Results from NASA's Hubble Space Telescope played a major role in preparing ESA's ambitious Rosetta mission for its new target, comet 67P/Churyumov-Gerasimenko (67P/C-G). For the first time in history, Rosetta will land a probe on a comet and study its origin. Hubble precisely measured the size, shape, and rotational period of comet 67P/C-G.
Hubble's observations revealed that comet 67P/C-G is approximately a three-by-two mile, football-shaped object on which it is possible to land. Mission scientists were concerned that the solid nucleus could be nearly 3.6 miles (6 km) across. The higher gravity on a comet that size might make a soft landing more difficult.
This photo shows three views of the 3-D reconstruction of comet 67P/C-G's nucleus: pole (top right), side (bottom left), and end (bottom right).