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Solar Sails And Space Propulsion
Doomie writes "The Economist has an interesting article about solar sails. It talks about the Russian ICBM that will launch Cosmos 1 (mentioned previously on /.) 'The first craft powered by solar-sail technology to orbit the Earth', and the link between this technology and interplanetary travel. Cosmos 1 will orbit Earth starting on June 21st and could, in theory, reach '200,000kph after three years of acceleration' due to the fact that 'particles of light, or photons, that strike a surface give it a tiny push'. The official homepage of the project has more details." Update: 06/18 18:57 GMT by Z : While space trains would be cool, that wasn't the intent of the story. Changed rails to sails.
Isn't this supposed to be a professional website? I'm not the first poster, I realise, which means I'm certainly not the first person to notice the spelling error. But... hasn't this gone past an editor? I mean... what is going on here. Every post has an error of some kind... spelling, grammar... anything...
I'd offer my services as a proofreader but I don't think I want to be associated with something so consistently shoddy...
Union Pacific is to build the ship?
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
Sail of the century
Jun 16th 2005
From The Economist print edition
One small step into orbit may be one giant leap for interplanetary travel
Rick Sternbach, The Planetary Society
ON JUNE 21st, a Russian nuclear submarine is due to launch an intercontinental ballistic missile (ICBM) from beneath the surface of the Barents Sea in the Arctic Ocean. Fortunately, this will not be the opening volley in a global thermonuclear war. Rather, it is intended to open up a new age of space exploration.
The ICBM's payload is Cosmos 1, an experimental spacecraft being launched by the Planetary Society (a space-advocacy group founded in 1980), in conjunction with NPO Lavochkin (a Russian firm which built the craft) and the Makeev Rocket Design Bureau (which modified the ICBM). If the mission, which will cost $4m and has been paid for entirely by private subscription, is successful, Cosmos 1 will become the first craft powered by solar-sail technology to orbit the Earth.
Solar sails rely on the fact that particles of light, or photons, that strike a surface give it a tiny push. Ideally, such sails should be as big as possible, to maximise the amount of sunlight collected, and as reflective as possible, because a photon bouncing off a perfectly reflective sail produces twice as much thrust as one absorbed by a non-reflective sail. Even so, the thrust generated is tiny: a sail with an area of one square kilometre would feel the same force that a kilogram weight exerts on a table on Earth. But there is no air resistance in the vacuum of space, and the sun shines continuously. Slowly but surely, the light-propelled tortoise outruns the rocket-driven hare, reaching 200,000kph after three years of acceleration.
The Planetary Society has details of the forthcoming launch of Cosmos 1. The Makeev Rocket Design Bureau modified the ICBM which will carry the craft.
Solar sails would thus be especially useful for journeys to distant planets or vastly more distant stars, as they do not need to carry any fuel with them. But while they have lived in the imaginations of scientists and science-fiction writers for over a century, their track record in real life has been limited. The Japanese Aerospace Exploration Agency has tested the unfurling of solar sails on sub-orbital rockets, but no one has put solar sails into orbit. Cosmos 1 should change that and, if it works, it will prove the feasibility of the technology for future missions.
Eight triangular sails arranged like the petals of a flower will propel the craft. Each of the sails is 15 metres long, and in total they span 600 square metres--roughly the size of the penalty area on a football pitch. During launch, the sails will be rolled up like so many sleeping bags. Once the ground crew has decided that the craft is in a stable orbit, though, a series of tubular "masts" will be inflated that will unfurl the sails as they expand.
Solar sails require special materials if they are to reflect sunlight efficiently while weighing as little as possible. They must also be able to fold up easily into a small space. Cosmos 1's sails are made from plastic sheets just five microns (millionths of a metre) thick. That is about a quarter of the thickness of a plastic dustbin liner. The plastic in question, Mylar, is coated with aluminium to make it reflective. Mylar is perhaps more familiar from its use in helium-filled party balloons.
If all goes as planned, the spacecraft will go into an orbit that flies over the Earth's poles. Four days later, the sails will be deployed. Once this has happened, the team will monitor Cosmos 1's altitude. The sails are able to swivel slightly, and the ground crew can tilt them individually in order to catch the most sunlight. The resulting increase in the altitude of the orbit will indicate that the sails are indeed feeling the sun's push.
Provided all this works well, the team will then try one last experiment. In order to use solar sails to travel to the outer planets, where the sun's l
Now all they need to do is hit a tachyon eddy and we can reach Cardasia
The only things certain in war are Propaganda and Death. You can never be sure which is which though
You tried to read the article?? You must be new here.
Untrue. By changing the angle of the surfaces reflecting the sunlight, one can change direction. Admittedly, this is like turning the Titantic with a spatula. But given enough time, you can change direction.
See my journal for slashdot ID's by year. Mine created in 2005. http://slashdot.org/journal/289875/slashdot-ids-by-year
Darn, I was in the middle of preparing a submission on Cosmos 1 when I saw this. Anyways, I have a little more info which people might find interesting, so I'll go ahead and paste it below:
Countdown to First Solar Sail Spacecraft
The Planetary Society's Cosmos 1, the first spacecraft to be propelled by a solar sail, has just been loaded onto a converted ICBM in preparation for its launch from a Russian submarine this Tuesday, June 21. This is the first mission by a non-profit space advocacy group and is being funded by private donations. Project Operations Assistant Emily Lakdawalla is posting a running description of events on the official blog. Videos and animations describing the mission are available, including commentary from the Planetary Society's Vice President, Bill Nye the Science Guy. Downloadable print-out model kits are also available.
One of the many neat things about this project is that if the first phase of regular solar sailing is successful, they'll run a later experiment with focusing a microwave beam on the sail to see how well it propels the craft. I wish the Planetary Society the best in this high-risk endeavour.
Check out this week's Quirks and Quarks podcast, which covers the same topic. They interview the Planitary Society project manager about the upcoming solar sail launch.
While I'm at it, they've also got a segment on quantum cryptography this week which is kind of interesting.
ENDUT! HOCH HECH!
The idea of rail-guns for launching vehicles came about because on other planets there wasn't enough atmosphere for aerodynamics to work or for jet engines to work. The relative vacuum and low gravity was an advantage for anything that didn't need to carry its own fuel. The rail gun would use electromagnetic fields to accelerate the vehicle to beyond escape velocity.
However, for Earth, you need a take off velocity of at least 7 miles/second (or 25,000 miles/hour). And that doesn't take into air friction. Assuming you could build such an aerodynamic capsule, you would need a considerable acceleration for a period of the launch phase.
To minimize the amount of energy you need to use, you'd want to travel straight up, and to generate enough energy you would probably have to burn gallons of hydrocarbons or run a whole chain of nuclear reactors. Since energy is most efficient when you use the least number of conversion stages, you really end up with a vertical rocket launch with solid or liquid fuel.
Vintage computer adverts: http://www.vintageadbrowser.com/computers-and-software-ads