# Rosetta Comet Probe: Comet's Water Has Different "Flavour" Than Earth's Water **URL:** \ **Category:** Factual Questions\ **Created:** [October 6, 2016, 2:03pm UTC](https://boards.straightdope.com/t/rosetta-comet-probe-comets-water-has-different-flavour-than-earths-water/767765 "2016-10-06T14:03:02Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [October 6, 2016, 2:03pm UTC](https://boards.straightdope.com/t/rosetta-comet-probe-comets-water-has-different-flavour-than-earths-water/767765/1 "2016-10-06T14:03:02Z")
According to this CBC article about Rosetta, one of it discoveries was about the water on the comet: > [@](#): > > “… water with a different ‘flavour’ to that in Earth’s oceans” What does that mean: space-berry instead of strawberry flavoured water? > **[Farewell Rosetta: 'bittersweet' end for space probe | CBC News](https://www.cbc.ca/news/canada/edmonton/farewell-rosetta-bittersweet-end-for-space-probe-1.3792559)** > > It was a difficult day for Matt Taylor, a project scientist with the European Space Agency, as he watched his beloved space probe crash land and die. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [October 6, 2016, 2:18pm UTC](https://boards.straightdope.com/t/rosetta-comet-probe-comets-water-has-different-flavour-than-earths-water/767765/2 "2016-10-06T14:18:41Z")
It is referring to the deuterium-to-hydrogen ratio, as described in [this article.](http://www.space.com/27991-rosetta-comet-water-earth-implications.html) ---
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [October 6, 2016, 2:46pm UTC](https://boards.straightdope.com/t/rosetta-comet-probe-comets-water-has-different-flavour-than-earths-water/767765/3 "2016-10-06T14:46:40Z")
If you drank it, could it sustain you, or might it kill you? ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [October 6, 2016, 3:02pm UTC](https://boards.straightdope.com/t/rosetta-comet-probe-comets-water-has-different-flavour-than-earths-water/767765/4 "2016-10-06T15:02:16Z")
According to [Wikipedia](https://en.wikipedia.org/wiki/Heavy_water), > [@](#): > > Because it would take a very large amount of heavy water to replace 25% to 50% of a human being’s body water (water being in turn 50–75% of body weight[33]) with heavy water, accidental or intentional poisoning with heavy water is unlikely to the point of practical disregard. Poisoning would require that the victim ingest large amounts of heavy water without significant normal water intake for many days to produce any noticeable toxic effects. However the water on 67P is not pure D[sub]2[/sub]O, it is only slightly enriched compared to terrestrial water. Earth’s water has about .015% deuterium while 67P has about .053% ([cite](http://sci.esa.int/rosetta/55118-deuterium-to-hydrogen-ratio-in-the-solar-system/)). So I would think it would be practically impossible to kill yourself by drinking water with the isotopic composition of 67P’s water. –Mark ---
**Author:** ![Some\_Call\_Me.Tim](https://avatars.discourse-cdn.com/v4/letter/s/439d5e/32.png) [@Some\_Call\_Me.Tim](https://boards.straightdope.com/u/Some_Call_Me.Tim)\ **Post date:** [October 7, 2016, 7:57am UTC](https://boards.straightdope.com/t/rosetta-comet-probe-comets-water-has-different-flavour-than-earths-water/767765/5 "2016-10-07T07:57:09Z")
It wouldn’t be even close to dangerous. Mammals show no obvious effect at 20% deuteration, so .053% should be quite safe. Kinetic isotope effects are pretty subtle, even for hydrogen.