From: Jet Propulsion Laboratory
Posted: Thursday, September 7, 2006
NASA's Mars Reconnaissance Orbiter fired its six intermediate-size thrusters for 210 seconds Tuesday in a maneuver to make the shape of its orbit closer to the planned geometry for the mission's main science phase, beginning in November.
The maneuver raised the portion of the elliptical orbit at which the spacecraft comes nearest to Mars -- the periapsis -- from 216 kilometers (134 miles) above the surface to 320 kilometers (199 miles). A thruster firing on Aug. 30 had lifted the periapsis high enough to end a five-month process of dipping into the atmosphere every orbit to gradually shrink the orbit. The spacecraft now completes each loop around Mars in just under two hours.
The Sept. 5 maneuver also fine-tuned the orbit's angle relative to Mars' equator, tweaking it less than one degree to 92.5 degrees.
A longer firing of the engines next week is planned for lowering the high point of the orbit to make the shape more circular and for locking into a pattern of keeping the periapsis over Mars' South Pole and the far point -- the apoapsis -- over the North Pole.
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