Rosetta spacecraft
The Rosetta spacecraft has sent back results that cast doubt on the theory that most water on Earth came from comets.
Scientists have been analysing data from the Europe-led mission, which landed the fridge-sized Philae probe on Comet 67P in November.
The data, published in the journal Science, shows the water on the icy comet is different to that on our planet.
The authors conclude that water is more likely to have arrived on asteroids, but other scientists say comets cannot be ruled out.
Philae appeared to have reached the end of its historic mission last month after its batteries ran out of power, but only after it managed to transmit a treasure-trove of scientific data back to Earth.
Mission controllers put the European Space Agency (ESA) lander to sleep after the power in its solar-powered batteries fell to dangerously low levels following its landing at a spot in the shadow of a crater wall, shrouded in darkness.
Before being shut down, Philae successfully operated its drill to obtain surface samples for analysis and sent back data from most of its suite of 10 instruments.
The latest findings, gathered by the mothership Rosetta, deal a blow to the theory that water was first delivered to earth by a bombardment of comets.
Two spectrometers called Rosina that "sniff" the gas that streams off the surface of the comet showed the ratio of 'heavy water' on the comet does not match Earth water's distinctive signature.
Prof Kathrin Altwegg, from the University of Bern in Switzerland, who is Rosina's principal investigator, told the BBC: "This ratio between heavy and light water is very characteristic. You cannot easily change it and it stays for a long time.
"If we compare the water in comets with the water we have on Earth, we can definitely say if the water on Earth is compatible with the water on comets.
"It is the highest-ever measured ratio of heavy water relative to light water in the solar system. It is more than three times higher than on the Earth, which means that this kind of comet could not have brought water to the Earth."
However Professor Monica Grady, who was pictured jumping for joy when Philae landed successfully, suggested the team could be "jumping the gun a bit".
She said: "The measurements that have been made by Rosina are of the gas that has come from the surface of the comet. We are going to have to wait to see what comes from the COSAC and Ptolemy [Philae lander instruments before we can say any more."
The Rosetta probe will continue to track and study Comet 67P throughout 2015.
Telegraph
Before being shut down, Philae successfully operated its drill to obtain surface samples for analysis and sent back data from most of its suite of 10 instruments.
The latest findings, gathered by the mothership Rosetta, deal a blow to the theory that water was first delivered to earth by a bombardment of comets.
Two spectrometers called Rosina that "sniff" the gas that streams off the surface of the comet showed the ratio of 'heavy water' on the comet does not match Earth water's distinctive signature.
Prof Kathrin Altwegg, from the University of Bern in Switzerland, who is Rosina's principal investigator, told the BBC: "This ratio between heavy and light water is very characteristic. You cannot easily change it and it stays for a long time.
"If we compare the water in comets with the water we have on Earth, we can definitely say if the water on Earth is compatible with the water on comets.
However Professor Monica Grady, who was pictured jumping for joy when Philae landed successfully, suggested the team could be "jumping the gun a bit".
She said: "The measurements that have been made by Rosina are of the gas that has come from the surface of the comet. We are going to have to wait to see what comes from the COSAC and Ptolemy [Philae lander instruments before we can say any more."
The Rosetta probe will continue to track and study Comet 67P throughout 2015.
Telegraph
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