The Mars Global Surveyor mission has finally entered into a mapping orbit after completing a successful campaign of aerobraking. The mission was originally scheduled to complete aerobraking over a year ago, but a problem with one of the spacecraft's solar panels prompted mission controllers to use more conservative aerobraking techniques, which took a lot longer.

The spacecraft's orbit was lowered from a highly elliptical orbit down to an orbit 367 kilometers (229 miles) above the surface. The orbit is perfectly circular and sun synchronous, which means that when the spacecraft passes over the equator, it is always the same time locally, 2:00 pm in this case.

Mapping of the Red Planet will begin in late March, after the orbit is fine-tuned and a period of instrument calibration. The mapping phase of the mission will last one Martian year or 687 days. When complete, future mission planners and scientists will have a complete map of the red planet at a resolution previously unavailable.

Also scheduled for next month is the deploying of the spacecraft's high-gain antenna, which will be used during mapping to send data back to Earth. There is some concern over this procedure because a large spring used to push out the antenna may be faulty. There recently have been some problems with similar mechanisms on other spacecraft and satellites.

Mars Global Surveyor has been orbiting Mars since September 1997. After mapping is complete it will act as a data relay satellite for the Mars Polar Lander and future missions. The aerobraking technique was used on this mission for only the second time on a spacecraft and the first time where it was relied upon so heavily. Relying on aerobraking allowed the spacecraft to carry less fuel and launch on a smaller rocket, and thus made the mission cost much less overall.