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Thread: Solar sails, etc.

  1. #1
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    Solar sails, etc.

    I did some cursory reading on these and thought they looked interesting, so of course I have some questions.

    1. Would it be possible, or plausible, to create a yacht-style solar sail that would accelerate towards a radiation source? How about for electric sails?

    2. What do existing designs for electric sails (i.e. using the solar wind) look like, in physical terms? How physically large would they have to be when fully unfurled, in order to be useful?

    3. Could any sort of sail whatsoever be practical for human missions, or are we talking about excessively large dimensions here?

    4. How does radiation pressure from solar wind compare to solar light in terms of Newtons?

    5. For those in the know: what sort of budget, at a minimum, might go into developing a workable space probe based on an electric sail?

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    1. No, though IIRC "tacking" is an option for certain circumstances.

    2. Wires sticking out straight. A Magnetic sail would use a large (miles wide) ring of superconductors.

    3. Yes and yes. Square miles, tens to hundreds.

    4. It's less, that's all I know.

    5. It's already been done: http://en.wikipedia.org/wiki/ESTCube-1
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Photon pressure gives about a thousand times as much thrust as the solar wind for a given cross section. And electric sails can only produce outward thrust, though magsails can tack to some degree.

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    Quote Originally Posted by cjameshuff View Post
    And electric sails can only produce outward thrust, though magsails can tack to some degree.
    Magsails also have the advantage of being able to thrust against a planet or moon's magnetosphere.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    I can see such being useful for unmanned cargo vehicles carrying storable items on regular flights. It doesn't matter how long it takes to get to the destination as long as the time between flights is short enough once the initial flight is over.
    Last edited by ravens_cry; 2014-Mar-25 at 01:18 AM.

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    Magsails do have one advantage; as they move into the outer solar system, away from the Sun, their own magnetic field can expand to catch more solar wind particles and maintain a fairly even thrust, even at distances where the Sun is just a fairly bright star and a lightsail would be unable to even twitch.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Gullible Jones View Post
    I did some cursory reading on these and thought they looked interesting, so of course I have some questions.

    1. Would it be possible, or plausible, to create a yacht-style solar sail that would accelerate towards a radiation source?
    If you start out in orbit around the Sun -- which of course all space probes do, -- it is possible to angle the sail so that the direction of thrust is opposite to the probe's orbital velocity (and approximately perpendicular to the Sun-probe line). That will act as a brake on the probe and cause it to spiral in toward the Sun.

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    Quote Originally Posted by Noclevername View Post
    Magsails do have one advantage; as they move into the outer solar system, away from the Sun, their own magnetic field can expand to catch more solar wind particles and maintain a fairly even thrust, even at distances where the Sun is just a fairly bright star and a lightsail would be unable to even twitch.
    On the other hand, they do the opposite as you get closer to the sun, shrinking down where a lightsail gets peak thrust.

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    Quote Originally Posted by cjameshuff View Post
    On the other hand, they do the opposite as you get closer to the sun, shrinking down where a lightsail gets peak thrust.
    But they provide some shielding against cosmic ray particles.

    So you have places for all three types of propulsion.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Ilya View Post
    If you start out in orbit around the Sun -- which of course all space probes do, -- it is possible to angle the sail so that the direction of thrust is opposite to the probe's orbital velocity (and approximately perpendicular to the Sun-probe line). That will act as a brake on the probe and cause it to spiral in toward the Sun.
    Agreed.

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    Les Johnson is the go to guy on the subject
    http://les-johnson.blogspot.com/2013...-to-stars.html
    http://lesjohnsonauthor.com/

    Sunjammer is his baby.

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    A shoebox-sized satellite will be launched in a few hours to bring to reality one of Carl Sagan's pet projects. Watch a young Carl Sagan talk about it on the Tonight Show way back in 1976.

    Bill Nye of The Planetary Society is now championing it. Read more about it in Spaceflightnow.

    http://spaceflightnow.com/2015/05/19...solar-sailing/

    A shoebox-sized satellite conceived and funded by members of the Planetary Society, an advocacy organization co-founded by Carl Sagan, is fastened to an Atlas 5 rocket for launch Wednesday to test one of the late celebrity-astronomer’s futuristic concepts for exploring the cosmos.

    Sagan and other proponents of solar sailing pitch the technology as a way to cheaply glide through the solar system, harnessing energy from sunlight to slightly nudge a spacecraft toward its destination.

    The solar sail prototype is going to an orbit a few hundred miles above Earth, where atmospheric drag will overpower any propulsion from the sun. A follow-up mission next year will try to use sun beams to change its orbit.

    “We won’t fly high enough above the Earth’s atmosphere for solar sailing, due to atmospheric drag, but we’ll do critical tests of several systems over a 28+ day mission, including a zero-gravity test of our sail deployment sequence and attempt to snap pictures documenting the operation of the booms that support the sails,” the Planetary Society wrote on in a summary of the mission.

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    The Japanese already sent a probe to Venus using a solar sail. Despite being named IKAROS, a name just begging for trouble,

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    Quote Originally Posted by ravens_cry View Post
    The Japanese already sent a probe to Venus using a solar sail. Despite being named IKAROS, a name just begging for trouble,
    Thanks for highlighting that. I was under the impression this was the 1st test of the technology.

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    We have take off.

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    Quote Originally Posted by selvaarchi View Post
    Thanks for highlighting that. I was under the impression this was the 1st test of the technology.
    Not only of the technology, but it's not even the first test from the Planetary Society.

    From wiki, I compiled a terse list of previous solar sail attempts.
    2001 Planetary Society, Cosmos 1. Rocket failure.
    2005 Planetary Society LightSail. Rocket failure.
    2006 JAXA, Solarsail Subpayload Satellite. Did not open completely.
    2008 NASA, NanoSail-D. Launch failure.
    2010 NASA, NanoSail-D2. Successful.
    2013 Estonia, EstCube-1 (tether). Did not unwind.
    Messenger also used the light sail effect to adjust its trajectory.

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    Quote Originally Posted by ravens_cry View Post
    The Japanese already sent a probe to Venus using a solar sail. Despite being named IKAROS, a name just begging for trouble,
    The Japanese used adhesives with better high temperature properties than did Daedalus
    Information about American English usage here. Floating point issues? Please read this before posting.

    How do things fly? This explains it all.

    Actually they can't: "Heavier-than-air flying machines are impossible." - Lord Kelvin, president, Royal Society, 1895.



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    Quote Originally Posted by NEOWatcher View Post
    Not only of the technology, but it's not even the first test from the Planetary Society.

    From wiki, I compiled a terse list of previous solar sail attempts.
    2001 Planetary Society, Cosmos 1. Rocket failure.
    2005 Planetary Society LightSail. Rocket failure.
    2006 JAXA, Solarsail Subpayload Satellite. Did not open completely.
    2008 NASA, NanoSail-D. Launch failure.
    2010 NASA, NanoSail-D2. Successful.
    2013 Estonia, EstCube-1 (tether). Did not unwind.
    Messenger also used the light sail effect to adjust its trajectory.
    Wow, The bad luck seems extraordinary. Rather commendable that they regardless persevered.

  19. #19
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    Quote Originally Posted by NEOWatcher View Post
    Not only of the technology, but it's not even the first test from the Planetary Society.

    From wiki, I compiled a terse list of previous solar sail attempts.
    2001 Planetary Society, Cosmos 1. Rocket failure.
    2005 Planetary Society LightSail. Rocket failure.
    2006 JAXA, Solarsail Subpayload Satellite. Did not open completely.
    2008 NASA, NanoSail-D. Launch failure.
    2010 NASA, NanoSail-D2. Successful.
    2013 Estonia, EstCube-1 (tether). Did not unwind.
    Messenger also used the light sail effect to adjust its trajectory.
    Planetary Society does not talk about their past failures. Their write up concentrates on their current efforts.

    http://www.planetary.org/blogs/jason...l-liftoff.html

    For the Planetary Society, the launch of LightSail marks the culmination of a six-year effort to send a solar sail CubeSat to space. The project began in 2009, but was temporarily sidelined by technical and funding challenges, as well as the need to find a sufficiently high-altitude flight. The spacecraft was originally built by San Luis Obispo-based Stellar Exploration, Inc. In 2014, Ecliptic Enterprises Corporation became the vehicle’s prime contractor, and Doug Stetson joined the team as project manager. Boreal Space serves as a contractor to Ecliptic. Testing and integration for LightSail occurs at Ecliptic as well as Cal Poly San Luis Obispo

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    Quote Originally Posted by selvaarchi View Post
    Planetary Society does not talk about their past failures. Their write up concentrates on their current efforts.
    That's a shame. You would think a group that is trying to empower the public with space would explain the difficulties in spaceflight.

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    I'm very glad that this recent launch succeeded. Good luck, LightSail!

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    Quote Originally Posted by NEOWatcher View Post
    That's a shame. You would think a group that is trying to empower the public with space would explain the difficulties in spaceflight.
    That is so true. It will get better but Risk and Failure are still a big part of Space Exploration. I am supposing that a space advocacy org may find it more convenient to stress the positive as it seeks to raise funds. But it does us a disservice in that a large number of enthusiasts seem to ignore the difficulties when advocating for exploration and so they adopt a tone of impatience.
    There must be an interesting human story of passion, disappointment and perseverance. Maybe somebody else will tell it.

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    It's not like they're trying to cover up or hide past challenges. As far as I know, they've written about them in various blog posts and news items around the time the failures happened, and I'm pretty sure the membership newsletter/magazines that go out don't gloss over anything either. That they might choose the blog as a forward facing and optimistic place isn't surprising, though.

    CJSF
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    Quote Originally Posted by NEOWatcher View Post
    That's a shame. You would think a group that is trying to empower the public with space would explain the difficulties in spaceflight.
    It may be that they were embarrassed with using the Volna SLBM to begin with: http://en.wikipedia.org/wiki/Volna

    Scratch that---Here is their report
    http://www.planetary.org/blogs/guest..._20050720.html

    Now I seem to remember that they tried a second launch on a Volna, but the second try was listed as a Falcon 1 failure.

    Here is what a solar sail looks like in space
    http://www.planetary.org/multimedia/...rom-dcam2.html
    Last edited by publiusr; 2015-May-23 at 08:01 PM.

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    Quote Originally Posted by publiusr View Post
    It may be that they were embarrassed with using the Volna SLBM to begin with: http://en.wikipedia.org/wiki/Volna

    Scratch that---Here is their report
    http://www.planetary.org/blogs/guest..._20050720.html

    Now I seem to remember that they tried a second launch on a Volna, but the second try was listed as a Falcon 1 failure.
    Their latest audio report has a brief mention of the Planetary Society LightSail rocket failure in 2005, as well as the Japanese probe that used a LightSail. I have posted it in the Dawn thread.

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    Risks and challenges

    You may have heard this before, but it bears mentioning here: space is hard. Indeed, the entire LightSail project is a proof-of-concept experiment, and there is no guaranteed outcome. Despite genius engineering and painstaking work, failure could come at various stages—at launch, at release, during radio/attitude control testing, and at sail deployment. Or, we could just be delayed in our launch—a day, a week or a month or more due to technical, weather or other scheduling issues.

    One of the great storylines in the LightSail saga is the project rising from the ashes (or in this case, the waters) like the Phoenix of Greek mythology. The Planetary Society lost our first solar sailing prototype spacecraft, Cosmos 1, in June 2005 (almost exactly 10 years ago!) when the Russian Volna rocket that was lifting it into orbit failed and went off-course, landing somewhere in the Barents Sea. The Atlas V and SpaceX Falcon Heavy rockets promise more reliable rides to the stars, but things can always take a turn because, well, space is hard.
    Thats from the Kickstart site https://www.kickstarter.com/projects...ing-spacecraft

    I've been fascinated for a while about this project. It would be great to be more involved, but at least I'll get a sweet poster out of my donation. I already picked a spot to hang it.

    All updates so far have been pretty positive, so hopefully, they got past the "space-is-hard" gremlin this time.


    TJ

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    So let's say a Block 2 SLS with a hydrogen upper stage to get it out of Earth-moon (or a Musk BFR with a non-hydrolox upper stage) but, say, 80 tons of the current material in free space. That would open up to, say, a mile or so on a side?

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    Problem - Planetary Society LightSail has been hit with a software glitch. Read all about it.

    http://www.planetary.org/blogs/jason...s-ls-test.html

    The Planetary Society’s LightSail test mission is paused while engineers wait out a suspected software glitch that has silenced the solar sailing spacecraft. Following a successful start to the mission last Wednesday, LightSail spent more than two days sending about 140 data packets back to Earth.

    But the long Memorial Day weekend here in the United States offered no respite for the LightSail team, as they scrambled to figure out why the spacecraft's automated telemetry chirps suddenly fell silent. It is now believed that a vulnerability in the software controlling the main avionics board halted spacecraft operations, leaving a reboot as the only remedy to continue the mission. When that occurs, the team will likely initiate a manual sail deployment as soon as possible.

  29. #29
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    A software glitch they seem to have been aware of, but could do nothing about. I think hoping for a cosmic ray hit for a reboot is a bit desperate... :-/

    CJSF
    "Off went his rocket at the speed of light
    Flying so fast there was no day or night
    Messing around with the fabric of time
    He knows who's guilty 'fore there's even a crime

    Davy, Davy Crockett
    The buckskin astronaut
    Davy, Davy Crockett
    There's more than we were taught"

    -They Might Be Giants, "The Ballad Of Davy Crockett (In Outer Space)"


    lonelybirder.org

  30. #30
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    Quote Originally Posted by CJSF View Post
    A software glitch they seem to have been aware of, but could do nothing about.CJSF
    It sounds like they became aware of it late in the game, and were preparing a fix (or at least a work-around) when the problem occurred.
    I wonder if they are certain an over-sized file is the problem. It sure highlights the importance of verification testing.

    Quote Originally Posted by CJSF View Post
    I think hoping for a cosmic ray hit for a reboot is a bit desperate...
    Maybe they should have included a watchdog timer. (Says the Monday-morning quarterback.)
    I may have many faults, but being wrong ain't one of them. - Jimmy Hoffa

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