First spacecraft to orbit comet changes theory of origin of Earth’s water
For a long time, most thought that water was brought to Earth when comets and asteroids impacted the Earth’s surface. However, data retrieved from a spacecraft that is currently on a comet would suggest otherwise, according to NASA.
The European Space Agency’s Rosetta spacecraft has a special instrument hooked up to it–the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis–that was able to determine that the composition of water vapor on the comet 67P/Churyumov-Gerasimenko has a significantly different chemical makeup than the water on Earth.
It’s a bit scientifically-dense, but essentially: There is a heavier hydrogen isotope that is found in our water but is much rarer than the most common hydrogen isotope. The ratio between these two isotopes is three times higher on the comet than it is on Earth. In fact, the ratio on the comet is one of the highest ever measured in the solar system.
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