Phoenix lands on arctic plains of Mars
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: May 25, 2008;
Updated after post-landing Odyssey data relay pass
With Newtonian inevitability, NASA's Phoenix lander plunged into the martian atmosphere today at 12,700 mph and then used atmospheric friction, a large parachute and finally, 12 individually controlled rocket engines to complete an automated landing near the red planet's northern polar cap. The successful touchdown at 7:53:44 p.m. marked a dramatic reversal of fortune for NASA, which suffered a devastating failure the last time the agency attempted a rocket-powered descent to Mars nine years ago.
This time around, telemetry from Phoenix, relayed to Earth through NASA's Mars Odyssey orbiter flying high above the landing site, indicated the small, 760-pound lander completed its action-packed descent as planned and in good health.
"Phoenix has landed! Phoenix has landed! Welcome to the northern plains of Mars!" mission commentator Richard Kornfeld exclaimed from the control center at the Jet Propulsion Laboratory.
"We're down, baby, we're down!" exulted an unidentified engineer as grinning managers and flight controllers exchanged hugs, handshakes and yelled with sheer elation. NASA Administrator Mike Griffin looked on from the back row of the control center, listening intently to the commentary.
"People really got uncomfortable," said Doug McCuistion, director of Mars exploration at NASA headquarters. "The pucker factor really kind of jumped."
Said NASA science chief Ed Weiler: "It was a hell of a lot scarier than two Mars rovers, I'll tell you that!"
As expected, Odyssey dropped below the martian horizon about a minute after touchdown, cutting off all data from Phoenix and forcing mission managers and engineers to wait an anxious hour and 50 minutes for the orbiter to swing back around the red planet to re-contact Phoenix.
But right on schedule, Odyssey picked up signals from Phoenix and sent back data and crystal-clear pictures showing both solar arrays fully deployed - a critical milestone for the $420 million mission - and dramatic shots of the martian horizon showing a smooth, relatively terrain littered with small rocks, just what scientists were hoping for. Other shots of the ground closer to the spacecraft showed a lattice-like expanse of polygonal areas believed to be caused by sub-surface ice.
One picture showed a white, angular feature near the horizon, but it was not immediately clear whether it was an actual surface feature, a discarded piece of the spacecraft or some sort of defect in the photo.
FIRST IMAGES: THE LANDSCAPE
Engineers were elated by the initial views from Phoenix, showing an apparently healthy lander on the northern polar plane at 68.22 degrees north latitude, 234.3 degrees longitude. While scientists expected the lander's 12 engines to kick up a fair amount of dust during the final few feet of the descent, the arrays appeared pristine in the initial black-and-white pictures.
Along with the solar arrays, the pictures showed a protective barrier shielding the lander's robot arm had deployed as planned.
"In my dreams it couldn't have gone as perfectly as it went tonight," Goldstein said after landing. "Right down the middle. We're on the surface. We can confirm we're at one quarter degree tilt, we're almost dead on to our azimuth."
Summing up, Goldstein said, "I'm speechless."
Telemetry showed Phoenix touched down with a vertical velocity of about 5.4 mph and a horizontal velocity of less than 0.2 mph, oriented with respect to north within 1 degree of what engineers expected. The battery was still 90 percent charged at touchdown and the lander's descent engines used up 82.8 pounds of propellant. The remaining 37.3 pounds were expected to freeze overnight.
Here is a transcript of the final minutes of entry, descent and landing as Kornfeld provided play-by-play commentary:
"Atmospheric entry on my mark... five, four, three, two, one, mark," Kornfeld said at 4:45 p.m. "Expected peak heating rate in one minute and 40 seconds. Standing by possible plasma blackout.
"Phoenix now one minute past the entry point. We still have signal by direct (to Earth), by Odyssey. At this point in time we notice a drop in Odyssey signal, but we still have OC data.
"At this point in time, Phoenix goes normally through peak heating. At this time we still see a signal by Odyssey.
Phoenix now two minutes and 25 seconds past entry point. We still have signal by Odyssey. Standing by for reacquisition by direct to Earth. Standing by for Odyssey switch to 32k data rate in 45 seconds.
"Stop of Odyssey (garble) data and switch to 32K. In 10 seconds.
"Odyssey switch to 32k detected. We have Odyssey locked up on the Phoenix carrier. Standing by for expected (garble) and Phoenix switch to 32k. At this point in time, Phoenix would have nominally deployed its parachute. Standing by for telemetry acquisition.
Suddenly, loud cheers and applause broke out in mission control.
"Phoenix switch to 32K detected. We have data lockup. Parachute deployment trigger detected. Heat shield trigger detected. Ground relative velocity 90 meters per second. Ground relative velocity 80 meters per second.
"At this point in time standing by for radar on and altitude convergence. Radar switch to altitude mode... standing by for altitude convergence.
"Landing leg deployment trigger detected. Ground relative velocity 60 meters per second. Standing by for altitude convergence.
"At this point in time, Phoenix would have nominally reached altitude convergence. Standing by for confirmation by telemetry.
"Radar reliable! (cheers) Altitude 2,000 meters. Altitude convergence detected. Altitude 1,800 meters, 1,700 meters, 1,600 meters..."
"Standing by for lander separation. Altitude 1,100 meters. Signal may drop out during lander separation. Altitude 1,000 meters.
"Separation detected! We have reacquired the signal, gravity turn detected. (cheers) Altitude 600 meters... 500 meters... 400 meters... 250 meters... 150 meters... 100 meters... 80 meters... 60 meters... constant velocity phase detected. Altitude 40 meters... 30 meters... 27 meters... 20 meters... 15 meters... standing by for touchdown. Touchdown signal detected! (cheers) Landing init sequence initiated. Helium vent detected!"
Mission managers burst into applause, sharing hugs and handshakes as Kornfeld continued his commentary.
"Standing by for normal termination of EDL comm. Standing by for nominal termination of EDL comm...
"We have nominal termination of EDL comm by Odyssey and direct to Earth! Phoenix... Phoenix has landed! Phoenix has landed! Welcome to the northern plains of Mars!"
"We're down, baby, we're down!" someone exclaimed.
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