ESA’s Rosetta spacecraft has discovered that the water vapor from the comet in which the Philae robotic probe, 67P / Churyumov-Gerasimenko, is found, is significantly different from that which exists on Earth. This finding, published in the journal Science, once again opens up an important unknown about the origin of the oceans on our planet .
Could a comet have brought water to Earth? After the expected first results of the Rosetta mission with its Rosina instrument -a mass spectrometer inserted in the spacecraft-, the chemical signature of the H20 captured by the spacecraft that has accompanied the comet since August 6 , is very different from the signature. chemistry of the water in our oceans on Earth , thus ruling out comets. Specifically, the ratio of deuterium and hydrogen in the comet’s gaseous envelope is three times higher than in water on Earth and also much higher than that of other similar comets.
“The origin of water and organic complexes on Earth and other terrestrial planets has been discussed for many time without reaching a consensus. Previous data and our new discovery suggest that there is a wide range of deuterium / hydrogen ratios in the water of the Jupiter family of objects and discard the idea that these deposits are water like Earth’s, ”explains Kathrin Altwegg of the University of Vienna and co-author of the study.
So, because according to these results, comets do not seem to be responsible for that “original deposit” of terrestrial water , scientists are now leaning towards another celestial object: asteroids.
” Asteroids today have very little water, it is clear. But it probably wasn’t always like this . The intense bombardment was about 3,800 million years ago and at that time the asteroids could well have had much more water than today ”, clarifies Altwegg.
