Scientists at NASA's Jet Propulsion Laboratory endured what they described as the "seven minutes of terror" as the Mars Phoenix Lander attempted a risky descent.
"It's like sending a child to kindergarten on the first day," said Ray Arvidson, professor of earth and planetary sciences at Washington University in St. Louis, and chairman of the landing-site working group.
After the silent, tense minutes of the descent, cheers and clapping broke out in the mission control room of the Jet Propulsion Laboratory and at 7:53 p.m. Eastern time, Richard Kornfeld, the lead communications officer for entry, descent and landing, announced the "touchdown signal detected."
"It was better than we could have possibly wished for," said Barry Goldstein, the project manager for the mission. "We rehearsed over and over again. We rehearsed all of the problems, and none of them occurred. It was perfect, just the way we designed it."
The first pictures from the northern arctic plains of Mars show a flat terrain marked by a polygonal pattern of shallow troughs and scattered pebbles.
Of 11 spacecrafts sent to Mars, only five have been successful. And many of the scientists working on Phoenix remember firsthand the terror - and grim defeat - when the Mars Polar Lander crashed as it tried to land in 1999.
The Mars Phoenix Lander is named after the mythical firebird "Phoenix," which legend says rises from the ashes of its deceased ancestors. The Phoenix spacecraft was remade from parts of a shuttle originally designed for a cancelled 2001 space mission, and reinvented to dig up ice from the Martian ground.
Time and place of descent were strategically chosen: in the sun on a flat area described as a "parking lot."
The main goal of the mission is to examine the soil and the ice just inches below the planet's surface to determine whether it is and ever was habitable, by searching for signs of microbial life. Using a built-in scoop and drill, the lander will dig up soil and ice and analyze the samples.
Scientists will then examine and measure the pH of the soil. If it's too acidic or too alkaline, it may never have been conducive to life, Bass said. They will look for organic molecules, namely carbon, hydrogen and oxygen, as well as more signs of past liquid water.
The twin rovers, Spirit and Opportunity, which have been exploring Mars for four years now, have already discovered rocks that were formed in the presence of water, Arvidson said.
"Mars was warm and wet for sure early in geologic time," Arvidson said. "It raises strongly in my mind the probability that it had the right stuff for life. I'd be surprised if life didn't start on that planet."
It's even possible, scientists say, that the polar region could have been an ocean once.
Arvidson and other scientists are now adjusting to Mars time: The planet takes slightly longer than earth to rotate on its axis, making a Mars day 37 minutes longer than an Earth day, which over time, results in a strange sort of jet lag.
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