Astro-physics

[joboy]

How close to the sun could a spacecraft get before it combusted or vapourized?

[jake-the-peg]

Rather depends on the spacecraft.

Nasa have a probe planned to approach 3 RS (solar radius about 700,000Km) so about 2.1 Million KM

http://solarprobe.gsfc.nasa.gov/solarprobe_mis sion.htm

67 RS is the previous best

[MatydaLover]

That does seem awfully close, say a thirtieth of our distance. That means the stuff falling on it will be about a thousand times stronger than that falling on us. Imagine the warmth you feel on your face on a sunny day upped by a thousand! And we have the protection of an atmosphere and a magnetic field. It must be made of something good.

Or perhaps they'll send it at night.

[dundurn]

You have a couple of options - heavy reflective shielding on the sunward side of the spacecraft and the majority of your instrumentation on the "dark" side with shuttered ports for cameras etc and/or 'barbecue' or 'rotisserie' mode where you give the craft a permanent spin so that the same area doesn't face the sun for long periods of time. Apollo used the latter method when in transit to and from the moon.

[dundurn]

Maty - I think your maths may be a little out - 2.1 million Km is around 1.3 million miles (I'm old, I can do both, but I'm so much happier in Imperial!) Earth to Sun is about 93 million miles so about a 70th of our distance. This gives approx 5000 times the incident heat/ light we currently experience. Plus there's probably various types of particle thrown off by the sun which aren'tenergetic enough to reach all the way out to here but are more than capable of reaching the spacecraft.

[MatydaLover]

Yes you're right, I tend to err for caution ... so as not to over-state the case. But I added 1SR to 3SR to get 4SR (assuming 3SR is how close they get to the surface) ... then I forgot to change 2.8kms to miles!!

As they say, I prefer the ton-mile-fortnight system.