This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
On November 12th 2014 the European Space Agency's Rosetta mission will eject the small robotic lander Philae on a trajectory that should take it down to the surface of comet 67P/Churyumov-Gerasimenko (or 67P/C-P for short). Already Rosetta is maneuvering from its 10 kilometer orbit to get into the right place to deploy Philae.
The landing site is on the 'head' of the rubber-duck shaped cometary nucleus (although it might also be likened to a half-eaten, and rather rotten apple core). This target area has now been named 'Agilkia' after an island in the Nile river here on Earth - a place where the ancient Temple of Isis was moved to after its original island home of Philae was flooded during the construction of the Aswan dam.
It represents a remarkable stage in the history of space exploration, but perhaps equally extraordinary is the tangible sense of just how alien and surreal this place is. Here is an image from 27 kilometers away, showing the landing site atop the bizarre tower of the cometary nucleus.
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Looking down from a different viewing angle the Agilkia site is shown here - expected to be somewhere within the 1 kilometer diameter red circle.
To get a slightly different perspective on the whole environment, here's 67P/C-P in full, with a hint of the out-gassing that's occurring from the 'neck' of the nucleus as volatiles sublimate away, carrying dust into interplanetary space. End-to-end the nucleus is about 4 kilometers.
During November 11-12th a go/no-go decision will be made on the release of Philae. With a 28 minute one-way light travel time from Earth this will be an entirely autonomous operation if given the 'go'.
It'll take Philae about 7 hours to drop towards Agilkia - and here's one of the trickiest and most nerve-wracking pieces of the landing. The nucleus of 67P/C-P is spinning, like an end-over-end dumbbell (yep, rubber duck, apple core, dumbbell, no single description quite captures the nature of this object). If that spin holds steady at about 12.4 hours per rotation Philae should hit the right spot - but as the comet heats up and loses material the spin rate may shift by tiny amounts.
With some luck it should all work out fine, but if you watch the following ESA video you'll see (around 0:50) that it's a bit like a fairground game where you try to hit a crazily tumbling target for the prize (except here you really want the prize).
If Philae lands successfully it'll fire up a host of experiments and instruments - using up the energy of its primary battery over the course of about 64 hours.
After that point Philae's life-expectancy hinges on how well its solar panels can recharge those batteries - hopefully well enough to take it through 67P/C-P's closest approach to the Sun in March 2015.
