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NASA Space Science

NASA Launches Micro Solar Sail 90

Posted by Soulskill from the still-working-on-micro-astronauts dept.
greyarea67 writes with news that NASA has successfully used a "microsatellite" (a term given to satellites weighing between 10kg and 100kg) to deploy a "nanosatellite" (a term given to satellites weighing between 1kg and 10kg). The deployed object, the first of six in the microsatellite's payload, was the NanoSail-D flight unit. NanoSail-D masses 4kg and is "about the size of a loaf of bread" until it deploys its solar sail. "...when the NanoSail-D sail is deployed it will use its large sail made of thin polymer material, a material much thinner than a single human hair, to significantly decrease the time to de-orbit the small satellite without the use of propellants as most traditional satellites use. The NanoSail-D flight results will help to mature this technology so it could be used on future large spacecraft missions to aid in de-orbiting space debris created by decommissioned satellites without using valuable mission propellants."
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NASA Launches Micro Solar Sail More

NASA Launches Micro Solar Sail

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  • First Pedant (Score:5, Insightful)

    by SleazyRidr ( 1563649 ) on Monday December 06, 2010 @05:28PM (#34465272)

    Someone else will probably beat me to this short bout of pedanticism questioning how micro and nano are applied in this situation (micro-ton?) and highlighting the fact that there are three orders of magnitude separating the micro and nano scale.

    • You mean like micro USB and micro SD cards?

    • Re:First Pedant (Score:4, Funny)

      by Locke2005 ( 849178 ) on Monday December 06, 2010 @05:31PM (#34465332)
      No, they are more likely to complain that going by this definition, I have a nanopenis...

      • Re: (Score:1)

        by Anonymous Coward

        Well, would you rather have a micropenis weighing between 10 and 100 kg?

      • Re: (Score:1)

        by Dabido ( 802599 )
        Oh, you bought an iCock Nano too!!!
    • It has to do with what words have been worn of their faddish potential. Micro has already been used to death, so the next is nano. It's similar to the 2G, 3G, 4G of cellphones; it's not about technical aspects, just whether the term has lost its pop.

    • Re:First Pedant (Score:4, Interesting)

      by LWATCDR ( 28044 ) on Monday December 06, 2010 @05:50PM (#34465610) Homepage Journal

      It is called a living language micro means small and nano means even smaller just as mega means big. Microcomputers where not an order of magnitude smaller then centicomputers. In fact we didn't have centicomputers or decicomputers.
      But wait you did have microprocessors and microcomputers used them so it makes sense... Nope just shifts it because we didn't have centiprocessors...
      So Microsats and Nanosats are just as valid as microcomputers, microcars, megaprojects and iPod Nanos. It is just a living language co-opting a word.
      And if that bothers too bad. I am still ticked off whenever I see organic salt for sale in a market!
      There IS NO CARBON IN TABLE SALT!!!!!!!

      • Re: (Score:1)

        by Anonymous Coward

        > It is called a living language

        But your post is trying so hard to kill it...

      • You do realize that before the micro computers there were mini computers, which in fact were smaller versions of the mainframe (the original macro computer).
        After the micro computer came the IBM PC, from there on all went down the hill.

        Oh, and I love carbon neutral salt.

        • Re: (Score:2)

          by LWATCDR ( 28044 )

          Yes I did know about Mini computers.
          Not only did you have Mini computers but you had Super minicomputers like the VAX and Maybe the DEC-10 and DEC-20 depending on who you asked.
          Then you had main frames like the IBM 360 and then you had the Super computers from CDC and Cray.
          And at one time you even had supermicrocomputers that used 32 bit cpus before they became mainstream.
          But that is kind of the point. Micro and Nano do not always mean a certain power of ten but have been used for a while as a general indic

      • Re: (Score:2)

        by Eil ( 82413 )

        I am still ticked off whenever I see organic salt for sale in a market!
        There IS NO CARBON IN TABLE SALT!!!!!!!

        Perhaps to get organic salt, they infuse the crystals with ashes from cremated unicorns?

      • Microcomputers where not an order of magnitude smaller then ...... what came before them.

        As a matter of fact, it was closer to two orders.

      • "It is called a living language..."

        The funny thing on this entire thread is that "small" and "even smaller" are the original meanings of them. The exact number we assined to them are the new language. The Romans didn't use SI prefixes.

        Yet, I can't happen being anoyed by people that use nanotechnology for things that aren't done botton up (by chemistry) or don't have a huge (nanoscale) structure. That is hipocrisy, I know.

    • Re:First Pedant (Score:4, Interesting)

      by idontgno ( 624372 ) on Monday December 06, 2010 @06:58PM (#34466626) Journal

      You do realize that unless the suffix part after micro- or nano- is an SI unit, micro- simply means "small" and "nano-" simply means "dwarf"? Only the SI framework applies a powers-of-ten interpretation of those prefixes.

      Naive examination of grade-school vocabulary bears this out. No microscope is capable of 1,000,000 x magnification. (Electron microscopes don't count. Optical microscopes existed long before, and are the canonical example.)

      Pedantry adds value when it's factually correct.

      • Naive examination of grade-school vocabulary bears this out. No microscope is capable of 1,000,000 x magnification.

        Don't forget your SI units. Optical microscope can observe details that are micrometers in size.

    • Someone else will probably beat me to this short bout of pedanticism questioning how micro and nano are applied in this situation (micro-ton?) and highlighting the fact that there are three orders of magnitude separating the micro and nano scale.

      It does make one ponder how far this terminology extends. Is 100-1000 kg a "mini satellite" and 1000-10000 kg just a "satellite"?

    • Its not pedantry, its a perfectly reasonable objection to the retarded way they name satellites.

      1U cubesats, whos mass limit was 1kg, were picosatellites - until they got more generous and said a 1U could now weight up to something like 1.3kg. Now its a nanosatellite! Woo!

  • ...why were satellites designed so that they would still remain in orbit after "death." Are there still dead satellites in orbit because of malfunction, did engineers not foresee this problem (hard to believe), or was it not feasible to include deorbit mechanisms in design?
    • i think in the beginning they probably thought the future scientists and engineers would deal with it because there was so much space relative to the number of satellites that it wasn't an issue 30-50yrs ago. now it is, and we are now the future scientists.

    • I had to dig long and hard to find the answer to this one...

      "The NanoSail-D flight results will help to mature this technology so it could be used on future large spacecraft missions to aid in de-orbiting space debris created by decommissioned satellites without using valuable mission propellants."

      It appears that it might have something to do with not wanting to waster mission propellants. My keen insight into human psychology tells me that since the satellite is dead, colliding with it is someone else's pr

      • Externalities in space are kinda hard to enforce, given there is no jurisdiction in space for any single government. For that matter, how does one go about enforcing an externality in space?

        (... in space!!)

      • If your abandoned satellite collides with someone else's working one you will pay for the damage (unless you are a government). All the private satellites have deorbit mechanisms[1] (of course nothing can be guaranteed to work for certain). Most of the junk up there belongs to governments.

        [1] From synchronous orbit they are moved to a higher "junkyard" orbit.

        • Can you cite a source for this? I don't think this is true. I have been wrong before (and often), so would appreciate seeing where you got this info.

    • We all know from Futurama that people in the 20th century didn't really think about how to efficiently deal with garbage. But fortunately there's a practical solution [youtube.com] to the problem.

    • Re:This topic begs the question... (Score:5, Informative)

      by Nyeerrmm ( 940927 ) on Monday December 06, 2010 @06:09PM (#34465820)

      It all depends on the orbit of the satellite, and the purpose of the mission.

      A low-Earth orbit satellite will naturally de-orbit due to atmospheric drag, and can be de-orbited in a controlled manner with a very low fuel cost since it just means bringing your perigee down ever so slightly so it burns up. This is good because LEO is the most crowded region you'll find, and the most likely place to encounter an accidental collision.

      However, when you start to get up middle altitudes, such as those used by GPS satellites, those things will stay up forever if you don't do anything about them. They're also a lot more expensive to de-orbit, in terms of fuel usage, and even if you do have fuel you plan to use for that, if you lose communications with the satellite you can't do anything about it anyway. Fortunately its much less crowded up there, so a collision is not a very large risk.

      Finally, geostationary orbits are interesting, because it gets a lot more crowded again. The costs of truly de-orbiting those is also extremely high, so its not done. Instead, you have what are called graveyard orbits that GEO birds are put into at their end-of-life. This works well enough, but there is an issue of what happens when you have a vehicle die before it can be moved to its graveyard orbit -- this gives you the aptly named zombie satellites that are a significant danger to geostationary spacecraft.

      So yes, satellite engineers foresee the problems, but its damned hard to design something that will behave perfectly for years and decades with no capability to go out and make physical repairs. A device to make satellites in high-orbits have the same self-deorbiting properties as LEO satellites would be quite handy.

      • Re: (Score:2)

        by blair1q ( 305137 )

        If you even bother to plan to deorbit it, you put in failsafe mechanisms to put it into deorbit mode if it loses communication for a long enough period. Of course, if it loses power to the deorbit system, then it becomes junk, so you focus on reducing the risk of that happening.

        But mostly you calculate the cost of that plus the cost of getting that part of the machine into orbit, and put that in your pocket as profit on the premise that nobody else ever had to bother so there's no reason you should.

        • Thats a scary proposition: spacecraft have weird things happen to them all the time, but most of the time you can bring them back. If a spacecraft were to de-orbit itself the first time it safed itself, or the comm system went wacky for a few days, whoever made that decision would be canned. Spacecraft are so expensive that every action is pre-meditated, and anything that has the potential to bring it down has a number of human-in-the-loop decision points. To a satellite operator, the cost of it unnecess

    • Early on they didn't worry about it. They've all had designed-in de-orbit mechanisms for quite a while now but they don't always work.

      • Re: (Score:2)

        by blair1q ( 305137 )

        Most LEOs have relied on orbital decay. GEOs rely on being parked or boosted out of the way - shich is in essence a form of deorbiting - but I've never heard of one that was designed to be removed from space entirely.

    • "Are there still dead satellites in orbit because of malfunction,..."

      Over 11000 dead satellites (or pieces thereof) are tracked by space command.

      • Over 11000 dead satellites (or pieces thereof) are tracked by space command.

        Mostly pieces, of course. It's only been about 50 years since we started putting things up there, and we haven't been averaging five satellite launches per week for the whole time.

    • Re: (Score:2)

      by blair1q ( 305137 )

      First, because it costs almost as much energy to get something out of a good orbit as it took to get it into that orbit.

      In low orbits, there's still some atmospheric molecules (billionths of an atmosphere at 400 km altitude) so you just wait for drag to bring it down. Here they're reducing the time by increasing the drag with a sail (making it more of a parachute).

      In higher orbits, that won't happen. But packing the fuel needed to cancel the orbital speed enough to make the orbit intersect the planet is c

    • This topic begs the question why were satellites designed so that they would still remain in orbit after "death."

      Generally, they're not. When large satellites reach end of life, they are either purposely deorbited, or they are boosted way above geosynchronous orbit where they can sit for centuries.

      These sails are meant for small satellites; small enough to not have any station keeping thrusters on board. They'd generally deorbit in a few months anyways, but the sail would hasten the process.
  • "about the size of a loaf of bread", "much thinner than a single human hair". How many football fields will this satellite travel? How many Statue of Liberties high will this thing orbit?
    • Oh shut up, those units are very good. When I read the summary I actually imagined the size of the satellite and the thinness of the sail. Bread and hair are ubiquitous items and they're much more useful in comparisons than measurement units (especially since this is an international site visited by people with different standards).

  • Solar Sail? I'm not sure... (Score:3)

    by RapmasterT ( 787426 ) on Monday December 06, 2010 @05:56PM (#34465670)
    Does this qualify as a "solar sail"? It seems more like it's a fractional atmosphere parachute. Solar sails are intended to interact with solar wind particles, but it would seem to be almost useless in an orbital situation, half the orbit you'd be head into the solar wind, half you'd have it at your back accellerating you. In either case, the solar wind is an exceedingly small force, which is why solar sails are proposed on the scale of square miles+. The solar wind would be dwarfed by stray atmospheric particles in earth orbit.

    This seems like they're using the term "solar sail" when they mean something completely different.
    • Actually, you can use a solar sail to accelerate yourself out of earth orbit. It's just a matter of orienting the sail parralel to the sun's radiation vector when it's head on, and perpendicular to it when it's in a position to increase your orbital velocity.

      • Actually, you can use a solar sail to accelerate yourself out of earth orbit. It's just a matter of orienting the sail parralel to the sun's radiation vector when it's head on, and perpendicular to it when it's in a position to increase your orbital velocity.

        While maybe possible in theory, it's hard to imagine it being practical. ignoring the size issue and the clutter in earth orbit, the amount of time it would take for a solar sail to escape the earth gravity well seems like it would be incredibly long.

        I've always heard solar sails proposed as the long term/low cost option for propulsion AFTER having been boosted out of the well by conventional propulsion.

        • You can get out of a circular Earth orbit with a solar sail, if you want, by altering the albedo of different parts of the sail (this is how the Japanese sail steers itself). Air particles are a larger effect than light pressure below about 1000km altitude, so NanoSail-D could never do this.

          Also, getting out of LEO this way is really, really slow, and results in you spending a long time in the van Allen belts. You can harden your electronics against this but you would avoid it if you can, hence why the Japa

        • Re: (Score:2)

          by radtea ( 464814 )

          While maybe possible in theory, it's hard to imagine it being practical. ignoring the size issue and the clutter in earth orbit, the amount of time it would take for a solar sail to escape the earth gravity well seems like it would be incredibly long.

          What you find difficult or easy to imagine is not an arbiter of reality. It has zero epistemic value, and it's a little weird you would bring it up.

          I find it hard to imagine anyone would be dumb enough to engage in a war of choice in Iraq, but one demonstrably exists. I find it hard to imagine that people think what they find hard or easy to imagine has any bearing whatsoever on what is real, but clearly lots of people think that.

          Science has been transforming the world for three hundred years, and is base

    • Actually, if the object is in low Earth orbit, it wouldn't be encountering very much solar wind regardless of whether the satellite is in Earth's shadow or not. The planet's magnetic field deflects most of the solar wind away at an altitude far above the orbits of most satellites.

      Even so, your point is valid; this is not, by any definition, a solar sail. It is a parachute.

    • While you will get a balanced force for a sail that is normal to the sun, once you move it slightly off normal, and account for shadow periods, you'll get an unbalanced force that will have a deterministic secular effect on the orbit. And it will be non-normal unless you're actively maintaining the attitude.

      Also, the sail is definitely not small. Its 100 square feet for a tiny satellite. Obviously if you wanted to use one as a failsafe mechanism for a large GEO comm bird you'd need something larger.

      • While you will get a balanced force for a sail that is normal to the sun, once you move it slightly off normal, and account for shadow periods, you'll get an unbalanced force that will have a deterministic secular effect on the orbit. And it will be non-normal unless you're actively maintaining the attitude.

        All of which would be swamped by the effects of atmospheric drag. This thing is a parachute, not a solar sail.

        • Depends on your altitude and attitude. In this orbit, yes, atmospheric drag is going to have a stronger effect, but in higher orbits, the solar effects could be effective for a well-designed system to facilitate disposal. I may try and look at that later if I have some free time (I'm actually doing simulations of spacecraft atmospheric passes right now...).

          But I agree at this altitude the sail is deployed to enhance atmospheric drag and is mischaracterized by the summary as a solar sail. TFA says nothing

          • TFA says nothing about it being a solar sail.

            actually, TFA uses exactly the term "Solar sail" to describe this project.

            In their defense, there seems to be three distinct goals for this project that have been combined into a single experiment, and then reported on badly.

            One project is the ejecting of the pico-satellite from the micro-satellite.
            Another is testing the deployment process for the "solar sail".
            lastly, there's testing the hypothesis of increasing drag on to reduce oribital decay time.

            Add one sloppy bit of science reporting, mix

          • Solar winds are deflected by the Earth's magnetic field at a distance of roughly 60,000km. In contrast, the orbits of geostationary satellites are only 35,000 km.

            • Correct me if I'm wrong but most of the force from a solar sail is from reflectance of photons, not solar wind particles, thus why understanding the reflectivity of your surfaces is critical to understanding solar radiation pressure effects.

              I dont think in most cases you even bother to consider the solar wind as far as trajectory analysis goes (obviously its more important for electronic protection).

              • No, I'm the one who's wrong here. As you say, solar sails work from radiation pressure, not solar wind. It's a common (and understandable) mistake made by about half the websites that talk about solar sails. (Although, if light can push a sail around, I think stream of particles

                The radiation pressure on a ten foot square works out to 8.5*10^-5 newtons. In comparison, the atmospheric drag on the shuttle was 0.4 newtons. Assuming this satellite has a tenth of the surface area of the shuttle, the drag wou
    • I agree. It seems atmospheric drag would have a far greater affect than solar winds and or light.
    • No, in this particular mission it isn't really being used as a solar sail at all. The material used for the sail is, in fact, what a solar sail would be/will be made out of. The idea of this mission is to demo the structural properties of the material so that there is some scientific data on hand that can be used for reference when designing future missions. This particular bird is, as you are saying, simply using solar sail material to act as an atmospheric parachute to induce drag. Ideally, after this mis

  • Wrong way, Silly! (Score:5, Interesting)

    by Bruce Perens ( 3872 ) <bruce@perens.com> on Monday December 06, 2010 @06:12PM (#34465850) Homepage Journal

    OK, it might be easier to test a solar sail by de-orbiting something faster, and it's important to not contribute further to orbital debris. But the interesting direction is UP! Get the thing from low-orbit to a higher orbit with the solar sail, like the Japanese have started to do with the IKAROS [wikipedia.org] satellite. Can we get from LEO to geostationary with a solar sail? Can we use it to maintain an orbit without propellant? That means less mass for delta-V to lift out of the atmosphere, and thus less cost but maybe a long time to achieve the final orbit.

    • Re: (Score:1)

      by Anonymous Coward

      IKAROS isn't a satellite in a higher orbit, IKAROS is a solar sail craft flying to venus. With the success of IKAROS (largely a technology demonstrator rather than a scientific mission), JAXA next plans a solar sail mission to Jupiter with a scientific payload.

    • Re: (Score:2)

      by blair1q ( 305137 )

      Force is force, so if the sail generates a force it can add energy to the system and raise the orbit. Angle the sail right at each point in the orbit and you can get the tangential force needed to spiral outward without going elliptical.

      But your cost argument breaks down in the time value of money. Just the waiting is expensive, but the risk of failure during the waiting may be more expensive. Best to pick a launch window that gets you through known regions of empty orbital space and to your orbit as exp

      • Re: (Score:2)

        by blair1q ( 305137 )

        Oh, and what's cooler is that it doesn't even take reaction mass to control attitude. IKAROS uses an array of LCDs [wikipedia.org] around the edges of the sail to create torque.

        Man, I want one of those for xmas.

        • Maybe I missed something here, but isn't there a Space Station still in orbit? Wouldn't building a "Solar Sail Tug" be a little more useful? Have the tug retrieve the satellite and use the Space Station as a "All 'Night' Garage". The parts and salvage value of the metal alone would make some return on value. One could even sell the photos to Wikileaks,(ouch). Maybe get more than one use out of a multi million/billion dollar paper weight.

          • Re: (Score:2)

            by blair1q ( 305137 )

            That's what the Russians are doing (I posted a link up yonder; if you don't find it, google for "russian space junk nuclear $2 billion" and you'll see recent stories).

            They'll put up a drone with a nuclear-powered ion drive that will move things from their current orbit to one that's less threatening. Most likely that means making the transition from a given GEO slot to one of the natural junk-magnet orbits more expeditious and certain than it is now.

            Actually deorbiting something to burn up in the atmospher

      • Well, it seems that atmospheric drag might be the dominant force in LEO. So, this isn't necessarily a solar sail when used to deorbit a satellite.
    • What you want is a way to get SOMETHING to slow down. You can get that by getting something ELSE to speed up. Find two satellites you want to toss, connect with a tether cable, spin them up, cast one forward in orbit and the other backward. Presto, the backward one de-orbits, the other may attain escape and go elsewhere (lots of choices). Cost? only the cost of rotational energy - a tiny amount compared to anything else, can be got from a solar panel. (No propellent cost at all).
    • That is very probably stage II of this project (not this mission). Once the deployment mechanisms and actual sail material are tested on orbit (which is what this mission is doing, neither of these pieces of hardware have been flown before), then they will be implemented on increasingly more complex missions and satellites until they are as ubiquitous as reaction wheel systems and bang-bang thrusters. However, researching and developing a fundamentally new technology for on-orbit use takes time...even decad
  • Hopefully the micro solar sail will give us enough power until Kirk returns with some humpbacks.

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