Did comets contribute chemical building blocks to a young Earth that led to life on our planet?
It’s one of many questions the scientists at the European Space Agency based in Darmstadt, Germany, wanted to find out when they designed and launched the Rosetta spacecraft carrying the fridge-sized Philae lander.
After a 10-year journey of more than six billion kilometres that began on March 2, 2004, the 100-kilogram Philae landed kind of bumpily on Comet 67P/Churyumov-Gerasimenko on November 12 to the elation of people around the world.
The comet itself is a pretty tough bull’s eye to hit. It’s only about four kilometres in diameter with a head, a body, and a neck giving it a rubber ducky outline. And it’s travelling at speeds up to 135,000 kilometres an hour. Given the orbits it has taken the Rosetta to catch up with the comet, communications between Earth and the orbiter had to be planned days or weeks in advance and the furthest away the orbiter went was a billion kilometres. It could take anywhere from 30 to 50 minutes for signals to travel between Earth and Rosetta.
But on Philae’s landing, excitement almost fizzled to near panic as scientists realized that the lander had bounced its way into a rocky shadow that deprived of life-giving solar energy to keep its battery charged.
But even in the few days it kept working, Philae has beamed back to Earth data to show that it has already detected organic molecules.
The compounds were picked up by a German-built instrument designed to ‘sniff’ the comet’s very thin atmosphere. But exactly what compounds it has found haven’t been analyzed yet.
The whole Rosetta venture has proven to be an engineering marvel up there with the Apollo landings of 1969 and the 1970s. Philae’s landing is the first soft touch-down on a comet. Philae is named after an island in the Nile River. While its unexpected bounce landed it in some sort of high-walled trap that cut off battery-charging sunlight, it still functioned according to plan for the first 60 hours of programmed power.
Knowing how precarious this comet-landing mission might be, scientists set up a program of data collection called First Science Sequence to cover off a worst-case scenario. That meant that each instrument on the lander would get its turn at collecting its own specific set of science data it had been programmed for. They all functioned brilliantly before the batteries went dormant, waiting for the comet’s travel and trajectory to realign sunlight onto the batteries once more. It’s possible, by August of next year when the comet has moved much closer to the sun in its orbit, that Philae’s solar panels will receive enough light to wake it up and get it working again. All it needs is a few days of sunlight to get it gathering data once more.
It takes close to half an hour for data to travel from the comet to Earth. The digital radio signal travels at the speed of light (299,338 kilometres per second). But this isn’t simple radio stuff. The data coming back has to be clean and uncontaminated. So the signal is manipulated and compressed using advanced mathematics.
The ambitious project was very much an international effort involving luminary minds from 15 countries including Canada. SED Systems in Saskatoon build three ground stations used by the ESA to communicate with the Rosetta spacecraft. SED’s three ground stations are located in Western Australia, Argentina, and Spain. Each one has a 35-metre antenna.
The Ottawa-based ADGA-RHEA Group provided MOIS software to support all the complex procedures and command sequences required throughout the Rosetta mission.
How cool is all this stuff?