Mars Odyssey begins orbital shift
NASA’ longest-serving Martian spacecraft, Mars Odyssey, which has circled the dusty plains of the Red Planet since orbital insertion in 2001 has a new mission and has been placed into the proper orbit to carry it out. NASA wants the orbiting probe to carry out the first comprehensive study of how morning fogs, clouds and surface frost develop in different Martian seasons.
Flight controllers from NASA’s Jet Propulsion Laboratory and Lockheed Martin Space Systems of Denver directed the spacecraft into its new orbit on Tuesday, February 11. This “nudge in the right direction” will gradually place Odyssey into a morning-daylight orbit, which the spacecraft should compete next year.
“We’re teaching an old spacecraft new tricks. Odyssey will be in position to see Mars in a more different light from ever before,” said Jeffrey Plaut, a project scientist working on the Mars Odyssey orbiter.
Since NASA’s Viking missions of the 1970s, all Mars orbiters have been positioned to observe late-afternoon conditions on the Martian surface. This repositioning will provide the Mars Odyssey orbiter with the optimal position to observe early-morning clouds and fog.
Odyssey flies a polar orbit, circling Mars in a trajectory synchronized with the Sun. Just as a spacecraft orbiting within the terminator would be in perpetual twilight, Odyssey passes from north to south within a slice of 5:00 p.m. local solar time, then from south to north at 5:00 a.m. For its first three years, it was in a 4:00 orbit, allowing time for the Thermal Emission Imaging System (THEMIS) to view the surface when the midafternoon warmth made the infrared emissions of the surface minerals more visible. It also allowed the gamma ray spectrometer to point away from the Sun. However, this placed the spacecraft’s solar panels in darkness for longer periods of time, putting a strain on the power system.
Philip Christensen, THEMIS’s Principal Investigator, suggested shifting to a 6:00 orbit, allowing the spacecraft to view the surface at 6:45 a.m. during the south-to-north orbit. The maneuver was done on Tuesday, February 11. Four thrusters, each providing five pounds of thrust, fired for twenty-nine seconds, nudging the spacecraft into a slow drift which will bring it into its new orbit by November of 2015. At that time another maneuver will stop the drift and stabilize the orbit.
“This veteran spacecraft performed exactly as planned,” said David Lehman, Odyssey’s project manager at JPL.
Early-morning observations should yield new information about the temperature changes that occur before and after sunset, and consequently the temperature-driven processes on the surface, such as carbon dioxide geysers fueled by seasonal frosting and defrosting at the poles, and dry ice floes observed on some slopes.
“We don’t know exactly what we’re going to find when we get to an orbit where we see the morning just after sunrise. We can look for seasonal differences. Are fogs more common in winter or spring? We will look systematically. We will observe clouds in visible light and check the temperature of the ground in infrared,” Christensen said.
When the maneuver is completed, the spacecraft will have enough propellant for about another nine to ten years, during which time it will not only perform its own orbital observations, but also serve as a communications relay for other probes in orbit above the flash-frozen world as well as the Opportunity and Curiosity rovers on the planet’s surface.
Mars Odyssey was launched from Cape Canaveral Air Force Station’s Space Launch Complex 17 Apr. 7, 2001, on a Delta II rocket It reached Mars on October 27 of that year. In its long life, Odyssey has revealed the presence of subsurface ice and mapped the landing site for the Mars Science Laboratory rover Curiosity.
Collin R. Skocik has been captivated by space flight since the maiden flight of space shuttle Columbia in April of 1981. He frequently attends events hosted by the Astronaut Scholarship Foundation, and has met many astronauts in his experiences at Kennedy Space Center. He is a prolific author of science fiction as well as science and space-related articles. In addition to the Voyage Into the Unknown series, he has also written the short story collection The Future Lives!, the science fiction novel Dreams of the Stars, and the disaster novel The Sunburst Fire. His first print sale was Asteroid Eternia in Encounters magazine. When he is not writing, he provides closed-captioning for the hearing impaired. He lives in Atlantic Beach, Florida.