/sci/ - Science & Math

*should stop trying
fuck typo

>>7286494
Why don't you give us reasons as to why its a stupid fucking idea if you're so goddamn adamant?

>>7286507
1. Shock dampeners would be too complex to build and maintain for prolonged period of time, let alone actually construct it
2. Creating a shield able to withstand the nuclear blast without denting for prolonged period of time
3. The acceleration would definitely be uneven and highly uncomfortable, maybe even unsurvivable without some kind of "stasis" mechanism

>>7286513
>3. The acceleration would definitely be uneven and highly uncomfortable, maybe even unsurvivable without some kind of "stasis" mechanism
Just cover yourself in goo while you sleep

>>7286494

Do you have a better idea?

>>7286535
Huge battery of ion engines?
1. We already have the tech, just scale it up
2. Easy to maintain, just replace one engine and keep few spares
3. Power it using nuclear fusion, again, tech we know how to use, just make it usable
4. Smooth ride, easy to change thrust magnitude

>>7286541
This or Deadalus project

>>7286541
>Power it using nuclear fusion, again, tech we know how to use, just make it usable
>nuclear fusion
>tech we know how to use

>nuclear fusion

The concept was demonstrated with chemical explosives sixty years ago, but we can't do it now with nukes?
https://www.youtube.com/watch?v=Q8Sv5y6iHUM

first of all we never had a manned mission to the moon. that should explain the orion very well
https://www.youtube.com/watch?v=NlXG0REiVzE
https://www.youtube.com/watch?v=-2FTZhyuJy8
https://www.youtube.com/watch?v=RH4IvQorjGA

>>7286826
Damn feels like pre 1969 in here!

>>7286494
cons of orions
- Nuclear bombs in space get all the crazies and hippies against you.
- some of the smallest designs still weighed more than all the spacecraft that humans have ever put into space (6000ton irc)
- for in system travel it would be more expensive due to weight and such than sending a chemical rocket
- lightweight radiation shielding is hard.
-requires massive shock absorbers to spread the load out so the human crew is not subjected to repeated 25g acceleration shocks
- cannot be used in earth orbit without seeding the entire magnetosphere with nuclear fission products
- cannot be used in earth orbit without knocking out all satellites with EM pulses
- cannot be used in earth orbit without killing hundreds from increased radiation on the ground
-cannot be used on the ground without destroying itself, would need to be boosted to several thousand metres before orion could take over.

pros
- gets people who want a better use of nuclear bombs on your side
- shortens travel times significantly
- would allow interstellar travel, taking flight times down from 40000 years to 100 or so
- can be used as an easy identifier of popsci fans

Personally I think it is a cool idea, but the sheer amount of additional work and research that need to go into getting it human survivable let alone safe and usable, outwieghs any cost benefits for the next couple centuries.

>>7287059
>Nuclear bombs in space

How does that work?

It's my understanding the bombs are detonated in the atmosphere where pressure can be generated.

When you detonate a nuke in space not much happens because there is no atmosphere to create a pressure wave.

>>7287063
Not the guy you're responding to. Wouldn't you still have the radiation, heat and light?

>>7287086
How much thrust can you generate with radiation heat and light?

Seems like conventional chemical or ion drives would be more efficient. (better specific impulse)

>>7287063

You want to cover the nuke in something that will soak up the heat and turn it into pressure (e.g. water), then use that pressure to drive you.

Alternative answer: Getting out of our air-covered gravity well is the hard part so have the orion drive for getting up to speed then do all the complicated-but-low-gravity maneuvering with chemical rockets.

Only feasible for extremely massive craft. Fission pile would be more efficient

>>7287112
>You want to cover the nuke in something that will soak up the heat and turn it into pressure (e.g. water), then use that pressure to drive you.

Wouldnt it make more sense to go with something like NERVA then?

>Getting out of our air-covered gravity well is the hard part so have the orion drive for getting up to speed then do all the complicated-but-low-gravity maneuvering with chemical rockets.

This was my understanding of how ORION was supposed to work.

>>7286826
Kek, conspirashit

>>7287100
See pic. Nuclear pulse units wouldn't be built like nuclear weapons. They're more like shaped charges that shoot out propellent in one direction, against the pusher plate.

>>7287220
They designed a similar shell for a plasma weapon to use against other ships and space stations.

It was designed to concentrate the impact to achieve penetration rather than spread it evenly for propulsion.

>almost all mentioned negative points only show that the posters don't know shit about nukes, radiation or engineering
Sci confirmed still shit.

>>7287063
the bombs planned for use in this sort of engines were shaped nuclear charge that directed as much of the force towards the pusher plate as possible. you are essentially turning a large percentage of the energy in the nuke to kinetic energy.

the pusher plate is hit with as much of the plasma and such given off by the nuclear blast, the hotter the blast the faster the plasma, and nukes can get quite hot.

>>7287364
Elaborate

anyone remind me why ion drivers are more popular than plasma rockets?
https://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket

my viewpoint is cathode erosion in ion drives sucks hard
while using electricity to accelerate (plasmaized) gases and using magnetic confinement to circumvent the energytime per time cap of chemical reactions and the heat cap on materials seems awesome without relevant drawbacks.

>>7287618
I thought that VASIMR engines were a subtype of ion engines.

https://en.wikipedia.org/wiki/Electrically_powered_spacecraft_propulsion#Ion_and_plasma_drives

They we

>>7287618
>anyone remind me why ion drivers are more popular than plasma rockets?
Scale and development effort.

VASIMR doesn't work. It's a project, not a product. It's not clear that when it does work, it'll have any advantages over any currently-mature devices.

Plasma rockets need to be a certain size to work efficiently, whereas ion thrusters can be tiny. That means they can be hand-built by one person or small teams and tested for thousands of hours at small cost in benchtop vacuum chambers. So this technology was cheap and fast to develop.

>>7287722
the advantage would be that you can be very liberal with how much energy you put into that plasma. if you want you can make it 5 000 000 000 K. if you have the energy. like say you got a nuclear source (fusion or fission).
firing electrons at a neutral gas doesnt do that. and pushing that much energy through the magnet grids also doesnt work (they cant handle it)
So if you wanna get places fast, without caring too much about I_sp, because you have a lot of energy aviable (nuclear), because electromagnetism isnt limited like chemical controlled explosions for energy transfer, VASIMIR type will allow that.
wich would be very useful for manned interplanetar travel.

Realistically speaking, it could work if it was built in space, boosted away from earth before it was turned on.

Problem is, that costs a lot of money and right now we don't have a means of putting stuff into space cheaply or assembling it once it's there.

Perhaps in 20-30 years we might revisit the idea if NASA wants to do an Alpha Centari probe. As others have noted, you can bring the travel time down to a few centuries (perhaps even under 100 years) if you build a big enough engine. Problem is that it's expensive.

Likewise, actually getting it to it's destination would be a bitch as well, and getting something from the craft onto an actual planet would be difficult as well.

There is no point in sending a probe to another star. The nearest star is simply too far away. You'd need to get up to a significant fraction of the speed of light in order to make the trip length tolerable to any degree... but slowing down at the target system means duplicating that fantastic feat. It was technologically and economically challenging enough to do the first part.

The stars are just too far away. We haven't done anything about forming a spacefaring civilization even around our own planet. Attempting a stellar probe is just overblown, unable to be repeated even if it's done once.

Stop dreaming and start planning prudently. Dreams are dumb. Work is the only thing that matters... that and sensible economic exploitation.

>>7286541
>Power it using nuclear fusion
>not just using a fusion plasma thruster

>>7287889
>slowing down at the target system means duplicating that fantastic feat.
Not necessarily. We imagine outer space to be frictionless, but it isn't, at relativistic speeds. The interstellar medium is thin, but it has hydrogen atoms scattered here and there.

The interstellar ramjet isn't such a great idea for getting up to speed, but it would make a fantastic brake. You could even store up propellant while travelling at high speed for decelerating to a full stop.