Philae landing on the nucleus of Comet 67P C-G Options

[vikingmars]

ADMIN EDIT: Unnecessary quoting removed. Please be mindful of rule 3.5

Thanks xflare for your question.
What I've heard is that it will take at least a month, if not 2, to have the batteries fully charged. So the CNES team is not expecting to receive signals from Philae soon...

[Jorn Barger]

ADMIN EDIT: Unnecessary quoting removed. Please be mindful of rule 3.5

Someone said they have to be heated to a minimal temperature to even recharge, so this wouldn't work.

[MahFL]

ADMIN EDIT: Unnecessary quoting removed. Please be mindful of rule 3.5

The main Solar Panel lady said it takes 5 or 6 hours to warm the battery up to 0C, so right now the battery won't even be close to being warm enough to be charged up. The hope is as the comet gets closer to the Sun the amount of warming the battery needs will be less. The main reason the lander would have failed would be over heating as the comet gets closer to the Sun, but as we know it's in a shady spot.

[jmknapp]

Re: warming the batteries

I was trying to find information online on this. Not totally clear to me, by this document states that there is a "warm" compartment and a "cold" compartment, the warm compartment evidently kept that way with passive heating:

Since no radioactive heaters are used and with very limited available electrical power, an efficient thermal insulation is required to keep the temperature inside Lander between −55 ◦C and +70 ◦C throughout the mission. This is achieved by thermally decoupling the structural elements in the warm compartment (with low conductive stand-offs) and a combination of two multi layer insulation (MLI) tents. On top of the hood two absorber foils with a TINOX surface of about 0.06 m^2 each (very high α/ε ratio) will collect energy during insolation periods. At 3 AU, up to 17.5 W thermal power can be collected, depending on the actual attitude upon landing.

Right now 67P is at about 3 AU. It'll reach 2 AU in about 4 months, which should about double the the insolation.

[ugordan]

OSIRIS spots Philae drifting across the comet

Wow.

[Sohl]

Ugordan, djellison: Thanks for taking the time to attempt to clarify things for me. I was posting based on this statement in the postscript in the blog entry:

In particular, the image that was indicated to have been taken at 15:30:32 UTC, just before touchdown, was actually an image taken at 16:30:32 UTC, about an hour after touchdown.

So I took the postscript to mean that the image was taken long after the bounce. If it was taken an hour after the bounce, I did not find it highly likely to be so near to the initial impact point. If the image is really just a minute or two after the bounce, obviously it increases the chances of the sighting of Philea dramatically. It would also provide a good directional vector to search for the final resting point.

[jmknapp]

So is Philae at rest at 15:43 in the latest image, or still going? Here's the 15:43 location in wider context (red dot):

[lunaitesrock]

OSIRIS spots Philae drifting across the comet

Wow.

Yeah... Wow! Between the 15:35 NAVCAM image released earlier with the dust cloud and the 15:43 OSIRIS image here, the dust cloud seems to have dissipated to show imprints of the 3 footpads as well as the main lander body in the center. So cool !! It's not as simple as drawing a straight line connecting the dots because the lander is above the surface at different altitudes in the images, but it shouldn't take too long now to locate the lander's final resting place.

[ugordan]

Sohl, the empty image that was supposed to show the landing point immediately before touchdown was mistakenly showing an image taken long after the bounce, after all the dust has settled again. For the purposes of analysing the other image - which was taken roughly 2 minutes after bounce - I'd say that's pretty irrelevant.

[jman0war]

Incredible images.
Poor little guy looks like he went straight into that dark cliff at the edge of the image.

[ugordan]

At that point in time, it was still going up at a hefty pace. What happened to be in the background at that point says very little. Given the (presumably lumpy) gravity field of 67P, I still wonder whether CONSERT ranging and triangulation data pinpoints its final position better than 2 images taken shortly after the start of the Big Bounce.

[anticitizen2]

Before/after enlarged 400%


The marks seem wider apart than the footpads, and not at the same angles - it must have had some lateral speed and rotation.

[lunaitesrock]

At that point in time, it was still going up at a hefty pace. What happened to be in the background at that point says very little. Given the (presumably lumpy) gravity field of 67P, I still wonder whether CONSERT ranging and triangulation data pinpoints its final position better than 2 images taken shortly after the start of the Big Bounce.

I think that the ground track can be calculated from the NAVCAM/OSIRIS images at 15:35 and 15:43 once they can determine Philae's respective altitude and speed and it will help with CONSERT to further triangulate it's final position. They will need to use Rosetta's exact location in space when the images were taken and a shape model of 67/P to determine where the other end of the parabolic trajectory is, but it can be done. Way above my pay grade though.

The uneven gravity field would blur the ground track somewhat, but not significantly since it appears to have stayed on the head of the comet.

[0101Morpheus]

Finding out the path makes the landing even more amazing. Philae could have easily came down on that bolder or hit the cliff and yet it survived. I have to agree with the team that so many things could have gone wrong, it is amazing it went so right!

[lunaitesrock]

Before/after enlarged 400%


The marks seem wider apart than the footpads, and not at the same angles - it must have had some lateral speed and rotation.

You are probably right. It had to have some lateral speed to rebound at an angle from the surface. I think the shallow depression in the center is from the lander body. I don't know what the ground clearance is, but it doesn't look like much.