After undertaking an incredible 10-year journey to become the first spacecraft to land on a comet, Philae gave up the ghost on Saturday — but not before it managed to transmit a treasure-trove of scientific data to Earth.
Mission controllers put the European Space Agency (ESA) lander to sleep after the charge in its solar-powered batteries fell to dangerously low levels with the craft having become lodged in the shadow of a crater wall.
An ESA blog post said, “Philae has fallen into ‘idle mode’ — a possibly long silence. In this mode all instruments and most systems on board are shut down.”
Scientists are hailing Philae’s flight and landing — described as the equivalent of aiming a fly at a speeding bullet — an outstanding success. The lander managed to successfully deploy its instruments, including an ice pick drill and hammer to obtain surface samples for analysis. The information includes results from sophisticated devices designed to analyse the comet’s chemical make-up and throw new light on what could have been the building blocks of the universe. Comets that bombarded early Earth are thought to have brought with them large amounts of water, along with complex organic compounds.
Dr Maggie Aderin-Pocock, space scientist and presenter of The Sky at Night, said, “The Rosetta mission has done amazing things already. It’s going to be running for the next 18 months. It’s landed on a comet, taken samples, sniffed and prodded. We have lots of data. I can’t see it as a failure at all. The ice hammer has been deployed. The data is coming in.”
Dr Stephan Ulamec, the Rosetta mission’s Philae lander manager at the DLR German Aerospace Center, said there was still a chance that the probe could be reawakened in the coming weeks or months as the comet, 67P/Churyumov-Gerasimenko, flies closer to the Sun, allowing more energy to flow into the solar panels and recharge the lander’s batteries.
Although a successful attempt to lift and rotate the lander was made on Friday night, it was not clear what difference this has made to the amount of sunlight falling on its solar cells and contact was finally lost on Saturday at 12.30am UK time, as the Rosetta mother ship fell below the comet’s horizon. A tweet from the official Philae lander account before contact was lost said, “I’ll tell you more about my new home, comet 67P soon... zzzzz.”
One of the devices being used to analyse surface samples from the comet is the British-led instrument Ptolemy, built and operated by scientists from the Open University, which can both “taste” drill samples and “sniff” dust and gases from the environment around the lander. Another instrument with British development input, Mupus, uses a “hammer” to test the mechanical and thermal properties of the comet surface.
It took 10 years for Philae and its mother ship Rosetta to reach comet 67P/Churyumov-Gerasimenko after an epic journey across four billion miles of space.
Scientists are still not sure of the probe’s precise location following Wednesday’s landing, which saw the dishwasher-sized craft bounce twice before coming to rest more than half a mile from its original landing site.
Two harpoons that were supposed to anchor the lander to the ground failed to deploy, causing the probe to shoot 0.6 miles into space after its initial touchdown.
The comet is a 2.5-mile wide lump of ice and dust, more than 300 million miles from Earth, littered with deep pits, craters, cliff walls and jagged outcrops.
Philae is the first probe ever to make a soft-landing on a comet. In 2005 the US space agency Nasa smashed a projectile into comet Tempel 1 to study the blast debris.
Attention will now turn to Rosetta, which is having to manoeuvre from its post-separation path back into orbit. Next year, as the comet becomes more active, Rosetta will fly unbound “orbits”, making brief fly-bys to within five miles of its surface.
The comet will reach its closest point to the sun on August 13 next year at a distance of about 115 million miles, roughly between the orbits of Earth and Mars.