On March 18, the MESSENGER space probe will become the first spacecraft ever to enter Mercury's orbit.

The probe will continue to orbit the planet once every 12 hours for the duration of its primary mission. The first few days after orbit insertion will be focused on ensuring that the spacecraft systems are all working well in the harsh thermal environment of orbit; this interval is known as the orbital commissioning phase.

On March 24, 2011, the instruments will be turned on and checked out, and on April 4, 2011, the science phase of the mission will begin and the first orbital science data from Mercury will be returned.

For additional information, read Mercury Orbit Insertion and Station Keeping.