Friday, November 6, 2015

Sailin' Through the Solar System

I first encountered the idea of solar sails in the Arthur C. Clarke story, "Sunjammer."  Yesterday, Les Johnson came up from the Marshall Space Flight Center in Huntsville to give an excellent talk on this topic -- I learned a few fun things I hadn't known before.  But first, a trivia question:  Do solar sails operate by catching the solar wind?

Answer: it sounds nice, but it's false. The solar wind is the "breeze" of charged particles spewed out by the sun, while solar sails are pushed by the sunlight itself. Here are a few more interesting takeaways from Les Johnson's talk:
  • Solar sails have been made possible by breakthroughs in materials science that allow the production of exceptionally strong, thin, and light materials. Materials science may not be the most glamorous subject in the world, but it has been powering an enormous number of recent technological breakthroughs.
  • One possible application of solar sails is the positioning of satellites to "hover" over the poles, just like geostationary satellites appear to hover over a fixed spot on the earth above the equator.
  • The Japanese already launched a successful solar sail several years ago. Somehow, this event totally escaped my notice.
The ultimate goal would be to use solar sails to power an interstellar vehicle. This forms a key idea in David Brin's novel Existence, which I highly recommend.


Kathy said...

I read Clarke's "Sunjammer" shortly after I got through "2010." the idea immediately struck me: could you build a solar sail so strong it could serve as a heat shield for aerobraking in a planet's atmosphere?

This was some years ago. In science fiction one can do anything with materials (see the tensile strength required by the base material in Ringworld, for example). But I never developed a story out of it.

Bobby B said...

Wasn't the other takeaway from this talk that you weren't going to be able to propel much mass with a solar sail?

Robert Scherrer said...

I think that's certainly true - solar sails are optimized for unmanned probes, not spacecraft carrying people.