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LightSail Test Mission Declared Success; First Image Complete

300 points by gokhan 11y ago

mod 11y ago
Does anyone know the actual purpose of the LightSail? The article doesn't seem to mention it, just the details of this successful mission.
- jameskilton 11y ago
  It's an experiment to build a spacecraft that sails through space powered by solar winds.
  - tedsanders 11y ago
    Actually, solar wind carries about 1,000 times less momentum than sunlight itself: http://en.wikipedia.org/wiki/Solar_sail#Solar_radiation_pressure http://en.wikipedia.org/wiki/Solar_sail#Solar_radiation_pres... Solar sails mostly capture the momentum of sunlight, not the solar wind. (Solar wind is the plasma of electrons, protons (hydrogen nuclei), and alpha particles (helium nuclei) that come off the sun.)
- devindotcom 11y ago
  They're testing a solar sail concept with the idea of using it as an ultra-lightweight way to move around the solar system. It's been theorized for decades and this is the first attempt to actually put it up there in space. Lots more info here: http://sail.planetary.org/ http://sail.planetary.org/ edit: as others point out, this isn't quite the first time. but it is the first time in a long time!
  - mod 11y ago
    Sweet! So this doesn't validate the theory, correct? (Is it actually validated yet?) Is this a viable method for long-distance traveling? Is it limited in direction (like the photons only push one way, and it's not like you can use a rudder in space, right?)
    - ceejayoz 11y ago
      The theory is already validated (Mariner 10 used solar pressure for attitude control in the 1970s, and a Japanese mission successfully tested a solar sail in 2010 - http://en.wikipedia.org/wiki/IKAROS http://en.wikipedia.org/wiki/IKAROS - and it can be demonstrated in an Earthbound laboratory too). Yes, it's viable. http://en.wikipedia.org/wiki/Solar_sail http://en.wikipedia.org/wiki/Solar_sail
    - jadell 11y ago
      It's not necessarily one way. Think of it like a sailboat: wind blows in one direction (at a time) but you can still steer, change direction, speed up, slow down, etc. just by changing the angle of your sail and how tense or slack it is. You can even travel against the direction of the wind. This is the same concept - a sail in wind - except the wind is solar wind: a stream of photons. The difference being that in sailing, the resistance of the water plays a part. For solar sails, you can't do as many complicated maneuvers as with sailing on water, but you can still make adjustments beyond juts being pushed in a single direction.
      - tedsanders 11y ago
        Just to clarify: Unlike a regular sailboat, you cannot sail against the wind with a solar sail. In space, there is no water equivalent to push off of.
        SoftwareMaven 11y ago
        On the other hand, you have a constant accelleration towards the sun, so you can use parabolic orbits to move sunward (at least, until you reach Voyager I).
        knodi123 11y ago
        acceleration can't move towards the sun, but you can build up some velocity with this, and then use a slingshot to head back to the sun. not very general-purpose, but sound in principal.
  - david-given 11y ago
    First attempt? http://www.isas.jaxa.jp/e/enterp/missions/ikaros/index.shtml http://www.isas.jaxa.jp/e/enterp/missions/ikaros/index.shtml IKAROS, launched by JAXA in 2010, passed Venus six months later in is still accelerating (slowly; it's getting about 1mN of thrust). It's even steerable, by using LCD panels in the sails to change the albedo. It was last contacted early this year. IKAROS' sail is 20m diagonal, which makes it considerably larger than LightSail1. There are even pictures of it --- it ejected a camera after deployment. http://www.space.com/25800-ikaros-solar-sail.html http://www.space.com/25800-ikaros-solar-sail.html
    - devindotcom 11y ago
      totally forgot about ikaros. you're completely right, of course. Lightsail is a smaller, cheaper, privately (and crowd) funded solar sail project.
      - fapjacks 11y ago
        How long ago was Ikaros designed? I've been a member of the Planetary Society since I was a child and this has been talked about since at least the early 90s, iirc. This has been a major goal of the Planetary Society for years and years and years, finally overcoming the setbacks with a successful crowdfund. I don't doubt Ikaros may have been conceived much earlier, considering how spacecraft design takes time.
- TheLoneWolfling 11y ago
  It's a solar sail, or rather a test thereof. Long story short, photons (and solar wind) impart a small amount of momentum on the sail. This can be used instead of rockets - as long as you don't mind it taking an absurd amount of time to get you anywhere, that is. And its a whole lot lighter.
  - fixermark 11y ago
    An absurd amount of time can be a workable tradeoff depending on the purpose of the mission. Historically, both thrust and delta-V have been sorely constrained on spacecraft. This is trading a lot of thrust for an infinite* amount of dV, which is a really valuable trade. (*Practically infinite. It runs out when the sun stops giving solar pressure ;) ).
    - TheLoneWolfling 11y ago
      I am well aware of the potential advantages of solar sails for many things. I'm just saying they aren't the be-all and end-all. There are many things where they aren't particularly useful (for instance: anything time-constrained. Or anything that requires largeish maneuvers to be done in the outer solar system. And there are certain maneuvers that are... difficult... with a solar sail.) Also, it's not infinite, nowhere near. Among other things, solar radiation and solar wind will degrade the sail over time. Especially with a lot of the materials they suggest using (mylar, etc.)
  - IndianAstronaut 11y ago
    It's mainly targeted at cube sats, which are very small satellites with usually one specific task or purpose. This could open up space even more to smaller teams of scientists. It is not meant to carry men to Mars.
    - TheLoneWolfling 11y ago
      I am surprised at it being targeted at cube sats. There's enough atmosphere in LEO that I am surprised that it's a net positive, frankly. I mean: the ISS requires a reboost every few months.
devindotcom 11y ago
Love this. I'm happy to say I just talked to Bill Nye on Friday (LS was still AWOL) about this and a recent science competition for kids and I love his enthusiasm for everything. He thinks of it as carrying on work that Carl Sagan started. Just gonna hijack this thread to share a couple quotes from my notes that didn't make it into my article[1], since you guys might appreciate them: "for me it's [lightsail is] really personal. i had carl sagan for one class, and it changed my life. and so i'm really excited to get this thing working. if not this mission, the next mission. oh god, the concept is just cool, to just be sailing around the solar system essentially for free. It's elegant." "there are two questions we all ask, and if you meet somebody who claims they've never asked these questions they're lying and that's all there is to it: where did we come from and are we alone in the universe? if you want to answer those questions, you have to look at the past and the future. You have to look at paleontological evidence, and you have to explore space." "talk to younger people. they expect great things from technology. that expectation i believe will carry over to every aspect of life - that we can do technological things to prevent climate change. that for any problem there's a technological solution." "this is what we talk about all the time in science ed. we want science every day in every grade. this is obvious to me and my colleagues in science ed. what's amazing is it's not amazing to everybody. science is as important a topic as writing and reading and arithmetic. if you want to have innovation, if you want to have the engineers of tomorrow, you have to have science." "kids have no trouble understanding climate change - it's grown-ups that are confused. climate change denial is almost entirely a generational issue." [1] http://www.nbcnews.com/science/science-news/bill-nye-boosts-future-science-guys-girls-kids-are-natural-n370706 http://www.nbcnews.com/science/science-news/bill-nye-boosts-...
- deleted 11y ago
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- monk_e_boy 11y ago
  "climate change denial is almost entirely a generational issue" ... I do wonder if this is a US thing. I've not seen a denier over here in the UK. Sure, on the TV they have debates about climate change with scientists. They argue and present data and talk about change. They may argue about the rate of change and the potential effects. But everyone agrees that change is happening. Just take a look at the G7 fossil fuel pledge by the Germans. That's pressure from everyday people over here in Europe, that's millions of us who understand.
magicmu 11y ago
This is absolutely amazing!! Pardon my ignorance, but how does this compare to ion thrust? Unless that's still theoretical, that is -- this seems like an even more elegant solution that ion thrusters.
- jameshart 11y ago
  Ion propulsion is not purely theoretical - the Dawn mission currently entering orbit around Ceres got there under ion propulsion, having previously rendezvoused with Vesta.
  - magicmu 11y ago
    Wow! Thanks for the info, looks like I've got some reading to do.
- mcv 11y ago
  Ion thrust of course has the advantage that it keeps working if you get farther away from the sun. But for the inner solar system, light sails are very promising.
tomphoolery 11y ago
"Mirab, his sails unfurled!"
- aaronharnly 11y ago
  So this comment is not a substantive engagement with the topic of the article; instead, a reference to a familiar (to a nerdy in-group) pop culture touchpoint.[1] As such, it is more of an /r/ comment than an HN comment. Nevertheless, it made me happy to read it, and I welcome it :-) (One could note the pleasing irony of the comment itself being an instance of the type of communication-by-reference-to-shared-myth that occurs in the episode. However, since its contribution to this conversation is not about that mode of communication, it's ultimately a distraction .) [1] http://www.theatlantic.com/entertainment/archive/2014/06/star-trek-tng-and-the-limits-of-language-shaka-when-the-walls-fell/372107/ http://www.theatlantic.com/entertainment/archive/2014/06/sta...
  - deleted 11y ago
    [deleted]
  - TeMPOraL 11y ago
    > As such, it is more of an /r/ comment than an HN comment. The river Temarc in winter. Kiteo, his eyes closed. ;). Honestly, this "familiar pop culture touchpoint" inspired a big part of a generation of scientists and engineers. As someone who thinks it has a significant impact on his life, I too appreciated the comment :).
  - SomeStupidPoint 11y ago
    A good example of a comment that adds nothing to the conversation would be saying the following in response to you: > Picard, his head in hand. [1] > [1] http://i.imgur.com/iWKad22.jpg http://i.imgur.com/iWKad22.jpg (Also, a second example of the communication-by-shared-myth idea, made more interesting by the evolution of what the images usage in culture.)
kolev 11y ago
Let's give it one last push! A bit more than 2 weeks and $150K to go: https://www.kickstarter.com/projects/theplanetarysociety/lightsail-a-revolutionary-solar-sailing-spacecraft https://www.kickstarter.com/projects/theplanetarysociety/lig...
Adam_O 11y ago
Minor side note for the audio-curious.. Neil DeGrasse Tyson's podcast had an episode recently where Bill Nye talked all about the LightSail.. https://soundcloud.com/startalk/cosmic-queries-lightsail-with-bill-nye https://soundcloud.com/startalk/cosmic-queries-lightsail-wit...
aswanson 11y ago
Am I the only one who thought, on first read, Danifong pivoted to space imaging?:https://news.ycombinator.com/user?id=DaniFong https://news.ycombinator.com/user?id=DaniFong
- DaniFong 11y ago
  Thanks for the H/T. ;-) We're fans of the project too
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300 points by gokhan 11y ago

mod 11y ago

Does anyone know the actual purpose of the LightSail? The article doesn't seem to mention it, just the details of this successful mission.

jameskilton 11y ago
It's an experiment to build a spacecraft that sails through space powered by solar winds.
- tedsanders 11y ago
  Actually, solar wind carries about 1,000 times less momentum than sunlight itself: http://en.wikipedia.org/wiki/Solar_sail#Solar_radiation_pressure http://en.wikipedia.org/wiki/Solar_sail#Solar_radiation_pres... Solar sails mostly capture the momentum of sunlight, not the solar wind. (Solar wind is the plasma of electrons, protons (hydrogen nuclei), and alpha particles (helium nuclei) that come off the sun.)
devindotcom 11y ago
They're testing a solar sail concept with the idea of using it as an ultra-lightweight way to move around the solar system. It's been theorized for decades and this is the first attempt to actually put it up there in space. Lots more info here: http://sail.planetary.org/ http://sail.planetary.org/ edit: as others point out, this isn't quite the first time. but it is the first time in a long time!
- mod 11y ago
  Sweet! So this doesn't validate the theory, correct? (Is it actually validated yet?) Is this a viable method for long-distance traveling? Is it limited in direction (like the photons only push one way, and it's not like you can use a rudder in space, right?)
  - ceejayoz 11y ago
    The theory is already validated (Mariner 10 used solar pressure for attitude control in the 1970s, and a Japanese mission successfully tested a solar sail in 2010 - http://en.wikipedia.org/wiki/IKAROS http://en.wikipedia.org/wiki/IKAROS - and it can be demonstrated in an Earthbound laboratory too). Yes, it's viable. http://en.wikipedia.org/wiki/Solar_sail http://en.wikipedia.org/wiki/Solar_sail
  - jadell 11y ago
    It's not necessarily one way. Think of it like a sailboat: wind blows in one direction (at a time) but you can still steer, change direction, speed up, slow down, etc. just by changing the angle of your sail and how tense or slack it is. You can even travel against the direction of the wind. This is the same concept - a sail in wind - except the wind is solar wind: a stream of photons. The difference being that in sailing, the resistance of the water plays a part. For solar sails, you can't do as many complicated maneuvers as with sailing on water, but you can still make adjustments beyond juts being pushed in a single direction.
    - tedsanders 11y ago
      Just to clarify: Unlike a regular sailboat, you cannot sail against the wind with a solar sail. In space, there is no water equivalent to push off of.
      - SoftwareMaven 11y ago
        On the other hand, you have a constant accelleration towards the sun, so you can use parabolic orbits to move sunward (at least, until you reach Voyager I).
      - knodi123 11y ago
        acceleration can't move towards the sun, but you can build up some velocity with this, and then use a slingshot to head back to the sun. not very general-purpose, but sound in principal.
- david-given 11y ago
  First attempt? http://www.isas.jaxa.jp/e/enterp/missions/ikaros/index.shtml http://www.isas.jaxa.jp/e/enterp/missions/ikaros/index.shtml IKAROS, launched by JAXA in 2010, passed Venus six months later in is still accelerating (slowly; it's getting about 1mN of thrust). It's even steerable, by using LCD panels in the sails to change the albedo. It was last contacted early this year. IKAROS' sail is 20m diagonal, which makes it considerably larger than LightSail1. There are even pictures of it --- it ejected a camera after deployment. http://www.space.com/25800-ikaros-solar-sail.html http://www.space.com/25800-ikaros-solar-sail.html
  - devindotcom 11y ago
    totally forgot about ikaros. you're completely right, of course. Lightsail is a smaller, cheaper, privately (and crowd) funded solar sail project.
    - fapjacks 11y ago
      How long ago was Ikaros designed? I've been a member of the Planetary Society since I was a child and this has been talked about since at least the early 90s, iirc. This has been a major goal of the Planetary Society for years and years and years, finally overcoming the setbacks with a successful crowdfund. I don't doubt Ikaros may have been conceived much earlier, considering how spacecraft design takes time.
TheLoneWolfling 11y ago
It's a solar sail, or rather a test thereof. Long story short, photons (and solar wind) impart a small amount of momentum on the sail. This can be used instead of rockets - as long as you don't mind it taking an absurd amount of time to get you anywhere, that is. And its a whole lot lighter.
- fixermark 11y ago
  An absurd amount of time can be a workable tradeoff depending on the purpose of the mission. Historically, both thrust and delta-V have been sorely constrained on spacecraft. This is trading a lot of thrust for an infinite* amount of dV, which is a really valuable trade. (*Practically infinite. It runs out when the sun stops giving solar pressure ;) ).
  - TheLoneWolfling 11y ago
    I am well aware of the potential advantages of solar sails for many things. I'm just saying they aren't the be-all and end-all. There are many things where they aren't particularly useful (for instance: anything time-constrained. Or anything that requires largeish maneuvers to be done in the outer solar system. And there are certain maneuvers that are... difficult... with a solar sail.) Also, it's not infinite, nowhere near. Among other things, solar radiation and solar wind will degrade the sail over time. Especially with a lot of the materials they suggest using (mylar, etc.)
- IndianAstronaut 11y ago
  It's mainly targeted at cube sats, which are very small satellites with usually one specific task or purpose. This could open up space even more to smaller teams of scientists. It is not meant to carry men to Mars.
  - TheLoneWolfling 11y ago
    I am surprised at it being targeted at cube sats. There's enough atmosphere in LEO that I am surprised that it's a net positive, frankly. I mean: the ISS requires a reboost every few months.

devindotcom 11y ago

Love this. I'm happy to say I just talked to Bill Nye on Friday (LS was still AWOL) about this and a recent science competition for kids and I love his enthusiasm for everything. He thinks of it as carrying on work that Carl Sagan started. Just gonna hijack this thread to share a couple quotes from my notes that didn't make it into my article[1], since you guys might appreciate them: "for me it's [lightsail is] really personal. i had carl sagan for one class, and it changed my life. and so i'm really excited to get this thing working. if not this mission, the next mission. oh god, the concept is just cool, to just be sailing around the solar system essentially for free. It's elegant." "there are two questions we all ask, and if you meet somebody who claims they've never asked these questions they're lying and that's all there is to it: where did we come from and are we alone in the universe? if you want to answer those questions, you have to look at the past and the future. You have to look at paleontological evidence, and you have to explore space." "talk to younger people. they expect great things from technology. that expectation i believe will carry over to every aspect of life - that we can do technological things to prevent climate change. that for any problem there's a technological solution." "this is what we talk about all the time in science ed. we want science every day in every grade. this is obvious to me and my colleagues in science ed. what's amazing is it's not amazing to everybody. science is as important a topic as writing and reading and arithmetic. if you want to have innovation, if you want to have the engineers of tomorrow, you have to have science." "kids have no trouble understanding climate change - it's grown-ups that are confused. climate change denial is almost entirely a generational issue." [1] http://www.nbcnews.com/science/science-news/bill-nye-boosts-future-science-guys-girls-kids-are-natural-n370706 http://www.nbcnews.com/science/science-news/bill-nye-boosts-...

deleted 11y ago
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monk_e_boy 11y ago
"climate change denial is almost entirely a generational issue" ... I do wonder if this is a US thing. I've not seen a denier over here in the UK. Sure, on the TV they have debates about climate change with scientists. They argue and present data and talk about change. They may argue about the rate of change and the potential effects. But everyone agrees that change is happening. Just take a look at the G7 fossil fuel pledge by the Germans. That's pressure from everyday people over here in Europe, that's millions of us who understand.

magicmu 11y ago

This is absolutely amazing!! Pardon my ignorance, but how does this compare to ion thrust? Unless that's still theoretical, that is -- this seems like an even more elegant solution that ion thrusters.

jameshart 11y ago
Ion propulsion is not purely theoretical - the Dawn mission currently entering orbit around Ceres got there under ion propulsion, having previously rendezvoused with Vesta.
- magicmu 11y ago
  Wow! Thanks for the info, looks like I've got some reading to do.
mcv 11y ago
Ion thrust of course has the advantage that it keeps working if you get farther away from the sun. But for the inner solar system, light sails are very promising.

tomphoolery 11y ago

"Mirab, his sails unfurled!"

aaronharnly 11y ago
So this comment is not a substantive engagement with the topic of the article; instead, a reference to a familiar (to a nerdy in-group) pop culture touchpoint.[1] As such, it is more of an /r/ comment than an HN comment. Nevertheless, it made me happy to read it, and I welcome it :-) (One could note the pleasing irony of the comment itself being an instance of the type of communication-by-reference-to-shared-myth that occurs in the episode. However, since its contribution to this conversation is not about that mode of communication, it's ultimately a distraction .) [1] http://www.theatlantic.com/entertainment/archive/2014/06/star-trek-tng-and-the-limits-of-language-shaka-when-the-walls-fell/372107/ http://www.theatlantic.com/entertainment/archive/2014/06/sta...
- deleted 11y ago
  [deleted]
- TeMPOraL 11y ago
  > As such, it is more of an /r/ comment than an HN comment. The river Temarc in winter. Kiteo, his eyes closed. ;). Honestly, this "familiar pop culture touchpoint" inspired a big part of a generation of scientists and engineers. As someone who thinks it has a significant impact on his life, I too appreciated the comment :).
- SomeStupidPoint 11y ago
  A good example of a comment that adds nothing to the conversation would be saying the following in response to you: > Picard, his head in hand. [1] > [1] http://i.imgur.com/iWKad22.jpg http://i.imgur.com/iWKad22.jpg (Also, a second example of the communication-by-shared-myth idea, made more interesting by the evolution of what the images usage in culture.)

kolev 11y ago

Let's give it one last push! A bit more than 2 weeks and $150K to go: https://www.kickstarter.com/projects/theplanetarysociety/lightsail-a-revolutionary-solar-sailing-spacecraft https://www.kickstarter.com/projects/theplanetarysociety/lig...

Adam_O 11y ago

Minor side note for the audio-curious.. Neil DeGrasse Tyson's podcast had an episode recently where Bill Nye talked all about the LightSail.. https://soundcloud.com/startalk/cosmic-queries-lightsail-with-bill-nye https://soundcloud.com/startalk/cosmic-queries-lightsail-wit...

aswanson 11y ago

Am I the only one who thought, on first read, Danifong pivoted to space imaging?:https://news.ycombinator.com/user?id=DaniFong https://news.ycombinator.com/user?id=DaniFong

DaniFong 11y ago
Thanks for the H/T. ;-) We're fans of the project too

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