The Nation

Mars probe to go on mission for a cold drink

JPL scientists plan to land the Phoenix in an area they're confident has ice -- one possible sign of life.

August 03, 2007|John Johnson Jr. | Times Staff Writer

The search for life on other worlds can be boiled down to a simple maxim: Follow the water. Life, at least the carbonaceous form we are familiar with, loves water.

Now, for the first time, NASA is about to land a spacecraft in a place on another planet where scientists are confident water exists. The Phoenix Mars lander is set to blast off from Cape Canaveral early Saturday for a journey to near the Martian north pole.

Once there, it will extend a 7-foot-long robotic arm to dig down to a layer of ice thought to lie just beneath the surface. If the ice is as hard as some scientists suspect -- think concrete -- Phoenix will use a tungsten carbide drill to bore into it.

The soil and ice will be analyzed by the most sophisticated suite of scientific instruments ever sent to the surface of another world. The instruments will scan, magnify and cook the compounds, finally sending them through a mass spectrometer to identify their parts.

"The Holy Grail would be to find organics," said Barry Goldstein, the project manager at the Jet Propulsion Laboratory in La Canada Flintridge. "That would be a major splash."

Finding organic compounds would not be proof of life. But it would be a major step forward in proving that Mars could be -- or once was -- a habitable place.

"We hope it will move us closer" to answering the life-on-Mars question, said project scientist Leslie Tamppari.

NASA isn't known for its sense of humor, but the name Phoenix was chosen for its symbolic value. The $400-million mission is the reincarnation of the 1999 Mars Polar Lander, which was lost as it descended toward the planet's south pole.

The name could also symbolize the rebirth of interest in Mars and its apparent capability of supporting some form of rudimentary life.

For two decades after the Viking missions of the 1970s, Mars was considered a dead-end world. "Self-sterilizing" is the term scientists used to describe a place that the Viking instruments found to be more barren than the harshest deserts on Earth.

Now the story has changed. NASA's two Mars rovers, Spirit and Opportunity, have found evidence that water once coursed over much of the surface. The orbiting Mars Odyssey spacecraft also detected a large subterranean storehouse of hydrogen at the north pole that scientists are confident is water ice. Then, a few months ago, the Mars Global Surveyor detected from orbit what appears to be evidence of current water flows on Mars.

"We're going to where the water is," Goldstein said. "Our plan is to go touch it, taste it, sniff it."

Phoenix, built by Lockheed Martin Corp., is scheduled to land in April, slowing from its 12,500-mph cruise speed to a 3-mph parachute landing at a place called the Scandia Formation.

The latitude is equivalent to Alaska on Earth. In winter, the ground is covered by a thick layer of carbon dioxide ice, so the plan is to land in early summer, when the CO2 has evaporated.

The landscape underneath is thought to be composed of small rocks and dust. "We hope to see ice" deposits, Goldstein said. "That would be pretty darned exciting."

Even if they don't, water -- in the form of ice, since the temperature is a chilly minus 4 degrees Fahrenheit -- is believed to lie only a couple of inches below ground.

The spacecraft's robotic arm is the longest NASA has ever put on a lander. The scoop had to be redesigned after scientists determined that the ice layer could be much harder than ice on Earth.

A New York company, Honeybee Robotics Spacecraft Mechanisms Corp., made the super-hard drill attached to the scoop. The shavings the arm collects will be placed in an instrument called a thermal and evolved-gas analyzer, or TEGA, which contains eight tiny ovens.

Each electric oven will be used once to analyze one of eight unique samples of ice and soil, heating it to about 1,800 degrees. The heating will occur over three days, during which controllers on Earth will monitor changes in the samples from solid to liquid to gas. The gases will then be analyzed by a mass spectrometer to reveal the chemistry of the compounds.

Anything boiling off at relatively low temperatures could indicate organic chemicals. That would almost certainly set the science world abuzz, both with excitement and with noisy debates as to whether the findings really indicate the presence of biological processes.

Tamppari emphasized that Phoenix "is not searching for life. We're trying to understand the environment. We're interested in the water story."

The other lab aboard the craft is the JPL-built microscopy, electrochemistry and conductivity analyzer, or MECA, which will add Earth water to Martian soil samples.

"It can tell you what the environment was like when the planet had water" in liquid form on the surface, Tamppari said.

Its microscopes can also detect bacteria.

Phoenix also carries a suite of five cameras, including one on a mast and another that will take pictures as the spacecraft descends to the surface.

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