Mars atmosphere discovery
JOINT ASTRONOMY CENTRE NEWS RELEASE
Posted: March 1, 2004
Astronomers have detected hydrogen peroxide (H2O2) in the atmosphere of Mars for the first time. This is the first time that a chemical catalyst of this sort has been found in a planetary atmosphere other than the Earth's. Catalysts control the reactions of the most important chemical cycles in the Earth's atmosphere. The result shows that scientists' knowledge of the Earth's atmosphere can be used to explain the chemistry of atmospheres on other planets, and vice versa.
The work is announced in the March issue of the journal "Icarus". The observations were made at the James Clerk Maxwell Telescope (JCMT), situated near the 14,000-ft summit of Mauna Kea in Hawaii.
Dr Brad Sandor, also at SSI, explains "We took advantage of the excellent 2003 opposition of Mars, when the Earth and Mars passed close by each other in their orbits around the sun, to measure Martian atmospheric H2O2 for the first time."
The Earth's atmosphere has been studied much more than that of Mars. Scientists have had to rely on their terrestrial experience to guess how the Martian atmosphere reacts to solar radiation, and how its overall photochemical balance is controlled.
Models predicted that hydrogen peroxide was the key catalytic chemical that controls Mars atmospheric chemistry. Until now, scientists were unable to detect the predicted amount of H2O2, so some researchers argued that the models were wrong.
However, the new measurements of hydrogen peroxide made with the JCMT agree with the predictions of standard photochemistry. Dr Clancy continues "We have largely confirmed that the chemical balance of the Mars atmosphere is determined by the products of the photolysis of water vapor, without the need for special or unknown changes to current theory."
What impact does this result have for the search for life on Mars? Dr Clancy says "Hydrogen peroxide is actually used as an antiseptic here on Earth, and so it would tend to retard any biological activity on the surface on Mars. For this reason, as well as the ultraviolet radiation and lack of water, bacteria-like organisms are not expected to be viable on the surface. Most arguments for finding life on Mars now center on subsurface regions."
The James Clerk Maxwell Telescope (JCMT)