It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Thank you.
Some features of ATS will be disabled while you continue to use an ad-blocker.
A solar balloon is a hot air balloon that is heated entirely by the sun. No flame or other external heat source is needed - the balloon gets its heat from the black material which it is made from. Dark colors absorb heat, so the black surface of a solar balloon absorbs heat from the sun, which heats the air inside the balloon. Thus, they can fly all day, without re-heating or re-inflating, as long as the sun is out.