The European Space Agency’s comet lander Philae has successfully delivered a long-anticipated data stream to Earth after several nerve-wracking months of silence.


The dishwasher-sized lander, dispatched from the Rosetta spacecraft which now orbits comet 67P/Churyumov-Gerasimenko, landed rather roughly on the surface back in 2014.Unfortunately, the machine unexpectedly settled in a shadowy crater and ran out of power after 60 hours without sunlight to charge its solar cells.

Because the comet has been moving nearer to the sun, the lander may have been able to harness the increased solar energy and recharge itself. The earthbound scientists at European Space Operations Centre in Darmstadt, Germany, held their breath and powered up the lander’s listening capabilities on March 12th.


A real-scale representation of the comet's size
compared to the city of Los Angeles.
On June 14th Philae’s message finally arrived, indicating that it is in fact receiving power.
Rosetta is the first man-made object to orbit a comet, and Philae the first to land on one. The mission promises to be rich with discoveries that will lend insight into many unanswered questions about the natural world. Comets and other such deep-space objects represent goldmines of information about the early universe and the physical history of the solar system, and by extension the Earth and her human inhabitants.

One such mystery that the mission hopes to investigate is the relative abundance of left-handed chemical isomers in the biological world. Many molecules come in mirror-image “versions” of one another. Despite being composed of the same atoms, and those atoms being connected in identical ways, they are physical reflections of each other and possess unique physical and chemical properties. For reasons poorly-understood, biological systems overwhelmingly favor the left- versions of molecules.

One theory proposed in 1983 posits that spiraling radiation generated during supernovae is responsible. The polarization of the radiation emitted during the collapse of primordial stars may have twisted those first molecules into left-handed orientations, resulting in a dominance that we still see today. If the preference for left- chirality is found to extend outside the Earth biosphere, a cosmic origin would be the most reasonable explanation.


The lander possesses an array of cutting-edge scientific instruments, including UV, visible and infrared spectrometers, remote imaging systems, and radar.

One of the first images received by the lander revealed what appeared to be
"sand dunes". The scale of this image is massive; the length of a human
being would be represented as a single pixel.
The mission has already uncovered an abundance of information about the comet. Although it is massive enough to have a gravitational field, the rock is only about ¼ to 1/8 the volume of the object that wiped out the dinosaurs. Its gravity, although strong enough to hold onto the Rosetta orbiter, is incredibly weak. The escape velocity of the comet is about 1/300,000th of Earth’s. In
simpler terms, if a person standing on its surface jumped with the amount of force needed to reach one centimeter from the ground on Earth, they would escape its gravity and float off into space, never to return. If you stepped off of a chair on this comet, it would take you a whole 1.3 minutes to eventually fall to the ground.


As it moves nearer the sun, the comet will heat up and begin expelling dust and gas. This stream of detritus, when comets such as Philae’s swing near enough to the sun, can become ionized by solar wind and produce the luminous glowing tail which is visible from Earth. These mysterious streaks of light have been objects of wonder since the dawn of human kind, and now through the culmination of our thousands of years of scientific inquiry, we will for the first time finally have the chance to reach across the vast gulf of the cosmos and touch one. 


Written by Aisling Williams

Sources

 Claudia. "The Sound of Touchdown." Web log post. ESA Blog. European Space Agency, 20 Nov. 2014. Web. 16 June 2015.

Doherty, Paul. “Rosetta Mission|Spring 2015 Update.” Online video. Youtube. Exploratorium, 15 May 2015. Web. Jun. 27 2015.

Wilson, Elizabeth K. “Comet Lander Philae Wakes Up.” Chemical & Engineering News: (2015) n. pag. 15 June 2015. Web. 17 June 2015.