THE results are in from the first direct survey of the distribution of hydrogen on Mars, which is almost certainly tied up in water molecules. And they show that the planet is, as one geologist put it, 鈥渟opping wet鈥�, with an average topsoil water content of 6.5 per cent, even in the dry equatorial regions.
Preliminary results from the Mars Odyssey spacecraft鈥檚 neutron-scattering detector had already revealed a high concentration of water at the planet鈥檚 poles, as expected. But now that a fully calibrated global map has been completed, it is clear that there is also a great deal of water ice in the equatorial regions. That鈥檚 good news for those who hope to find signs of ancient life or even living microbes under the surface.
The results could help solve the long-standing mystery of Mars鈥檚 missing water. Planetary scientists calculate that it must have taken vast amounts of water to carve its ancient valleys and canyons, yet until now only a small fraction had been detected in and around the polar caps and in the atmosphere.
Advertisement
Although the neutron-scattering experiment can only detect water in the top metre of soil on the planet鈥檚 surface, some geologists think the level of saturation detected by Mars Odyssey may go as deep as a kilometre. If it does, that would account for all the missing water.
To know for sure how deep it goes, scientists will have to use the ground-penetrating radar on the upcoming Mars Express mission, to be launched in May and June of this year. But it is already clear that there is plenty of water on the Red Planet.