Scientists Are About To Experience '7 Hours Of Terror'

Of all space missions in history, the most difficult kind is, without question, landing a space probe on an extraterrestrial surface, like the moon, Mars, and Venus.

Even more difficult? Landing on the surface of a tiny, spinning, rocky comet.

Humans have never landed on a comet before, but the European Space Agency hopes to on Nov. 12 in what might be the hardest space mission ever attempted. That day, the ESA Rosetta spacecraft will deploy the Philae lander in an attempt to make history.

After deployment, the ESA team - along with scientists around the world - will hold their breath for "7 hours of terror" as Philae approaches and lands on comet 67P/Churyumov-Gerasimenko, as Project Scientist for the US Rosetta Project Claudia Alexander explains in a NASA ScienceCasts video How to land on a comet."

If the mission is successful, this comet will be only the seventh celestial body on which the human race has ever landed. So far, we've landed on the moon, Mars, Venus, Saturn's moon Titan, and two asteroids. But none of these compare to landing on a comet.

The comet will be traveling 40 times faster than a speeding bullet. Spinning on it's axis once every 12 hours. And all the while shooting jets of gas out of it's rocky and uneven surface. Not very welcoming!

Nonetheless, Philae will brave this uninviting surface and risk it all as it homes in on its small landing point, called Agilkia, on the head of the comet, shown below.

To make things more terrifyingly heart-pounding, no scientist will be steering the lander as it descends.

Here's what will happen on Nov. 12:

Step 1: The Rosetta Spacecraft will descend to 13.6 miles above the comet.

Step 2: At that point, Rosetta will deploy Philae, which will use the navigational system scientists installed on it 10 years ago, to find its way to the spinning, jet-spewing comet surface.

Step 3: Philae will slowly descend to the surface. If everything goes according to plan, this decent will take seven, nerve-racking hours. When it reaches the surface, Philae will drill itself three feet to the comet, securing itself for the long haul. If the surface is covered with loose dust, this could be a problem.

Watch the entire video, from NASA's ScienceCasts, below: