Phoenix's robotic arm digs a trench in the ice-rich
martian soil, seeking signs as to whether Mars may
be hospitable to life. Corby Waste (JPL)
If the weather holds along Florida's Atlantic coast, NASA's Phoenix spacecraft should blast off from Cape Canaveral this Saturday. Its target: the frozen plains of northern Mars. After a voyage of nearly 10 months, the probe will set down in the Red Planet's polar region next May to study the history of water at the landing site and whether the martian arctic can support life.
To residents of Arizona's Valley of the Sun, Phoenix may seem an odd name for a mission to the frigid martian pole. Instead, Phoenix's name follows from the mythological bird consumed by fire, which then rose, renewed, from the ashes. It's an apt name for the spacecraft because much of it derives from two previous NASA craft that suffered ignominious fates. Phoenix's main structure was resurrected from the 2001 Mars Surveyor lander, which was mothballed when that mission was canceled. And many of Phoenix's scientific instruments are from either that Surveyor or from the ill-fated 1999 Mars Polar Lander, which apparently crash-landed.
Unlike the successful Spirit and Opportunity rovers and, before them, Mars Pathfinder — all of which bounced to safe landings on cushions of airbags — Phoenix will use retrorockets to come to a soft landing. Phoenix simply weighs too much to use an airbag landing. And NASA has plans to send even heavier rovers and science laboratories to Mars.
Phoenix won't be roving the surface, either. It will stay put, using a robotic arm to dig a trench in the ice-rich soil. The arm will deliver samples to two instruments designed to see whether Mars was ever hospitable to life. Other instruments will image the surroundings and monitor the polar climate. NASA expects the solar-powered spacecraft to last 3 months.
The Mars Odyssey and Mars Reconnaissance Orbiter spacecraft have been scouting specific landing sites. Right now, the leading candidate site lies at 233° east longitude and 68° north latitude, a latitude equivalent to northern Alaska. These two orbiters also will serve as communications relays for the Phoenix lander. If the mission works as expected, a year from now we'll be basking in results from NASA's latest venture to understand the Red Planet.