On Saturday morning at 5:26:34 a.m. EDT, NASA is planning to launch a new probe to Mars. If everything goes according to plan, Phoenix will touch down on the Red Planet in the afternoon of May 25, 2008. It would be the first soft landing on Mars in three decades. The mission is designed to study the ice near the Martian north pole.
Landing in the Martian polar region presents some major challenges. Even in the summertime, temperatures at night can drop to 100 degrees below zero and there's not a lot of sunlight. So, NASA's solar-powered landers have to run on a tight energy budget.
But the Martian poles have a unique appeal. One of the most tantalizing features is that there's water in the form of ice at the poles. NASA's focus for the past decade has been trying to understand as much about the water on Mars as possible.
An Icy Landing
The leaders of the Phoenix mission say they picked a landing site as far north as they dared.
"We're landing at about 70 degrees north, which on Earth is northern Greenland, northern Alaska, northern Siberia," says Peter Smith of the University of Arizona and the lead scientist for Phoenix. "In fact, the same latitude and longitude on Earth is in the middle of the Siberian permafrost."
To gather up the ice, Phoenix is equipped with a robotic arm.
"The question is, how deep is the ice?" Smith says. "We suspect the ice is only a few inches deep, and in that case, we'll be doing a lot of horizontal digging, and clear an area."
But the ice may be buried beneath the surface. The robotic arm is capable of digging a trench as deep as three feet, although digging that big a hole will take the lander most of the mission to finish.
Once it has the ice sample, the arm carries it to a set of instruments on the lander's deck. One of them is called TEGA for Thermal Evolved Gas Analyzer.
"[TEGA] is basically an oven, which cooks the surface soils and ice to the point where they release the gasses that are trapped inside of them and we can measure the types of gasses that are inside," Smith says. "This releases carbonates, sulfates, all different kinds of minerals. But also, we can detect organic materials. We can't tell whether it's DNA or protein, but we can tell if it's complex organics."
Life on Mars?
You can bet that any reading suggesting organic molecules will touch off intense speculation that there was once life on Mars.
But before it can search for organic molecules on the Red Planet, it has to get there in one piece — and in working order. Phoenix is an extremely complicated spacecraft.
"The one thing that gives me a lot of confidence is that we found a lot of problems," Phoenix project manager Barry Goldstein says. He says he's secure the hardware will work when it gets to Mars.
"What would make me very nervous is if we'd gone through these last few years, and hadn't found problems, because then I would think that we may not have even been looking hard enough, or looking in the right place, because there are always issues to be pulled out of these complicated system," he says.
Phoenix is a departure from the last three successful Mars landers. Those all bounced down to the surface cushioned by giant airbags. After a heat shield and parachute do the initial slowing, Phoenix is supposed to touch down gently using rockets for its final descent.
"As far as how confident I am in the landing system, ask me again on the evening of May 25, 2008, and I'll tell you," Goldstein says. "I'm going to be very nervous until then, no matter what."
By then, Goldstein will know whether Mars will have another functioning robotic visitor from Earth. Or not.
Past Blasts to Mars
Mars exploration has followed a long and bumpy interplanetary road. There have been 38 separate missions to Mars, and more than half have failed. The latest mission — the Phoenix lander — marks the 39th journey. Here, highlights of these Earthly attempts to film, circle and touch the cold Red Planet.