[LINK] "Voyage of the Sunjammer: Sailing on Solar Winds"

[rfmcdonald]

I picked up Discovery's article on the latest solar sail news from Supernova Condensate's associated Tumblr.

The sun, like all other stars, emits an immense amount of photons, as well as a steady stream of charged particles. This “solar wind” actually exerts a not insignificant amount of pressure on everything which orbits the sun. It’s enough to blow out the glorious tails of comets, like the ones that should be visible in the skies later this year, and to be gradually eroding Venus’ atmosphere. Also, just like the wind here on Earth, space weather can be used to power sails.

Despite being a mainstay in some science fiction works, solar sails are a very real and attainable technology. The latest development being the Sunjammer, a joint project between NASA and California-based aerospace company L’Garde.

At over 1,200 square meters (13,000 sq. ft.) in area, Sunjammer will be the largest solar sail ever constructed. It’s currently scheduled for launch in 2014, and will travel approximately 3 million kilometers (1.9 million miles).

[. . .]

The sail, with an area just under a third of an acre, will be deployed after the craft is launched into space — unfurling from a vehicle the size of a dishwasher, weighing just over 30 kilograms in total. This is probably one of the most ambitious spacecraft propulsion concepts ever tested. However, at the same time, the deployment mechanisms for solar sails have been well tested previously.

The sail itself will be made from a high tech material called Kapton — also used in space suits, where it serves the threefold purpose of thermal insulation, shielding from solar radiation, and protection from micrometeoroids. Made from this surprisingly tough material, the sail will be buffeted by photons from the sun, together with the charged particles which make up the solar wind; solar charged particles, mostly protons and electrons, also get caught up in the Earth’s magnetic field and cause the stunning displays of aurorae in polar regions.

The effective thrust which a solar sail can achieve is roughly 0.1 Newton — around the same force exerted by Earth’s gravity on a packet of sugar which you might stir into your morning coffee. This may seem tiny to us here on the surface of our planet, but it’s comparable with certain existing space propulsion technologies. For example, that’s actually more power than the ion thrusters that are currently propelling NASA’s Dawn spacecraft from Vesta to Ceres in the asteroid belt.