Thruster Glitch May Hinder Philae Spacecraft's Landing on Icy Comet 67P

Astronomers are officially preparing for the first-ever landing by a spacecraft on a comet. At 8:35 a.m. GMT today, a robotic lander called Philae will be released from the European Space Agency Rosetta spacecraft. The lander will then spend the next seven hours descending to the comet.

"We have waited over 10 years for this day, but with the comet being over 317 million miles away, all we can do now is cross our fingers and hope," said Alan Fitzsimmons from the Astrophysics Research Centre at Queen's University, in a news release. "The Rosetta mission realizes the ambition of mankin to explore our origins, and discover what is out there."

The scientists hope to receive a successful touchdown signal on Earth at about 4:00 p.m. GMT, along with the very first pictures from the comet's surface. This will be the first time that a comet has been explored so in depth and should tell researchers quite a bit about these icy bodies.

Actually getting to this point wasn't easy, though. The researchers involved in the project have spent over a decade studying the comet, named 67P/Churyumov-Gerasimenko, from Earth and measuring its properties. They used powerful telescopes in order to perform reconnaissance and learn all they could before launching the spacecraft.

In 2004, the scientists launched the Rosetta spacecraft. Since then, it's spent a decade maneuvering to rendezvous with the comet. So far, it's performed three flybys of Earth, one of Mars, and also passed closely to two asteroids. Now, it's finally making its last step toward the comet.

And yet there may be a few issues when it comes to the landing. There is apparently a thruster system problem on the Philae lander. At the end of the seven-hour trip toward the surface of the comet, a cold-gas thruster system is supposed to be fired to hold the lander steady and keep it from bouncing off the surface while harpoons are shot into the comet to secure it in place. However, it doesn't appear to be working, according to NBC News.

That doesn't mean that the mission has failed, though. The project scientists are praying that Philae doesn't land on a boulder or steep slope, but believe that even with the failed thruster, the spacecraft will make the landing-albeit perhaps a bit harder than expected.