Rosetta Mission: Where’s Philae?

Subject: Rosetta Mission: Where’s Philae?
From: Alex Kemp
Date: Tuesday, 18 November 2014 02:50:59 +0000
To: Oliver Kemp, Micaela Kemp, Liisa Kemp, Davin Kemp

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There is a kind of “Where’s Wally?” going on at the moment, as the Philae lander has still not been found. However, the ESA folks have issued some interesting photos...

Rosetta & Philae have spent 10 years together, travelling 6.5 billion km through space. Then, after an almost unimaginable journey together, last Wednesday 12 October at 08:35 GMT, Philae was cast out on her own for a 7 hour un-powered drop to the comet 67P surface.

The haunting photo above was taken by the Rosetta OSIRIS narrow-angle camera a couple of hours after separation (10:23 GMT). You can see that both the 3 landing legs & also the aerials are deployed.

Philae has a downward-facing camera (ROLIS) and this sent back a photo of the landing site from just 40m away, shortly before it touched down at 15:35 GMT:-

The large rock at top-right is about 5m in diameter. The rest of the structure at top-right is part of the Philae lander. This dusty corner of the comet is also the last known location for Philae...

The red circles are the identical before (left, 15:30GMT) / after landing (right, 15:35:32GMT) images of the same bit of the comet. The green square is where the lander actually touched down, whilst the grey blob inside the right circle is the shadow of a plume of dust. But there is more!

ESA released the 15:35:32 image & the commentators said: “that looks like the lander and it’s shadow, to the right of the dust plume”. ESA checked it out, and they were right! Now compare these 2 images (identical except for the annotation) (the first one is essentially the same as the second one above, just without the green square):-

It took a long time for ESA to realise that Philae had bounced. We got a possible reason for the bounce from the results of the MUPUS experiment. It had a drill bit to test temperature & other things... but it broke! It may well be, then, that the harpoon & foot-screws all failed because the surface is so hard that they could not penetrate it. Whatever the reason, Philae ended up spending 110 minutes bouncing a mile vertically & (possibly) 3.3 km horizontally.

Using the OSIRIS narrow-angle camera, ESA have been able to spot Philae as it dropped to it’s first touch-down:

The photo-mosaic above covers a 30 minute period (times shown are GMT). The camera was 15.5 km from the surface. The main photo resolution is 28 cm/pixel, whilst each enlarged inset is 17 x 17m.

You can see that the lander sharply changed direction after first touchdown (heading ‘East’ at about 0.5 m/sec).

Here is another photo from a commentator, showing the same info, but with greater scope & less clutter:

Finally, and also from a commentator, here is where it may have ended up on a 3D-model of 67P (although using a 2.4km flightpath):