On November 12, the European Space Agency’s Rosetta orbiter will do the unthinkable: attempt to land a rover on the surface of a comet for the first time in history.

The Rosetta orbiter, launched in 2004, has finally completed its ten-year journey and is ready to deploy the lander Philae onto comet 67P/Churyumov-Gerasimenko. On August 6, the spacecraft finally reached the comet, prompting scientists to debate over the exact landing spot of the rover.

The two-mile-long comet has numerous landing spots, and ESA scientists had a difficult time choosing which area to land Philae on. They finally settled on an area called Site J, one of the comet’s two smoother lobes. On the rocky comet’s surface, Site J has few boulders and slopes with less than 30 degree angles, making it a unanimous choice among ESA astronomers.

On November 12 at 12:35 a.m. PST, Rosetta will release Philae for a 14-mile journey towards the comet. It will take the rover approximately four hours to land. Scientists will receive confirmation around 8 a.m. PST that the rover has successfully landed on 67P’s surface.

Plan B, considered equally robust, involves deploying the rover to another area known as Site C. The rover will only have to travel 7.8 miles to the comet, with landing time confirmed at 9:30 a.m. PST.

Final landing site reviews will be discussed by the ESA on October 14, along with a public competition to choose a name for the rover’s landing site.

67P/Churyumov-Gerasimenko is significant because of its advanced age. It’s an ancient remnant from the beginning of the solar system 4.6 billion years ago. Philae will conduct a detailed scientific study of the organic and inorganic materials of the comet, which will hopefully answer questions about where Earth’s water and life forms originated.

The European Space Agency is currently receiving help from NASA on the Rosetta project.