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.
For the first time, NASA is about to land a spacecraft in a place on another planet where scientists are confident that water exists. The Phoenix lander is set to blast off from Cape Canaveral early tomorrow for a journey to near the Martian north pole.
Once there, it will extend a 7-foot-long robotic arm to dig 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 instruments that NASA has ever sent to the surface of another world. They 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.
Finding organic compounds would not be proof of life. But it would be a major step toward proving that Mars could be, or once was, habitable.
"We hope it will move us closer" to answering the life on Mars question, said project scientist Leslie Tamppari.
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 ability to support 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 Odyssey spacecraft detected a subterranean storehouse of hydrogen at Mars' north pole that scientists are confident is water ice. Then, a few months ago, the Global Surveyor detected from orbit what appears to be evidence of water flows on Mars today.
"We're going to where the water is," Goldstein said. "Our plan is to go touch it, taste it, sniff it."
Phoenix, built by Bethesda-based Lockheed Martin Corp., is scheduled to land in April, slowing from 12,500 mph to a 3-mph parachute landing at a place called the Scandia Formation.
The latitude is equivalent to Alaska's 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 C02 has evaporated.
"We hope to see ice" deposits, Goldstein said.
Even if they don't, water - in the form of ice, since the temperature is a chilly minus 4 degrees Fahrenheit - lies only a couple of inches below ground.
John Johnson Jr. writes for the Los Angeles Times.