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[sluissa]

*cough* http://en.wikipedia.org/wiki/Nuclear_thermal_rocket

Just to be clear, Nuclear-thermal engines on spacecraft doesn't refer to a fission reaction,
but rather some radioactive matter decaying in a water tank, running a turbine, running an ion engine.
It's what we use on deep space probes, that gets too far from the sun to run on solar panels, like the voyager missions.
!! Science !!

That would actually be an ion engine with a radioisotope thermoelectric generator or a traditional nuclear reactor as in the cancelled Project Prometheus. In your case it's not actually the nuclear material that is directly propelling the craft, it's just generating electricity.

The NERVA rockets were actually quite successful, but ended up the casualty of politics and budget cutting. (Imagine, we could have been on Mars in the 80s, if not for Nixon.) There was also, if I remember correctly a plan to build jet engines off of a similar principle, but that was canned pretty early as they realized it'd leave a trail of radioactive exhaust wherever it went. NERVA probably also had similar problems, but given that it wouldn't spend much time in the atmosphere, the benefits were likely to outweigh the risks as long as you launched away from populated areas. Still not sure if it would pass as viable today, but back when we were doing tons of atmospheric testing anyway, I doubt anyone cared.


Edit: took a while and got ninja'd sorta, but oh well.

[ank]

Oh, I stand corrected... I did write burning science...
I love being wrong and learning something new!
And this is way more awesome than the thermopile radioisotope shit.

[alway]

but given that it wouldn't spend much time in the atmosphere, the benefits were likely to outweigh the risks as long as you launched away from populated areas. Still not sure if it would pass as viable today, but back when we were doing tons of atmospheric testing anyway, I doubt anyone cared.

You wouldn't launch with it, you launch with conventional rockets and use it in space. It wouldn't be used in-atmos.

[LoSboccacc]

sadly we still are limited by newton law, so to obtain force you need to propel something out of the other side of the rocket.

with two exception (that I know off, I'd like to be proven wrong as the topic fascinates me):
using solar wind or climbing the solar magnetic field.

[Rose]

Solar winds still involve newton's laws. Light itself has a mass, that can push you.

As for the second, I presume it's bollocks.

[LoSboccacc]

Solar winds still involve newton's laws. Light itself has a mass, that can push you.

As for the second, I presume it's bollocks.

yes but solar wind mass is a mass you need not to carry with you from ground to space

the second is real, http://en.wikipedia.org/wiki/Electrodynamic_tether but the power is soooooooo low

[scriver]

Spoiler: Recent Kerbal Sociological Research Shows Wings are For Ksissies (click to show/hide)

In other news, public support for the Space Programme recently increased with +40%, +75% "if there will be more explosions" promised citizens.

[kaian-a-coel]

Solar winds still involve newton's laws. Light itself has a mass, that can push you.

here are the cries of a million physicians, before being suddenly silenced:
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH!
Light has a mass of exactly 0. That's why it goes to lightspeed by the way. Because Einstein.

But no mass does not mean no energy. There is an energy transfer when light hit you, and therefore a force is applied. But it's not exactly newton.

[LoSboccacc]

Light has a mass of exactly 0. That's why it goes to lightspeed by the way. Because Einstein.

there is some bug in current equations when you put mass at 0, because it works for modelling their speed but it fails to explain the photon emission effect - in some way: I've not understood fully the problem and I can't find references now because I can't remember the magic words to put in google.

[andrea]

if I remember correctly, light has no mass, but it has momentum. which is why it can push you.

[Vactor]

Solar winds still involve newton's laws. Light itself has a mass, that can push you.

here are the cries of a million physicians, before being suddenly silenced:
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH!
Light has a mass of exactly 0. That's why it goes to lightspeed by the way. Because Einstein.

But no mass does not mean no energy. There is an energy transfer when light hit you, and therefore a force is applied. But it's not exactly newton.

Solar Wind is not light, it is electrons and protons being expelled from the sun.  Solar sails could ride the Solar Wind, or they could ride the electromagnetic radiation from a Star, via radiation pressure, or a combination of both.  You could also point a laser at a solar sail and push it, again using radiation pressure.

-edit this post is in support of kaian, not in argument

[majikero]

Yes, light has mass. That's how the universe was created.

First, there was light. Then the universe collapsed and imploded. What remained is light given form that's why each particle in the universe has a shadow. Also explains why the shadow worlds what to destroy the universe and why magical girls are needed to stop them.

On topic, where can I get this and how much? Also whats the minimum specs, don't want my computer to explode as well.

[sluissa]

but given that it wouldn't spend much time in the atmosphere, the benefits were likely to outweigh the risks as long as you launched away from populated areas. Still not sure if it would pass as viable today, but back when we were doing tons of atmospheric testing anyway, I doubt anyone cared.

You wouldn't launch with it, you launch with conventional rockets and use it in space. It wouldn't be used in-atmos.

I kind of assumed it'd be used for launch as well, I mean, the plan for Nuclear pulse engines was also to launch them from the ground with a nuclear blast. (Or at least still within the atmosphere.) I suppose you could send it into space in chemical rockets, but geeze... it'd be heavy.

From Project Orion(Wikipedia):

But the main unsolved problem for a launch from the surface of the Earth was thought to be nuclear fallout. Any explosions within the magnetosphere would carry fissionables back to earth unless the spaceship were launched from a polar region such as a barge in the higher regions of the Arctic, with the initial launching explosion to be a large mass of conventional high explosive only to significantly reduce fallout; subsequent detonations would be in the air and therefore much cleaner. Antarctica is not viable, as this would require enormous legal changes as the continent is presently an international wildlife preserve.
Freeman Dyson, group leader on the project, estimated back in the 1960s that with conventional nuclear weapons (a large fraction of yield from fission), each launch would cause statistically on average between 0.1 and 1 fatal cancers from the fallout.

It just seemed they weren't as concerned about the side effects of radiation back then, as long as it wasn't radiation from weapons.

I was also under the impression that light was more of a wave than a particle and thus might appear to have mass without actually having any. Also I learn my theoretical physics from the internet, so don't mind me.

[alway]

Keep in mind what the magnetosphere is: http://en.wikipedia.org/wiki/Magnetosphere
It's outside of the atmosphere.

But yeah, 1 to .1 is a pretty tiny number. For example:

The researchers calculated for every 100 million passengers who fly seven one-way flights a year, six of them could get cancer as a result of the radiation exposure from the full-body scans.

But yeah; you wouldn't use them in atmosphere for a number of reasons, radiation only being one.

[LoSboccacc]

On topic, where can I get this and how much? Also whats the minimum specs, don't want my computer to explode as well.

http://kerbalspaceprogram.com/kspstore/

18$

you'll need a decent graphic card (I had this playable with mixed result on a hd4000, a gefroce9400; with maximized setting on a geforce 545 and a geforce gt650 but I don't use that because of heat)

and a fast processor. a 2.5ghz allow you to control medium sized rockets. my core i7 has some issues in running larger ships, but is a mobile cpu, I guess that a proper desktop cpu would be better.