Rock On
Rosetta's 10-year quest to land a robot on a comet is complete
Amanda Wills
The European Space Agency (ESA) completed one of the biggest space feats in years on Wednesday when it landed a robot on a comet speeding between Jupiter and Mars at nearly 40,000 mph.The Rosetta spacecraft dropped the refrigerator-sized Philae lander onto comet 67P/Churyumov-Gerasimenko, which is made up of plunging cliffs and rocky terrain.It's the first time mankind has ever attached a robot to a comet. The chance of success was just 70 percent.
Why This Mission Is a Really Big DealComets are like time capsules packed into rocky nuggets that speed around our solar system. Scientists believe they hold clues to the story of our solar system because they may have formed about 4.6 billion years ago — around the same time as Jupiter, Saturn, Uranus and Neptune.
It's possible that these planets and comets are made up of the same chunks of ice and dust that the Sun spit out during its birth.
Many scientists even think comets were a crucial part of Earth's formation because they crashed into our planet during its formative years, spewing organic molecules that were essential to life, something that the Rosetta team hopes to uncover on this mission.
HOW THEY DID IT
Target SpotOn Nov. 12, the Rosetta spacecraft landed Philae on the surface of comet 67P. It was no small feat: The comet is traveling nearly 40,000 mph, and Rosetta, which is speeding alongside, dropped the lander on a site known as "Agilkia," located on the smaller "head" lobe of the comet, which is kind of shaped like a duck.Just days before the landing, Rosetta's navigation camera took a photo of the landing site. The image below was captured from about 19 miles away.
The landing site, which is a little less than one square mile, is made up of large, jagged boulders, making the landing very risky.
What HappenedRosetta deployed Philae around very early on Wednesday from about 14 miles away from the center of the comet. Once released, Philae was on its own — all ESA could do from there was watch the descent, which took about seven hours.
Another thing that made this mission even harder? The time difference. Because the event took place about millions of kilometers from Earth, it took ESA controllers 28 minutes and 20 seconds to communicate with Rosetta each way.As Philae slowly made its journey without any propulsion or guidance, the orbiter continued on its trip away from the comet's nucleus, looking back to monitor the lander's progress.When Philae reached the surface, its speed was about the same pace as walking. That may sound like a gentle landing, but the comet's gravity is about 100,000 times weaker than Earth's gravity, so ESA had to prevent the lander from essentially bouncing back into space. In order to do this Philae deployed an ice screw from each foot into the surface of the comet. Meanwhile, the lander fired two harpoons to lock itself into place.Initially, the Rosetta team thought the first deployment of the harpoon was a success, but they later learned it didn't work, so they tried a second time.
ESA/Rosetta/Philae/CIVA
6 BIZARRE FACTS ABOUT THE MISSION
1. GoT's Lord Baelish and Rosetta have something in common.To promote the Rosetta mission ESA made a fantastical, highly produced short film starring Aidan Gillen, the actor who plays Littlefinger in Game of Thrones. The video, called "Ambition," features a post-apocalyptic planet in which humans have magical powers to create solar systems. ESA said the film is "a larger tribute to how contemporary space exploration is crucial to searching for clues to our own origins."
2. Scientists have an inside joke about a rubber duck.Scientists have jokingly dubbed Comet 67P/Churyumov-Gerasimenko a “rubber duck” in space due to its irregular shape. Others say it would be more accurately described as a “black swan” due to the deep black color caused by its non-reflective surface. Explanations for the comet’s unique shape vary. Some experts believe it is a true “contact binary,” meaning it is made of two objects that melded together after impact. Alternatively, it could have been molded into its irregular form through impact with other objects.
3. Rosetta's comet stinks — literally.According to researchers at the University of Bern in Switzerland, the cloud of gas surrounding comet 67P smells like rotten eggs, horse urine, methanol and formaldehyde — odors not uncommon for comets like this. As the comet nears the sun, it will release more gases and smell even worse, the Los Angeles Times reported.
4. Of course William Shatner is involved. It only makes sense, right? In a video released by ESA, actor William Shatner sent well wishes to the Rosetta Mission. "I am so excited and I wish you such good luck," the Star Trek actor said.
5. The comet is singing.As the Rosetta spacecraft neared comet 67P, researchers were taken by surprise by a low, songlike hum coming from the comet. It turns out, the “singing” is caused by the release of electrically charged particles, a phenomenon scientists still don't fully understand. ESA has uploaded the comet’s song on a Soundcloud page using the hashtag #cometlanding for your listening pleasure.
6. Rosetta has been taking selfies.The Comet Infrared and Visible Analyser (CIVA) on Philae is comprised of seven cameras that are capable of taking 360 degree photos of the comet's landscape once the spacecraft lands. CIVA can also take selfies from its place on the Rosetta spacecraft. This image shows the side of the Rosetta spacecraft with the comet in the background. 
ESA/Rosetta/Philae/CIVA
TIMELINE OF THE 10-YEAR JOURNEY
THE COMET
The Comet's Size (in Earthling Terms)
6 QUESTIONS, ANSWERED
INSIDE PHILAE
Rosetta's Philae lander is about the size of a refrigerator with 10 key instruments:APXS: Alpha Proton X-ray SpectrometerThis instrument studies the chemical composition of the comet at the landing landing site. It will also look at how the comet changes as it gets closer to the Sun.CIVA: Comet Nucleus Infrared and Visible AnalyzerSix cameras that will take panoramic pictures of the comet's surface.CONSERT: Comet Nucleus Sounding Experiment by Radiowave TransmissionThis tool will study the internal structure of the comet nucleus with Rosetta orbiter.COSAC: The Cometary Sampling and CompositionAn experiment that will detect and identify complex organic molecules.PTOLEMY This instrument will use the MODULUS protocol (Methods of Determining and Understanding Light elements from Unequivocal Stable isotope compositions) to understand the geochemistry of light elements, such as hydrogen, carbon, nitrogen and oxygen.MUPUS: Multi-Purpose Sensors for Surface and Sub-Surface ScienceThis will be used to study the comet surface and sub-surface's properties.ROLIS: Rosetta Lander Imaging SystemThis instrument will provide us with the first close-up images of the landing site.ROMAP: Rosetta Lander Magnetometer and Plasma Monitor ESA will use this to observe the comet's magnetic field and plasma environment.SD2: Sampling, drilling and distribution subsystem This will be used for drilling up to 23 centimeters deep. It will also deliver material to onboard instruments for analysis.SESAME: Surface Electric Sounding and Acoustic Monitoring ExperimentESA will use this to probe the mechanical and electrical parameters of the comet.