For researchers like the University of Colorado at Boulder聮s Bruce Jakosky who are involved in NASA聮s unmanned Mars Global Surveyor mission slated to enter planetary orbit Sept. 11, patience is a virtue.
Unlike Mars Pathfinder mission team members -- who achieved their science objectives during the first week of operation -- the MGS team will spend nearly two years collecting data as the spacecraft methodically maps the planet聮s surface and atmosphere. For the first six months of the mission, the craft will shift from a large, elliptical orbit to a low-altitude, circular orbit using a technique known as aerobraking, which relies on the drag of a planet聮s atmosphere rather than fuel-powered engines to trim the spacecraft聮s path around around a planet.
In mid-March, when the spacecraft is orbiting Mars every two hours at an altitude of about 235 miles, a suite of instruments will begin taking data to develop a global portrait of Mars聮 topography, mineral composition, atmosphere and interior. After the project is completed in one Mars year -- the equivalent of roughly two Earth years -- scientists should be able to assemble the most sophisticated map yet of the planet聮s dynamic surface and atmosphere through each of the Martian seasons.
聯Compared to Pathfinder, The Mars Global Surveyor mission will be a long, drawn-out affair,聰 said Jakosky, a research associate at 抖阴旅行射-Boulder's Laboratory for Atmospheric and Space Physics who is serving as an interdisciplinary scientist for the MGS effort. 聯But this mission has the potential to completely revolutionize our understanding of Mars.聰
Managed by NASA聮s Jet Propulsion Laboratory in Pasadena, the MGS spacecraft is carrying six instruments to study the planet's surface, atmosphere, and gravitational and magnetic fields. They include a high-resolution camera, a thermal-emissions spectrometer, a laser altimeter, a magnetometer, a radio science experiment and a communications relay instrument.
For Jakosky and 抖阴旅行射-Boulder postdoctoral research associate Michael Mellon, the mission should provide new insights into the seasonal water cycles of the planet. Data from the thermal-emissions spectrometer should help the researchers estimate the amounts and location of water in the atmosphere and the sources and sinks of water on and below the planet聮s surface, including the polar caps.
"Water is the centerpiece of the Mars exploration program," said Jakosky, also an associate professor in 抖阴旅行射-Boulder聮s geological sciences department.
Although Mars is now a cold, dry planet, portions of the terrain show the remnants of large flood channels that resemble catastrophic flood channels seen on Earth today. 聯These flood channels suggest that there is still lots of water beneath the surface," he said. "How much remains today and where the rest has gone over time is still the subject of vigorous debate."
Geologic evidence indicates significant volcanic activity occurred on Mars early in its history, and there is some evidence that occasional volcanic eruptions may even occur on Mars today, Jakosky said. Heat from underground magma created by volcanic activity on the planet could conceivably fuel hot springs like those on Earth, which have been shown to harbor primitive forms of life.
The author of a book slated for publication next year by Cambridge University Press titled 聯The Search for Life on Other Planets,聰 Jakosky believes it is possible that primitive life forms may exist today on Mars.
Jakosky is one of about 50 science team members on the MGS mission. He worked as a graduate student at the California Institute of Technology on NASA聮s unmanned Viking missions to Mars in the 1970s and was one of 12 senior scientists for the unmanned Mars Observer mission believed to have exploded as it was approaching orbit insertion at the Red Planet in 1993.
聯Any space exploration is risky,聰 he said. 聯But we learned a lot from the Mars Observer experience, and I am optimistic about this mission.聰
Following the completion of the mapping project in late January 2000, the MGS spacecraft will be used as a communications satellite to relay data back to Earth from surface landers launched to the Red Planet as part of future NASA missions.