The seven minutes of terror are over.

NASA's Curiosity rover touched down safely on the surface of Mars early Monday morning, Eastern Daylight Time, sticking the landing in what had been one of the most anticipated—and feared—arrivals in the history of robotic planetary exploration.

The 900-kilogram rover autonomously navigated its landing sequence, slowing from 21,000 kilometers per hour at the top of the atmosphere to a dead stop on the surface, with nary an apparent hitch. The elaborate process, which involved a detachable heat shield, a supersonic parachute and finally a hovering sky crane that lowered the rover to the surface, had been branded the "seven minutes of terror" in a NASA video released in June. In the end, based on preliminary data at least, the fears were for naught.

"It looked good, in short," said entry, descent and landing engineer Adam Steltzner in a post-landing news conference. "Good and clean."

The data from the descending rover were relayed to Earth by the Mars Odyssey orbiter, which passed nearby as Curiosity executed its landing sequence. On NASA TV Steltzner could be seen pacing in front of his workstation in the control room at NASA's Jet Propulsion Laboratory (JPL). But each successive step of the landing sequence passed by without incident, and finally a mission controller announced words that caused the room to erupt in cheers: "Touchdown confirmed. We are safe on Mars."

Within minutes Curiosity relayed its first images of the Red Planet, beaming back a low-resolution shot of one of its six wheels. A higher-resolution version followed, along with a photograph of the rover's own shadow cast across the Martian soil.

In a nearly two-year, $2.5-billion mission, the rover will explore Gale Crater, a basin with a towering mound of sedimentary layers. The mission should help determine what Mars was like during an earlier, wetter era billions of years ago, and whether the planet could have once been hospitable to extraterrestrial life.

The three-meter-long, two-meter-tall rover comes equipped with 10 science instruments, including an onboard sample analysis unit for assessing the chemistry of rock and soil samples and a laser that can vaporize small regions of rocks several meters away to analyze their composition. Curiosity's unprecedented science payload draws its power from a radioisotope thermoelectric generator, a 4.8-kilogram plutonium fuel source whose radioactive decay provides heat, which devices called themocouples convert to about 110 watts of electricity.

"Nobody has ever done anything like this," John Holdren, the White House science adviser, told NASA TV. "This is by far the most capable device, set of instruments, we've put up there for determining whether Mars ever could have supported life."

Nobody had ever attempted anything like the sky crane–enabled landing, either. But some saw good omens, even before the seven minutes of terror had begun. At the post-landing news conference, JPL Director Charles Elachi said he had stepped outside to look at Mars in the evening sky shortly before the landing sequence commenced. "In an hour and a half, you're going to have a visitor," Elachi said as he gazed to the west, he recalled. "And the planet smiled."