NASA To Demonstrate Largest-Ever Solar Sail in Space

Zothecula writes "NASA's upcoming Technology Demonstration Missions are intended to 'transform its space communications, deep space navigation and in-space propulsion capabilities.' Three project proposals have been selected for these missions, which should be launching in 2015 and 2016. One of those projects will involve demonstrating a mission-capable solar sail. While NASA has recently tested a solar sail measuring 100 square feet (9.29 square meters), this one will be the largest ever flown, spanning a whopping 409 square feet, or 38 square meters."

NASA, I am disappoint

[Reverand Dave]

Is this something that Neil Armstrong would be disappointed about? I think this is some pretty cool news myself, even though I don't exactly believe it to be the best use of government funds ATM.

Re:

[khallow]

While fiscal prudence should be happening in all government agencies, including NASA, the solar sail is a very interesting piece of technology that should have been explored decades ago. I would suggest that it would be a much more effective use of funds, restricted to NASA, than the SLS (Space Launch System) heavy lift proposal that was aired a couple of weeks ago.

The key advantage is that the propulsion system doesn't run out of fuel. As long as it is exposed to sunlight, one can maneuver it around the

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[LifesABeach]

When it comes to money spent, NASA is still the Red Headed Step Child. But from my backyard view of the Multi-verse, humanity currently comprehends 3 curious methods to climb out of our gravity well. Rockets, Elevator, and Anti-Gravity. One works,(but NASA Administrators act like Edith Bunker and won't use Burt Rutan's solution set). The Elevator is still being developed, and looks to be serviceable, eventually, given humanities comprehension of applied Newtonian Mechanics. Anti-Gravity is still the Hig

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[scottrocket]

When it comes to money spent, NASA is still the Red Headed Step Child. But from my backyard view of the Multi-verse, humanity currently comprehends 3 curious methods to climb out of our gravity well. Rockets, Elevator, and Anti-Gravity. One works,(but NASA Administrators act like Edith Bunker and won't use Burt Rutan's solution set). The Elevator is still being developed, and looks to be serviceable, eventually, given humanities comprehension of applied Newtonian Mechanics. Anti-Gravity is still the High School Prom Royalty that can not see me for dirt. The first two are mechanically problematic; but the third one, oh the third one, is the one I still have thoughts for.

Don't forget mass-drivers/electromagnetic launchers. I am not a physicist, but it seems to me that EM launchers (of some sort) should be an area of more than passing interest, for both ground- and space-based launches. Oh yeah,$$...Forgot about that.

Re:

[Skywolfblue]

Friction is a HUGE problem for mass drivers. It's pretty much completely impractical to accelerate something to Escape Velocity in the lower atmosphere because the air resistance will fry anything at that speed. Also, unless you build an absurdly (I mean REALLY absurdly) long track, no person is going to be able to survive the G forces. Now it'd be great for say the Moon, or other places with low to no atmosphere.

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[scottrocket]

Yeah, over the years I've seen vaporplans for absurdly long rails; however, since the projectile pops out of the thickest parts of the atmosphere in just a few seconds, it seems to me that a sacrificial, ablative shield (like an attritive, onion skin) could possibly sink away the "frying" heat. Who knows, maybe the sheer pressures of the airflow would force the ablated vapors into a boundary layer around the rest of the craft, thus protecting it from friction, and possibly sponsoring a transient, superlam

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[khallow]

Perhaps; but that doesn't change the fact that it still costs a lot of money and fuel to break free of the gravity well.

If you're ok with passing through the Van Allen belts a bunch of times, then you don't need to break free of the gravity well, you just need to get into low Earth orbit. Past that, solar sails can then take you anywhere else in the Solar System. Not everything can solve the cost of putting things into space, but solar sails do help with the problem you mention above for very radiation insensitive payloads.

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[Ogive17]

So should the government cut all funds to science research and development? We really didn't need those jobs anyway.

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[Reverand Dave]

Last time I checked, NASA isn't the only agency that does science. NOAA [noaa.gov] comes to mind as well as the NSF [nsf.gov] just to name a few. I my point is that there are terrestrial concerns that are a tad more pressing for the immediate term. Drop the hyperbole.

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[M8e]

Not Safe For GOVernment?

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[Doc Ruby]

Oh, so as long as there's just one agency, science and employment will grow just fine. That is your hyperbole - or rather hypobole.

Look, why don't you concentrate on the $TRILLIONS in military/intel expenses and the $TRILLIONS in rich people tax cuts that are actually killing our budgets and economy, instead of the fractions of a percent that are the good reasons we have anything left to work with.

Re:

[Reverand Dave]

I don't think I stated that "defense" spending or tax cuts for the "job creators" wasn't a huge waste of taxpayer dollars and is in fact sinking our economy in an almost criminal fashion. I didn't advocate nixing NASA, but I think that our sights should be set a little closer to home. Again, jumping to the ultimate conclusion of any statement is hyperbole and you have just engaged in it yourself.

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[Doc Ruby]

You need to look up the definition of hyperbole [reference.com].

I didn't say you said anything about military spending or tax cuts. What I said is that nickel/diming the most productive public investments is a waste, when those other sources of crisis are begging for attention. Every minute you spend talking about cutting NASA is a minute you're not talking about cutting military/intel or collecting taxes from rich people. If you can link to somewhere you've asked for that real benefit somewhere in the past month or six, I

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[Reverand Dave]

have fun with that [ientry.com]

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[Doc Ruby]

Otherwise I'll stick to the reasonable assumption that you just pick on NASA instead of where the problem really lies. Jerk.

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[Reverand Dave]

you're funny [motifake.com]

SIX POINT TWO TRILLION DOLLARS A YEAR

[Shivetya]

that is the estimated combine budgets of every form of government in the United States. Federal, state, and local.

and people seem to have a never ending list of wants, yet it is so very disappointing what little we are getting for that expenditure. So little of the money goes to non-vote buying schemes that we become desperate to find dollars to spend on something right.

There is no best use of government funds atm because atm the Congress controls nearly fou trillion of it, a good amount that doesn't even e

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[thed8]

Disappointed is right. China launches a new part of a lab now, and maybe possibly in 10 or 12 years we get to launch Humma Kavula's nose rag..... Achoo

An important step towards propusion

[Covalent]

At this size (0.000038 km^2) the amount of thrust generated by this sail will be 0.0003477N. If the total mass of sail and attached spacecraft is 100kg, then the acceleration will be 3.477E-6 m/s^2. After a month at this acceleration, the craft will be traveling at 9m/s. That's only about 20mph. Not very fast, but an important proof of concept.

Re:

[Covalent]

In open space, yes. But 20mph is not enough to escape Earth's gravity. So if this is in orbit, it'll stay in orbit. But this is more a proof of concept than an actual speed test.

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[AlecC]

No - it accumulates continually, provided it is high enough to avoid atmospheric drag. OK, the velocity difference between LEO and escape velocity is still of the order of 20,000 mph, so it would take 1,000 months to escape from Earth's gravity well. But what is eighty odd years on the cosmic scale?

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[Coren22]

At that point you turn the sail. Sailboats don't stop when going near to direct into the wind; some sailboats can even come as close as 5deg off of directly at the wind. Think of it as a big sailboat, the only time it slows down is in that 10deg area directly towards the sun.

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[captainpanic]

Correct me if I'm wrong but the photons will have an accelerating effect, so even if it's 20mph after one month, wouldn't it be faster than 40mph in 2 months? I.e. will speed then be superlinear? With nothing slowing it down (besides its own mass) the particles will keep nudging the object ever faster, and since it's in a field of basically limitless "fuel" it'll achieve incredibly fast speeds... after a long while.

If the acceleration is constant, then velocity increases linearly.
But the craft will move away from the sun, photon density will decrease, so the acceleration will actually decrease, and the velocity will increase with a less-than-linear amount in time.

I think that the mass of 100 kg that we're working with in this little example is a bit too much.

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[rgbatduke]

Right, but as the craft moves away from the Sun (in particular) solar gravity drops off at exactly the same rate that solar flux drops off (both 1/r^2). OTOH the craft isn't trying to pull directly away from the Sun, it is angling the sail to get a maximum transverse acceleration to increase its orbital speed. OTOOH as its transverse speed increases F_\perp v_\perp (to r) increases with v_\perp as F_\perp remains nearly constant, so the power delivered to the mass is nearly constant. Eventually it all

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[khallow]

The good news is that once you are in Earth's orbit it is free. The bad news is that getting to low Earth orbit already cost you half the energy required to escape, and that's a lot of energy -- moreso since you have to spend the energy to lift the sail, not just the payload, with all of those early nonlinearities multiplied by 3+. A win, but not an enormous one, and a rocket lets you step right up to escape speed and get there MUCH earlier.

Energy is insignificant. For a rocket (or indeed anything that moves by throwing out reaction mass), the real restriction is delta v. The mass fraction, the amount of the rocket that can be something other than propellant is proportional to some number raised to the delta v power. If you double the delta v, then you have to square the mass fraction (which is already significantly less than 1) to get the new mass fraction.

This means that for rockets which operate at very low mass fractions, any reduction

Re:An important step towards propusion

[rolias]

Except that the article is wrong. The sail will be 38m wide, or 1444m^2. That's 0.013N: 2 * (38m)^2 * 1368W/m^2 / (300,000,000m/s)

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[schlachter]

Yes, but the point is that it will add another 20mph the next month and so on in a cumulative fashion...and light speeds the limit (in theory)...and it could be combined with other propulsion tech such as ion energy or gravity assists.

Comment removed

[account_deleted]

Comment removed based on user account deletion

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[Anonymous Coward]

Whopping? That's only about four times larger. Certainly not "whopping".

That's what she said

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[MadKeithV]

How many football fields is one whopping?

Approximately 1000 Volkswagen Beetles, or 0.15 Libraries of Congress.

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[kimvette]

How many empty Dorito bags is it, though? To specify: neither crumpled up nor laid out flat.

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[LWATCDR]

Sorry you are wrong. In the Slashdot system of universal measurements you only have to have a 2x expansion to == a whopping. An 8x or greater requires the addition of the prefix great and a 64x an additional prefix of huge as in a huge great whopping. You transition to hugenormus once the surface area == one standard library of congress rendered in courier 10 point font, double sided on A4 sized paper, at standard temperature and pressure.
Hope that cleared it up for you.

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[nschubach]

Thanks for the clarification, but I have one other question on a recently used measure:

What about ton? ("I have a ton of iso/mp3s")

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[moondawg14]

We need to know which "ton" you're speaking about. Is it a shit-ton, a metric shit-ton or a butt-ton?

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[LWATCDR]

A ton of digital data is that can not fit on common mass storage costing less than $60. That is the the technical use. So in say 1983 it would have been about two mega bytes using Elephant floppies at around 177k each In the colloquial use. Today it is about 1 TB. Also anything large fraction of a SLOC "Standard Library of Congress" would be a ton of. The less formal use means "so much I have no idea what I have", "I have a netfix account and rip and send", or "I have more than you do".
 

Re:

[AlecC]

Unless it is expressed in football pitches, or maybe micro-Belgiums, how can I possibly understand it?

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[LWATCDR]

Football pitches? What are you a 10 year old girl or a sissy EU type. This here board was started in Michigan in the U.S. of the freaking A. We use football fields here! micro-Belgiums? Well since everything in Europe is small and frankly unimportant a micro-Belgium== a smige.

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[Bucky24]

It takes bigger balls to play football in Europe ;)

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[sir_eccles]

Well, how big is YOUR solar sail?

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[stackOVFL]

Don't need one. I use two swallows with a string tied under the dorsal guiding feathers. I made small air tanks from empty coconuts. Rocket science, meh.

Microwave Power

[cobrausn]

If Sim City is to be believed [mastermarf.com], I expect this to go into production as a viable energy source around 2020. As long as they don't cut funding. They would regret that.

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[AikonMGB]

Solar sail, not solar collector.

Aikon-

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[cobrausn]

Ah. Maybe I should RTFA first next time. :-(

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[Bucky24]

Or at least the title...

409 sq. ft.?

[wisebabo]

Ok I know I RTFA. But just 409 sq. ft.? (and no I don't think they meant 409 ft. square, they also said 38 sq. meters). I'm really hoping that's a journalistic error because 409 sq. ft. is just 20x20 feet! I think the sun shield used on the hopefully-not-to-cancelled JWST is bigger than that. And there are 5 layers!

In terms of size there are lots of things solar sail-ish that are bigger than that. Like the solar arrays on the ISS. Or how about Echo 1, a giant slivered balloon that was put into orbit

Re:

[rolias]

The Gizmag article was... imprecise. The sail will be a square 38m wide, with an area about 1400 m^2. It's based on a 20m wide sail L'Garde built and tested for NASA in 2005. More info here: http://www.nasa.gov/offices/oct/crosscutting_capability/tech_demo_missions.html [nasa.gov]

Re:

[wisebabo]

Thank you very much, that was a MUCH more informative link.

I especially like the "station keeping" applications, over the poles or at pseudo-lagrangian points. Someday, they could perhaps use this technology for station keeping directly over the SUN!

Alas, I'm afraid that thanks to the debacle of the space shuttle and ISS, space exploration may have been sent back by a generation (maybe longer if you consider the loss of "momentum" in political will). What I had hoped to see in my lifetime will now only be

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[rolias]

Glad to help. Yeah, a sufficiently large (thrust) and lightweight (acceleration) sail could counteract and even exceed the sun's gravity. A sail mass/area of ~1.5 g/m^2, which accelerates at ~6 mm/s^2 at Earth would achieve this. Lower performance sails could still linger over the sun in "halo" orbits.

I think it's an opportunity when large organizations fail do do something new. They get out of the way, giving more flexible and innovative parties have a chance. I think expansion into space has, in part, bee

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[wisebabo]

Oh, by the way, the name of the story was "The Wind from the Sun".

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[element-o.p.]

Thanks for posting that. I loved A.C.C.'s stories when I was a kid, but I don't remember reading a story about a solar sail race to the moon. I was about to search for it (it sounds interesting), but you've saved me the work :)

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[camperdave]

Both Echo 1 and Echo 2 experienced solar sail effects. Anything, regardless of size or shape, will experience solar sail effects. However the effects are generally negligible unless the object has a huge area relative to its mass.

Headline in 2016

[elrous0]

"Press Has Forgotten Five-Year-Old NASA Promise"

Sorry but the Japanese deployed a larger one.

[jklovanc]

In July 2010 the Japanese deployed IKROS [wikipedia.org] with a surface area of almost 2200sq.ft. That is almost 5.5 times the size of this sail. Maybe Gizmag should learn to use Google.

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[Wingfat]

for one that is a Wiki site.. on the 2nd note, it says it was the first? lies.. the Russains were the first in 1993. and the Russians were the ones that came up with the idea of it. just like the light bulb.. we invented it.. they make it better.

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[rolias]

The Russians deployed the Znamya [space.ru] space mirror from a Progress resupply ship in 1993, and tried a second time in 1999. The Progress propelled and steered it to reflect a spot of light down on the Earth, so it didn't do actual solar sailing. IKAROS [www.jaxa.jp] has that distinction. This new mission [nasa.gov] will actually test a 38m x 38m sail, so it will be the largest.

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[camperdave]

just like the light bulb.. we invented it.. they make it better.

You're British?

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[Wingfat]

Scott/Irish/Norse/NativeAmerican - you pick. Swan did make one first.. but Edison made the long lasting Filament

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[camperdave]

Scott/Irish/Norse/NativeAmerican - you pick. Swan did make one first.. but Edison made the long lasting Filament

Swan who? Edison's cohort? Not by a long shot. People were making incandescent light bulbs before Swan was even born. But why let a few stray facts spoil such a pervasive American Myth.

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[camperdave]

1802, Humphry Davy created the first incandescent light by passing the current through a thin strip of platinum
1835, James Bowman Lindsay demonstrated a constant electric light at a public meeting in Dundee, Scotland.
1840, British scientist Warren de la Rue enclosed a coiled platinum filament in a vacuum tube and passed an electric current through it.
1841, Frederick de Moleyns of England was granted the first patent for an incandescent lamp, with a design using platinum wires contained within a vacuum bu

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[RivenAleem]

Gizmag is wrong, but not in the way you think. The sail is 38m in width, 1444m^2 area or 15,542.6089sq.ft

Star Trek DS9 - Bajoran solar-sail vessel anyone?

[Wingfat]

I always thought Solar sails would be awesome after seeing the DS9 epsiode where Commander Sisko constructed his own lightship and took his son, Jake Sisko, along for the maiden voyage. http://www.startrek.com/database_article/bajoran-solar-sail-vessel [startrek.com]

Complete story

[Anonymous Coward]

For the complete story, see the NASA announcement from August 22nd: http://www.nasa.gov/offices/oct/crosscutting_capability/tech_demo_missions.html

The sail is 38x38m. Two 20x20m sails were developed for NASA in 2005 by L'Garde and ATK. The thrust on the sail is approximately: 2 * (38m)^2 * 1368 W/m^2 / c ~= 0.01 N

Solar Sail can be very useful

[aurizon]

A small thrust like this can be used to keep the station up permanently and even to adjust the orbital attitude as needed.

This will save those missions to send up maneuvering fuel from time to time and save lots of $$

Funding

[RogerWilco]

Like NASA will still be funded then. I don't think NASA will make it past 2013 if even FEMA funding is in question.

That's Not Whopping

[Doc Ruby]

spanning a whopping 409 square feet, or 38 square meters.

That's not "whopping". In microgravity and near vacuum, "whopping" would be a square kilometer, or a dozen square kilometers. Accelerating probes into outer solar orbits in a few years, dropping network nodes along the way, charging fuel stations for planetary exploration, eventually capturing asteroids for making machines that exploit other planets' resources, eventually colonizing the whole system. The future of inhabiting space is long, but there's little reason to wait for a truly "whopping" sail to get

That's A Good Thing!

[Jane Q. Public]

I sure am glad they are going to demonstrate it in space!

Demonstrating it here on Earth would cause all kinds of problems.

Re:

[skelly33]

/. summary must be wrong.Gizmag itself states in the caption, "this one will be the largest ever flown, spanning a whopping 15,543 square feet, or 1,444 square meters."

I was gonna say - roughly 20x20 feet never sounded so exciting before!

Planetary Society

[Jazari]

The Planetary Society should get kudos for getting the ball rolling early on this: http://www.universetoday.com/44551/planetary-society-to-launch-three-separate-solar-sails/ [universetoday.com]