7 ms·

World's first solar sail unfurled in orbit

69 points by joshrule 16y ago

noahlt 16y ago
Not quite. According to the article, the Japanese deployed a solar sail with a Venus probe. This, though, is the world's first solar sail on a probe designed for Earth orbit.
- robin_reala 16y ago
  The Planetary Organisation tried to deploy a solar sail back in 2005 ( https://secure.wikimedia.org/wikipedia/en/wiki/Cosmos_1 https://secure.wikimedia.org/wikipedia/en/wiki/Cosmos_1 ) but the rocket failed.
- nfg 16y ago
  The probe in question: http://en.wikipedia.org/wiki/IKAROS http://en.wikipedia.org/wiki/IKAROS
- tel 16y ago
  The article does mention IKAROS, though changing the title from "Solar Sail Stunner" was probably a good move. This satellite is interesting however in that it uses what sounds like a much simpler sail deployment design. IKAROS used centrifugal force to pull the sail out whereas NanoSail-D seems spring loaded.
- jpadvo 16y ago
  "World's first unfurling of a solar sail in orbit" would be quite a bit more accurate.
wingo 16y ago
Is it a sail or a drag parachute?
- Femur 16y ago
  It is a proper sail propelled by light pressure instead of wind. https://secure.wikimedia.org/wikipedia/en/wiki/Solar_sail https://secure.wikimedia.org/wikipedia/en/wiki/Solar_sail
  - dedward 16y ago
    "NanoSail-D will remain closer to home. "Our mission is to circle Earth and investigate the possibility of using solar sails as a tool to de-orbit old satellites and space junk," explains Alhorn. "As the sail orbits our planet, it skims the top of our atmosphere and experiences aerodynamic drag. Eventually, this brings it down."" Pretty clearly not a solar sail...
    - 51Cards 16y ago
      "They'd also like to measure the pressure of sunlight on the sail, although atmospheric drag could overwhelm that effect." Dual purpose study.
- flatline 16y ago
  Excellent question, the article called it a solar sail but only mentioned its drag properties. I kept wondering why you would need a solar sail to keep something in orbit...?
- jpadvo 16y ago
  It is a lightweight, inexpensive, spaceship-deployable sheet. Currently it is being used as a drag parachute, but it could just as easily be used as a sail. I think.
riledhel 16y ago
"For reasons engineers still don't fully understand, NanoSail-D spontaneously ejected itself." Best line of the article!
- jarin 16y ago
  I'm going to point people to this article next time some code inexplicably starts working.
rlpb 16y ago
In what way is this a solar sail? It's a drag sail. From the article, it seems to me that the sun doesn't propel it any more than the sun propels my car.
- dandelany 16y ago
  Because it's so close to Earth, the drag force will be much greater than any propulsion force achieved from solar particles, which means its orbit will decay and it will fall out of orbit. However, this doesn't preclude it from being a solar sail, it just means it's not a very efficient sail. Eventually, we'd like to send these into deep space, where there is no drag from the atmosphere, allowing the craft to accelerate indefinitely. But for now, it makes sense to keep it in orbit and study it at close range so we can be sure the "sail" effect works as predicted. More info: http://www.nasa.gov/mission_pages/smallsats/10-109.html http://www.nasa.gov/mission_pages/smallsats/10-109.html "The relatively low-deployment altitude means drag from Earth's atmosphere may dominate any propulsive power it gains from the sun, but the project represents a small first step toward eventually deploying solar sails at much higher altitudes... because the sail will deploy relatively close to Earth, researchers will have a difficult time detecting the slight solar effects."
  - jacquesm 16y ago
    > allowing the craft to accelerate indefinitely. In theory that's all very nice, in practice the power available for acceleration decreases as the cube of the distance. Of course a bit of acceleration is better than nothing but this will only work well if you have very large amounts of time, and since all systems will have to survive for all that time I don't see this as a practical means of propulsion. Bussard Ramjets are a lot harder to construct (and shield) but I think if there ever is going to be a practical means of achieving speeds that are a significant fraction of lightspeed then I think that's where it's going to come from, not from solar sails (even though the technology definitely has its charm).
    - jimmyk 16y ago
      >In theory that's all very nice, in practice the power available for acceleration decreases as the cube of the distance. This is why any solar sail intended to move very quickly will open up somewhere closer to Mercury.
iwwr 16y ago
It would be interesting to see if the magsail or electric sail concepts are developed as well. The simplest design appears to be the electric sail, which only needs radial conductive wires (easy to manufacture and deploy, although it needs to be launched well outside the Earth's magnetosphere). http://en.wikipedia.org/wiki/Magnetic_sail http://en.wikipedia.org/wiki/Magnetic_sail http://en.wikipedia.org/wiki/Electric_sail http://en.wikipedia.org/wiki/Electric_sail
JacobAldridge 16y ago
I see that this is expected to, as one outcome, help reduce further space junk in orbit. I wonder what impact existing space junk - which is predominately small pieces of metal orbiting the earth at speed - would have on the sails? Without knowing its altitude, even the 70-120 day lifespan makes it a target. I wonder how resistant a 10m^2 piece of thin polymer sheet would be to a lazy 2-inch screw hurtling into it?
- dandelany 16y ago
  > I wonder how resistant a 10m^2 piece of thin polymer sheet would be to a lazy 2-inch screw hurtling into it? Presumably, not resistant at all... Even the heavy shielding on the ISS can only protect from debris less than 1cm in diameter. The question is, would such a debris hit shred the sail, or would it punch a neat hole, leaving it mostly intact?
  - JacobAldridge 16y ago
    Yes, 'not' is how I would have described the resistance. As long as it were a fairly direct hit, I imagine a neat hole would be most likely (though these could add up fairly quickly over time).

69 points by joshrule 16y ago

Not quite. According to the article, the Japanese deployed a solar sail with a Venus probe. This, though, is the world's first solar sail on a probe designed for Earth orbit.

robin_reala 16y ago
The Planetary Organisation tried to deploy a solar sail back in 2005 ( https://secure.wikimedia.org/wikipedia/en/wiki/Cosmos_1 https://secure.wikimedia.org/wikipedia/en/wiki/Cosmos_1 ) but the rocket failed.
nfg 16y ago
The probe in question: http://en.wikipedia.org/wiki/IKAROS http://en.wikipedia.org/wiki/IKAROS
tel 16y ago
The article does mention IKAROS, though changing the title from "Solar Sail Stunner" was probably a good move. This satellite is interesting however in that it uses what sounds like a much simpler sail deployment design. IKAROS used centrifugal force to pull the sail out whereas NanoSail-D seems spring loaded.
jpadvo 16y ago
"World's first unfurling of a solar sail in orbit" would be quite a bit more accurate.

wingo 16y ago

Is it a sail or a drag parachute?

Femur 16y ago
It is a proper sail propelled by light pressure instead of wind. https://secure.wikimedia.org/wikipedia/en/wiki/Solar_sail https://secure.wikimedia.org/wikipedia/en/wiki/Solar_sail
- dedward 16y ago
  "NanoSail-D will remain closer to home. "Our mission is to circle Earth and investigate the possibility of using solar sails as a tool to de-orbit old satellites and space junk," explains Alhorn. "As the sail orbits our planet, it skims the top of our atmosphere and experiences aerodynamic drag. Eventually, this brings it down."" Pretty clearly not a solar sail...
  - 51Cards 16y ago
    "They'd also like to measure the pressure of sunlight on the sail, although atmospheric drag could overwhelm that effect." Dual purpose study.
flatline 16y ago
Excellent question, the article called it a solar sail but only mentioned its drag properties. I kept wondering why you would need a solar sail to keep something in orbit...?
jpadvo 16y ago
It is a lightweight, inexpensive, spaceship-deployable sheet. Currently it is being used as a drag parachute, but it could just as easily be used as a sail. I think.

riledhel 16y ago

"For reasons engineers still don't fully understand, NanoSail-D spontaneously ejected itself." Best line of the article!

jarin 16y ago
I'm going to point people to this article next time some code inexplicably starts working.

rlpb 16y ago

In what way is this a solar sail? It's a drag sail. From the article, it seems to me that the sun doesn't propel it any more than the sun propels my car.

dandelany 16y ago
Because it's so close to Earth, the drag force will be much greater than any propulsion force achieved from solar particles, which means its orbit will decay and it will fall out of orbit. However, this doesn't preclude it from being a solar sail, it just means it's not a very efficient sail. Eventually, we'd like to send these into deep space, where there is no drag from the atmosphere, allowing the craft to accelerate indefinitely. But for now, it makes sense to keep it in orbit and study it at close range so we can be sure the "sail" effect works as predicted. More info: http://www.nasa.gov/mission_pages/smallsats/10-109.html http://www.nasa.gov/mission_pages/smallsats/10-109.html "The relatively low-deployment altitude means drag from Earth's atmosphere may dominate any propulsive power it gains from the sun, but the project represents a small first step toward eventually deploying solar sails at much higher altitudes... because the sail will deploy relatively close to Earth, researchers will have a difficult time detecting the slight solar effects."
- jacquesm 16y ago
  > allowing the craft to accelerate indefinitely. In theory that's all very nice, in practice the power available for acceleration decreases as the cube of the distance. Of course a bit of acceleration is better than nothing but this will only work well if you have very large amounts of time, and since all systems will have to survive for all that time I don't see this as a practical means of propulsion. Bussard Ramjets are a lot harder to construct (and shield) but I think if there ever is going to be a practical means of achieving speeds that are a significant fraction of lightspeed then I think that's where it's going to come from, not from solar sails (even though the technology definitely has its charm).
  - jimmyk 16y ago
    >In theory that's all very nice, in practice the power available for acceleration decreases as the cube of the distance. This is why any solar sail intended to move very quickly will open up somewhere closer to Mercury.

iwwr 16y ago

It would be interesting to see if the magsail or electric sail concepts are developed as well. The simplest design appears to be the electric sail, which only needs radial conductive wires (easy to manufacture and deploy, although it needs to be launched well outside the Earth's magnetosphere). http://en.wikipedia.org/wiki/Magnetic_sail http://en.wikipedia.org/wiki/Magnetic_sail http://en.wikipedia.org/wiki/Electric_sail http://en.wikipedia.org/wiki/Electric_sail

JacobAldridge 16y ago

I see that this is expected to, as one outcome, help reduce further space junk in orbit. I wonder what impact existing space junk - which is predominately small pieces of metal orbiting the earth at speed - would have on the sails? Without knowing its altitude, even the 70-120 day lifespan makes it a target. I wonder how resistant a 10m^2 piece of thin polymer sheet would be to a lazy 2-inch screw hurtling into it?

dandelany 16y ago
> I wonder how resistant a 10m^2 piece of thin polymer sheet would be to a lazy 2-inch screw hurtling into it? Presumably, not resistant at all... Even the heavy shielding on the ISS can only protect from debris less than 1cm in diameter. The question is, would such a debris hit shred the sail, or would it punch a neat hole, leaving it mostly intact?
- JacobAldridge 16y ago
  Yes, 'not' is how I would have described the resistance. As long as it were a fairly direct hit, I imagine a neat hole would be most likely (though these could add up fairly quickly over time).