CAPE CANAVERAL -- An $800 million pair of roving NASA robot geologists will head to Mars this month to look for evidence of past liquid water and renew humankind's search for life beyond Earth.
Wherever biologists have found the basic building blocks of life together on our planet, whether on the highest mountain peaks or in the deepest ocean trenches, they've also found some type of living organism. Scientists have discovered most of those same building blocks on Mars except for one: liquid water. The search for that missing ingredient has become the focus of the National Aeronautics and Space Administration's plan to explore the Red Planet.
Simply put, the plan is to "follow the water."
"The reason we're following the water is because water is a necessity for life," said Steve Squyres, a Cornell University professor who is the mission's principal scientist. "You can think of these rovers as being robot field geologists. Their job is to go to these sites, to read the geologic record, just as a geologist with a hand lens and a rock hammer does, and try to assess what it was like back then."
In the past five years, two NASA probes orbiting Mars have uncovered compelling evidence that liquid water recently existed on the planet and could be there still.
Pictures taken from orbit since 1997 by the Mars Global Surveyor suggest gullies carved by water are scattered around the Martian globe. The Mars Odyssey orbiter launched in 2001 found large amounts of ice crystals mixed with soil at the planet's higher latitudes, as well as possible evidence of ancient snowpacks.
"If we can show that water actually filled lakes or oceans and stayed there for thousands or tens of thousands or millions of years, then the possibility of life on Mars, either past or current, goes up dramatically," said Ed Weiler, NASA's associate administrator for space science. "That is exactly what these missions are going to do: determine what is the history of water."
A pair of robot rovers has been designed to uncover that history.
The first of two identical spacecraft -- dubbed Mars Exploration Rover-A but scheduled to receive a new name this morning from among 10,000 suggestions by students -- is set to begin a seven-month journey to the Red Planet today aboard a Delta 2 rocket launched from Cape Canaveral Air Force Station.
The Rover-A mission has a pair of launch opportunities at 2:05 p.m. and 2:44 p.m. However, forecasters are predicting only a 40 percent chance of favorable weather. The Rover-B is scheduled to follow on June 25.
Around the globe in Central Asia, the European Space Agency launched its Mars Express spacecraft, which includes a small lander named Beagle 2, aboard a Russian Soyuz rocket last Monday. The Beagle is designed to survey the Martian surface for six months with cameras, sensors, a microscope, a robot arm and a drill built to penetrate 5 feet into the soil.
The timing of all three probes will take advantage of an astronomical rarity: On Aug. 27, Mars will make its closest approach to Earth in at least 60,000 years, a time well before the beginning of recorded human history. The Red Planet will be 34.7 million miles away, offering an opportunity for scientists to dispatch spacecraft more cheaply on smaller rockets.
LOOKING FOR WATER
Researchers chose the NASA rovers' destinations from 155 potential landing sites based on the best prospects for landing safely and finding evidence of water.
Rover-A will head to Gusev Crater, a 95-mile-wide chasm south of the Martian equator. The crater is thought to have once been the site of a lake. The lake is long gone, but researchers suspect the floor of the crater still contains sediments that will show whether watery conditions were present when the sediments were deposited.
Rover-B is targeted for Meridiani Planum, a region of smooth plains near the equator that lies halfway around Mars from Gusev Crater. The site was selected after a spectrometer on the Mars Global Surveyor detected lots of an iron oxide mineral called gray hematite there. On Earth, gray hematite usually forms in conjunction with liquid water.
Measuring about 5 feet long, the 384-pound robots are designed to operate for at least 90 days on the Martian surface before the planet's growing distance from the sun critically reduces the generating capacity of the rovers' power-producing solar panels. The robots are expected to roam a total of 600 yards to 1,000 yards around their landing sites during their planned three-month missions.
The rovers are equipped with cameras to take photographs and spectrometers to analyze the surface's mineral composition. In addition, they have extendable arms outfitted with a trio of tools: a combination camera-microscope that will photograph close-ups of rocks and soil; additional spectrometers for more-detailed analysis of mineral composition; and a grinding wheel that can cut almost a quarter-inch into rocks to remove dust and weathered surfaces, revealing the fresh rock underneath.