Solar Sails... your thoughts?

[BabyHeadCrab]

Recently i've been facinated with the idea of a "Solar Sail" apparenly light excerts a certain amount of force against surface particles when reflected, so in theory if you created a giant solar "sail" near light speed travel might be possible. The most popular theory lately is anti-matter fueld ships, but im starting to think a solar sail might be the future of space travel. Keep in mind when I said light speed travel I mean a solar sail would be gigaantic. The reason such fast speeds would be possible theoretically would be because of the absense of friction (light has very little meterial).

some links
http://www.ugcs.caltech.edu/~diedrich/solarsails/intro/
http://www.planetary.org/solarsail/
http://science.howstuffworks.com/solar-sail.htm
http://science.slashdot.org/article.pl?sid=05/02/01/1351223&from=rss

 

[Tr0n]

Solar sail will be one of the things to help us get further into space...but anti-matter is the future of space travel due to the power and energy it puts out.

 

[lePobz]

Solar sails would get ripped to shreds by micro-meteorites. The future of space travel lies with ZPE or warp. Or both?

 

[LittleB]

The future of space travel lies with bicycles. Check out this awesome super-bicycle, capable of flying to low orbit already: http://www.funnyworldrecords.com/Diashow1/07.jpg

 

[HadouKen24]

Solar sails would get ripped to shreds by micro-meteorites. The future of space travel lies with ZPE or warp. Or both?

There would be tons of drag with the sails, too. I can see some certain situations in which using solar sails would be useful, but after we've found some FTL drive and spread to other systems. Perhaps they would work well if power was scarce, but that's the only reason to use them.

 

[Fishlore]

Drag isn't a concern in space because there is no air. Drag is the result of air friction and isn't possible in space. Aerodynamics mean nothing out there. Micrometeorites would definitely be a concern though. One of the problems with a solar sail though is the incredible amount of time it takes to accelerate to high speeds, let alone speeds approaching light speed. The money angle though is important since solar particles are basically limitless. This could be a very viable means of cheap space transportation in the future especially if combined with a means to get it up to speed quicker. Slowing down would be tricky as well, because you'd have to spend an eqaul amount of time going backwards and slowing your velocity to zero.

The problem with anti matter drives is the obscene amount of energy/cost it takes to make even a few atoms of this material. Granted, who knows how the costs associated with this stuff wiill come down over the years, but as of now it's unthinkable.

As of now, nuclear is still the most efficient option. Hopefully that will change. I think the use of laser lights will become a very viable solution in the very near future. The idea being, you use a ground based, highly accurate laser to "paint" the spacecraft in space. They already have earth based prototypes working. The advantage being, you don't have to carry much fuel at all. Aside from course adjusting thrusters which use tiny amounts of fuel all of the power comes from earth. Less weight = less cost to get into space.

 

[PvtRyan]

I remember that you need a sail the size of Texas if you wanted to get to 1/10 lightspeed in a reasonable amount of time.

 

[short recoil]

Nuclear is the definite way to go, trouble is people go mental about the idea.

 

[Fishlore]

Nuclear is the definite way to go, trouble is people go mental about the idea.

LOL, no doubt. The funny thing is that the sun is in essence a gigantic nuclear bomb. The same mechanics are in place. They're great when they get into space safely.

I do agree to a small extent though. Imagine if the space shuttle challenger had a large nuclear reactor in it. Assume for a second that the reactor couldn't have been protected in the explosion. A terrible incident would have turned into one of the most tragic events on US soil in history at that time. Radioactivity from the blast, fallout falling to the ground and water. The huge crowd watching that important launch would be glowing or dead, the local ecosystem ruined for decades and possibly and EMP type effect killing all electrical units for miles.

 

[The Dark Elf]

Anybody mentioned micrometeorites? (cba reading every post or looking at the links) Just thought wouldn't they and other debris in space pretty much shread sails like that. Or have they developed something to deflect them? (no trekkie comments lol)

 

[short recoil]

LOL, no doubt. The funny thing is that the sun is in essence a gigantic nuclear bomb. The same mechanics are in place. They're great when they get into space safely.

I do agree to a small extent though. Imagine if the space shuttle challenger had a large nuclear reactor in it. Assume for a second that the reactor couldn't have been protected in the explosion. A terrible incident would have turned into one of the most tragic events on US soil in history at that time. Radioactivity from the blast, fallout falling to the ground and water. The huge crowd watching that important launch would be glowing or dead, the local ecosystem ruined for decades and possibly and EMP type effect killing all electrical units for miles.

They should ship smaller quantities of nuclear fuel into space and assemble long distance craft in space......the crew on long space journeys suffer more from cosmic radiation than anything they would get using the thermo nuclear expansion engines.
And by the way you are wrong about the effects of the nuclear fuel, unless it somehow came together into a critical mass it would be just a dirty bomb, which would be quite bad but it would not create an EMP or a huge nuclear explosion unless it was critical, it is easily possible to make spherical containers that can survive a rocket explosion, and fall back to earth safely with the fuel still intact.

With a space factory set up, nuclear fuel and propellant are bought up by standard rocket or the next "shuttle" design, the craft are assembled perfectly for space without the need to be aerodynamic like trans earth orbit craft.....aimed into deep space and the reactors started....blasting out superheated hydrogen out the back and propelling it into space faster than any other method.

 

[Razor]

Anybody mentioned micrometeorites? (cba reading every post or looking at the links) Just thought wouldn't they and other debris in space pretty much shread sails like that. Or have they developed something to deflect them? (no trekkie comments lol)

Deflector shields at maximum, captain .


I was reading a bit ago that solar sailors might be one of the ways to make Earth - Mars journeys both shorter and cheaper, turning a 9months journey into a 1month journey. But solar sails have the same problem as normal sails, you can't sail towards the sun and they would end up losing power the further out of the solar system you fly, due to less sunlight from the sun hitting it.

Oops, i think i remember the article about using them to take people to Mars and back was more a long the lines of a laser ship. Instead of using sunlight, you use a laser beam projected at the sails to push the ship a long.

The best course for interplanetary travel in the next 50 - 100 years, or so, would be nuclear fusion, lasers shooting a sailor, as mentioned above, or anti-matter, if the technology can be put into action soon enough.

 

[Dan]

I once heard an idea to make a hydrogen bomb powered spaceship. We already have thousands of them. Just put a giant metal plate to absorb radiation on the back of the ship and detonate hydrogen bombs behind you.

 

[short recoil]

I once heard an idea to make a hydrogen bomb powered spaceship. We already have thousands of them. Just put a giant metal plate to absorb radiation on the back of the ship and detonate hydrogen bombs behind you.

That would be a kick in the pants experience , i prefer using nuclear reactors to super heat propellant gas.

 

[The Dark Elf]

Deflector shields at maximum, captain .


I was reading a bit ago that solar sailors might be one of the ways to make Earth - Mars journeys both shorter and cheaper, turning a 9months journey into a 1month journey. But solar sails have the same problem as normal sails, you can't sail towards the sun and they would end up losing power the further out of the solar system you fly, due to less sunlight from the sun hitting it.

Oops, i think i remember the article about using them to take people to Mars and back was more a long the lines of a laser ship. Instead of using sunlight, you use a laser beam projected at the sails to push the ship a long.

The best course for interplanetary travel in the next 50 - 100 years, or so, would be nuclear fusion, lasers shooting a sailor, as mentioned above, or anti-matter, if the technology can be put into action soon enough.

hmm but don't solar sails or some kind of theoretical sail design simply use the light given off, which of course would continue in a straight line and even if the star is far away, light still comes from it. So it would still work?

meh i don't know, im far too tired to think about this right now lol

 

[short recoil]

hmm but don't solar sails or some kind of theoretical sail design simply use the light given off, which of course would continue in a straight line and even if the star is far away, light still comes from it. So it would still work?

meh i don't know, im far too tired to think about this right now lol

Its a simple concept, light from the sun (or star) bounces off the reflective sail, kinetic energy is transfered to the sail and pulls the craft through space, as it got further away the acceleration would get smaller but it would still be travelling at speed and would not slow down for a long time, a very, very long time (unless it hits a planet)
Thats why i dont like the solar sail system, its a one way trip.....unless they have normal fuel as well, a solar sail/nuclear hybrid would work well for 2 way trips.

 

[Razor]

I once heard an idea to make a hydrogen bomb powered spaceship. We already have thousands of them. Just put a giant metal plate to absorb radiation on the back of the ship and detonate hydrogen bombs behind you.

Yes, the ship would have a large metal plate that would get propelled by a constant stream of nuclear explosions behind it.

http://www.futurepundit.com/archives/000058.html

But then, being a passenger on a spaceship that has a nuclear warhead detonated 5 feet away from it to push it along, must be one heck of a kick in the teeth when it comes to g-forces .

 

[Maxi]

Light has no mass, light is photons and photons have no mass.

A sail would be theoretically possible, practicly, making a sail VERY large would require either ALOT of material or VERY litle making it very thin, but then there's the trouble of it breaking when it hits some kind of space debri. Also how do you slow down?

 

[Razor]

Light has no mass, light is photons and photons have no mass.

A sail would be theoretically possible, practicly, making a sail VERY large would require either ALOT of material or VERY litle making it very thin, but then there's the trouble of it breaking when it hits some kind of space debri. Also how do you slow down?

It depends what the journey is, depending on how you would slow down.

If it was inter system, from Sol to Proxima Centauri, you could accelerate using our sun, then in about 50 years when you reached Proxima, spin round and decelerate using Proxima. If it was interplanetary, a laser source at the destination to slow it down or some sort of breaking rockets.

 

[The Dark Elf]

Its a simple concept, light from the sun (or star) bounces off the reflective sail, kinetic energy is transfered to the sail and pulls the craft through space, as it got further away the acceleration would get smaller but it would still be travelling at speed and would not slow down for a long time, a very, very long time (unless it hits a planet)
Thats why i dont like the solar sail system, its a one way trip.....unless they have normal fuel as well, a solar sail/nuclear hybrid would work well for 2 way trips.

thats what i was saying, it would work and not crap out just cause its too far from a star, since it would then just keep accelerating and going in a straight line.

 

[Razor]

thats what i was saying, it would work and not crap out just cause its too far from a star, since it would then just keep accelerating and going in a straight line.

It would keep on accelerating, but the acceleration would drop off to next to nothing when you reach out past Uranus or Neptune.

 

[kirovman]

I worked it out in electromagnetism, it would accelerate pretty rapidly actually. I'll post some actual values here later, maybe.

 

[The Dark Elf]

It would keep on accelerating, but the acceleration would drop off to next to nothing when you reach out past Uranus or Neptune.

would it though? to slow down you need friction, there is none in space, so wouldn't you simply just keep going faster and faster, since there's nothing to slow you down so it simply adds to the speed.

 

[short recoil]

would it though? to slow down you need friction, there is none in space, so wouldn't you simply just keep going faster and faster, since there's nothing to slow you down so it simply adds to the speed.

Things dont get faster and faster unless they have a force on them........after it leaves the solar system the little light getting to it would hardly accelerate it at all........it would continue at near enough the same speed.

 

[kirovman]

would it though? to slow down you need friction, there is none in space, so wouldn't you simply just keep going faster and faster, since there's nothing to slow you down so it simply adds to the speed.

Acceleration would drop as the inverse square of distance to the sun. But you're right that everything extra would add to an ever-increasing velocity.

 

[The Dark Elf]

Things dont get faster and faster unless they have a force on them........after it leaves the solar system the little light getting to it would hardly accelerate it at all........it would continue at near enough the same speed.

pretty sure I read that they do in space continue to accelerate as there's simply nothing stopping them from slowing down or staying at a constant speed. could be wrong but i don't care anyway, it'll never happen in my lifetime, and probably never happen anyway, NASA can barely keep shuttles off the ground, what chance they have with a giant kite i don't know heh.

Acceleration would drop as the inverse square of distance to the sun. But you're right that everything extra would add to an ever-increasing velocity.

ahh cool, i felt sure i'd heard it before, and it does make sense. Thanks

 

[Razor]

would it though? to slow down you need friction, there is none in space, so wouldn't you simply just keep going faster and faster, since there's nothing to slow you down so it simply adds to the speed.

I think the mass of the object would still create a force that can not be overcome, the faster you go, the more energy you require to keep on accelerating as the more massive you are. If the energy from the light you're getting from the sun drops off to 0, then you will stop accelerating, you won't stop, just stop accelerating.


Shadow, the space ship would have a huge sail that would get painted with the laser, the people would be sat in a little capsule behind the sail. There would then be a laser at the other end to slow the ship down to dock at a space station. Secondly, the maximum speed of a light sail ship, from what i have seen, would be roughly 1/10th the speed of light, about 18,000 miles per second, it will never break the light barrier.

 

[Razor]

Acceleration would drop as the inverse square of distance to the sun. But you're right that everything extra would add to an ever-increasing velocity.

It wouldn't be an ever increasing velocity, once the sail runs out of energy to accelerate, it won't carry on accelerating.

 

[kirovman]

It wouldn't be an ever increasing velocity, once the sail runs out of energy to accelerate, it won't carry on accelerating.

My definition of ever increasing is with the presumption you are always adding momentum (ie everything extra added), from the sun's light or otherwise eg your projected laser.

Sorry if that wasn't clear.

 

[TheAmazingRando]

Too bad the money I sent to TPS went to a Solar Sail that crashed into the ground shortly after takeoff. I had high hopes for that thing too.

 

[Razor]

My definition of ever increasing is with the presumption you are always adding momentum (ie everything extra added), from the sun's light or otherwise eg your projected laser.

Sorry if that wasn't clear.

But wouldn't the energy given off the by suns light, or the laser, given both are giving out a constant amount of energy against the sail for the period of the journey, eventually equal the same mass of the starship as it carries on increasing speed (mass increases as speed increases) thus equalling out the energy given to the ship by the laser/sunlight to the mass, and the acceleration slows until the mass and energy are equal = acceleration stops?

 

[mindless_moder]

2 things the mass of the spaceship would increase to an infinite number
AND ! what about light coming at u from the opposite direction ? hmmm ?

i think that space travel will always be impossible for man because near lightspeeds are just unattainable.

 

[kirovman]

But wouldn't the energy given off the by suns light, or the laser, given both are giving out a constant amount of energy against the sail for the period of the journey, eventually equal the same mass of the starship as it carries on increasing speed (mass increases as speed increases) thus equalling out the energy given to the ship by the laser/sunlight to the mass, and the acceleration slows until the mass and energy are equal = acceleration stops?

You mean relativistically speaking?

You will keep on accelerating, but as you approach c, the velocity difference caused by the same amount of momentum will be less, but it will always increase, in a decaying way.

eg 1% added to velocity, then 0.1%, then 0.01%.

But when you reach these speeds near c, most of the momentum goes into increasing the mass.

And for this, solar sails wont get close to relativistic speeds, in a reasonable time frame, my statement about ever increasing velocity was perhaps misguiding, I just meant ever increasing until you decide to deccelerate, about halfway from the destnation or whereever.

 

[Razor]

You mean relativistically speaking?

You will keep on accelerating, but as you approach c, the velocity difference caused by the same amount of momentum will be less, but it will always increase, in a decaying way.

eg 1% added to velocity, then 0.1%, then 0.01%.

But when you reach these speeds near c, most of the momentum goes into increasing the mass.

Exactly, so you will stop accelerating to a point.

But Zofrex has told me in the irc chatroom that it isn't mass increasing, it is the time dialation that increases so the perception that mass increases is there, but mass doesn't actually increase.

 

[Fishlore]

ummm i dont know if im missing something here but theirs 2 problems w/ that....

firstly if the craft is painted w/ a laser... how can people sit in it??

secondly if it is light, how can it go faster then light?

Picture a large parabolic mirror, shaped like a big radar dish. That would always need to point at the source of the laser light, or in other words it would have to sit at the back of the craft. The front of the craft could be shaped in any way you wish. You could very easily have crew compartments and a bridge and most likely protection from micrometeorites. Picture a wine glass on it's side with you sitting where the wine goes. As long as the "mirror" for lack of a better term is pointed precisely at the laser you're good to go. You'd have to take a laser with you though so you could get back.

The ground based laser, which would constantly be in motion compared to the craft, is the important aspect here. It would need to powerful enough to reach across the solar system, huge costs there, and it would need to be able to find and track a tiny spec in the sky while in constant motion from the revolution of the earth. It would fire laser pulses that literally cause tiny explosions when they hit the reflective surface and in turn provide thrust. You also have to consider the time when your laser station on the side of the planet pointed away from the craft.

This laser system as well as a solar sail would never be able to take you past the speed of light by themselves. Like you said if you're using light you can't possibly go faster than the speed of light unless the craft has a means of providing thrust on it's own. The idea here would be to reach a speed just slightly slower than the speed of light. Any faster and the light won't catch you to provide further thrust.

 

[kirovman]

Exactly, so you will stop accelerating to a point.

But Zofrex has told me in the irc chatroom that it isn't mass increasing, it is the time dialation that increases so the perception that mass increases is there, but mass doesn't actually increase.

The rest mass doesn't change. The relativistic or "percieved" mass does.

Exactly, so you will stop accelerating to a point.

I don't know, I am in the 3rd year of a physics course, but I've only done special relativity, not general relativity, which takes into account acceleration.

GR is very mathematical and involves tensor calculus, and geodesosics etc.
I imagine you could accelerate forever, no problem, but you would need GR to explain it.

 

[Razor]

The rest mass doesn't change. The relativistic or "percieved" mass does.



I don't know, I am in the 3rd year of a physics course, but I've only done special relativity, not general relativity, which takes into account acceleration.

GR is very mathematical and involves tensor calculus, and geodesosics etc.
I imagine you could accelerate forever, no problem, but you would need GR to explain it.

When you mean "accelerate forvever" you mean that you would carry on accelerating, just that the amount you're accelerating will slow down and get to a point where you won't notice any speed change

i.e. when you said "You will keep on accelerating, but as you approach c, the velocity difference caused by the same amount of momentum will be less, but it will always increase, in a decaying way.

eg 1% added to velocity, then 0.1%, then 0.01%."

 

[kirovman]

Yes that's what I meant. An exponentially decaying acceleration.

 

[kaf11]

i understand that it catches available light behind the sail, but how does it just ignore the particles bombarding the front of the sail?

 

[kirovman]

i understand that it catches available light behind the sail, but how does it just ignore the particles bombarding the front of the sail?

You have to purposefully bombard it with enough light to overcome that - either use the sun or fire a laser at it.

As for drag factor particles, there's only about 100 particles per square metre of Gallactic space on average (well at least a problem I solved one time said that)

So the drag factor is pretty negligible.