Comments on: Solar Sail Space Travel One Step Closer to Reality

By: General Zod

General Zod — Fri, 25 Apr 2008 02:35:08 +0000

Why not? By altering the charge of certain cables, you could steer it. Also, couldn't it also be used to collect energy whenever it isn't being used as propulsion?

We do still need quicker short distance transportation, but say, long term, you use solar sails to get up to speed on an earth/moon transit vehicle, making use of solar sails and gravity assists. Or an Earth/Mars transit vehicle?

But we will still need rocketry.

By: Al Hall

Al Hall — Fri, 25 Apr 2008 00:48:06 +0000

Perhaps instead of dreaming of unrealistic ideas of deploying arrays kilometers wide, maybe we should encourage our engineers to perfect solar cells. Yes I said â€œcellsâ€, not â€œsailsâ€. Cells that are near 100% efficient and a storage device that can dissipate that collected energy to a tolerable engine at increasing rates. Cells that are capable of collecting photons (or possibly even electrons from solar or cosmic rays).
We're not going to do anything appreciable until we get travel time worked out.
Solar sails? C'mon….

By: marcellus

marcellus — Thu, 24 Apr 2008 16:32:35 +0000

I like it and I think they'll make it work.

Just think, even if it is not practical for human space travel, we'll be able to put Cassini-type orbiters around EVERY planet, dwarf planet and major asteroid in the Solar System.

We'll NEVER get away from the computer!

By: Astrofiend

Astrofiend — Thu, 24 Apr 2008 15:00:47 +0000

Cheers Adam. As I said, interesting concept!

By: Al Hall

Al Hall — Thu, 24 Apr 2008 14:08:09 +0000

Hmm… I'll believe it when I see it. Doesn't seem to be practical. At least in this half of the century. And let's hope that before we get to the latter half, we will have come up with better and more practical propulsion systems.

By: Adam

Adam — Thu, 24 Apr 2008 08:28:49 +0000

Hi Astrofiend

The proton density is ~ 5E+6 per m^3, speed roughly ~ 400 km/s (800-900 km/s is unusually high) and so the ram pressure is ~ 1.34E-9 Pa. The light flux incident on a reflector at 1 AU is 1368 W/sq.m on average. The pressure is 2E/c = 9.13E-6 Pa for perfect reflection. Thus the light pressure is much higher than the ram pressure.

The advantage of the "wire sail" is that the wires can, in principle, mass a lot less than a sail. Can't do it with photons, but you can with the solar wind. Also the proposed design seems to have a pretty easy deployment system compared with the difficulties of photon sails.

Solar sails, in principle, can get much higher final velocities than solar wind sails – over 0.01c – but for near term missions the solar wind seems the easier option.

By: Astrofiend (Syd, Aust)

Astrofiend (Syd, Aust) — Thu, 24 Apr 2008 00:48:06 +0000

Interesting concept. Any idea how the charged particle sail compares with the photon sail in terms of acceleration and whatnot? Protons at that speed should impart a higher momentum per particle as compared with most photons streaming from the sun, but I should also think there would be far less of them to provide their kick…

By: cheech

cheech — Wed, 23 Apr 2008 22:32:46 +0000

dont you need somone to help sail it?

By: Alex

Alex — Wed, 23 Apr 2008 20:14:19 +0000

This technology does not seem practical for trips over short distances or for short durations… probably not manned flights at all. It would be even slower than Ion systems.

To be fair to rockets… when you say that sails would be 6 times faster than rockets… do not forget fusion rockets. They could hit better than .1C. If the solar particles are only going at less than .01C… That would mean rockets still have the potential to be much faster.

By: Watchful Stone Guardian

Watchful Stone Guardian — Wed, 23 Apr 2008 19:27:12 +0000

It doesn't look like there'd be much room in the "tin can" below the solar panels in the graphic shown. No place to stretch your legs on a trip to Mars or Ceres! It would be interesting to see how large of a capsule could be driven by the momentum generated by the proton repulsion on practically sized cables (i.e. how many kilometres of cables would be needed for a ship of practical size for a Moon or Mars trip?).

By: Ronals Lynn Jackman

Ronals Lynn Jackman — Wed, 23 Apr 2008 17:06:28 +0000

Conventional sails would give us six times the speed of a rocket. It will be interesting to see how much faster these new sails can go if the calculations are correct. It may help us to build the dream of solar cells on the Moon, helping to drive down pollution. By getting to asteroids cheaper, we do not have to do as much mining on the Earth. This would also cut down on pollution. It would also improve the economy here on the Earth.

We would be able to go other places such as Mercury, Mars, Venus and Ceres. It would be a boom to mankind.

By: Gerald

Gerald — Wed, 23 Apr 2008 17:01:08 +0000

Actually, most solar sail projects have not used "tin foil." They use extremely thin plastic film — usually polyester (Mylar) — that has been aluminized. It's a very thin version of the same film used to make those shiny, helium filled birthday or Valentine balloons you get at the local supermarket.