In 1967, the Soviet Venera 4 spacecraft entered the atmosphere of Venus and transmitted data back to Earth before losing contact about 15 miles above the surface.

CNN: Sunday,

The reason astronomers want to observe reflected sunlight during the transit of Venus is to test whether they can detect the faint imprint of passage of the sun's light through the atmosphere of Venus.

CNN: A transit of Venus, an age of wondrous science

They proved that it cannot, as some had suspected, be an effect of Venus's atmosphere.

ECONOMIST: Transits of Venus

Venus Express will make unique studies of this atmosphere and conduct the first radar soundings of the Venusian subsurface.

BBC: Venus mission is on