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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.
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!
Two things: the sails are maneuverable, so you can get different thrust vectors within a certain rangle of angle.
More importantly, you have solar gravity pulling you in the exact opposite direction of the photon pressure. So, to go towards the sun, just use the solar sail to kill some of your orbital momentum. This also works around smaller bodies such as the earth, assuming you already are in orbit (which is a given for the Cosmos I satellite).
Remain calm! All is well!
Its about a training voyage with six cadets and a instructor who thorougly trains his cadets by making the voyage a living nightmare of failures, as well as making sure they make it on their own ( as he's already seen to it the radio does not work, and he's let it be known very clear to the cadets he expects to die in space - the ship is theirs to navigate using the forces of nature at their command, and he's not lifitng a finger to help.).
Jack seems to have his physics pretty accurate -
I have re-read that story often. It would make a helluva movie.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
If this is to "orbit" the earth it faces alot of challenges. Out atmosphere extends quite a distance to the moon. Sure it is atoms per cubic meter but it's appreceable . I suspect there will some frictional losses that will constrain the top end velocity. If it orbits that means that it has to go back around the other side, while the front surface is facing to the sun. Sure you can play tricks where maybe one side is reflective and the other approaches an ideal black body object and just absorbs. Or maybe when it is on it's orbit facing to the sun and while it is "tacking the wind" you retract the solar sail to reduce drag. Lots of challenges there to consider. You probably could get better performance if it had a highly elliptical orbit, in other words, more acceleration as it has the "wind in it's sails" and then when it reaches apogee you close the sails and let it accelerate back to earth using gravitational attraction. As this thing accelerates the orbit would become even more elliptical and as it does a swing by the earth (to go back into space) it faces frictional heating, geomagnetic forces where the electric charges on the instrumentation packages begin to wear on the electronics packages. Remember what happens when you move a piece of metal rapidly through a magnetic field, it induces voltages into the object being moved. It would be cooler, probably easier and more impressive if you sent it into deep space. Then when in mid course to another star, once it senses decelleration caused by the star it's heading to it would either close or eject the sail. Think of a solar sail built like a umbrella. Put the instrumentation package in the "handle" and also a microwave transmitter and feed horn. Face the feed horn right at the surface of the solar sail and this thing can do double duty as a giant microwave antenna (50-100 meters across). This would have a greater communication range than any deep space probe out there that are limited by the gain that their antennas can produce because of their relatively small size (a few meters across). Let's say you want to decellerate at the other end. Use a small thruster to turn the thing around mid-course and re-deploy the sail. The probe would slow down the closer it gets to the distant star. Possibilities, possibilities, my mind is awash.
Tisha Hayes