Welcome to the comet: Rosetta mission makes space history

Mankind has just cleared another hurdle in space exploration: landing the first spacecraft on a comet.

The European Space Agency's Philae lander, which detached from the Rosetta spacecraft around 1 a.m. PT Wednesday morning, successfully touched down on comet 67P/Churyumov-Gerasimenko seven hours later. A confirmation signal was sent to the mission control center in Darmstadt, Germany, indicating that Philae is now officially along for the ride.

"How audacious, how exciting, how unbelievable to be able to dare to land on a comet?" Jim Green, NASA's Planetary Science Division director, said triumphantly at a ESA press conference Wednesday. "It is the start of something important. The Solar System is mankind's. This mission is the first step to take it."

Early reports from the ESA said the spacecraft successfully deployed harpoons and screws to fasten itself to the soft surface, yet the agency confirmed that harpoons did not fire and engineers are investigating the issue. Possible solutions include refiring the harpoons, the agency said, but Philae is otherwise in "great shape" according to the most recent telemetry data.

Rosetta, which has been orbiting the comet since August, deployed the 220-pound Philae lander in what has been described as a nail-biting descent to a landing site called Agilkia -- in keeping with the Rosetta mission's Egyptian theme -- on the comet's surface. The spacecraft, now 300 million miles away from Earth, had to travel 34,000 miles an hour in order to get in orbit with the comet. The lander mission cost around $275 million, with both NASA, the ESA and universities around the globe pitching in.

With 10 onboard instruments, the lander is analyzing the comet by drilling into its surface and snapping photos to send back to Earth, the first ever up close shots of a comet. The information will help scientists gain a better understanding of the makeup of the giant ice-covered dust conglomerations hurling through space.

At around 10:05 a.m. PT, Philae transmitted its first photo -- which takes about 28 minutes to travel to Earth -- taken on its descent to 67P/Churyumov-Gerasimenko from just 3 kilometers away.

More important than these landmarks, however, Philae will help us discover more about the origins of life and whether comets may have carried water and other organic materials to Earth, crashing into our planet and potentially kicking off the start of humankind.

Space exploration has not had a heartening few weeks. Late last month, two rocket anomalies that are still being investigated resulted in the explosion of a Orbital Sciences Corp. rocket carrying supplies to the International Space Station. Just a few days later, a Virgin Galactic spacecraft exploded over the Mojave desert in California, resulting in the death of one of its pilots.

With Philae traveling aboard a moving comet, all the scientists, engineers and space enthusiasts who have been involved with the Rosetta mission for as long as two decades can rejoice in a resounding victory for planetary science and humanity itself.

The journey was long. Rosetta launched in March 2004 and spent more than 10 years getting to 67P/Churyumov-Gerasimenko, becoming the first spacecraft to orbit a comet in the process. The landing mission was also fraught with potential failure at every step.

Tiny miscalculations in Philae's descent could have thrown off the lander's trajectory toward the tiny, six-tenths-of-a-mile landing area scientists deemed safe for a touchdown. Even then, landing on a comet's surface had never been done before. Philae could have bounced when it made contact, or failed to drill fast enough under the constraint's of lower gravity to secure itself to the comet's surface before tipping over or being pushed by a dislodged boulder. The landing, however, was softer than ESA engineers expected.

Philae, now on the comet's surface but yet to be secured, can function for around two and a half days before its batteries run out. Rosetta will continue orbiting the object through 2015, while Philae will be able to analyze the surface intermittently over the coming months for up to one hour every two days or so using solar-charged back-up batteries.

Rosetta's long journey from here to a comet (pictures)

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Update at 10:55 a.m. PT: Added information about Philae's harpoons not firing, as well as the ESA's ongoing analysis of the situation and how to safely secure the lander. Included Philae's first photograph of the comet's surface taken during its initial descent.