We received an interesting and timely submission to the Maple Application Center this morning that I think people might be interested in.  It's called:

The Comet 67P/Churyumov-Gerasimenko, Rosetta & Philae, by Dr. Ahmed Baroudy. From the abstract:

Our plan is rather a modest one since all we want is to get , by calculations, specific data concerning the comet and its lander.
We shall take a simplified model and consider the comet as a perfect solid sphere to which we can apply Newton's laws.

We want to find:

I- the acceleration on the comet surface ,
II- its radius,
III- its density,
IV- the velocity of Philae just after the 1st bounce off the comet (it has bounced twice),
V- the time for Philae to reach altitude of 1000 m above the comet .

We shall compare our findings with the already known data to see how close our simplified mathematical model findings are to the duck-shaped comet already known results.
It turned out that our calculations for a sphere shaped comet are very close to the already known data.

Click on the link above if you want to take a look.

eithne