PASADENA, Calif. -- The Mars Global Surveyor fired its main rocket engine to descend toward the fringes of the Martian atmosphere in an effort to tighten its orbit around the red planet.
The 14.8-second engine burn Wednesday morning was successful in using aerobraking to slow the spacecraft's speed. Engineers are trying to narrow the spacecraft's large elliptical orbit into a tight circle.
The $250 million mission, launched in 1996, began orbiting the planet in September 1997. It was designed to map Martian terrain for a Martian year, equivalent to 687 Earth days.
It was supposed to begin mapping the surface of the planet last March, but a problem with a solar panel in October 1997 forced a suspension of aerobraking and a delay in the overall mission plan.
The rocket firing was designed to drop its altitude at the point of closest approach from 106.5 miles to 79 miles. At the farthest point of its elliptical orbit, the spacecraft is 11,083 miles from the planet.
Dips into the atmosphere should now occur every 11.6 hours, JPL said. After five more months of aerobraking each orbit should take less than two hours.
Mars is currently 213 million miles from Earth.