EZE DIRECTORY

NASA's Phoenix Mars Lander closed in on the Red Planet this afternoon, accelerating under the growing pull of the the planet's gravity while anxious space agency officials watched and waited with no plans to send further commands.

Signals confirming the three-legged spacecraft's touchdown on the frozen plains of the unexplored North Pole were expected to reach NASA's Jet Propulsion Laboratory at 6:53 p.m. CDT.

The blue and gold lander is the cornerstone of a 7 million mission designed to dig below the barren polar terrain in search of ice and other evidence that Mars once harbored a warmer, wetter climate suitable for some form of life.

"What's scariest for me?" Peter Smith, the University of Arizona physicist who leads the lander's science team, told a midafternoon news briefing. "If you see me freak out, it's because we lost signal and we don't know what that means."

All of the commands that will guide the spacecraft into the Martian atmosphere, trigger the release of a parachute, lower three shock-absorbing lander legs and fire a dozen braking rockets were loaded into the flight computer last week.

At midafternoon, Phoenix was about 30,000 miles from its destination. If the spacecraft was carrying an astronaut, the voyager's face would likely be plastered to the window.

"If you were to look out the window right now, you would see Mars about 10 times the size of the full moon and growing rapidly in the sky," Smith said. "My anticipation is growing just as rapidly."

Late Saturday, mission managers decided the spacecraft's trajectory was so accurate, there was no need for a final course correction maneuver, said NASA's Barry Goldstein, the Phoenix project manager. Phoenix is headed toward an elliptical landing zone about 44 miles long and 12 miles wide, with no ability to turn away.

Only five of 11 or 13 American, Russian and British landers dispatched to Mars have succeeded. NASA's tally depends on how one failed spacecraft with three landers is tallied.

Images of the region collected by the Mars Reconnaissance Orbiter, another NASA spacecraft circling the planet, show the region relatively free of rocks that could tip over the spacecraft or block the unfurling of two circular solar panels.

Though critical descent commands were loaded aboard Phoenix days ago, NASA expects to follow the final minutes of flight through signals relayed to Earth by the Odyssey, another American spacecraft circlilng the planet.

A European spacecraft, Mars Express, and the Reconnaissance Orbiter will be prepared to record signals from the descent and play them back to Earth as well. A large radio observatory in Greenbank, W. Va., will be listening for signals from Phoenix as well.

During the final 15 minutes of a 422-million-mile journey from Earth, Phoenix must slow from 12,600 miles to 5 miles per hour. The commands stored in the spacecraft will cast off a heat shield, deploy a parachute with a mortar and ignite a dozen braking thrusters 18 seconds before touchdown.

A minute after landing, Phoenix's radio will go silent as Odyssey moves out of range. During the radio silence, Phoenix must unpack two circular solar arrays and start to generate electricity.

As Phoenix recharges its batteries, cameras will snap photos of the solar arrays and the first images of the terrain surrounding the spacecraft.

Odyssey will pass over the landing site, about 90 minutes after Phoenix touches down, ready to check in and attempt to relay those first pictures.

Article Source: EZEDIR.COM