why doesn't nasa...

[Shalmanese]

So what your effectively saying is that there is a 5th form of energy apart from the Conventional Gravity, ElectroMagnetism, weak and strong nuclear force. Furthermore, this mystical 5th energy field is large enough to power space ships but subtle enough to escape the intense probing of thousands on physicists into the structure of space-time yet, when discovered, will be easy enough to utilize so that you can plop them onto every space cruiser?

Excuse me for being sceptical but this is beginning to sound a lot like most perpetual motion machine descriptions I have seen.

 

[Jeff7]

Originally posted by: sgtroyer
Jeff7,

You're exactly right. 300e6 m/s divided by 10m/s^2 is 30e6 seconds. Roughly a year to top out just under light speed. Then you need another year to decelerate, also at 1G. In space there are no brakes, the only way to slow down is to turn 180 degrees and fire the rockets backwards.

Only a year? Huh, I thought it'd take longer than that.

Originally posted by: Shalmanese
sgtroyer: Relativity makes the math a bit more difficult than that.
sao: What do you mean by vector fields? We are already using gravitational fields to get a boost, as far as I am aware, the others would be too trivial in deep space to bother with.

Relativity messes up everything. Can't the Bush administration just make a new Patriot Act to reverse that law?
The whole relativity thing is just weird - 2 obeservers, one still, one moving. Each observer thinks the other one is the one moving, and that the moving one's clock is running slower. And it works both ways. If I can really concentrate on it awhile, it almost makes sense, briefly. If Morbo from Futurama was here, he'd probably comment about puny human brains or something...

Originally posted by: Fencer128

Originally posted by: sao123
shalmanese.
I dont know exactly how to explain it because it is an abstract scientific concept but....

I believe there are more natural vactor fields in existence than just gravity, electric, and magnetism.
Much the same way that an electric field exerts no force on anything, until a charged nonstationary point particle is placed within it...and gravity has nothing to pull until a particle with mass is placed within its field... There must be some other type of natural high energy vector field (that we have not yet discovered) that when the right type of particle is placed within it a force is created and motion occurs...

The key would then to be able to create a localized field, and then use it for propulsion. Similar to the Warp Field theory.

Where is the evidence that has led you to believe in the existance of other vector fields? I'm trying to see if you're coming from a logical progression - or whether it's just wishful thinking?

Cheers,

Andy

Don't know if it's something like what you're looking for; I read something in Scientific American not too long ago (and lets see how good my memory is) about multi-verses - groups of Universes, that are being pushed apart by a force, and are doing so faster than the speed of light, relative to each other. It was such that, even if other Universes did exist, we would simply be unable to ever reach them, no matter how fast we travelled, nor how long we would continue at that speed, like they were separated by some uncrossable gulf. Sort of like an anti-gravity. I envision it as, a black hole is a downward sinkhole in spacetime, this anti-gravity is an upward bowing, pushing things away.

Originally posted by: Shalmanese
So what your effectively saying is that there is a 5th form of energy apart from the Conventional Gravity, ElectroMagnetism, weak and strong nuclear force. Furthermore, this mystical 5th energy field is large enough to power space ships but subtle enough to escape the intense probing of thousands on physicists into the structure of space-time yet, when discovered, will be easy enough to utilize so that you can plop them onto every space cruiser?

Excuse me for being sceptical but this is beginning to sound a lot like most perpetual motion machine descriptions I have seen.

Our technology is limited, as are we ourselves. I mean, come on, people have some trouble navigating a car successfully - that's mainly a 2-dimensional task. Put humans in space - 3 dimensions. Then try to have them deal with stuff like the fabric of space, other dimensions...we'd probably wind up crashing a spaceship into an asteroid in a time back before we even evolved. Or something like that.
There's still a lot to discover out there; some of it may simply be beyond our present scope of understanding and even imagination.

 

[Peter]

Originally posted by: Jeff7The whole relativity thing is just weird - 2 obeservers, one still, one moving. Each observer thinks the other one is the one moving, and that the moving one's clock is running slower. And it works both ways. If I can really concentrate on it awhile, it almost makes sense, briefly. If Morbo from Futurama was here, he'd probably comment about puny human brains or something...

That one's easy to resolve. The one who is ACTUALLY moving experiences acceleration. It can both be felt and measured, so there's no real dilemma in telling who's moving and who's not.

 

[ClueLis]

Originally posted by: Jeff7

Originally posted by: sgtroyer
Jeff7,

You're exactly right. 300e6 m/s divided by 10m/s^2 is 30e6 seconds. Roughly a year to top out just under light speed. Then you need another year to decelerate, also at 1G. In space there are no brakes, the only way to slow down is to turn 180 degrees and fire the rockets backwards.

Only a year? Huh, I thought it'd take longer than that.

Originally posted by: Shalmanese
sgtroyer: Relativity makes the math a bit more difficult than that.
sao: What do you mean by vector fields? We are already using gravitational fields to get a boost, as far as I am aware, the others would be too trivial in deep space to bother with.

Relativity messes up everything. Can't the Bush administration just make a new Patriot Act to reverse that law?
The whole relativity thing is just weird - 2 obeservers, one still, one moving. Each observer thinks the other one is the one moving, and that the moving one's clock is running slower. And it works both ways. If I can really concentrate on it awhile, it almost makes sense, briefly. If Morbo from Futurama was here, he'd probably comment about puny human brains or something...

The problem is that, according to relativity. It is impossible to the exceed the speed of light. As you approach that speed, your mass increases asymtotically, making it so that no matter how hard you push, your speed will never reach c. You can get very close, but after a while it just becomes inefficient to press farther for small gains.

As for the "Warp field" idea, there are two possibilities. One would be to change the properties of space around a vessel so that it would be possible. The other is the kind of thing you see in Star Trek. The idea would be bend space using gravitational fields and thus propel yourself by altering the dimensions of space. Mind you, both these concepts are impractical at the current time and probably remain so for at least hundreds of years. We haven't even nailed down the fundamental particles responsible for gravity and mass (although there are theories).

Ion drives, since they are so efficient, would pass by a traditional rocket by the time they reach Saturn, so it wouldn't be useful for a jorney to Mars.

 

[Webthug]

Originally posted by: Jeff7

Originally posted by: Mday
it's being tested. their next thing is ion propulsion. and it would still take forever to get to mars.

Yeah, the force they exert was described as being similar to that exerted on your hand by a piece of paper resting on it. Not a good way of speeding up a craft, but it will provide that little bit of force for a long time.

There needs to be some system, assuming it's even possible, to reduce the inertial forces acting on the passengers of a ship, before we can really get anything fast. I unfortunately can't remember enough of my physics math to figure out how long it'd take to accelerate to the speed of light, and keep the forces under 1G...I'll try though.
Assume 10m/sec squared acceleration. Light travels at around about 300,000,000m/sec. I don't think it's as simple as 300,000,000/10; isn't it a trinomial equation here? I just can't remember it anymore.
It'd take a really long time though just to get to that speed. Then there'd be the wait while the ship would decelerate without killing everyone onboard. Even going to the Enterprise's 1/4 impulse speed would take awhile.

Originally posted by: Fencer128

We already do on a regular basis. Not for propulsion but for onboard power.

I was under the impression that very nearly all satellites use solar power for onboard systems. Could you link me to some of these nuclear reactors that go up on a regular basis?

Cheers,

Andy

Satellites that orbit Mars or planets closer to the Sun use solar power; I think that Galileo around Jupiter is nuclear powered - beyond Mars, the sunlight is just too weak to power a satellite, using current solar cell technology anyway, so they use nuclear generators. Not many interplanetary probes are launched though.

Originally posted by: sgtroyer
It's been done. Cassini (which went to Saturn, I believe) had a small nuclear reactor, and it was very controversial. Lots of risk assessment to figure out whether it could come back down and contaminate something. Lots of people were pretty worked up about it.

I don' t think the benefit was lots of thrust, but rather a very small light source of long lasting power.

Ah yes, that controversey. I think that NASA said that the way the (small amount of) radioactive material was contained, it could have survived re-entry without killing everything on the planet, and even better, without spreading any dangerous radiation into the environment. All these people worked up over this...we face a greater threat of nuclear disaster from sources already on the planet, contained in warheads that are designed to cause destruction.

Originally posted by: Smilin
Sorry Andy, no immediate link for you on this. I became aware of it because of some big protests over the launch of this one with a particularly large reactor. I didn't even know we did such a thing but when I was reading the news concerning this one launch I found out that it was far from the first launch of a reactor into space.

I think the Pioneer spacecraft that went out past Jupiter were nuclear powered; both Voyager craft were also nuclear powered.

I am lead to believe that all of the russian satelites put up during the SOVIET era were combined solar/nuclear powered. As for US spacecraft i am not shure.

 

[Shalmanese]

Our technology is limited, as are we ourselves. I mean, come on, people have some trouble navigating a car successfully - that's mainly a 2-dimensional task. Put humans in space - 3 dimensions. Then try to have them deal with stuff like the fabric of space, other dimensions...we'd probably wind up crashing a spaceship into an asteroid in a time back before we even evolved. Or something like that.
There's still a lot to discover out there; some of it may simply be beyond our present scope of understanding and even imagination.

Actually, navigating through space is a relatively easy task. With computers, it becomes trivial. Every space probe we have put up has carefully mapped out its path so as to minimise fuel and maximise travel speed. There are things known as "launch windows" which are the optimum times to launch spacecrafts so as to gain gravitational boosts from as many planets as possible. We have a comprehensive list of launch windows for more than 100 years from the present. Theres no guesswork involved with getting around our solar system anymore.

 

[Jeff7]

Originally posted by: ClueLis

Originally posted by: Jeff7

Originally posted by: sgtroyer
Jeff7,

You're exactly right. 300e6 m/s divided by 10m/s^2 is 30e6 seconds. Roughly a year to top out just under light speed. Then you need another year to decelerate, also at 1G. In space there are no brakes, the only way to slow down is to turn 180 degrees and fire the rockets backwards.

Only a year? Huh, I thought it'd take longer than that.

Originally posted by: Shalmanese
sgtroyer: Relativity makes the math a bit more difficult than that.
sao: What do you mean by vector fields? We are already using gravitational fields to get a boost, as far as I am aware, the others would be too trivial in deep space to bother with.

Relativity messes up everything. Can't the Bush administration just make a new Patriot Act to reverse that law?
The whole relativity thing is just weird - 2 obeservers, one still, one moving. Each observer thinks the other one is the one moving, and that the moving one's clock is running slower. And it works both ways. If I can really concentrate on it awhile, it almost makes sense, briefly. If Morbo from Futurama was here, he'd probably comment about puny human brains or something...

The problem is that, according to relativity. It is impossible to the exceed the speed of light. As you approach that speed, your mass increases asymtotically, making it so that no matter how hard you push, your speed will never reach c. You can get very close, but after a while it just becomes inefficient to press farther for small gains.

As for the "Warp field" idea, there are two possibilities. One would be to change the properties of space around a vessel so that it would be possible. The other is the kind of thing you see in Star Trek. The idea would be bend space using gravitational fields and thus propel yourself by altering the dimensions of space. Mind you, both these concepts are impractical at the current time and probably remain so for at least hundreds of years. We haven't even nailed down the fundamental particles responsible for gravity and mass (although there are theories).

Ion drives, since they are so efficient, would pass by a traditional rocket by the time they reach Saturn, so it wouldn't be useful for a jorney to Mars.

The warp drive, as I understand it, expands space in front of the ship, and collapses it behind, so the ship is sort of squished through space.
Or we need wormhole generation technology, but we don't know much about effecting changes in subspace, much less punching through to it.

Originally posted by: Shalmanese

Our technology is limited, as are we ourselves. I mean, come on, people have some trouble navigating a car successfully - that's mainly a 2-dimensional task. Put humans in space - 3 dimensions. Then try to have them deal with stuff like the fabric of space, other dimensions...we'd probably wind up crashing a spaceship into an asteroid in a time back before we even evolved. Or something like that.
There's still a lot to discover out there; some of it may simply be beyond our present scope of understanding and even imagination.

Actually, navigating through space is a relatively easy task. With computers, it becomes trivial. Every space probe we have put up has carefully mapped out its path so as to minimise fuel and maximise travel speed. There are things known as "launch windows" which are the optimum times to launch spacecrafts so as to gain gravitational boosts from as many planets as possible. We have a comprehensive list of launch windows for more than 100 years from the present. Theres no guesswork involved with getting around our solar system anymore.

Carefully mapped. By scientists with advanced degrees in astrophysics. We'd be fine, just so long as nothing would go wrong. A probe is one thing; a ship with fragile life forms on board could pose other problems - making certain maneuvers might not be possible. I don't know a lot unfortunately about the nature of the radiation belts around Jupiter, but they could be dangerous for life forms passing through them. That would limit how close a ship could get to a planet, and how much gravity assist it would get. I suppose with enough calculations (with computer aid of course) this could be dealt with.

 

[Giscardo]

Originally posted by: Peter

Originally posted by: Jeff7The whole relativity thing is just weird - 2 obeservers, one still, one moving. Each observer thinks the other one is the one moving, and that the moving one's clock is running slower. And it works both ways. If I can really concentrate on it awhile, it almost makes sense, briefly. If Morbo from Futurama was here, he'd probably comment about puny human brains or something...

That one's easy to resolve. The one who is ACTUALLY moving experiences acceleration. It can both be felt and measured, so there's no real dilemma in telling who's moving and who's not.

Not quite so. If you are moving at constant velocity you aren't accelerating. If you were floating through space at 3 times the speed of sound, without slowing down or speeding up, you wouldn't know you were moving. You could see some stars passing by, but you wouldn't know if you were moving or the stars were.

 

[kevinthenerd]

Originally posted by: Mday
it's being tested. their next thing is ion propulsion. and it would still take forever to get to mars.

been there. done that.

My dad invented Aluminum ion propulsion.

 

[kevinthenerd]

Originally posted by: Jeff7
Assume 10m/sec squared acceleration. Light travels at around about 300,000,000m/sec. I don't think it's as simple as 300,000,000/10; isn't it a trinomial equation here?

Relativity, my dear Watson.

 

[Shalmanese]

Carefully mapped. By scientists with advanced degrees in astrophysics. We'd be fine, just so long as nothing would go wrong. A probe is one thing; a ship with fragile life forms on board could pose other problems - making certain maneuvers might not be possible. I don't know a lot unfortunately about the nature of the radiation belts around Jupiter, but they could be dangerous for life forms passing through them. That would limit how close a ship could get to a planet, and how much gravity assist it would get. I suppose with enough calculations (with computer aid of course) this could be dealt with.

Actually, I had a friend who considered doing something like this for his final HS physics project (assuming ideal bodies of course). The problem is not the math, its getting quality data. Even if we impose arbitratry limitations like maximum accelaration or avoidance of radiation (we can just treat radiation like a massless planet that we can't collide with), its still a trivial problem. We were solving these sorts of equations as soon as we got high quality telescopes and even before.

 

[nyarrgh]

Not quite so. If you are moving at constant velocity you aren't accelerating. If you were floating through space at 3 times the speed of sound, without slowing down or speeding up, you wouldn't know you were moving. You could see some stars passing by, but you wouldn't know if you were moving or the stars were.

that's the point... 3 times the speed of sound? relative to what?
If somebody misreads this... I am actually agreeing with him

Anybody who's interested in relativity should read/listen to Wolfson's lectures
http://www.teach12.com/ttc/Assets/courseDescriptions/153.asp

Then you would find that there's even more things to consider e.g. It might be one year for you, but how long will it be for the people you left behind on earth? and things like that. There's even a chapter on producing power.

 

[tweeve]

I once read that if the technolgy was there we could make a star trek warp drive and it could work.

 

[Fencer128]

Originally posted by: tweeve
I once read that if the technolgy was there we could make a star trek warp drive and it could work.

I can't decide whether that's a really subtle bit of humour or you're deadly serious!?

"If we had the technology - we could use it"



Cheers,

Andy

 

[Zephyr106]

It is hard to find data on exoatmospheric nuclear detonations but the US did conduct some prior to the 1963 Limited Test Ban Treaty:

Prior to entry into force of the 1963 Limited Test Ban Treaty, which prohibits nuclear testing in the atmosphere, in outer space, and under water, U.S. nuclear testing in space disrupted U.S. civilian radio and television signals and crippled some U.S. reconnaissance and communications satellites. Panofsky pointed out that a late 1950s series of small nuclear test explosions in space "generated interference with radio astronomy for a decade."

-from http://www.armscontrol.org/pressroom/2002/mdadvapril02.asp

The purpose of these tests was to explore capabilities for an anti-ballistic missile system. The technical hoopla today is because the modern system effectively "hits a bullet with a bullet", a purely kinetic kill. If you use nukes the X-rays, neutron flux (from a neutron warhead), or mere explosion itself easily destroys incoming warheads. Interestingly, from April 1975 to February 1976, the US had an operational ABM system protecting the Grand Forks ND missile silo fields. The system consisted of Sprint and LIM-49A Spartan ABMs. Congress ordered the system shut down the day after it was declared fully operational on Oct. 1st 1975. The reason given was that the site's radars were too vulnerable to nuclear attack. This data taken from James Norris Gibson's The History of the US Nuclear Arsenal.

Also see the four programs listed here (largest font): http://www.fas.org/spp/starwars/program/complete.htm

The Soviets also had various ABM systems during the Cold War, again utilizing nuclear warheads. Details can be found here:

http://www.fas.org/spp/starwars/program/soviet/index.html

On the subject of nuclear reactors in spacecraft, the benefit is more power for longer duration with smaller volume than chemical batteries. And at long ranges from the sun solar power is impractical and also the arrays take up some room in the rocket when launched. IIRC the Voyager and Pioneer probes had some, as well as the two Viking probes which are now sitting dormant on Mars.

Zephyr