How Rosetta's Philae Lander Will Pull Off Comet Landing

— -- Catching up to a speeding comet is no easy feat, but the Rosetta spacecraft's Philae lander is closing in this morning on a historic landing.

Rosetta already has gone where no other spacecraft has ever attempted to go before, becoming the first to orbit a comet -- in this case one that can move at more than 80,000 miles per hour.

The spacecraft's Philae lander began its separation and seven-hour journey this morning to land on 67P. The rubber duck shaped comet is less than three miles wide, making the landing, which has been ten years in the making, an even more impressive feat.

When Rosetta phoned home today to the European Space Agency’s mission control in Darmstadt, Germany, it took 28 minutes for the signal to reach Earth, traveling more than 317 million miles.

Once on the comet, Philae will fix itself to the comet using a harpoon and ice screws.

The European Space Agency said a third component, an active descent system that helps Philae have a smooth landing and not bounce off the surface of the comet, was not able to be activated.

"We'll need some luck not to land on a boulder or a steep slope," said Stephan Ulamec, the Philae Lander Manager, according to the Associated Press.

The spacecraft is scheduled to land at 8:30 a.m. ET, and by 11 a.m. ET we will know if Philae hit its target and is functioning.