Venus Express spacecraft investigation finds atmospheric loss of hydrogen

It has long been known that Venus is hot with clouds high above in the atmosphere producing a greenhouse effect which traps heat . But underneath Venus' clouds, were there hot oceans or deserts / dry land? Then radar showed the landscape to be dry and arid with no water. Scientists understood that Venus had water, once like Earth but then lost its water. But the mystery was how ? Now the Venus Express spacecraft has made the first detection of an atmospheric loss process on Venus's day-side. The spacecraft has yielded data that revealed that most of the lostatmosphere escapes from the night-side. Planetary scientists are closer to understanding what happened to the water on Venus and all the processes that caused the water to disappear from Venus.

More at:
http://www.esa.int/esaSC/SEM8MYSTGOF_index_0.html