Mars Probe Entourage Poised to Welcome Phoenix

May 9, 2008 -- The last time NASA dispatched a spacecraft to a polar region of Mars, it fell into a radio silence seconds before landing. What happened during Polar Lander's descent has been the subject of countless debates, a top-level investigation and Congressional hearings.

Suffice it to say that whatever happens when the replacement craft Phoenix hones in on Mars on May 25, Earthlings will be watching.

Technically speaking, listening would more accurately describe what a trio of orbiters already circling Mars will be doing for flight controllers as Phoenix descends toward the planet's north pole.

NASA hopes to land the craft so it can burrow down into the frozen tundra and retrieve ice samples that may determine if conditions were suitable for life to develop.

Mars Odyssey will relay the descent and landing live, or what passes for live when the action takes place 171.5 million miles away. At that distance, radio signals traveling at the speed of light take 15.3 minutes to reach Earth. By the time flight controllers know if Phoenix began the descent through the planet's atmosphere, it should have already landed.

Mars Reconnaissance Orbiter and Europe's Mars Express are the backups. They will record signals from Phoenix during the descent and landing which can be relayed to Earth for later analysis.