On September 11, 1997, Mars Global Surveyor fired its main engine and was captured into orbit around Mars, ending a cruise of about ten months that began with its launch on November 7, 1996. It was the first American spacecraft to reach Mars since the failures of Mars Observer in 1993 and Mars Climate Orbiter's predecessor programmes, and its arrival restarted the US planetary programme at the planet.
The arrival used a technique not flown at Mars before. It was called aerobraking. Instead of carrying the fuel to brake into a circular orbit, the spacecraft dipped into the upper atmosphere hundreds of times over several months, letting drag do the work, and raised its periapsis with thruster burns to keep from dipping too deep. One of its two solar panels turned out to be damaged on deployment and the aerobraking had to be slowed down and redesigned while it was happening. The mapping orbit was finally reached in early 1999.
What came back over the following nine years rebuilt the picture of the planet. The Mars Orbiter Laser Altimeter fired more than 600 million laser pulses and produced the first global topographic map of another planet, giving elevations accurate to a few metres and settling arguments about the height of Olympus Mons and the depth of Valles Marineris that had gone on for a century of Earth-based observation. The magnetometer found remnant magnetization in the ancient crust, evidence that Mars once had a global magnetic field and had lost it.
The images caught public attention. The camera showed layered rock in the canyon walls and in crater floors, which meant deposition over long periods, and it found gullies on crater and valley walls, some with deposits that changed between observations, which raised the possibility of liquid water at the surface in geologically recent times.
The mission was planned for two years and ran for nine. Contact was lost in 2006. A command error had left the solar array pointed the wrong way, and the batteries drained. NASA declared the mission over in January 2007.