NASA probe enters Mars orbit

Vehicle to take pictures to help scientists pick landing sites for manned missions


NASA's Mars Reconnaissance Orbiter safely entered orbit around the red planet yesterday afternoon for a planned two-year mission to monitor Martian weather, look for signs of life and find potential landing sites for future manned missions.

The successful orbital insertion followed a seven-month, 310-million-mile flight from the Cape Canaveral Air Force Station, where it was launched Aug. 12.

It will be six more months before the craft settles into its final polar orbit and begins snapping high-resolution images of the planet's surface.

The 2-ton probe, the size of a school bus, carries the largest telescope ever launched beyond Earth orbit. Researchers hope it will provide surface pictures of unprecedented resolution and clarity, imaging items as small as a foot across.

Scientists believe it might even provide pictures of NASA's two surviving Mars rovers, as well as the crash sites of failed missions, such as the European Space Agency's lost Beagle 2 probe.

The craft has a nine-foot circular antenna that will allow it to beam back unusually large amounts of data, more than all previous Mars probes put together.

The probe has been cruising toward Mars at about 7,000 mph, but as it entered Mars' gravity well yesterday morning, it accelerated to more than 11,000 mph.

The onboard computer fired the craft's six engines at 1:24 p.m. PST, initiating a 27-minute burn that consumed 230 gallons of fuel and slowed the craft by 2,200 mph.

The last six minutes of the burn were carried out after the orbiter had gone behind Mars, out of sight of Earth. Engineers at NASA's Jet Propulsion Laboratory in La Canada-Flintridge waited anxiously until it emerged from Mars' shadow on schedule at 2:16, and its signal was re-acquired by the antennas of NASA's Deep Space Network system.

Cheers erupted in the control room and voices could be heard saying, "It's right on the money!"

A few moments later, navigators confirmed that "Mars Reconnaissance Orbiter is in orbit around the planet Mars."

The craft was expected to enter a highly elliptical orbit ranging from a low point of 250 miles above the planet's surface to a maximum of 27,000 miles.

Over the next months, the craft will carry out a procedure called aerobraking, dipping into Mars' atmosphere 550 times to be slowed by friction. Ultimately, it will enter a two-hour polar orbit at an altitude of 190 miles.

The craft joins five other missions now at Mars: NASA's two rovers and the Mars Odyssey and Mars Global Surveyor orbiters and the European Space Agency's Mars Express.

The high-resolution camera will enable scientists to see large rocks on the Martian surface, allowing them to choose potential landing sites where there is less danger of rocks interfering with a manned or unmanned landing.

A smaller imaging spectrophotometer will survey the surface in infrared and ultraviolet light to identify minerals, especially those that might be associated with water.

Another camera, called the context camera, will take black-and-white pictures of a 20-mile-wide swath to identify sites where high-resolution imaging will be conducted.

The Mars color imager will provide daily global views of the atmosphere and surface to provide weather maps, track surface changes and identify the composition of clouds. The Mars climate sounder will study water vapor, dust, ice and temperatures in the atmosphere.

The final instrument is a ground-penetrating radar that will look for ice under the surface and other geological features.

Thomas H. Maugh II writes for the Los Angeles Times.

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