why doesn't nasa...

[Chloraseptic]

use nuclear propulsion as a way of getting further into the solar system?

if i remember correctly, the main reason they don't explore manned missions to the far reaches of the galaxy (apparently that means whatever is past the moon) is because it would take so long to get there. wouldn't nuclear propulsion if applied correctly get the job done?

i apologize ahead of time for not doing any research on it, i assume nasa has experimented or at least researched on it, but i figured you guys would know more than anyone i know and it'd save me a whole helluva lot of time.

 

[Mday]

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

 

[Peter]

Point is, as long as you're propulsion driven, you need to propulse MATTER out your rear end so the counterimpulse drives your vessel forward.
Nuclear fission sure provides a lot of heat from tiny amounts of stationary matter, but then what?

 

[Fencer128]

I think you're missing the big point. With the *odd* explosion occuring every now and then, do we want (I don't!) to send nuclear reactors up into space on the back of a rocket?

Really, really bad idea.

Andy

 

[Smilin]

Originally posted by: Fencer128
I think you're missing the big point. With the *odd* explosion occuring every now and then, do we want (I don't!) to send nuclear reactors up into space on the back of a rocket?

Really, really bad idea.

Andy

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

 

[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

 

[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.

 

[Fencer128]

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.

Hi,

Thanks, I'm sure it's been done - but I don't think it's the "norm" or even "regular".

Cheers,

Andy

 

[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.

 

[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.

 

[Spacehead]

Discover magazine comes thru again 🙂 I just read an article about this today.

One of the problems is you still need to pack away your fuel for the trip. You'd need alot of nuclear material to get outside the solar system.
You also need radioactive shielding for manned missions.

A fusion ramjet was one of the most promising designs, but the technology isn't there yet.


Another new design:
The Planetary Society is planning on testing it's laser sail this year or next.

 

[wacki]

When I was a undergrad a General gave a speech at my school. I asked him about nuclear propulsion and he told me that nuclear material in space had been banned. But nuclear decay (as for batteries go) are okay, just not fisal or fusal products.

Don't know how much truth there is to that, but considering I heard it from a General standing 3 feet away from me, i'm sure its accurate.

 

[Shalmanese]

The problem is that the maximum speed attainable is limited by how fast you can push propellent out the other way. Your inherently limited to low speeds with chemical rockets since theres a limit to how fast you can blow things up. But they tend to have huge thrusts which is good for getting out of a gravity well. Nuclear is the opposite, its very low thrust but you can push the fuel out very, very fast. Thus, its more of an interplanetary fuel system.

 

[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.

 

[dmw16]

The reason is totally because people dont want to launch that amount of nuclear material into space. People protest the satellites and such that use nuclear material for fuel, but that amount is peanuts compared to enough to travel decent distances. Fusion would be a great option if they could figure that one out, because we launch hydrogen up there all the time as it is. And it only presents a danager to those in close proximity to the ship.
-doug

 

[sao123]

The most definate thing that must be acoomplished is to understand the vector fields that exist in every unit of space from all natural forces. This will allow us to accomplish interstellar travel by...

1) Allowing us to find a way around inertia.
2) Take advantage of these natural vector fields for high speed propuslion. (The vector fields i am speaking of are:
Gravity, Electrical, Magnetic, High energy photons, and the existence of space itself.
3)Given that light speed velocity travel, probably cannot happen...so...We need to find & harness a vector field which bends the fabric of the space continuuom through a medium (SP) so that travelling between 2 distant areas is shortened.

 

[titanmiller]

I remember watching a show on the discovery channel once that said the US acctualy detonated a nuclear bomb in space. At the time I was a bit skeptical, have any of you heard anything about this.

 

[nboy22]

one reason is, because, think of why we don't send up ALL of our nuclear waste and throw it into space.., the reason is, because if an explosion happens, radioactive matter everywhere.. but that's only one out of a few.. or else it wouldn't be here on earth if we had fool proof non-explosive ships.. lmao

 

[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.

 

[sgtroyer]

Shalmanese,

Yes, of course you're right. It's a valid approximation most of the way up to c, but I should have been explicit.

nboy 22,

Beyond the danger of sending up our nuclear waste, there's the cost. We have thousands of tons of waste, and it's just too expensive to send heavy things up into space.

 

[Cadaver]

Originally posted by: titanmiller
I remember watching a show on the discovery channel once that said the US acctualy detonated a nuclear bomb in space. At the time I was a bit skeptical, have any of you heard anything about this.

I've never heard this, and a Google search turned up nothing.

 

[RossGr]

Originally posted by: sgtroyer
Shalmanese,

Yes, of course you're right. It's a valid approximation most of the way up to c, but I should have been explicit.

nboy 22,

Beyond the danger of sending up our nuclear waste, there's the cost. We have thousands of tons of waste, and it's just too expensive to send heavy things up into space.

Actually I think your approximation begins to break down as soon as you reach an appriciable fraction of c, say greated then .1, by the time you reach .5 c it is totally off. Newtonian Physics results from a linear approximation to the taylor series expansion of the Gamma term in Relativity. This approximation is good only as long as (V/C)<< 1 .

In general such approxicmations are good only as long as you are less the .1, much after that they lose accuracy fast. For example, check the period of a pendulum against the common formula when the angle of swing is 45deg. (This common formula relies on a small angle approximation)

 

[Spacehead]

Originally posted by: titanmiller
I remember watching a show on the discovery channel once that said the US acctualy detonated a nuclear bomb in space. At the time I was a bit skeptical, have any of you heard anything about this.

Did a Google search on "united states nuclear detonations" & came up with these links, among others.
http://www.fas.org/nuke/guide/usa/nuclear/209alpha.pdf
http://nuketesting.enviroweb.org/hew/Usa/Tests/

I didn't see anything about a detonation in space but i didn't go thru an exaustive search either. Might of been a high altitude detonation.





Even with nuclear prepulsion, as it stands today, their only talking about hitting about 10-12% of the speed of light. Pretty fast but still takes about 40-50 years just to get to our nearest star(Proxima Centauri, not our Sun).

 

[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.

 

[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