One Legacy of Carl Sagan May Take Flight Next Week -- a Working Solar Sail (arstechnica.com) 78
As early as next Monday night, a SpaceX Falcon Heavy rocket will launch a cluster of 24 satellites for the US Air Force. From a report: Known as the Space Test Program-2 mission, the rocket will deposit its payloads into three different orbits. Perhaps the most intriguing satellite will be dropped off at the second stop -- a circular orbit 720km above the Earth's surface. This is the Planetary Society's LightSail 2 spacecraft. After a week in space, allowing the satellites deposited in this orbit to drift apart, LightSail 2 will eject from its carrying case into open space. About the size of a loaf of bread, the 5kg satellite will eventually unfurl into a solar sail 4 meters long by 5.6 meters tall. The Mylar material composing the sail is just 4.5 microns thick, or about one-tenth as thick as a human hair. This experiment, which will attempt to harness the momentum of photons and "sail" through space, is the culmination of decades of work by The Planetary Society. "This goes back to the very beginning, to Carl Sagan, Bruce Murray, and Lou Friedman," the organization's chief executive, Bill Nye, told Ars in an interview. "We are carrying on a legacy that has been with us since the founders. It's just an intriguing technology because it lowers the cost of going all over the place in the Solar System."
Really excited to see this work (Score:4, Interesting)
I have always loved the idea of solar sails and am anxious to see how this performs.
I had always wondered if solar sails could maybe be some kind of emergency backup system for interplanetary space flights in case the main boosters failed... would take a lot longer to work with them but you could store quite a large array for very little space/weight.
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You have absolutely no understanding of how large a place space is. This is real life, not a science-fantasy movie.
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You have absolutely no understanding of how large a place space is.
Douglas Adams explained it very clearly:
Space is big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.
Time is on your side (Score:3)
You have absolutely no understanding of how large a place space is.
I'm not sure it would be feasible for any kind of manned mission but solar sails may be enough to alter trajectory meaningfully for an unmanned craft, though it might take years longer to get to where it needed to be... I have no illusions about it being a speedy alternative.
This is real life, not a science-fantasy movie.
Indeed it is, and in real life they are launching a solar sail craft! So we'll know viability soon.
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I have always loved the idea of solar sails
So did Johannes Kepler who first proposed the idea [wikipedia.org] more than 400 years ago.
Giving the credit to Carl Sagan is ridiculous. Carl Sagan did some great things, but this wasn't one of them.
Re:Really excited to see this work (Score:5, Informative)
The very spacecraft mentioned in the title was designed, built and payed for by the Planetary Society, which Carl Sagan was a founder (one of). Additionally he was the very strong proponent of using solar sails for space exploration, he did not invent them of course, and nowhere in the summary it is even suggested.
Thus this cubesat, which will fly soon is very truly the legacy of Carl Sagan.
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I had always wondered if solar sails could maybe be some kind of emergency backup system for interplanetary space flights in case the main boosters failed... would take a lot longer to work with them but you could store quite a large array for very little space/weight.
If your main boosters fail in a space flight, the flight fails. Just like with aircraft. At best you can have multiple engines and design the craft to operate successfully with some fraction of the engines failing (multi-engine aircraft, and SpaceX's BFR are designed this way), but you still need to consume all of your planned fuel load.
The notion that you can just throw a "light weight" solar sail package on to a rocket powered mission just in case your main propulsion system fails, and have it do anything
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SJWs are by and large all rapists and paedophiles. [twitter.com]
Peter Bright was recently outed as one of them when he was arrested for soliciting sex with minors online. [dailydot.com]
But don't let me keep you away from sexually harassing women and molesting children, you sicko fuck.
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I dunno, did you have to decide not to attend your cognitive therapy sessions?
Clarke (Score:4, Informative)
"Sunjammer" is a science fiction short story by British writer Arthur C. Clarke, originally published in the March 1964 issue of Boys' Life,[1]. The story has also been published under the title "The Wind from the Sun" in Clarke's 1972 collection of short stories with this title. It depicts a yacht race between solar sail spacecraft.
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It's been done already (Score:1)
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There is no innovation. It's a cool idea that's been disputed by some [wikipedia.org]. Like earlier experiments on these things it likely won't work for any number of reasons all relating to some kind of failure to deploy properly. My impression is that the experiments are a scam and someone somehow is making money off it.
Someone Convince Me that the Sail Will Survive (Score:2)
This sail is 22.4 sq. meters and 4.5 microns thick. I have a disposable Mylar blanket in my bag and it's 12 microns thick. I've torn these before without issue. How long will this thing survive in orbit? From what I understand, we have a lot of crap floating around up there.
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It won't survive - at low earth orbit it will be bombarded by atomic oxygen (far more aggressive than molecular oxygen) and slowly eat the blanket - probably within 12 months. For reference there was a science package that was placed into orbit before the Challenger shuttle disaster and collected some time later where materials were exposed to the low orbit "ionic breeze" - some fairly serious erosion was observed.
The question is will the sail unfurl in a zero G environment? Static electricity could make th
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It won't survive - at low earth orbit it will be bombarded by atomic oxygen (far more aggressive than molecular oxygen) and slowly eat the blanket - probably within 12 months. For reference there was a science package that was placed into orbit before the Challenger shuttle disaster and collected some time later where materials were exposed to the low orbit "ionic breeze" - some fairly serious erosion was observed.
The question is will the sail unfurl in a zero G environment? Static electricity could make the film layers cling to each other with "considerable force".
That package was up there for years. The sail should be gone in weeks...
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Missed the part where it's going into a 750 km orbit? It's in the summary.
It's also not supposed to operate for an extended period.
Fuel (Score:2)
The thing about a solar sail, is that it never runs out of fuel. Long after a rocket has gone cold, the sail is still producing force. And going faster and faster. After a few years, if the control systems last, it could be going faster than any other human spacecraft ever has. (Until it is too far from the sun, of course, then it stays at that speed.)
Which means it might well be a useful emergency device for "manned" spacecraft. The rockets fire for only a few minutes and then coast for weeks. The sail add
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Or we could give the solar sail an extra little push [youtube.com] into the right direction till there's no more beam cohesion.
That might be useful for probes that don't have a lot of mass. Something as heavy as being equipped with life support, passengers and cargo... probably not so much.
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Or we could give the solar sail an extra little push [youtube.com] into the right direction till there's no more beam cohesion.
That might be useful for probes that don't have a lot of mass. Something as heavy as being equipped with life support, passengers and cargo... probably not so much.
It's not the payload weight, it's the relation of the weight (mass) to the size of the sail. There are experimental plans for much larger solar sails, possibly miles across. In micro-gravity it does not need to support it's own weight, and even a small force applied over days or weeks could reach higher speeds than any rocket.
The real problem is keeping the sail from twisting or tangling.
Not new by a long shot (Score:2)
The Planetary Society already did this already years ago.
The '2' in 'Lightsail 2' was a dead giveaway.
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This is the first light sail mission to actual do sailing. Light Sail 1 was a technology demonstrator to test deployment of the sail - something never before accomplished. Light Sail 2 uses the sail to do actual work -- raising the apogee, testing direction control.
It is not the case that the first limited successful of a technology makes everything "old hat" forever after. You have crawl before you can walk, walk before you can run. run a little before you can run fast or far. Lightsail 1 was crawling. Lig