On Sunday, May 25, the Mars Phoenix Lander will plunge through the red planet's atmosphere in search of water – and possibly look for evidence of life on Mars.

In less than two weeks, the Mars Phoenix Lander could realize scientists' long-delayed dream of directly finding Martian ice for the first time. To date, the evidence for water on Mars has been indirect.

And while the Phoenix Lander isn't specifically looking for life, the lander's instrumentation may also find evidence of extraterrestrial organisms.

"If we're successful, this mission will be remembered for being the first to do direct analysis of ice or water on the surface of Mars," said NASA's Mike Gross, who engineered the mission's scientific instrumentation. "We'll dig through the topsoil layers and ice to learn ... whether that environment is or was possibly suitable for microorganisms to grow and reproduce."

The $420 million Phoenix mission is also the first to have its own Twitter feed, which has been sending out updates as the Phoenix approaches Mars.

The lander has traveled nearly 120 million miles since its August 2007 launch. On May 25, it will attempt a landing inside an area about twice the size of Hong Kong, a mere 2,000 square kilometers.

An animation of the Mars Phoenix Lander's entry, descent, and landing. For more, visit wired.com/video. The new NASA mission comes after two major setbacks for Martian landers. NASA's Mars Polar Lander mission disappeared in January 1999 after arriving at the planet, and the European Space Agency's Beagle 2, which was designed to search for signs of life, met the same fate on Christmas Day in 2003.

After these two failed missions, NASA cancelled the Mars Surveyor in 2001 and mothballed the lander. That lander, newly outfitted and upgraded, became the Phoenix.

With the difficult history of lunar missions in mind, the Phoenix team, which has been working on the project for more than five years, will experience some difficult moments as the lander descends, followed by the watchful cameras of the planet's three current orbiters.

"Mars is a pretty dangerous place to visit and landing is always the most tense moment," Gross said. "In the landing, there are no second chances."

Once on the ground, the lander will only have access to a 160-square-foot patch of Martian land within reach of its robotic arm. Within that bedroom-size sample, the lander's arm and array of scientific instruments will dig into the ground of the polar icecap, looking for a history of water and possibly life.

"We can potentially identify organic molecules," Gross explained. "We can identify molecules that have hydrogen and carbon in them, but the goal of the mission is not to look for life."

While the Viking missions of the 1960s dashed hopes that Mars is home to pervasive life, scientific momentum has been building that life could have existed in Mars' distant past, when it is believed that liquid water persisted on the planet.

At the same time, evidence has been mounting that extremophile life can find a way to survive almost anywhere water exists. Microorganisms called psychrophiles live in temperatures as low as negative 12 degrees Celsius. Although the surface of Mars is known to be considerably colder than that, some scientists have theorized that the subsurface of the planet could harbor liquid water, providing habitat for life.

"There's this idea that there are reservoirs of liquid water down there and as soon as you see liquid water, you say, 'Why couldn't there be microbes?'" said Edward Young, the principal investigator of the UCLA IGPP Center for Astrobiology. (Young is not involved with the Phoenix mission.)

In addition to analyzing ice and looking for the ingredients of life, the Phoenix mission is likely to shed light on the climactic history of Mars as well as its present-day weather.

Along with its robotic arm and molecular analyzers, it also has a weather station and an imaging instrument that can snap two one-megapixel images that can be merged into stereoscopic photos. The dune-buggy-size lander and all of its instruments are powered by a large set of solar panels that charge lithium-ion batteries.

All of the data and images that the lander is collecting will be relayed at a maximum of about 15 kilobytes a second to the Mars Odyssey and Reconnaissance orbiters in the UHF band, which will beam the data back to Earth.

The mission is slated to last for about 90 days, or until the Martian winter freezes the lander, ending its working lifespan.

The Phoenix mission is the first of a number of relatively modest missions to Mars. It is the result of collaboration between the Jet Propulsion Laboratory, Lockheed-Martin and the University of Arizona. Together, they beat out two dozen other proposals for NASA grant money under the Mars Scout Program, and with the start of the mission mere days away, spirits are running high on the team.

"From the payload standpoint, I'm very confident that we'll be successful," Gross said.