Tuesday, 18 November 2014

Comet Cruising: Why the Rosetta Mission is the Most Impressive Thing Ever

Well humanity, it’s time to break out the bubbly. Every once in a while the ingenuity of the world’s smartest people accomplishes something truly remarkable. Whether it is sending the first satellite into space, mapping the human genome, slicing bread, or putting a man on the moon; sometimes we earn the right to pat ourselves on the back. On November 12, 2014 the European Space Agency (ESA) gave us our most recent reason to feel smug as a species by dropping a lander onto the surface of a comet. A first in human history.

The mission is called Rosetta, the lander is named Philae in reference to the famous Rosetta Stone which allowed people to decode ancient Egyptian hieroglyphics. Philae is the name of the island where carvings were found and compared to the Rosetta Stone to help break the code. The lander settled down on comet 67P/Churyumov-Gerasimenko after first reaching its orbit in August 2014. The goal of the mission is to collect and analyze samples from the comet's surface to learn more about the early days of the solar system and the origins of the Earth itself.


If you’re wondering why it took so long for us to reach the surface of a comet, you are seriously underestimating the difficulty involved. Rosetta isn’t a new thing. It was launched in 2004 and has spent the past decade as a $1.75 billion pinball in the inner solar system, circling the sun 4 times and using the gravity of entire planets as paddles to finally make it to comet 67P. The cool thing about space is that you can use the gravity of large objects to slingshot you further and further away from your starting point. Rosetta has done this 3 times with the earth itself and once with Mars. If you’re interested in a video mapping the whole 12 year journey of the spacecraft check out the ESA’s very cool video here.


After it's long ride, Rosetta finally met up with comet 67P in May 2014 and after 3 months of getting closer and closer, settled into orbit in August. Since then it has been mapping the surface of the 2.5 mile (4 km) wide comet looking for a good spot to drop Philae. When the day finally came on November 12 everyone involved crossed their fingers that their landing systems would go off without a hitch so they could claim the historic achievement.


Unfortunately in the world of space exploration things practically never go off without a hitch. The plan was for Philae to fire 2 harpoons into the comet’s surface to help hold it in place as it landed. The problem is that when the thing you are controlling is 300 million miles away from the place you are controlling it, sometimes things don’t work properly. The harpoons, which relied on nitroglycerin (which apparently doesn't work that well in a vacuum), didn’t fire and Philae was left hurtling towards the surface without it’s safety net.

In the end, the lander bounced twice before coming to rest. Bouncing is not a word you want to hear with regards to your $1.75 billion spacecraft at the best of times, but when you’re landing on a comet it is enough to get you panicking. The first “bounce” lifted the lander 0.6 miles (1 km) of the comet’s surface and lasted 2 hours. The thing about comets is that compared to planets they are tiny and have next to no gravity. The speed needed to escape the surface of 67P and fly into space is about 1 mile per hour (1.6 km/h) compared to 25,000 mph (40,230 km/h) to escape the Earth. Philae’s first bounce was at about 85% the speed it needed to be hurled into deep space. The second  bounce lasted only 7 minutes and wasn’t nearly as chancey. In the end, a group of European scientists did get to celebrate... presumably after changing their underwear.



And with that begins the real sciencey stuff. The lander will spend the next few days collecting and analyzing major samples until it’s batteries run out. After that will hopefully be able to use its solar panels and auxiliary batteries to keep working until March 2015. The Rosetta orbiter will keep sending us data until hopefully the end of next year. Regardless of what we learn from here on out we know one thing for sure: when human’s set our best minds to achieving things, there is very little we can’t do with a little luck… and a couple crappy harpoons.



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