That doesn't work with the comet radius being so small ( note - the force of gravity goes over radius squared - F = G M1 M2 / r^2 )

Going from a surface 2km from the center of mass, to 1km altitude - 3km from the center of mass - gravity drops to approx 44% of what it did at the surface.

I had at crude stab at applying F=GM1M2/r^2 on 15 second basis back on landing night and came up with values between 400m and 1.5km.

Doug

The Philae ProjMan during the press conf the morning after landing. The words he used were to the effective of "We bounced, maybe as much as a kilometer"

Beagle 2 had a wide angle that could be actuated over one of its cameras for exactly that purpose
http://www.mssl.ucl.ac.uk/planetary/missio...agle_DM_pic.php

The problem is - there's always a chance it could get stuck - thus rendering your camera useless.

And indeed - it could have been used during descent, particularly in the case of visiting 46P, not 67P. But for 67P it was NOT planned to be used during descent - they so said several times during pre-landing briefings.

That was the nominal plan from the beginning. Moreover the ADS was not planned ( even if it had been operational ) to be used during the descent - only on touchdown.

It may not be lost. Perhaps it could have a life beyond its prime mission like Stardust did.

Typically spacecraft have some low-level logic (on MER it's known as the battery control board - details here : http://trs-new.jpl.nasa.gov/dspace/bitstre...5/1/01-1682.pdf ) that arbitrates battery voltage, solar array input and deciding to powering on an actual flight computer.

And for fun - not supposed to represent the actual location of Philae at any time.....

As a starter - here's a 3D Philae generated by using http://blogs.esa.int/rosetta/files/2014/11...ll_Philae_2.png and http://www.esa.int/var/esa/storage/images/...-angle_view.jpg

Nice GIF, Jam Butty

One could almost speculate that the slab like 'rock' on the SW corner of the touchdown point has been kicked up significantly by bounce 1 - perhaps it kicked the lander to a harder 'slap down' with the other two legs which triggered the bounce.

There are various papers that explicitly states the gear is designed to take the landing loads, but could well bury itself (the landing gear) in the process.

Nothing happened to it. The 'after' image is - to cite ESA themselves " 1 min 26 seconds after first touchdown"

Assuming an approx 1km traverse across the comet in the 113 minutes until the second bounce..... that 1min 26sec should only be 13 meters from the first touchdown point.

That correlates well with what we see in the image.

How do you come to the conclusion that 2MPa is 'nothing'

The ranges of Ice you cite can exceed that.

It's also worth noting from the same paper you cite.....

"and the compressive strength varies from 5–25 MPa over the temperature range −10°C to −20°C"


Again - as I mentioned a few posts ago - please look at some MUPUS papers on line - you will learn a lot.

Yes. It has a low thermal inertia.

However comets are not expected to be made of Styrofoam.

Some parts of comets are thought to be almost solid ice or rock, and some no more solid than a pile of cigarette ash.



Yes and yes - but results have not been released yet.

A very quick google for "Rosetta MUPUS pdf" will unveil a swath of PDF papers that discuss, in detail, the capabilities of the instrument.

You should also check, regularly, the MUPUS twitter feed ( as Paolo mentioned )
https://twitter.com/Philae_MUPUS

They are basically live-tweeting rudimentary analysis of their data.

Go read the tweets. Rapid temperature change thru the diurnal cycle means a low thermal inertia which infers low density, 'fluffy' material.



No - not surprising. But awesome to confirm it via an in-situ measurement.

1) You are inferring a 5% slip at all times - which seems excessive
2) You are assuming SPICE data from which Joe is pulling his drives is not bundle adjusted for distance, which it is.

So no - you shouldn't be applying an assumed 5% slip to that odometer reading.

I disagree. I see three feet all oriented toward the 'cliff' in the CIVA images. Moreover - if the feet were pointed away from the cliff and the top of the spacecraft (and it's S-Band patch antennae) were facing the cliff - then we would have appalling downwind from Philae to Rosetta...however the control team report they have a good connect to the spacecraft.

Finally - the MUPUS deployment is being talked about as something that may contact a surface. It goes 'down' relative to Philae....i.e. towards a cliff face 'below' the bottom of Philae.

You make the assumption that every picture taken during that period has made it to the ground. We know for a fact the relay between Philae and Rosetta was unreliable - especially at that time - so it's quite likely the downlink of those products was incomplete.

I don't know if Philae had the capacity to store those images so they could then be recovered using a retransmit command from Rosetta during a later track.

A very very crude stab at some sort of Philae orientation against a cliff that would roughly match the images we're seeing. (anim gif)

The image with the model in the middle makes it pretty obvious. In a 'nominal' situation - we would simply have the near-field of the landing site in a spherical panorama in that image.

However - we can see sky in the 2 O'clock position, and then from 3 O'Clock round to about 11 O'Clock - we see ground. Thus we can estimate the 'down' for the spacecraft is near the 7 O'clock position in that image.

They already have. This is the '360' from the lander. Obviously - lying on its side - half of it is pointing into space. There is PLENTY of detail to be seen in the sunlit parts of the surface - and given a different time of 'day' - I'm sure other areas will be visible

http://www.esa.int/spaceinimages/Images/20...comet_panoramic

No. The circumference of a roughly spherical object, of roughly 4km across is very roughly 12 km.

1 km is 1/12th of that..not 1/4

2 hrs would put us 1/6th of a comet rotation apart and therefore the second touchdown might be off the 'head' and closer to the back of the neck of the comet. Or it might have got a direction to the rebound sending it another direction completely. I'm not very confident that a 500m 2hr bounce really did occur - but it's a thrilling thought. 2 landings for the price of one

Fingers crossed OSIRIS can spot Philae on the surface and we can then compare that to Machi's exceptional location chart.

I would be surprised if we see anything more before the press conf tomorrow afternoon CET.

FWIW - reading very much between the lines ( the notion that after the first touchdown there was an approx 2hr period of the spacecraft exhibited rotation and then came to a stop which infers a long bounce ) - my basic math suggests a 2hr bounce would reach about 530m altitude and start with a 0.3m/sec rebound.

As more things are added to the saturn category at the photojournal - that link will no longer have the maps on it.