Mars Express Analyses the Earth
SPICAM Detects Ozone
SPICAM/Mars Express detects strong quantities of ozone in the atmosphere of the Earth, allowing life on this planet.
On July, 3, 2003, a spectrum of Earth illuminated by solar light was recorded by the Ultra-Violet spectrometer SPICAM, on board Mars Express. Taken from a distance of 7 million km, the spectrum shows only some signal at 310 nanometers, and nothing at shorter wavelengths, though the instrument sees plenty of UV light from another star. This is what is expected if the atmosphere of the Earth contains ozone, a gaseous species made of 3 atoms of oxygen, known to provide a natural screen to harmful UV solar radiation.
"Together with the OMEGA infrared spectrometer detection of water vapour and oxygen, the detection of copious amounts of ozone in the atmosphere indicates that this planet that we call Earth could sustain life", says Jean-Loup Bertaux, a French CNRS scientist from Service d'Aéronomie/IPSL, responsible for the SPICAM instrument.
The interpretation of SPICAM spectrum is completely supported by simulations of the effect of the atmosphere on the solar radiation which is scattered by the Earth (with MODTRAN software). Ozone absorbs all solar radiation between 200 and 300 nm, preventing harmful effects on the DNA molecules of all living species exposed to the Sun.
Credits: SPICAM is a dual UV-near IR spectrometer , designed and built by Service d'Aéronomie (France, BIRA (Belgium), and IKI Space Research Institute (Russia), under the leadership of Jean-Loup Bertaux, Paul Simon and Oleg Korablev.
Further questions may be channelled to: bertauxaerov.jussieu.fr