COMETS DID NOT BRING WATER TO EARTH
The landing of the Philae probe on Comet 67P on 12 November was a magnificent achievement. Despite the bumpy landing and early loss of signals due to lack of power from the solar panels, important scientific results are being obtained. One of the most significant relates to measurements of the water found on 67P:
Results show that the water on the comet is unlike that on our planet, and helps answer the question of whether a bombardment by comets brought water to earth billions of years ago.
Two mass spectrometers on Rosetta have been able to test the gas streaming off the surface of the comet. Findings indicate that the ratio of heavy water to 'ordinary' light water is three times higher than on the Earth. Heavy water has the hydrogen atom replaced by the heavier atom of Deuterium.
Professor Kathrin Altwegg from the University of Bern said 'This means that this kind of comet could not have brought water to the Earth'.
Although previous research on other comets in different regions of the solar system have given different results, Prof Altwegg believes that asteroids, which formed closer to the Sun than comets, seeded our oceans.
Comment: Although Philae is currently 'asleep' due to lack of power from its shaded solar panels, there is hope that as Comet 67P moves closer to the Sun the batteries will recharge sufficiently to enable further measurements to be made on the comet's surface. This has been a highly successful scientific mission already yielding valuable data which will extend our knowledge of the solar system.