While I was sitting in traffic this morning, scientists were busy landing a washing-machine-sized lander, Philae, on a distant comet. The milestone occurred early on Wednesday after a 10-year journey that covered well over 500 million miles—and in the process, flew past Earth, Mars and orbited Jupiter.

It wasn’t that long ago when the European Space Agency’s (ESA) Rosetta spacecraft (carrying Philae) awoke from its 957-day slumber. The goal is to gather data about Comet 67P/Churyumov-Gerasimenko and use that information to better understand how our solar system was formed. Rosetta has actually been a part of many firsts since it originally launched back in March of 2004; the first spacecraft to orbit a comet; the first probe to land on a comet’s nucleus, and the first mission to rely solely on solar cells for power generation (hence the lengthy hibernation period).

The last portion of Rosetta’s journey was the most perilous, and a few setbacks actually threatened to unravel the entire mission. As both Comet 67P and Rosetta moved at incredibly high speeds, Philae was released and began a seven hour free fall (known as seven hours of terror) toward the comet. Landing anything on a moving object is challenging enough on Earth, but imagine doing it in the expanse of space. Although the lander sank about 4cm on the comet’s surface, the harpoons designed to fasten the spacecraft to the surface did not fire as intended, so the ESA is reassessing its next move; the spacecraft’s thruster system also failed. The challenge now is keeping Philae from bouncing back into space.


“Since comets are so primitive, they can give scientists a chance to understand how the solar system formed, where it came from,” explained Andrea Accomazzo, Rosetta spacecraft operations manager.

ESA chose a spot on Comet 67P’s southern hemisphere, where scientists say the landscape has already been eroded by the perils of space, and will therefore be easier to drill into. Not only that, but scientists say the southern hemisphere offers a safer drilling environment because it’s protected from extreme temperature variations. The mission is expected to last until the end of summer next year, when the comet will reach its closest point to the Sun.

So far this morning I’ve walked my dog, taken the trash out and sat in traffic for an hour. And you thought landing a probe on a comet was hard.