In Mercury's orbit around the Sun (Solar orbit, not Mercurial orbit), what are the conditions like? What shielding or heat management would be required for a manned spacecraft? Could a spacesuited astronaut survive a space walk?


Basic research on NASA's site gives me plenty of information about Mercury proper which is hot in the sunlight. :) NASA's MESSENGER mission site specifies some of the countermeasures that the MESSENGER orbiter uses. The ever-helpful Atomic Rockets site also has some helpful information about Mercury itself and heat radiators.

Mercurial orbit also has to contend with reflected thermal radiation from Mercury's surface, but I'm specifically interested in Solar orbit (e.g. Sol-Mercury L4 or L5), where the only problem is Solar radiation.

However, I have been able to find nothing specific about the concerns of human habitation Mercury's distance from the sun. Hence this question!

  • $\begingroup$ Welcome to the site David, thanks for checking for info and adding that to your question. If you have questions about the site visit the help center or feel free to check out Worldbuilding Chat $\endgroup$
    – James
    May 25, 2016 at 17:44
  • $\begingroup$ @AndreiROM I hope that satisfies you that I've taken reasonable measures on my end. :) And thanks, James. $\endgroup$
    – David Eyk
    May 25, 2016 at 17:51
  • $\begingroup$ Comment deleted, and I didn't down-vote. The question is indeed much better framed. $\endgroup$
    – AndreiROM
    May 25, 2016 at 17:54

1 Answer 1


Solar Probe Plus is a NASA spacecraft scheduled to launch in 2018. It will come as close as 6 million kilometers from the Sun.

It has a carbon-carbon heat shield that has to withstand temperatures of over 1300C (2500F). Radiation exposure will also be very high (SP+ is supposed to study radiation for future manned missions to the Moon & Mars).

An astronaut would be able to survive a space walk, as long as he remains in the shade of the heat shield. He will probably be exposed to a large amount of radiation and might get radiation sickness though.

  • $\begingroup$ Ah, I hadn't considered radiation. I suppose that would require the same sort of radiation shielding you'd need for surviving a solar flare out in non-circumsolar space. Could our intrepid astronaut simply hide behind a water tank? $\endgroup$
    – David Eyk
    May 25, 2016 at 20:28
  • $\begingroup$ @DavidEyk Yes, water provides great radiation shielding. As long as there is enough water between you and the Sun you''ll be fine. $\endgroup$
    – ventsyv
    May 26, 2016 at 3:11

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