Wednesday, June 01, 2011
Dawn's team has been irritatingly slow with releasing pictures of Vesta, imaging the asteroid/protoplanet once per week:
To help target the probe for survey orbit, controllers have commanded it to observe Vesta once a week since the beginning of the approach phase on May 3. As we saw that day, the pictures allow navigators to gain a better fix on Dawn's trajectory relative to Vesta. So far, the images reveal little more than the desired important information of where Vesta appears against the background of stars.
but without releasing a picture since the first one, take on the 3rd of May. We do however have an update from four days ago-, which is where that quote comes from.
In addition to that, it also tells us that 6 June will be the date at which Dawn reaches the incredibly close distance of that between the Earth and the moon. That distance takes three days for a conventional rocket to traverse, while Dawn with its ion drive will be slipping into orbit at a much, much slower speed. The journal does a good job going over the mechanics of this as it really is vastly different from conventional propulsion.