Craft In Nominal Orbit For Mars Observation

NASA's newest spacecraft at Mars has completed the challenging half-year task of shaping its orbit to the nearly circular, low-altitude pattern from which it will scrutinize the planet.

The Mars Reconnaissance Orbiter fired its six intermediate-size thrusters for 12.5 minutes Monday afternoon, shifting the low point of its orbit to stay near the Martian south pole and the high point to stay near the north pole. The altitude of the orbit ranges from 155 miles to 196 miles above the surface.

"This maneuver puts us into our science orbit," said Dan Johnston, deputy mission manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Getting to this point is a great achievement."

The flight team used a maneuver called "aerobraking," which used friction between the orbiter and Mars' atmosphere to reduce the altitude of the orbiter.  Aerobraking has many benefits, chief among them the reduction in fuel needed to change the craft's velocity. During the procedure, carefully managed by researchers at JPL, Lockheed Martin Space Systems in Denver, NASA's Langley Research Center and elsewhere, the craft saw altitudes as low as 61 to 65 miles.

For the first three weeks after its arrival on March 10, the spacecraft took more than 35 hours for each elongated orbit. After aerobraking, the vehicle is flying more than 10 orbits a day. "The pace of work got extremely demanding as we got down to two-hour orbits," Johnston said. "We had shifts working around the clock."

Work now begins to prepare the craft for its mission. This includes deploying a 33ft-long radar antenna, stowed during aerobraking, and removing a lens cap from an imaging spectrometer. The two-year investigation, slated to begin in November, promises to return more data about Mars than all previous Mars missions combined.

FMI: http://www.nasa.gov/mro