In the hours before the Phoenix Mars Lander successfully touched down onto Martian soil May 25, about 160 space enthusiasts crowded into a room in Cornell's Space Sciences Building to watch the event unfold live via broadcast on NASA TV. The lander will aim to answer the question: "Was Mars once habitable?"

But for the so-called "seven minutes of terror" Sunday, as the Lander entered the Martian atmosphere and began its risky decent, many of those watching had a more immediate question in mind: "Will it even get the chance?"

Hosted by Cornell's astronomy department, the viewing drew a large crowd from Cornell and local communities, including a number of families visiting for Commencement Weekend. Astronomy graduate students Ryan Anderson and Briony Horgan, who research Martian geology with Cornell professor Jim Bell, were on hand to answer questions about the mission and decode the occasionally jargon-heavy broadcasted updates.

During those seven minutes, the lander had to slow its descent from 12,700 mph to 5 mph, endure intense temperatures generated by the friction of the atmosphere, deploy its parachute and finally fire 12 retrograde boosters, all executed autonomously via commands sent by mission control at the Jet Propulsion Laboratory in Pasadena, Calif.

"I'm nervous, but at the same time excited," said Callun Taylor, 11, while watching the landing with family at the public viewing.

"It's the first time I've seen something land on Mars, added 12-year-old Aaron Taylor, Callun's brother. "I've seen [the movie] Apollo 13, but this is real."

During the decent, the lander also broadcast updates of its health back to mission control, relayed to Earth by the Mars Odyssey Orbiter, a satellite that has orbited the red planet since 2001.

The 276 million miles separating Mars from Earth produces a lag of about 15 minutes in communication between the lander and mission command. This lag makes real-time "steering" of the lander impossible, adding further to a sense of uncertainty in the mission.

"By the time we hear that [the lander] has touched the atmosphere, it will already be on the ground, in pieces or one piece," said Anderson, jokingly, but clearly expressing the mission's inherent risks.

His words reflected the cautious optimism that has surrounded the Phoenix mission. The lander is built from equipment salvaged from two earlier missions to Mars that were canceled after a previous series of NASA spacecraft failed to reach Mars safely.

Those fears, however, vanished at 7:53 p.m. when the announcement came: "Phoenix has landed." The mission controllers and those watching erupted into cheers and applause.

"Every single event in the whole intricate process of entry descent and landing went perfectly," said Cornell professor Steven Squyres, in a blog on CNN.com after the landing. Although Squyres is not directly involved in this mission, he is the principal investigator for NASA's Mars Exploration Rovers, Spirit and Opportunity.

Now safe on the northern plains region of Mars, the lander will be passed to its controller Peter Smith at the University of Arizona.

Previous discoveries by Mars Odyssey determined that large quantities of frozen water exist below the surface of the northern plains. Phoenix, which will not rove, will manipulate its 7.7-foot robotic arm to dig for samples of underground ice on the plains, hoisting the soil and ice back to onboard instruments for analysis.

The composition of the soil could give clues to whether Mars undergoes long-term climate cycles (Martian global warming and cooling), if the soil contains carbon organic molecules (the building blocks of biology) or if it once had been favorable for microbial life.

The first analysis of surface soil is expected in about two weeks.

Graduate student David Bernat is a writer intern at the Cornell Chronicle.