Our Red Neighbor

In the past, Mars has been thought of as Earth’s smaller, colder, drier, redder brother. With new information about the planet being gathered all the time, our perception might be changing soon.

“We have imaged the planet many times, and taken high resolution images,” says Arden Albee, PhD, project scientist for the Mars Global Surveyor Mission at NASA's Jet Propulsion Laboratory (JPL). “The globe of Mars we had before was a flat globe. It had no projections on it. Now we have a globe of Mars that is a detailed representation of the shape of Mars. We know that it is egg-shaped. We know that it is lower in the north than in the south. And indeed, we know the mountains and the valleys and the lowlands much better than we actually know the Earth.”

Studying Mars helps scientists better understand our own planet. “The Mars atmosphere is a lot like that of the Earth,” explains Albee, who writes about JPL’s recent discoveries about Mars in the June, 2003 issue of Scientific American. “It has a tilt of 23 degrees, so it has seasons. It has an atmosphere that is much thinner than the Earth, but the storms move from west to east, and there are other complications--the dust in particular--that we don’t have on Earth. But on Earth we have oceans; on Mars we have the change of the icecap, almost like the Ice Age on Earth, but the icecaps grow and recede twice a year, in the north and the south.”

image: NASA

The Global Surveyor has studied the entire Martian surface, atmosphere, and interior, and has returned more data about the red planet than all other Mars missions combined. It launched on November 7, 1996, entered orbit on September 12, 1997, and began its prime mapping mission in March 1999, observing Mars from a low-altitude, nearly polar orbit over the course of one Martian year, which is about two Earth years. It completed its primary mission on January 31, 2001, and is now in an extended mission phase. The pictures it took suggest that there may be current sources of liquid water at or near the surface of the planet.

Also in orbit around Mars is the Odyssey, which was designed to determine the composition of the Mars’ surface, detect water and shallow buried ice, and study its radiation environment. It launched on April 7, 2001, and arrived on October 24, 2001.

As NASA continues to gather information about Mars, a big question remains: Could it support life as we know it?

image: NASA

“Personally, I don’t believe there is life on Mars now, based on the best evidence we have,” says Albee. “Mars is bathed in radiation that would make it very difficult for things to survive on the surface. At the same time, it is very cold and there is not liquid water, except for very short periods of time, possibly. So at the moment, I don’t think it is likely that there is life on Mars. Whether there was life in the past, we cannot establish that. We simply don’t know at this point.”

The discovery of water beneath the surface would shed more light on the subject. NASA’s next two Mars missions, Mars Exploration Rovers and Mars Express, will continue to search for conclusive evidence of the existence of life. Mars Express launches in June, and will arrive in December to explore the atmosphere and surface of Mars from polar orbit in order to search for sub-surface water. The Exploration Rovers will also launch in June, and will arrive in January 2004 to search for evidence of liquid water that may have been present in the planet's past.