Mars Reconnaissance Orbiter Adjusts Angle of Orbit
September 6, 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.