New Mars Orbiter's Strategy: 'Follow the Water'

By Rick Weiss
Washington Post Staff Writer
Monday, August 15, 2005

Every 26 months or so, Earth uses its inside track around the sun to lap its slower-circling neighbor Mars. At that point, the two planets are at their closest, and the amount of energy required to fly from one to the other is tantalizingly modest by interplanetary standards.

Since 1996, NASA has taken advantage of every one of those biennial opportunities to launch spacecraft to Mars, and last week was no exception. On Friday, with Earth coming up fast on the Red Planet's heels, NASA launched the Mars Reconnaissance Orbiter (MRO), the latest and most sophisticated package of scientific instruments ever tossed toward the war-god planet.

The MRO is designed to orbit Mars for as long as eight years. Its prime mission is to help determine whether life has ever existed there and whether, perchance, any kind of life resides there today in some of the planet's less hostile niches.

It will also look for landing spots for future spacecraft -- including a very special lander that NASA hopes will someday carry life-forms of its own, namely earthlings.

The SUV-size spacecraft rode atop a 19-story, candlestick-thin Atlas-Centaur rocket that crackled skyward at 7:43 a.m. Eastern time. (Speaking of SUVs, the Atlas guzzled 200 tons of fuel and oxygen in just over four minutes.)

About an hour later, already halfway around Earth and more than 100 miles high, the two-ton MRO blasted free of its launch vehicle and, like an awakening bat, unfolded its two 20-foot-long solar panels. They will power the craft during its seven-month, 310 million-mile journey to Mars, and for years to follow.

As it approaches its destination in early March, a 30-minute rocket burn will slow the $450 million craft, allowing it to be captured by Mars's gravitational field. Once snagged into orbit -- where it will join the three other satellites now circling the planet -- the craft will begin a series of "aerobraking" maneuvers, dipping briefly and repeatedly into the thin Martian atmosphere like a skipping stone.

That will gradually slow the craft, dropping it into lower orbits. By November 2006, the MRO will be the lowest orbiting satellite ever sent to Mars, regularly passing within 158 miles of the surface.

From that radically low vantage, MRO will begin its two-year scientific mission -- one that scientists expect will teach them a lot about our own planet by providing new insights into how Earth was formed, how life may have evolved here and how natural forces can contribute to climate change.

One thing is central to all those issues, both on Earth and on Mars: water. So it should come as no surprise that NASA's chief scientist for Mars exploration, Michael Meyer, sounded a little like Deep Throat last week when he summarized MRO's MO: "Follow the water," he told a Washington Post reporter, speaking by phone from an undisclosed location that probably was not a parking garage.

Recent Mars missions have offered compelling evidence that Mars once had substantial amounts of water, and there are clues that it may yet have large reservoirs, albeit underground or beneath frozen caps. Those clues, in conjunction with recent revelations that some earthbound organisms can thrive in environments far more inhospitable than science had thought capable of supporting life, lead many scientists to suspect that the Red Planet may be home to at least some relatively simple microbes.

To look for the water that would support that life, or for evidence of its existence in the past, the MRO carries six instruments.

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