spaceship damage from solar radiation

[Drifter]

Originally Posted by Anthony

An M2 dwarf has a typical luminosity of about 0.03, and at 0.05 AU that's multiplied by 400 for a total of 12 x sunlight, or about the same as 0.28 AU from the sun. That should actually be survivable indefinitely with a basic parasol design, as long as the parasol can withstand the temperature; it's too hot for something like aluminum, but there's no shortage of materials that can handle 600K or so (because it's a thin sheet, temperature is somewhat higher), and as long as the parasol is properly sized, only a quite small fraction of the heat will actually reach the ship.

So basically a bedsheet made of any reasonable TL9 material is going to do the job. Sort of takes the drama out of diving into a sun.

[Fred Brackin]

Originally Posted by Drifter

So basically a bedsheet made of any reasonable TL9 material is going to do the job. Sort of takes the drama out of diving into a sun.

At .03 AU (which is still nearly 3 million miles from the photosphere) the real problems might be x-rays and/or fast particles from the corona rather than simple heat.

[Drifter]

Originally Posted by Fred Brackin

At .03 AU (which is still nearly 3 million miles from the photosphere) the real problems might be x-rays and/or fast particles from the corona rather than simple heat.

I certainly wouldn't want to be in a spacesuit trying to rig up a heatshield when you're that close to the star. But the craft overall is probably going to be armored enough to take care of that sort of radiation.

Then again it might have to list a certain armor rating. No armor means it wasn't mean to get that close to a powerful radiation source.

[vicky_molokh]

Originally Posted by Drifter

Then again it might have to list a certain armor rating. No armor means it wasn't mean to get that close to a powerful radiation source.

Just use the PF values of the ship for that, I think.

[Fred Brackin]

Originally Posted by vicky_molokh

Just use the PF values of the ship for that, I think.

If you're depending on a reflective surface layer to increase albedo and reduce heating then erosion through surface ionization is a possible concern.

[Anthony]

Originally Posted by Fred Brackin

If you're depending on a reflective surface layer to increase albedo and reduce heating then erosion through surface ionization is a possible concern.

For comparison, this is about the same luminous intensity as was dealt with by the Helios 2, which has a build that's about typically flimsy for a TL 7-8 probe. Solar Probe + is supposed to get to 0.034 AU, and that's from the sun, not a wimpy M2 dwarf.

[Drifter]

Originally Posted by vicky_molokh

Just use the PF values of the ship for that, I think.

What is the PF for a given ship? I'm not seeing a listing for that in the books I have (mostly Traveller). Would it be equivalent to DR?

Considering that a solar flare, at Earth's orbit, gives out about 15 rad/minute, and the current US safety guidelines for astronauts is 25 rad per mission, that might be a good level to use.

[Drifter]

Originally Posted by Fred Brackin

If you're depending on a reflective surface layer to increase albedo and reduce heating then erosion through surface ionization is a possible concern.

Originally Posted by Anthony

For comparison, this is about the same luminous intensity as was dealt with by the Helios 2, which has a build that's about typically flimsy for a TL 7-8 probe. Solar Probe + is supposed to get to 0.034 AU, and that's from the sun, not a wimpy M2 dwarf.

From what I understand such erosion would be minimal in the short term, at least for spacecraft of a mature, spacefaring culture, around TL9.

However, M2 stars should have a large number of flares. Significant bursts of UV, gamma and X-rays and simple heat spikes might cause problems. I'm not sure if actual matter ejected would cause drag problems, but the gas itself can be 100 million degrees Kelvin. It doesn't seem reasonable that a craft flying into that would suddenly be over a million degrees, but maybe it could be subject to hot spots and other stresses.

[Anthony]

Originally Posted by Drifter

I'm not sure if actual matter ejected would cause drag problems, but the gas itself can be 100 million degrees Kelvin.

It's very, very diffuse. Mostly it's a radiation problem and a problem for electronics.

[vicky_molokh]

Originally Posted by Drifter

What is the PF for a given ship? I'm not seeing a listing for that in the books I have (mostly Traveller). Would it be equivalent to DR?

Considering that a solar flare, at Earth's orbit, gives out about 15 rad/minute, and the current US safety guidelines for astronauts is 25 rad per mission, that might be a good level to use.

The PF varies depending on the mass of stuff surrounding the module in which a person resides. It tends to be PF10ish for the smallest (SM+4), lightly-armoured ships with lots of empty space. The reference table is found on page 41 of Spaceships 5.