Posted on 03/20/2011 8:23:42 AM PDT by BenLurkin
At some 36 million miles from the sun, temperatures on the planet's daylight half hit 800 degrees F., while temperatures on the night half plunge to nearly minus 300 degrees F. – a 1,100-degree temperature swing that the craft will experience every 12 hours.
The craft is outfitted with a ceramic-cloth sun shield that sheds enough of the sun's heat to keep instruments inside the orbiter at room temperature. Solar panels, which ordinarily would aim face-on to the sun, must be feathered, like a rowboat oar, to keep the panels from overheating. In addition, the panels contain mirrors to help shed some of the intense sunlight.
The business side of the craft, which will be facing the planet's roasting surface on the sunlit side, also requires a cool-down. Thus the craft's orbit will take it to within 124 miles of the surface on the sunlit side and out to just over 9,000 miles on the night side for cooling. Also on that side, the craft will take measurements of the space environment in Mercury's immediate vicinity.
MESSENGER is expected to help provide an explanation for the planet's structure, in addition to gathering detailed information on the topography and composition of its surface.
One intriguing mystery involves odd signatures from Earth-based radar observations of crater floors at Mercury's poles. The bottoms of these craters are in permanent shadow, similar to craters at the moon's poles. On the moon, those crater floors have been shown to contain relatively high abundances of water ice. With Mercury's polar craters returning radar signatures similar to those from other, well-known icy regions on Mars or on Jupiter's moons, scientists are eager to see if Mercury also might have frigid reservoirs of water ice, despite its proximity to the sun.
(Excerpt) Read more at csmonitor.com ...
Wonder how this will boost muzzie self esteem in light of NASA’s new goal of making them feel good about themselves as the wun has ordered?
Ironically, it takes more energy to put a space craft in orbit around Mercury than Pluto. It takes more fuel to slow down a craft that has fallen from the earth’s orbit to Mercury’s orbit down to a speed that will allow it to stay in orbit around Mercury than it does to toss a space craft from the earth’s orbit to Pluto, especially with a boost from Jupiter.
I’ve been fascinated by this mission, for some reason. Maybe because we haven’t paid that much attention to Mercury in the past- except for one of the Mariner missions.
It isn’t going to happen anytime soon, but I’d love to see some lander shots of the Mercurian regolith with the large, glaring disk of the Sun in the sky. Or some surface shots of the massive escarpment that I’ve seen in the orbital photos.
The monochrome starkness and extremes of climate kind of remind me of the prison planet Crematoria, from Vin Diesel’s movie ‘The Chronicles of Riddick’. You *don’t* want to be outside when the sun comes up, although I doubt that a planet like that could sustain a breathable atmosphere.
I saw the live coverage of the orbital insertion a few days ago. Pretty exciting stuff I tell ya.
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