NASA Mars Spacecraft Begins Adjusting Orbit

NASA Mars spacecraft begins adjusting orbit

LOS ANGELES, March 31 (Xinhua)– The Mars Reconnaissance Orbiter, the most advanced spacecraft to explore the red planet, has begun a crucial six-month campaign to shrink its orbit for the science mission.

Three weeks after successfully entering orbit around Mars, the spacecraft is in a phase called “aerobraking,” which uses friction with Martian atmosphere to transform a very elongated 35-hour orbit to the circular two-hour orbit, NASA’s Jet Propulsion Laboratory (JPL) said on Friday.

The orbiter has been flying about 426 km above Mars’ surface at the nearest point of each loop since March 10, then swinging more than 43,000 km away before heading in again.

While preparing for aerobraking, the flight team tested several instruments, obtaining the orbiter’s first Mars pictures and demonstrating the ability of its Mars Climate Sounder instrument to track the atmosphere’s dust, water vapor and temperature.

The spacecraft fired its intermediate thrusters for 58 seconds at the far point of the orbit on Thursday, lowering its altitude to 333 km when the spacecraft next passed the near point of its orbit, the JPL said.

This maneuver is “not low enough to touch Mars’ atmosphere yet, but we’ll get to that point next week,” said Daniel Kubitschek, deputy leader for the aerobraking.

The phase includes about 550 dips into the atmosphere, each carefully planned for the desired amount of braking. At first, the dips will be more than 30 hours apart. By August, there will be four per day.

Mission controllers said the orbiter should not dive too deep, or parts of the orbiter could be overheated. “The biggest challenge is the variability of the atmosphere,” Kubitschek said.

Using aerobraking to get the spacecraft’s orbit to the desired shape, instead of doing the whole job with thruster firings, reduces how much fuel a spacecraft needs to carry when launched from the Earth.

“It allows you to fly more science payload to Mars instead of more fuel,” Kubitschek said.

Once in its science orbit in this November as scheduled, the orbiter will return more data about the planet than all previous Mars missions combined, scientists said.

The data will help researchers decipher the processes of change on the planet, and help future missions to the surface of Mars by examining potential landing sites and providing a high-data-rate communications relay.