"Scientists Ready Russian Rocket to Venus"

The Venus Express -- ready for hell.

Not only is Venus the nearest planet to Earth within the solar system, but the two share also roughly the same mass and density. Both have inner cores of rock and are believed to have been formed at roughly the same time.

But the two have vastly different atmospheres, with Venus' composed almost entirely of carbon dioxide with very little water vapor. It is also the hottest surface of all the planets and lacks atmospheric pressure.