back to article No sail: NASA spikes Sunjammer

Reports are emerging that NASA has decided not to go ahead with next year's Sunjammer mission, which was to demonstrate the use of “solar sail” propulsion. The project has attracted US$21 million of NASA cash under a contract awarded in 2011 to Californian company L'Garde. The agency's interest had been piqued by vacuum …

  1. Graham Marsden
    Happy

    One for...

    ... El Reg's Special Projects Bureau?

    1. Marcus Aurelius
      Happy

      Re: One for...

      What could we name this one?

      1. Ian Michael Gumby
        Thumb Up

        Re: One for...

        "What could we name this one?"

        Why the 'Flying Dutchman' of course.

        Considering that you have a relatively limitless supply of solar wind from the sun, it could sail forever...

        (Which is the life of the craft. )

        I guess the first step would be to write computer sailing programs. Where you enter your destination and let the computer plot the course tracking your GPS, wind speed and direction, etc ...

        Could be fun.

  2. Mage Silver badge

    Awww

    What a pity no suitable spacecraft partner,

  3. batfastad

    No propulsion?

    No propulsion? Surely there would need to be some sort of thrusters to correct its trajectory within space?

    Otherwise once it picks up some decent speed it's going to be slingshotting unpredictably around the galaxy using gravity of the nearest stars/planets. Sounds like a prototype for an Infinite Improbability Drive to me!

    1. Destroy All Monsters Silver badge
      Windows

      Re: No propulsion?

      If you are designing it right, you can orient the sail to get an orientable thrust vector, for the rest you can design your orbits correctly or do chaotic-based orbit transfers for maximum coolness.

      Solar sailing has been in the "planning stages" since the mid-70s at least, with nice images by Vincent DiFate or whomever; there were even plans to have a comet-rendezvous mission use this .... now it's 2014 and it's still marked "cancelled". NASA ... just another gummint outfit.

    2. Voland's right hand Silver badge

      Re: No propulsion?

      Ever sailed a boat?

      With a correct sail design or correct payload attachment design you can make it do whatever you like. In fact, in space all you need is a moveable payload attachment design where you move the payload relative to the sail in order to adjust the centre of gravity. Designs like these do not require any thrusters except for emergencies. All they need is an energy source and a couple of rails to move the payload along. The design of solar carrier is de-coupled from the payload so you can carry nearly anything (the solar sail assembly becomes a solar "tugboat").

      1. Richard Ball

        Re: No propulsion?

        I haven't sailed a boat, but I do know its keel is about as important as its sail. If you can come up with a space-keel, like a knife that slips through the butter of space, then yes it's like sailing a boat.

        Boats work by exploiting the interface between two fluids that are flowing relative to one another. They have a 'foil' that interacts with each fluid and the resultant force pushes them where they want to go.

        In the absence of that keel it is more like being a plastic bag carried along with no control in the current under the surface of the water. Where the currenty water is the solar wind.

        1. Chris Miller

          Re: No propulsion?

          I was going to say much the same thing, Richard, but I don't think you've got it quite right. The keel allows a boat to sail into the wind, but a solar sail can only change its angle to the two forces that act on it - sunlight and the solar wind (usually, but not always, aligned, which is why comets sometimes show two 'tails'). There's also the force of gravity acting in the opposite direction, so (if you can furl the sail or orient it perpendicular to the flow) you can get a fair degree of freedom of movement.

          1. Destroy All Monsters Silver badge

            Re: No propulsion?

            On the other hand, I don't think the sail is supposed to interact with the solar wind. Except in the negative sense, you don't want it to pick up nasty charges.

            1. Chris Miller

              Re: No propulsion?

              I'm not sure how you'd stop the sail interacting with the solar wind. In most of the inner solar system, it dominates the effect of sunlight.

              1. Destroy All Monsters Silver badge
                Headmaster

                Re: No propulsion?

                LOLNO

                With all that comes from Jimbopedia:

                Solar Wind:

                "The wind exerts a pressure at 1 AU typically in the range of 1–6 nPa, although it can readily vary outside that range."

                Light Pressure:

                perfect absorbance: F = 4.54 μPa

                perfect reflectance: F = 9.08 μPa (normal to surface)

                That's three order of magnitude difference, advantage light sail.

                Anyway you need a special kind of sail (actually: a set of wires) for the solar wind: Electric solar wind sail

          2. Richard Ball

            Re: No propulsion?

            Fair enough Chris

          3. cray74

            Re: No propulsion?

            Solar sails are mirrors and get thrust from both the light pressure hitting them and the sunlight reflecting away from them, allowing them to maneuver in fashions completely unlike wind sails. That allows some useful maneuvers other than "running straight away from the sun." For example, you can tilt the solar sail with respect to the sun so that the reflected sunlight produces thrust in a direction tangential to an orbit.

            http://en.wikipedia.org/wiki/Solar_sail#Physical_principles

            Solar sail principles have been used successfully several times with spacecraft. The IKAROS probe is the stand-out success, having buzzed Venus and using a sail with integrated solar panels and LCD panels that act trim tabs (clever design). Mariner 10 and Messenger used light pressure for attitude control during their flights to Mercury. Hayabusa used light pressure for improvised attitude control after reaction wheel failures. The Planetary Society keeps valiantly attempting to launch sail probes. And there's been a few others.

  4. Anonymous Coward
    Anonymous Coward

    Damn!!

    Bloody spoilsports! I'd just got my 12 year old niece really into this idea; we had a very long chat about it last week and it got her asking all sorts of pertinent questions. She was trying to harangue her science teacher onto having the idea as a class project, and nothing helps to spur them on like a live project.

  5. Pen-y-gors

    Spacecraft partner?

    At least NASA want all the work that's been done so far, so it's not a total loss. Time to call in SpaceX and see if they have a bit of spare capacity?

  6. Neil Barnes Silver badge

    Rumours are untrue

    that scientists have detected an anomalously bright object in the outer solar system, decelerating from 0.7C. It's also untrue that the object has the same spectrum as the sun, but blue-shifted...

    1. Craig McGill 1
      Alien

      Re: Rumours are untrue

      OK, it's from a book but what one?

      1. Neil Barnes Silver badge

        Re: Rumours are untrue

        The Mote in God's Eye. Niven and Pournelle.

        Fyunch(click).

        (Also, I think I meant 0.7%C)

        1. Destroy All Monsters Silver badge

          Re: Rumours are untrue

          Unfortunately we have no orion-tier spacecraft ready for an intercept.

          ADIOS, MOTIES!

        2. Ian Michael Gumby

          Re: Rumours are untrue

          I thought it was the Pak ?

          That would be the Protector.

          Which is also a character in the Ringworld books.

          1. Destroy All Monsters Silver badge
            Alien

            Re: Rumours are untrue

            No, the Pak come with their own fusion engine (plus stack of edible roots and inbuilt instinct for xenocide and genetic purification)

            Ayyy lamo icon, of course.

            1. Neil Barnes Silver badge

              Re: Rumours are untrue

              Definitely Moties. Pak come in sneaky and then kill you if you don't smell right; Moties are oh-so-friendly and then outbreed you.

              1. Ian Michael Gumby

                Re: Rumours are untrue

                Heh!

                Its been 15+ years since I read any of his stuff.

                And yes, I am down to my last living brain cell and he wants to go on vacation.

        3. Ian Michael Gumby

          Re: Rumours are untrue

          I believe that it meant 7/10th the speed of light.

          But I'm going from memory.

    2. Alistair
      Coat

      Re: Rumours are untrue

      On the gripping hand, however, we do have a few observational craft floating around out there. One might be available to give it a closer look.

      (mine's the one with the motie coffee pot in the pocket)

  7. Colin 4
    Happy

    Planetary Society

    They're working on this too, smaller scale though and they have to wait for a lift ... http://www.planetary.org/explore/projects/lightsail-solar-sailing/

  8. Anonymous Coward
    Anonymous Coward

    Erm... what about braking?

    So you can accelerate to enormous speeds, then once it reaches that speed, how do you stop it? Unless you want to have a very fast object traveling space forever, of course.

    1. Neil Barnes Silver badge

      Re: Erm... what about braking?

      All you have to do is dive straight at a star. The nearer you are, the better the braking gets.

      Of course, you have to pick the right sized star...

  9. Frosted Flake

    Professor Bhattacharya and his team at the University of Michigan have invented a new form of LASER that emits polaritons instead of light. Polaritons are a novel form of matter, not light, not electrons, but both. Polaritons have mass. That means the Polarition beam is a rocket as well as a laser.

    The kicker is, it's electric. A solar panel or Nuclear Thermogenerator will power one indefinitely.

    Screw the Solar Sail. Give me a Polariton Beam. Then we need never decommission a Satellite because of fuel, ever again.

    1. Brandon 2

      You say propulsion, I say weapon... potato, po-tah-toe...

  10. Alistair
    Boffin

    @Brandon

    more like you say flamethrower I say rocket engine.

  11. druck Silver badge
    WTF?

    How big?

    The plan was to create a sail that would weigh just 110 pounds (around 50 kg) and furl to “the size of a dishwasher”. When deployed, the 0.005 mm thick sail...

    What the hell is it made of to be so thin, but have such a large mass? Either it includes the sails support structure (massively hefty for such a small thrust), or it unfurls to quite a bit bigger than a dish washer.

    1. Colin 4

      Re: How big?

      It FURLS to the size of a dishwasher.

      It UNfurls to 1200 square metres, or a square nearly 35 metres on a side ...

      Presumably the mass figure includes the furling/unfurling mechanism, attitude thrusters, comms equipment, etc etc

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