NASA Plans Probe to the Sun 352
FudRucker writes "For more than 400 years, astronomers have studied the sun from afar. Now NASA has decided to go there. 'We are going to visit a living, breathing star for the first time,' says program scientist Lika Guhathakurta of NASA Headquarters. 'This is an unexplored region of the solar system and the possibilities for discovery are off the charts.'"
Re:Okay? (Score:5, Informative)
The problem isn't to contain such a temperature, but to do it in a way that is compatible with space travel (i.e. not involving heavy and brittle insulation.)
Re:Okay? (Score:4, Informative)
http://en.wikipedia.org/wiki/Image:TPScube.jpg [wikipedia.org]
Re:Okay? (Score:1, Informative)
Re:Okay? (Score:5, Informative)
And certainly not at the temperature of the Sun's corona (which probes will most likely have to travel through to get to the inner 'cooler' layers..)
This is where we need 'shielding' technology similar to Star Trek, or to jump physical dimensions directly into the desired location with technology similar to Event Horizon, etc..
"The coolest layer of the Sun is a temperature minimum region about 500 km above the photosphere, with a temperature of about 4,000 K."
"The chemical element with the highest melting point is tungsten, at 3695 K (3422 C, 6192 F) making it excellent for use as filaments in light bulbs. The often-cited carbon does not melt at ambient pressure but sublimates at about 4000 K; a liquid phase only exists above pressures of 10 MPa and estimated 4300-4700 K. Tantalum hafnium carbide (Ta4HfC5) is a refractory compound with a very high melting point of 4488 K (4215 C, 7619 F)" http://en.wikipedia.org/wiki/Melting_point [wikipedia.org]
Even diamonds are not tough enough... Above 1700 C (1973 K / 3583 F) diamonds are converted into graphite.
Re:isn't the corona really hot? (Score:4, Informative)
If you go here [hypertextbook.com]
[snip]So wouldn't that tend to prevent anything man made from getting near the sun, much less its "surface" / chromosphere?
RS
From your own link: Though the corona's temperature is high it's molecules are so far apart that the gases release little heat. If a person were to stand on the sun's corona they wouldn't burn, they would freeze in the near vacuum of the corona.
Re:Okay? (Score:5, Informative)
Re:isn't the corona really hot? (Score:3, Informative)
Re:Okay? (Score:5, Informative)
Re:Okay? (Score:2, Informative)
It's not the heat, it's the humidity. (Score:4, Informative)
Re:isn't the corona really hot? (Score:3, Informative)
Re:Okay? (Score:3, Informative)
Re:Okay? (Score:5, Informative)
But they're not entering the corona. From TFA:
I'm not saying 1400 degrees isn't hot, but it's not unmanagable.Re:Okay? (Score:4, Informative)
Re:Bad project name (Score:5, Informative)
"Sunshine" 2007 scifi movie about traveling to Sun (Score:3, Informative)
Re:isn't the corona really hot? (Score:3, Informative)
Infrared photons would be my guess, just like most radiant heat.
Re:isn't the corona really hot? (Score:3, Informative)
Oh, they'd burn alright - but it would be a really bad tan. The side facing the Sun would absorb insane amounts of radiation; the side facing away would freeze... A good example (though far away from the corona): the extreme surface temperatures of Mercury, depending on the amount of sunlight, range from around 100 K to over 700 K.
Obligatory Star Trek reference (Score:3, Informative)
Re:Okay? (Score:2, Informative)
"To solve these mysteries, Solar Probe+ will actually enter the corona," says Guhathakurta. "That's where the action is."
Spend years behind Venus? (Score:3, Informative)
But more importantly, you start gaining it right back, as soon as you're no longer behind Venus. It'll take years to go from Venus's orbit to where they want to get, simply because it's that hard to go down into a gravity well. You need to lose a heck of a lot of energy, but being that it's in space and you don't have friction as a cheap brake, it means as much firing the rockets as if you wanted to gain the same energy. So it'll have a heck of a lot of time to warm up right back.
And again, see Steffan-Boltzman. The farther you got from equilibrium by sitting in the shade, the bigger the difference will be between incoming energy and energy you radiate, hence the faster you warm right up. If you managed to get, say, 100K lower than equilibrium in the sunlight, the first 25K of that gain will be lost a lot faster than the last 25K.
In short, past a point, every Kelvin you go lower by sitting in the shade, will take longer to get it, and the faster you'll lose it when you get out of the shade.
Re:Okay? (Score:2, Informative)
Um, no. You know how if you drop a thimble of 200 degree water into a 5 gallon bucket of 70 degree water, it fails to raise the temperature to even 71 degrees, despite the much higher temperature it had? High temperature doesn't heat things much if there isn't a lot of material that has it.
If you were to walk into a room full of solar corona gas, you wouldn't be incinerated. You wouldn't even be heated. The instant evaporation of the water on your skin would cool you several orders of magnitude more than the million degree gas would heat you. Overall, your temperature would drop. And then you'd die of being exposed to a near vacuum. But the point is, the instant effect would not be the room's gas vaporizing you, it'd be you cooling the room's gas to approximately body temperature, just as the water in the thimble is almost instantly cooled to the temperature of the water in the bucket.
Re:That doesn't really answer the question (Score:5, Informative)