Mars Odyssey enters orbit

This Tech Talk column originally appeared in The Exponent (University of Alabama in Huntsville), Vol. 33, No. 10 (November 1, 2001). Digitized issue: UAH LOUIS archive. Reproduced here courtesy of that archive.

Bacon

Last week, NASA broke a losing streak when Mars Odyssey successfully entered orbit around the planet Mars. According to a press release from NASA’s Jet Propulsion Laboratory (JPL), Matt Landano—who is Odyssey project manager at JPL—said, “Odyssey flawlessly achieved last night’s one-time critical event of Mars orbit insertion. Hundreds and hundreds of things had to go right, and they did.” Inlight of the failures of the most recent missions to Mars—Mars Climate Orbiter and Mars Polar Lander—the success of the mission thus far has been a public relations win for the nation’s space agency.

Mars Orbit Insertion, as JPL scientists refer to the maneuver, began at 9:26 p.m. Central Time on Tuesday, October 23 when Odyssey fired its main engine. Soon after, Odyssey was behind Mars from Earth’s perspective, so radio communication was impossible. At 9:55 p.m., the Deep Space Network received a signal from Odyssey, and the Odyssey team met the news with jubilant cheering.

Putting Odyssey in position for orbit insertion was no simple task. Mission planners at JPL had to aim Odyssey for a point in space that the orbit of Mars about the sun would intercept, similar to the way a quarterback throws the ball beyond, or leads, the receiver so the receiver can make the catch on the run. The process may be conceptually simple in football, but analysts at JPL, who were obviously up on their linear algebra, identified approximately 220,000 critical variables that Odyssey must track. Despite the complexity, the team’s aim was deadly: according to Bob Mase, Odyssey’s lead navigator, “We were aiming for a point 300 kilometers (186.5 miles) above Mars and we hit that point within one kilometer (.6 miles).”

Before Odyssey can begin pursuing its primary science objectives, the next step is an adjustment from Odyssey’s current elliptical (eggshaped) orbit to a circular orbit about the Red Planet. Odyssey will use a maneuver known as aerobraking whereby the spacecraft will brush against the Martian atmosphere, using its solar panel as hybrid sail and rudder. Each successive “drag pass” will bleed off some of the orbiter’s velocity and compress the orbit. Aerobraking has only been used twice before: with Magellan around Venus and with the Mars Global Surveyor. The Odyssey team expects the aerobraking phase to last about three months.

According to JPL’s Mars Odyssey website, “2001 Mars Odyssey will map chemical elements and minerals on the surface of Mars, look for water in the shallow subsurface, and analyze the radiation environment to determine its potential effects on human health.” These objectives are part of a broader set of goals for the Mars Exploration Program: (1) determine whether life ever arose on Mars, (2) characterize the climate on Mars, (3) characterize the geology of Mars, and (4) prepare for human exploration.

For more information, visit JPL’s 2001 Mars Odyssey Home Page at http://mars.jpl.nasa.gov/odyssey/.