the excitement that is

flashgordon · 2005-06-21 10:10:02

Just wait till the public rocket tourism companies get their hands on solar sails!

Not practical for human space flight? Space is very different from our experience here on earth; a thousand kilo's might sound large on our human size scale, but out in space that isn't so large, and really, that extra size helps keep the overall structure going if a micrometeorite hits one blade; even a meter long asteroid couldn't totally destroy a solar sail blade, and the human quarters will still be farelly small; nobody worries about a space station sized craft going to mars getting hit, I think Solar Sails can work out alright!

SpaceNut · 2005-06-21 10:31:19

I believe that eventually we will use solar sails much like one uses a sail boat on a lake but it will only be useful probably within the orbit of jupiter or possibly mars.

idiom · 2005-06-21 16:18:32

How do you go upwind without a keel? How do solar sails solve the journey back in?

Will placing one nearly perpendicular to the solar wind you could generate reverse thrust I guess, and cause your orbit to decay, but you are still going to have a lot of drag away from the sun?

There isn't a useful 'ambient' cosmic pressure as far as I am aware...

GCNRevenger · 2005-06-21 17:22:06

No, pure solar sails will never be practical for human transport, they are just too SLOW.

For example, a trip to the Moon from Earth orbit...
-Rocket: 3-4 days tops. Hours if fuel efficency is unimportant.
-Sail: six months, perhaps even nine

How do solar sails "reverse" closer to the Sun? They turn the sail so the light pressure pushes in the opposite direction of your orbital path, so that the Sun's gravity pulls you back inward.

clark · 2005-06-21 17:25:55

Hurmph.

People don't take cruise's because they are fast.

Slow pace, low fuel requirements = $$$ for the old folks cruise to the moon.

GCNRevenger · 2005-06-21 17:34:36

Oh come on, the lower fuel bill will be nothing compared to the food, life support, maintenance, and so on for a six-month journey, particularly when Lunar fuel is available.

Especially difficult given that you can't keep many people in a cramped little tin can light enough, particularly with all those supplies, for such a long trip. Solar sail payload comes at a premium without a VERY big sail.

And six months for that little hop?

clark · 2005-06-21 17:39:48

Hey, I didn't say it would be easy. I merely pointed out that a long trip to the Moon is not a deal breaker.

As for the logistics for a 6 month trip, I think it is manageable in some unspecified future.

Anyway, the thing to remember is that while most here want to get *there* (wherever there happens to be for you) as quickly as possible, many people don't need to travel at a sprint.

And if lunar fuel is cheap, use lunar fuel. Hell, use both, I'm sure there is room for synergy.

BWhite · 2005-06-21 19:01:00

Hey, I didn't say it would be easy. I merely pointed out that a long trip to the Moon is not a deal breaker.
As for the logistics for a 6 month trip, I think it is manageable in some unspecified future.
Anyway, the thing to remember is that while most here want to get *there* (wherever there happens to be for you) as quickly as possible, many people don't need to travel at a sprint.
And if lunar fuel is cheap, use lunar fuel. Hell, use both, I'm sure there is room for synergy.

van Allen belts? Humans need to leave LEO fast. Or so I hear.

clark · 2005-06-21 19:05:03

Radiation protection?

Barring that, short fast burn through the belts, then slow cruise to the Moon...

Just a thought.

Come on, if space tourism is predicated on a space hotel (all the orbital guru's basically say the only way people are going to shell out and suffer in a cramped tin can to space is if they have something waiting for them on the other end), then heading off to the Moon is nothing more than a giant hotel RV.

GCNRevenger · 2005-06-22 07:57:57

"short fast burn through the belts"

With that big flimsey sail? The thing would crumple around your ship.

The belts took up to a few hours for Apollo to pass through them, and that was cooking at a pretty high speed perpandicularly. A rocket burn to raise your orbit out of them isn't practical, since you might as well not bring the sail at all if you are making that big of an altitude change.

Six months without gravity, just to get to Lunar orbit where there is more no-gravity, and maybe to get down to the surface where there is only a little-bitty-bit of gravity... and then to go home after all that, would decondition hardcore ex-military professional astronauts. What would it do to civilians?

And frankly, six months is a long long time for a cruise, to be stuck in that little light-as-possible tin can. Too long.

Commodore · 2005-06-22 13:36:34

Maybe in the distant future when half kilometer asteroids are hollowed out, spun for gravity, decked out with closed loop life support, and used as nomadic space colonies that make orbital "port calls" once every couple of years.

Even then, it would be much quicker to take a shuttle to and from it.

GCNRevenger · 2005-06-22 19:58:42

Nope.

The mass of a major rock like that would be way, way beyond the reasonable payload limit of a solar sail. And the inertia of the rock being so great, you couldn't rotate the thing to make big solar sail angle changes to navigate.

flashgordon · 2005-06-23 16:22:41

alright,

however, I have now come up with an insight where Solar Sails 'will' come into play in the human near term future!

They will be the sport of the future; we will race them to see who gets to the outer rim faster, or who gets around the solar system from the 'outside lane' fastest. We'll have our solar sails coming in all kinds of shapes, colors and pictures; we'll have camera's on them which will always at least have a nice view of the galactic arm and nearby stars(and maybe even a comet or two).

We'll see who can build the biggest solar sails!(this should get avengers goat!)

Besides all that money building, the winners maybe tempted to cross the gulfs of space to send scientific instruments to nearby stars(proxima centeury and mabye even the recent fifteen light year distant star with a giant waterworld planet; now, that should have some different lifeforms on it!)

GCNRevenger · 2005-06-23 17:19:42

Nah, because you would know who would win before the race ever started. Just calculate the mass and divide by the area of the sail.

We are a long, long way from making a probe reliable enough for long-range interstellar reconisance.

Fledi · 2005-06-23 17:25:22

Nah, because you would know who would win before the race ever started. Just calculate the mass and divide by the area of the sail.

I guess this is what makes the race affordable after all, that you actually don't have to build the hardware.

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