LOS ANGELES (AP) -- A NASA spacecraft is halfway toward Mars where it is expected to collect more data on the Red Planet than all previous Martian explorations combined.

The Mars Reconnaissance Orbiter successfully fired its six engines for 20 seconds last week to adjust its flight path in anticipation of a March arrival. It will fine-tune its trajectory two more times before it enters orbit around Mars, said Allen Halsell, deputy navigation chief at NASA's Jet Propulsion Laboratory in Pasadena.

Once in orbit, the two-ton spacecraft will join a trio of probes currently flying around Mars.

The orbiter is loaded with some of the most sophisticated science instruments ever flown into space, including a telescopic camera that can snap the sharpest pictures yet of the planet's rust-colored surface.

Previous spacecraft that have landed, circled or zipped past Mars have shot tens of thousands of images, but only about 2 percent of the planet has been seen at high resolution.

The orbiter also will continue to seek evidence of water, scan the surface for sites to land future robotic explorers and serve as a communications link to relay data to Earth. Already, it has successfully returned data at 6 megabits per second--about the speed of filling a CD-ROM every 16 minutes.

The reconnaissance orbiter was launched aboard an Atlas V rocket in August for the 310-million mile journey to the Red Planet. Its primary mission ends in 2010, but scientists say it has enough fuel to last until 2014. The $750 million mission is managed by JPL.