By KURT LOFT
The Tampa Tribune

TAMPA - Consider it the great cosmic ice breaker.

That’s how scientists describe tonight’s planned touchdown of the Phoenix Mars Lander, the first robot to dig into ice on the Red Planet. If all goes well, the $386 million craft will plunge through the atmosphere and settle atop the northern arctic plain, where researchers hope to find treasure below the surface: frozen water.

“We know Mars is a wet planet in its own weird way, but we’ve never tasted the water,” said James B. Garvin, chief scientist for NASA. “This is exploration at its best. This is a bold stroke.”

The United States and Russia have been attacking Mars since the 1960s, and a squad of machines is sniffing the surface and orbiting overhead. But none has poked under the polar ice, the mostly likely place to find frozen water - and prized organic compounds.

“Phoenix is sort of like CSI does Mars,” Garvin said. “It will tell us what’s in the frozen water and whether it could have been an abode for life.”

The Martian ice may act as a time capsule, holding clues about the planet’s history that could be relevant to Earth’s evolution, said Carol Williams, retired professor of mathematics and astronomy at the University of South Florida.

“I don’t know what we will find out about the poles of Mars, but because Mars has poles, we can’t lose,” she said. “If we dig into the polar ice and get information about the climate of Mars, that could help us understand a lot more about our own world.”

Mission scientists at the Jet Propulsion Laboratory in Pasadena, Calif., are in for a white-knuckled day. Everything must work precisely as planned as the craft ends its 10-month, 420 million-mile journey. As it slips into the Martian atmosphere about 80 miles above the surface, it will jettison a protective heat shield, open a parachute and deploy landing gear equipped with radar.

Small rockets will slow the probe while the radar searches for a flat spot to settle down at 7:38 p.m. But scientists won’t know what happened for 15 minutes - the time it takes radio signals to travel 170 million miles to Earth.

High-definition cameras then will start sending images of what should be a spectacular landscape.

“Landing on Mars is hard, so Phoenix has a big job to do,” Garvin said. “But we’re all very optimistic that we’re going to see a new Mars for Memorial Day weekend.”

If all systems are working, the solar-powered Phoenix will unfold its 8-foot-long arm and begin scooping samples of underground ice and soil. A barrage of sensitive instruments - including a microscope and gas analyzer - will study the makeup of the samples.

But looking for Martian microbes presents a problem. What if germs from Earth came along for the ride, and scientists mistake them as Mars natives? To discourage any hitchhikers, Phoenix spent months in a sealed clean room at NASA’s Planetary Protection Unit in Littleton, Colo., where technicians disinfected exposed surfaces.

“We’ve done all we can do, so we don’t think we’re carrying any microbes to Mars,” Garvin said. “We’ve done everything to remove Earth contaminants from the craft.”

Phoenix is the first project in NASA’s Mars Scout program - a series of low-cost probes that will study the planet over the next decade. Phoenix was made of parts taken from a canceled mission in 2001.

However, the robot won’t last long, at least compared with the Spirit and Opportunity rovers that have been roaming the Martian surface for more than four years.

The rovers are in a warmer climate with abundant sunlight. A stationary Phoenix will be stuck in the cold, and its solar panels won’t draw enough sunlight to recharge the batteries. By late summer, the vehicle will be covered in ice.

But in its short life, Phoenix could hit the jackpot, Garvin said.

“We’ve learned that digging two or three inches of soil is the least likely place to find life because it’s pounded by radiation,” Garvin said of the rovers’ terrain. “So, the strategy is to look in the ice sheet because hydrogen in the ice will protect any organic molecules.

“If anything is alive on Mars, it would be deep in aquifers or under the ice sheets. This is a good strategy for exploration.”

ON TV

Watch live updates and commentary during the special “Mars Live: The Phoenix Lands,” from 7 to 9 p.m. on the Science Channel; ongoing mission coverage can be found on the NASA channel.

ON TBO.COM

Keyword: Mars, to watch an animation of an artist’s rendering of the Phoenix’s entry, descent and landing.

Reporter Kurt Loft can be reached at (813) 259-7570 or kloft@tampatrib.com.