Artist impression of Messenger approaching the first planet.
A lot of space fans are watching NASA TV tonight as the Messenger space probe begins its orbital insertion of the planet Mercury. Until tonight, we have managed to send probes to make passes by the small rocky planet, but this is the first spacecraft designed to stay in orbit.
NASA TV has been live broadcasting, interviewing the project scientists and watching the spacecraft mission control as the main engine fired to slow the craft into its orbit. As each step in the procedure was completed successfully, there were bigger and bigger grins and applause. At this time the spacecraft should be in orbit, according to incoming telemetry. However, there will be a lot of checking and double-checking of information as it is downloaded from the High-gain antenna aimed towards Earth. Absolute confirmation will come late tonight.