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Kapton was used extensively in the Apollo program. It was used as thermal insulation on the Lunar Module. During the return journey from the Moon, Apollo 11 astronaut Neil Armstrong commented that during the launch of the Lunar Module Ascent Stage, he could see "Kapton and other parts on the LM staging scattering all around the area for great distances."
The NASA Jet Propulsion Laboratory has considered Kapton as a good plastic support for solar sails because of its long duration in the space environment.
.... the solar sail-propelled vehicle will build up speeds that rocket powered vehicles would never be able to achieve. Such a vehicle would eventually travel at about 56 mi/sec (90 km/sec), which would be more than 200,000 mph (324,000 kph). That speed is about 10 times faster than the space shuttle's orbital speed of 5 mi/sec (8 km/sec). To give you an idea how fast that is, you could travel from New York to Los Angeles in less than a minute with a solar sail vehicle traveling at top speed.
If NASA were to launch an interstellar probe powered by solar sails, it would take only eight years for it to catch the Voyager 1 spacecraft (the most distant spacecraft from Earth), which has been traveling for more than 20 years. By adding a laser or magnetic beam transmitter, NASA said it could push speeds to 18,600 mi/sec (30,000 km/sec), which is one-tenth the speed of light. At those speeds, interstellar travel would be an almost certainty.
Originally posted by Damsel
I think the major problem with your theory is that you're neglecting the testimonies that this foil and balsa wood seen at Roswell reported to have only looked comparable to those materials. They was no aluminum foil and there was no balsa wood among the debris. The balsa wood-like material could not be burnt or cut. The foil is typically called "memory metal," since you could crumple it in your hand, then open your hand up and it would unfold itself without any creases.
Originally posted by James1982
Would a solar sail work between stars?
From what I understand a solar sail rides the solar winds, which would carry a craft AWAY from a star. This would work to leave the star the craft came from, but when the craft approached a new star (ours in this case) wouldn't the solar winds work AGAINST the craft, as the winds would be blowing from the direction the craft is traveling (towards our star) slowing it down, or perhaps turning it around and shooting it back out into interstellar pace?
In other words, a solar sail only works to move a craft away from a star, not towards it. Just as you couldn't use a solar sail to travel from Pluto to Earth, because you'd be working against the winds, surely it would be impossible to enter a solar system and travel towards the inner planets under power of a solar sail, as the new star's winds would just blow you away, right?
I'm no expert on this kind of stuff so I'm curious what others think. It's a cool idea for sure, perhaps roswell was a solar sail craft, but it came from aliens living on Mercury instead of aliens living outside our solar system.
Originally posted by James1982
reply to post by nv4711
Either way it's still being "pushed" by a force that is coming FROM a star, so you can only travel in the direction that force is moving, which is outward from the star, not towards it.
If you are approaching our star from another solar system, once you get close enough the photons from our sun will start pushing AGAINST the craft in the opposite direction, right?
The most common material in current designs is aluminized 2 µm Kapton film. It resists the heat of a pass close to the Sun and still remains reasonably strong. The aluminium reflecting film is on the Sun side. The sails of Cosmos 1 were made of aluminized PET film (Mylar).
Originally posted by Druscilla
reply to post by nv4711
I'm of the opinion that solar sails might be economical means for craft to scoot about inside a solar system, but, as means to go interstellar, the lengths of time involved in travel from point A to point B would, at least for humans, make the proposition a no-go.
Suspended animation, plus an on-board nuclear powered or equivalent laser to constantly fire into the sail for continued push once outer solar system winds are essentially ineffective would help matters, but, cost, time, feasibility and the sheer immensity required of any "practical" solar sail would seem to make solar ailing a fun idea, but, impractical compared to something like a fusion jet propelled craft.
Originally posted by ImaFungi
reply to post by Druscilla
how long would the fusion jet engine be able to be used for before its energy was spent?
Originally posted by nv4711
All I can say is that NASA and JAXA beg to differ. They think it is a very good contender for interstellar flight.
Originally posted by Druscilla
Originally posted by nv4711
All I can say is that NASA and JAXA beg to differ. They think it is a very good contender for interstellar flight.
Certainly; for robots.
Anything, at this point, for robots, is an excellent solution if it proves workable and cost effective.
If there were celebrity American style Football kickers available that could put enough spin and force into a kick such they could serve as a launch platform alternative, if such alternative were cost competitive with other solutions, NASA, JAXA, ROSCOSMOS, any and every space agency would be signing up football kickers.
With robots, any solution that's cost competitive compared to others is a viable solution.
Biological cargo?
Sentient Biological Pilots/crew?
That's a different story unless you add in the suspended animation thing.
We're talking sub-C travel, and pretty much anywhere, from a human lifespan and functionality perspective is a lifetime away at the velocities we're looking at for Solar Sails, Fusion Jet, or any currently proposed solutions.
Originally posted by winofiend
Point an arrow into the dark sky. Fire.
And hit a bullseye thousands of years away.
Plausible if we live in a straight line to the next life forms in space. Not so much if you look around us.
Originally posted by nv4711
Druscilla, I wasn't talking about whether or not a solar sail powered craft is suited for manned space travel. I was talking about the idea that the ominous "aluminum foil" could have been a solar sail from an unmanned space probe, launched by an alien civilization perhaps tens of thousands of years ago. It crashed on Earth, and the pieces of the solar sail littered the fields of Roswell.
Just imagine what will happen on a distant planet, a few ten thousand years from now, when the Voyager probe crashes there. Maybe its a relatively young Planet, the people there just mastered nuclear power only 3 years earlier, they are making the first baby steps with radio astronomy, jet air planes just came into service and space travel is science fiction.
We send out these space probes - it is plausible that other civilizations would do the same. Forget about how long it would take to get anywhere, that wasn't the point of Voyager either, it is about sending a "message in a bottle".