Comet Hartley 2 has a close encounter with Earth Oct. 20, making it a prime target for amateur astronomers and the comet mission, which already observed comet Tempel 1 when its companion probe crashed into it five years ago. On Nov. 4, EPOXI (which stands for Extrasolar Planet Observation and Characterization investigation - Deep Impact eXtended Investigation) will fly just 435 miles from Hartley 2's nucleus, plunging through its green atmosphere.
Cassini is the size of a small school bus. Imagine a Robot that big wheeling (or walking around mars). You could shove every instrument you ever needed on it. one step at a time I suppose. This new rover looks promising.