In Brief:

October 12, 1999
Web posted at: 4:53 p.m. EDT (2053 GMT)

(CNN) -- Flight operators have set October 20 as the date for a fourth planned thruster firing to correct the course of a lander speeding toward Mars, a matter of intense scrutiny following the recent loss of another NASA spacecraft due to a navigation error.

Missions commonly undergo such course corrections so engineers can fine tune the path of a spacecraft after it is launched and approaches its target.

In this case, NASA is under added pressure to send accurate navigation commands to its Mars Polar Lander, set for a December 3 touchdown, as its sibling spacecraft, Mars Climate Orbiter, was lost September 23 after receiving garbled navigation commands from NASA and its commercial partner Lockheed Martin.

A fifth correction to Polar Lander could come the day before landing if engineers find it is necessary. The navigation commands to Climate Orbiter were garbled because NASA failed to convert data from Lockheed Martin in English units into the metric system.

Meanwhile, flight engineers also are scrambling to re-program Polar Lander so it can transmit all its data independently to Earth or via another orbiter without help from Climate Orbiter, which had been designed to collect data on Mars' atmosphere and relay data transmissions from the lander to Earth.

Polar Lander is healthy, operating normally and not afflicted by the same metric conversion problem that doomed Climate Orbiter, NASA says.

That spacecraft now is thought to be orbiting the sun, likely in pieces, following a failed attempt to enter the orbit of Mars during which it plunged precipitously into Mars atmosphere and sped out of NASA's control beyond the planet.

Last weekend, safety software shut down Polar Lander temporarily in response to communications problems between its navigation and operating software.

Later in the day, the flight team returned the spacecraft back to normal.

Project managers believe all of Polar Lander's science objectives will be met during its planned three-month study of the history of water on Mars, despite the setback with the loss of Climate Orbiter.

As of Monday, Polar Lander was 23.6 million kilometers (14.7 million miles) from Mars, approaching at a speed of 4.6 kilometers per second (10,300 miles per hour) relative to the red planet.

(CNN) -- High-tech methods to find planets around nearby stars are the focus of three graduate students selected to receive Michelson fellowships offered by NASA's Origins Program and its Space Interferometry Mission.

The fellowship program is named for Dr. Albert Michelson, the first American to win a Nobel Prize in physics. He is known as the father of interferometry, a technique that combines and processes light from multiple telescopes to obtain a clear image of distant objects.

Interferometry is an essential part of Origins, which includes several missions to study the formation of galaxies, stars, planets and life. The Michelson Fellowship Program is designed to develop expertise in interferometry.

The recipients are Philip Hinz and Erin Sabatke of the University of Arizona, Tucson, and Benjamin Lane, a student at the California Institute of Technology in Pasadena.

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