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Japan sets sail for Venus with solar-powered space yacht - Comments

Richard Dawkins's Avatar Comment 1 by Richard Dawkins

I remember being inspired by this when I first read it as a futuristic suggestion in a book by Arthur C Clarke. I don't know whether it was his idea originally, but what a visionary that man was.

Richard

Sat, 01 May 2010 12:41:00 UTC | #464534

Steve Zara's Avatar Comment 2 by Steve Zara

It's such an exciting technology if it can be made to work. It may even be a way to travel between the stars, as a sail can perhaps be propelled by a laser that stays behind: the engine doesn't need to be carried in the spacecraft.

Sat, 01 May 2010 12:45:00 UTC | #464538

TNathan's Avatar Comment 3 by TNathan

Venus? How can a solar sail work if we are not traveling away from the sun? Don't tell me this thing can "tack into the wind"?

Sat, 01 May 2010 12:49:00 UTC | #464539

SaintStephen's Avatar Comment 5 by SaintStephen

Happy Saturday Richard! May Day 2010!

P.S. Didn't Clarke write some kind of deism-riddled book about space travel?

Give me a minute... the name will come to me.

;-P

Sat, 01 May 2010 12:51:00 UTC | #464541

Quetzalcoatl's Avatar Comment 4 by Quetzalcoatl

Richard Dawkins-

Arthur C Clarke was one of the first to write about them in science-fiction but not the first to my knowledge. I think the original idea of using photons to provide momentum was put forward in the twenties.

Sat, 01 May 2010 12:51:00 UTC | #464540

Quetzalcoatl's Avatar Comment 6 by Quetzalcoatl

SaintStephen-

You're thinking of the Rama series of books.

Sat, 01 May 2010 12:53:00 UTC | #464542

Quetzalcoatl's Avatar Comment 7 by Quetzalcoatl

TNathan-

Venus? How can a solar sail work if we are not traveling away from the sun? Don't tell me this thing can "tack into the wind"?


The wind being the pressure from the light, then yes, that's exactly how it works.

Sat, 01 May 2010 12:55:00 UTC | #464545

SaintStephen's Avatar Comment 8 by SaintStephen

Rendevouz With Rama was a great book, but I'm DEFINITELY thinking of that other one... what was its name?

A movie was made about it... some strange, eccentric English director... Evolution was one of the main themes...

Sat, 01 May 2010 12:56:00 UTC | #464546

Quetzalcoatl's Avatar Comment 9 by Quetzalcoatl

SaintStephen-

2001: A Space Odyssey?

Sat, 01 May 2010 12:58:00 UTC | #464547

Quetzalcoatl's Avatar Comment 10 by Quetzalcoatl

Steve Zara-

Personally I can't see it being used for interstellar travel, it would be very slow, and the practicalities of the propulsion in interstellar space, well away from any other light sources, would be prohibitive. As a means of getting around the inner system though it would be perfect.

Sat, 01 May 2010 13:00:00 UTC | #464548

Lapithes's Avatar Comment 11 by Lapithes

I'm slightly confused as I thought it were protons (solar wind, I think) that gave comets their tails, not photons.

Sat, 01 May 2010 13:00:00 UTC | #464549

SaintStephen's Avatar Comment 12 by SaintStephen

10. Comment #485333 by Quetzalcoatl on May 1, 2010 at 2:00 pm

2001: A Space Odyssey?
Yes! Thank-you Quetz.

How could I possibly have forgotten.

Sat, 01 May 2010 13:02:00 UTC | #464551

Steve Zara's Avatar Comment 13 by Steve Zara

Comment #485333 by Quetzalcoatl

It wouldn't be slow. As I mentioned, you could leave a huge laser behind in the solar system. That could accelerate a spaceship to a significant fraction of the speed of light. Robert Forward has written sci-fi using this idea. Whether it is practical or not is another matter.

Comment #485324 by TNathan

To travel towards the Sun you need to reduce your orbital velocity. To do that you tilt the solar sail to get a net braking force.

Sat, 01 May 2010 13:04:00 UTC | #464552

Richard Dawkins's Avatar Comment 14 by Richard Dawkins

Personally I can't see it being used for interstellar travel, it would be very slow, and the practicalities of the propulsion in interstellar space, well away from any other light sources, would be prohibitive. As a means of getting around the inner system though it would be perfect.
I may have misremembered Clarke, and I must confess that I now don't understand the point. But my memory is that he said something like the following. Although acceleration would be slow, given enough time to build up speed the sail could get up to colossal speeds and might constitute the best hope for interstellar travel. The more I think on that, the less plausible it sounds, and I can't remember which book it was in, to look it up. I'll try and find it. I don't think it was fiction. Probably one of his books of fact-based speculation about the future. And I think he was talking of sails many miles across.
Richard

Sat, 01 May 2010 13:06:00 UTC | #464554

Quetzalcoatl's Avatar Comment 15 by Quetzalcoatl

Steve Zara-

Sorry, I meant if relying on the sun alone rather than a laser for propulsion, should have been clearer on that.

The laser is an interesting idea, I'll have to look up the fiction on it, but there would be a lot of practical issues. Not to mention the fact you would need a laser per ship, and building a laser capable of working over that kind of distance would be difficult.

Sat, 01 May 2010 13:10:00 UTC | #464555

Shiva's Avatar Comment 16 by Shiva

Comment #485337 by Steve Zara on May 1, 2010 at 2:04 pm

To travel towards the Sun you need to reduce your orbital velocity. To do that you tilt the solar sail to get a net braking force.


Now, that's science! :)

Sat, 01 May 2010 13:11:00 UTC | #464556

mmurray's Avatar Comment 17 by mmurray

There is a site here explaining solar sail tacking.

http://www.ugcs.caltech.edu/~diedrich/solarsails/intro/tacking.html

I guess with boats you play off the force from the wind versus the force of the water on the keel whereas in this case you are playing off the solar force on the sail and the gravitational force.

I wonder if interstellar pirates with solar sail ships are approaching to take Stephen Hawking away ?

http://www.guardian.co.uk/science/2010/apr/30/stephen-hawking-right-aliens

Michael

Sat, 01 May 2010 13:22:00 UTC | #464560

chawinwords's Avatar Comment 18 by chawinwords

. Comment #485319 by Richard Dawkins on May 1, 2010 at 1:41 pm
avatarI remember being inspired by this when I first read it as a futuristic suggestion in a book by Arthur C Clarke. I don't know whether it was his idea originally, but what a visionary that man was.

Richard, being only a bit older than you, I too grew up with the imaginations of Asimov, Heinlein, and Clarke.

I had hope to live long enough to see mankind walk the dunes of Mars and explore the ocean depths of Jupiter's moons.

Mankind could have accomplished the dreams, but alas, too many stupid wars and religious regressions (including religious insanities). Those who can only look inward lose their outward reaching visions.

Sat, 01 May 2010 13:47:00 UTC | #464563

JamesR's Avatar Comment 19 by JamesR

Nasa sent up a few solar sail experiments and I tink they all failed to deploy. Maybe malfuntions maybe it jsut isn't feasable. I checked Nasa website and no luck. I can't imagine that anyone would venture to experiment on this if all previous attempts ended in failure. So maybe something is going on that is real?

You know really it wouldn't be hard to test this solar sail idea from the Int.Space station. Just have someone go out and fly a solar kite. End this once and for all. And on the cheap.

Actually I never have understood this. Light doesn't have mass so how can we expect it to move anything at all? Also as noted above, maybe those solar sails worked perfectly but it is just a bad idea.

Sat, 01 May 2010 13:47:00 UTC | #464564

Steve Zara's Avatar Comment 20 by Steve Zara

Comment #485349 by JamesR

Light has no rest mass, but it has energy and so it has momentum. It is that momentum that is transferred to the solar sail. Light can't slow down, so the momentum transfer results in the light having reduced energy, and so reduced wavelength - it gets red-shifted.

Sat, 01 May 2010 14:05:00 UTC | #464565

Quiddam's Avatar Comment 21 by Quiddam

Cordwainer Smith wrote The Lady Who Sailed the Soul in 1960 about 4 years before Clarke's Sunjammer I don't know who had the idea first, but I don't think it was either of them.

Light sails work by a combination of solar wind (charged particles) and radiation pressure. The challenge is to get completely outside the atmosphere. The space station is too low for a kite

[edit]Carl Wiley published an article Clipper Ships of Space in the May 1951 issue of Astounding Science Fiction.

Then in May 1951 the leading SF magazine of its time, Astounding Science Fiction, published a detailed account of how solar sails could be assembled in orbit and used for space travel. The account was a nonfiction article, "Clipper Ships of Space," by an engineer named Carl Wiley. Given that he published his article in a science fiction magazine, and wrote it under a pseudonym (Russell Saunders), Wiley himself apparently feared that respectable scientific circles were not yet ready for the solar sailing concept. It took another seven years for a paper on solar sails (by Richard Garwin) to appear in a professional journal


http://www.planetary.org/programs/projects/innovative_technologies/solar_sailing/science_fiction.html

Sat, 01 May 2010 14:07:00 UTC | #464566

God fearing Atheist's Avatar Comment 22 by God fearing Atheist

Interstellar solar sails:

I assume the space craft spirals out from one solar system until it reaches the "Lagrange point" between the two solar systems and then spirals into the target system. Given I think the nearest star is about 4 light years away, at the "Lagrange point" both stars will be tiny dots and the solar force bugger all.

The solar force (hence acceleration) will be proportional to the inverse square distance from the star. The gravitational vector will be inversely proportional to the square of the distance from each star, so near one star the reduction in solar force with distance will be proportional to the reduction in gravity, but the "excess force" necessary to spiral out, will also be decreasing inversely proportional to the square of the distance. Where stat-craft-star line up, the gravity of one star will cancel out the gravity of the other (on the craft) until it is zero at the "Lagrange point", Where craft-star-star line up, the sail will be opposed by the gravity of both stars. I'm not even going to try to write the equation for that, but writing a simulation (2 stars, one craft) might make an interesting maths/physics/computer science project for 1st year undergrads.

EDIT: And I suppose the two stars in the scenario will be orbiting around each other otherwise the system is unstable (or the gravity of multiple stars has to be accounted for)

Sat, 01 May 2010 14:20:00 UTC | #464569

bladesman's Avatar Comment 23 by bladesman

I'm reading The Mote In God's Eye by Larry Niven & Jerry Pournelle at the moment, and the alien Moties send out an interstellar probe using just the solar sail and left-behind-laser combo mentioned above. Damn good read.

Sat, 01 May 2010 14:42:00 UTC | #464575

deftmasterofdisguise's Avatar Comment 24 by deftmasterofdisguise

What can guarantee the sails to be fail-safe when they are so thin? For example, will they be prone to catching fire, or prone to ripping due to random space objects piercing the sail?

Sat, 01 May 2010 15:12:00 UTC | #464580

Stafford Gordon's Avatar Comment 25 by Stafford Gordon

Breath-taking stuff.

Sat, 01 May 2010 15:20:00 UTC | #464582

Quiddam's Avatar Comment 26 by Quiddam

>>will they be prone to catching fire
No

>>prone to ripping due to random space objects piercing the sail?
Yes

Sat, 01 May 2010 15:46:00 UTC | #464595

bluebird's Avatar Comment 27 by bluebird

Wow, mid-May is gonna rock with the launch of this "space yacht" and STS-132 :D

"We have lingered too long on the shores of the cosmic ocean. It's time to set sail for the stars"...
http://www.planetary.org/programs/projects/solar_sailing/

Sat, 01 May 2010 15:49:00 UTC | #464596

Damien White's Avatar Comment 28 by Damien White

As I recall the original 'Planet Of The Apes' novel by Pierre Bouille used this concept too.

Unfortunately this is one instance where science fiction and actual science probably can't meet. When I think of an interstellar solar sail trying to get through the Oort Cloud in one piece I start thinking that the idea might be unfeasible.

Sat, 01 May 2010 16:07:00 UTC | #464602

Nunbeliever's Avatar Comment 29 by Nunbeliever

Is this article a joke???

Sat, 01 May 2010 16:37:00 UTC | #464615

Cartomancer's Avatar Comment 30 by Cartomancer

Interestingly enough the island of Tanegashima has always been associated with alien encounters and futuristic technologies by the Japanese. In 1543 it was the site of a first contact event with traders from Portugal - the first Europeans to set foot on Japanese soil, and coincidentally the first to introduce black powder firearms to the Japanese. For many decades later the Japanese still called their pistols and rifles tanegashima after the place.

Sat, 01 May 2010 17:15:00 UTC | #464629