NASA has been busy with space probes lately. One probe's mission is ending today, but several others are just getting underway. We can look forward to a lot of new information in the months ahead.
Stardust was a NASA comet hunter launched on February 7, 1999. In January 2004 Stardust flew past Comet Wild 2, collecting dust samples from the comet's tail. The canister containing the sample was successfully returned to Earth 2 years later. Stardust then continued on to Comet Tempel 1, to image the crater formed by the Deep Impact mission.
As its last hurrah, today Stardust will burn the rest of its fuel to allow NASA to compare calculated fuel burn rates to the actual values. Its transmitter will then be turned off, to prevent it inadvertently interfering with communications with other spacecraft.
On March 17 (2418 days after launch) the Messenger spacecraft successfully entered orbit around Mercury. After spending a few weeks doing system checks, Messenger is supposed to begin its science mission on April 4, which will include taking high-resolution photos of the Mercurian surface. This is made more complicate because Messenger has to keep its ceramic-cloth sunshade facing the Sun at all times to prevent damaging the craft or its instruments, so there is a lot of maneuvering necessary during the mission.
On March 21, the Dawn spacecraft powered up its instruments for a system check, including checking the cameras. Dawn is en route to the Asteroid Belt, where it will rendezvous this July with Vesta, then in 2015 with Ceres.