NASA Messenger set to visit planet Mercury

CAPE CANAVERAL, Fla. – NASA is about to embark on its hottest mission ever – to Mercury.

The Messenger spacecraft, to be launched on Aug. 2, will be blasted by up to 840-degree heat as it orbits the tiny planet closest to the sun – so close that it would be as though 11 suns were beating down on Earth.

Remarkably, the only thing between the probe’s room-temperature science instruments and the blistering sun and pizza-oven heat will be a handmade ceramic-cloth quilt just one-quarter of an inch thick.

Messenger will be the first spacecraft ever to orbit Mercury and the first in more than 30 years to come close.

Even at that, members of the Johns Hopkins University spacecraft team assembled in Cape Canaveral realize this mission can’t compete with Mars and its rover or with Saturn and its newly arrived sentry, Cassini.

But there are plenty of cool facts about this red-hot mission, besides the off-the-charts-SPF sunscreen that was baked for days in ground testing.

Even though Mercury is 50 million miles from Earth at closest approach, Messenger will travel 5 billion miles to get there. It’s technologically infeasible to fly straight to Mercury, a trip of a few months, and so the spacecraft must swing once past Earth, twice past Venus and thrice past Mercury before slowing down enough to slip into orbit around Mercury.

Estimated arrival time: March 2011.

Scientists want to know how the planet turned out the way it did and whether the perpetually dark carters at the poles hold ice. Anything scientists can learn about how Mercury formed will shed light on the origins of the other inner rocky planets of the solar system: Venus, Earth and Mars, each one so very different.

Once its mission is accomplished in 2012, Messenger will keep orbiting Mercury until it eventually crashes onto the surface.