NASA's $2.5 billion Mars Science Laboratory Curiosity rover has landed on the surface of the red planet following an eight month, 352-million-mile journey. NASA says it received a signal from the Curiosity rover after a plunge through the Martian atmosphere described as "seven minutes of terror."

A chorus of cheers and applause echoed through the NASA Jet Propulsion Laboratory just after 1:30 a.m. EDT Monday when it was confirmed the rover had landed successfully.

"Touchdown confirmed," said engineer Allen Chen. "We're safe on Mars."

Minutes later, Curiosity beamed back the first pictures from the surface showing its wheel and its shadow, cast by the afternoon sun — giving earthlings their first glimpse of a touchdown on another world.

Mars Curiosity is NASA's latest and boldest attempt yet to go where robots -- but no man -- have gone before. Before this mission, the U.S., Russia, Japan and Europe had sent 40 spacecraft to explore the fourth planet from the sun since the space age began. Twenty-six had failed.

Curiosity, an intrepid chemistry set on wheels, packed with cameras and gadgets galore, was designed to look for signs that life once existed on Mars. Not Marvin the Martian, but signs that Mars could once have had the chemical resources needed to support microbial life. This could mean potential sources of water, food and energy that could someday support visiting humans from Earth.

The landing has been dubbed "Seven Minutes of Terror" by the engineers who figured out the best way to land. Adam Steltzner, team leader for the entry, descent and landing of Curiosity, said that as the ship was in the planning stages and then heading to Mars, he found himself waking up in the middle of the night, thinking about the sequence of events that would have to go perfectly.

"The big trick is you are going 13,000 miles an hour," he said. "You slam into the Martian atmosphere and you want to gracefully get the spacecraft down sitting quietly on the surface on her wheels, and all of that takes different changes in the configuration of the vehicle, 79 events that must occur."

Curiosity was set to land when Mars was 154 million miles from Earth. It weighed 5,293 pounds on Earth -- the size of a small car and much, much bigger than the rovers Spirit and Opportunity, which were cushioned by airbags when they landed in 2004. Engineers quickly figured out that airbags would burst if they were tried on Curiosity. So they designed it to be lowered to the Martian surface by a heat shield, then a parachute, then retro-rockets, and finally a sky crane -- something that had never tried before -- and that's what made this so scary for them. Just one slip would mean $2.5 billion down the drain.

Curiosity launched on Thanksgiving weekend 2011 and traveled 354 million miles in eight months. Its target: Gale Crater, a site where many layers of Martian bedrock are believed to be exposed.

The landing was set to happen in an area that would be facing away from Earth as the planet turned. The spacecraft was equipped with an X-band transmitter to let the rover communicate directly with Earth, but its first attempt to phone home would be relayed by an older U.S. probe in orbit around Mars. Controllers cautioned in advance that Curiosity could make a perfectly good landing -- but hours or even days could pass before confirmation reached Mission Control at the Jet Propulsion Lab here in Pasadena.

How long was Curiosity designed to roam the planet? One Martian year, which is 22 months on Earth. Spirit and Opportunity -- NASA deliberately played down expectations -- were only expected to run for 90 Martian "sols," or days on Mars (each lasts 24 hours and 39 minutes), but Spirit kept on going until 2010 and Opportunity is still puttering around on Mars.

The U.S. has had its share of failures getting to Mars, but it has done better than other countries. Russia has the most dismal record: it launched 19 missions and 19 failed. You have to give them credit for trying. Phobos Grunt, a mission to return a small soil sample from one of Mars' tiny moons, ended in spectacular fashion last fall, unable even to leave Earth orbit. India just announced it would fund its first mission to Mars to launch next year.

Why do this? Aswin Vasavada, a project scientist for Mars Curiosity, said there is an elemental drive in humans.

"We are humans, we want to explore," he said. "We see a mountain, and we want to climb it. As scientists we want to answer the big questions."  (Source: Sky News)