Just a brief post here to mention that NASA has formally approved sending Deep Impact on to comet Hartley 2 for a rendezvous on October 11, 2010. As I mentioned a couple weeks ago, Deep Impact had been planning on flying by comet Boethin on December 5, 2008, but astronomers have not been able to find Boethin in order to target Deep Impact at it. NASA did approve Deep Impact to set up its December 31 Earth flyby to travel to Hartley 2 instead, but withheld approval to actually let the mission continue to spend money for the two extra years it will take to get to Hartley. Well, today they approved spending the necessary money, so that the Deep Impact extended mission will cost a total of $40 million. That's not chump change, but at less than 10 percent of the cost of a new mission, NASA appears to consider it money worth spending.
The release contained a couple of details about the mission to Hartley 2. The comet nucleus is about a kilometer wide, and Deep Impact will fly by at about a thousand kilometers. To get there, Deep Impact will need a total of three Earth flybys, the first of which happens in three weeks.