After years of planning followed by a ten-month journey, the Mars Phoenix Lander is slated to touch down near the red planet's north pole on May 25.
If successful, the probe will be the first lander to reach a Martian pole and the first to actually touch the planet's water ice. (Related gallery: "Phoenix Lander's Search for Mars Water" [August 3, 2007].)
What's more, it could settle the debate over whether Mars was once a habitable world.
Now, as Phoenix closes in on the last 12 million miles (19 million kilometers) of its journey, NASA scientists are gearing up for the "seven minutes of terror" that could make or break the $420-million mission.
"Approximately 14 minutes before touchdown, the vehicle separates from its cruise stage," Barry Goldstein, Phoenix project manager at the Jet Propulsion Laboratory in California, said today at a press conference.
"At this point we lose communication from the vehicle."
Once the craft reaches Mars's atmosphere, the next critical seven minutes make up what's known as the Entry, Descent, and Landing (EDL) phase.
Screaming down at about 12,600 miles (20,270 kilometers) an hour, the craft must open a parachute to slow itself for a three-minute glide to the surface about 70 miles (113 kilometers) below.
The craft's landing sequence then includes steps such as jettisoning its heat shield, extending its legs, and firing its landing thrusters.
"There are 26 pyrotechnic events, and each of those have to work perfectly for this to go as planned," Goldstein said. "Getting EDL communication [at touchdown]—that'll be the three seconds that I am really biting my nails over."
Risen From the Ashes
The tension for this mission seems especially intense, since Phoenix is not the first craft to attempt a landing at a Martian pole.
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