difficult and more risky. No site on a comet meets 100% of the engineering requirements. They didn't do any estimations for current successful landing chance percentage as it'd take lots of time to do that and still would not affect the mission in any way - they still will do the very best they can. Comet coma is very difficult to predict and it's effect on the approach will be crucial. Scientists still have trouble distinguishing effects of gravity from effects of coma, right now they can predict approach path with an accuracy of roughly a kilometre. To compare - they can estimate previous path of a comet and where exactly photos were taken with an accuracy down to few dozens of centimetres. The ways outgassing progresses is different than anything estimated or modelled before comet have been approached. Sublimation is some areas is much faster than anything anyone expected at this distance from the sun. Two months make a huge difference to the approach trajectory.

An interview with Philae project manager.

Journalist: Rosetta will cost as much as 5 days of war in iraq (I guess it's 5 days of French costs?)

BTW: Looks like ESA loves anaglyph. They made another one for the presentation (shows landing site J) and seems like they equipped all of the reporters, visitors and speakers with anaglyph glasses, hehehehe

Edited by Sky_walker
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