Project Orion: A discussion of Science and Science Fiction

[YNM]

3 hours ago, kerbiloid said:

4 hours ago, mikegarrison said:

You're saying you think the "350 rem" notation is outside the crew area, not the crew dose.

I mean, it's inside the crew compartment  without additional protection, like a 0.5 cm thick armor floor.

Calculating the ratio of radiation between "top of pusher" vs. the crew area does give a distance ratio from the detonation center of 2:1, which is about what's shown in the pic, so I presume this is the case that the crew area shielding hasn't been included. (although the "top of pusher plate" figure has been calculated with the shielding effect because the top of the pusher plate is not 7 times farther from detonation center compared to the "bottom of the pusher plate" as the radiation ratios would show.)

But yeah, Orion is deffo pretty darn difficult to justify still. Though if we really want to go interplanetary then it won't be doable with merely chemical-reaction rockets.

3 hours ago, Scotius said:

And this here is clearly the best project for car propulsion ever envisioned:

3 hours ago, Scotius said:

Like this?

Have you not seen the Boston Dynamics dog thing ? It's basically that.

Edited January 10, 2021 by YNM

[JoeSchmuckatelli]

4 hours ago, Scotius said:

Like this?

I bet we'll see walking cars on the roads faster than we'll see Orions flying.

...

That's actually a nice idea for a car, and I've seen similar floated for future, larger planetary rovers.

Anyone ever build a working prototype (car, not rover) yet?

[magnemoe]

Interesting idea: Now I don't think you could do the entire compression for an start shot easy and you have variable yield nuclear bombs. 
However it would be very nice for an warship. Then under attack you would both want to evade and fire with rail guns and lasers both who draw lots of power. 
Under intense combat you would also tend to run open loop cooling, in short you dump water after you heated it. 

For civilian use however I don't see much use on an standard orion, on mini-mag it might be relevant again as unlike orion this uses lots of power running its drive and you will burn for much longer as trust is lower. 
 

[JoeSchmuckatelli]

Decelerating an Orion drive ship has always seemed... problematic to me.  Doesn't seem like it would be fun to be on such a ship

[Spacescifi]

50 minutes ago, JoeSchmuckatelli said:

Decelerating an Orion drive ship has always seemed... problematic to me.  Doesn't seem like it would be fun to be on such a ship

 

Nukes of various yields would be needed...especially plenty of low yield ones for rendezvous and docking with other vessels or stations.

 

Might wanna retract solar panels and rad fins on the receiving vessel when the mighty Orion begins blasting to slow down.

[kerbiloid]

The Orion project has two obsolete parts:

1. The pusher plate.
Its purpose is to receive the flow of tungsten ions and reflect it.
As the ions are charged, they can be stopped by an immaterial magnetic field eliminating the problem of the plate damaging.
Also, unlike the solid plate, the field can be adjusted to match varying yield and sudden radial offset of the hit.

2. The full-featured fission nukes.
When they were proposed in 1950s, they were just a by-product of bottomless military arsenals.
Using such propulsion now looks too expensive, both economically and technologically.

Also they cause fission products which is not good.
And their yield set is discrete, you can't adjust the yield to maych the desired thrust.

So, fusion pellets should be used instead. They are potentially cheaper, do not give fallout, can have microscopic yield (so you can change the thrust by changing the burst interval).

To burn the pellets you have to use beams. Photonic, electronic, positronic ones, doesn't matter.
Also they are safe in proliferation sense.  Without a fission primer you can spread them around, and nobody can gather and reuse them.

They still should be ignited behind the ship and cause same tungsten jet, directed forwards, matching the angular size of the pusher plate magnetic trap.

If use the cheapest fuel (LiD), they would produce a lot of neutrons.
This is bad in sense of radiation safety of the crew, materials activation, and needing in beryllium filler between the pellet and the tungsten membrane.

So, like in the on-board reactor, an aneutronic fusion should be used.
The pellets should contain, say,  some hydrazine or hexaborane enriched with corresponding isotopes of nitrogen or boron.

In this case you get almost no neutrons, but a positive tungsten jet and a positive helium ball.
Both get caught and reflected by the magnetic trap.

There is no need in toxic and expensive beryllium in this case, as the filler must be just lightweight, not also neutron-reflective.

Also such pellets would be non-cryogenic, this makes them better also in the storage sense.

[magnemoe]

2 hours ago, Spacescifi said:

Nukes of various yields would be needed...especially plenty of low yield ones for rendezvous and docking with other vessels or stations.

Might wanna retract solar panels and rad fins on the receiving vessel when the mighty Orion begins blasting to slow down.

Not really an problem to get close to an station or other things to dock to, you always do an orbit or two before it anyway. You need secondary engines anyway for fine tuning trajectory. 

Nor is braking, yes you are fireing in the direction you are going but you are not driving into an radioactive cloud, every part of the bomb will go much faster than you after it blows up. 

 

2 hours ago, kerbiloid said:

The Orion project has two obsolete parts:

1. The pusher plate.
Its purpose is to receive the flow of tungsten ions and reflect it.
As the ions are charged, they can be stopped by an immaterial magnetic field eliminating the problem of the plate damaging.
Also, unlike the solid plate, the field can be adjusted to match varying yield and sudden radial offset of the hit.

2. The full-featured fission nukes.
When they were proposed in 1950s, they were just a by-product of bottomless military arsenals.
Using such propulsion now looks too expensive, both economically and technologically.

Also they cause fission products which is not good.
And their yield set is discrete, you can't adjust the yield to maych the desired thrust.

So, fusion pellets should be used instead. They are potentially cheaper, do not give fallout, can have microscopic yield (so you can change the thrust by changing the burst interval).

To burn the pellets you have to use beams. Photonic, electronic, positronic ones, doesn't matter.
Also they are safe in proliferation sense.  Without a fission primer you can spread them around, and nobody can gather and reuse them.

They still should be ignited behind the ship and cause same tungsten jet, directed forwards, matching the angular size of the pusher plate magnetic trap.

If use the cheapest fuel (LiD), they would produce a lot of neutrons.
This is bad in sense of radiation safety of the crew, materials activation, and needing in beryllium filler between the pellet and the tungsten membrane.

So, like in the on-board reactor, an aneutronic fusion should be used.
The pellets should contain, say,  some hydrazine or hexaborane enriched with corresponding isotopes of nitrogen or boron.

In this case you get almost no neutrons, but a positive tungsten jet and a positive helium ball.
Both get caught and reflected by the magnetic trap.

There is no need in toxic and expensive beryllium in this case, as the filler must be just lightweight, not also neutron-reflective.

Also such pellets would be non-cryogenic, this makes them better also in the storage sense.

Agree 100%, we just need fusion power first
Yes its plenty of fusion engine designs, many who are pretty practical, the problem is that they require lots of power to run. 
In short they are electical engines like ion drives except they are much heavier as in 50 ton something and they get an serious ISP boost over an electrical engine because of the fusion process. 

[kerbiloid]

34 minutes ago, magnemoe said:

Agree 100%, we just need fusion power first

What happens earlier: the fusion power or several hundred decommissioned nukes per flight? 

And that's not exactly fusion power, as there is no self-supporting continuous fusion process.
Such fusion power is known very well.

Ion drives are not an option. They can't bring human to other planets in several months, so without an artificial gravity. They are for robots only, so they don't solve the problem.

Edited January 10, 2021 by kerbiloid

[mrfox]

Re. The original blog post

Why go through all that trouble with converting linear motion into rotary motion, if all you want is a electrical generator/motor set? Its like they’ve never heard of linear generator/actuators...

 

[Scotius]

Noooo. We need a big contraption of crankshafts and electric generators! It's not like we can build relatively small, lightweight and safe nuclear reactors, that could provide our ship with all electricity it needs.

[sevenperforce]

12 hours ago, mrfox said:

Re. The original blog post

Why go through all that trouble with converting linear motion into rotary motion, if all you want is a electrical generator/motor set? Its like they’ve never heard of linear generator/actuators...

That was my first thought as well. Magnetic linear generators in the pistons. Easy peasy, metal squeezy. 

[wumpus]

What would you want the power for anyway?  The challenge is harnessing the energy of the Orion without melting the spacecraft.  The amount of energy is the problem, not the fact that you waste nearly all of it.  The point was figuring out a way to *use* that enormous [low mass] energy in *some* way.

Also the only real reason you would want this is for "Fallout" [US 1950's "gas-punk" retro future] styling.  Of course, you'd have to make it a V-8.

1 hour ago, sevenperforce said:

That was my first thought as well. Magnetic linear generators in the pistons. Easy peasy, metal squeezy. 

Don't forget that every Watt of power that isn't being used as a spring (Orion needs dampers, doesn't it?  Those produce nearly all the heat anyway) will heat up the spacecraft eventually.  I'd probably try to tap the waste heat of the dampers myself...

On 1/10/2021 at 10:16 AM, JoeSchmuckatelli said:

Decelerating an Orion drive ship has always seemed... problematic to me.  Doesn't seem like it would be fun to be on such a ship

Same as acceleration.  Exhaust velocity would have to be considerably faster than ship velocity, so I wouldn't expect to see the exhaust again.  Just don't ever think about landing on a planet.

[mrfox]

Well they did mention that the gen-set was going to be used for repositioning the plate in the event of a “dud” round... but yeah... certainly sounds like a nuclear bike shed design.

[Arugela]

On 1/10/2021 at 4:36 AM, Scotius said:

Like this?

I bet we'll see walking cars on the roads faster than we'll see Orions flying.

Again: Orion was a child of it's times. When:

A: We thought nukes are answers to everything. Want a canal? Dig it with nukes. Want to reach deep oil reservoir? Blast it open with a nuke. Want to flatten mountain top for a new observatory? Blast the sucker with a nuke!

B: Didn't knew better yet.

Today we know better than to repeatedly nuke our own home. Also, good luck getting politicians and environmentalists on your side (without Apocalypse looming over the Earth). It's a slow slog getting approval for sending nuclear reactors to space, or getting nuclear thermal engine project rolling - and you want Orion?

Not gonna happen'.

What if we made a nuclear producing factory around the sun so we can do the radiactive part in space. The rest could be lifted into space.

[MatterBeam]

On 1/11/2021 at 5:20 PM, sevenperforce said:

That was my first thought as well. Magnetic linear generators in the pistons. Easy peasy, metal squeezy. 

The trouble is power density. Linear generators, as I mentioned in the post, are easy to install inside the spring arms, but they are much heavier for the power they deliver than a rotating generator, by a factor 10+.

On 1/15/2021 at 5:25 AM, Arugela said:

What if we made a nuclear producing factory around the sun so we can do the radiactive part in space. The rest could be lifted into space.

The issue is where to get that nuclear fuel. There's plenty on Earth's surface, and little anywhere else.

[Spacescifi]

You know I like project Orion. I also like the Starship project (Elon's 'baby').

Now when you think of project Orion you usually think of it launching via a bunch of booster stages which it drops away and I presume also are obliterated when the orion begins blasting bombs out the back.

Actually, you don't have to waste boosters at all. The ENTIRE orion can be designed to reach orbit on it's own with ZERO infrastructure.

How? Imagine this:

1. On the launch pad the SSTO Orion is shaped like a massive cylinder. The bottom end has a cluster of rocket engines within the 'skirt' of the cylinder, much like Elon's Starship. The top of the ship has the pusher plate supported by pistons and shock absorbers.

2. Orion launches via rocket engines using the most thrustiest chemical propellant and rocket engines mankind can currently bring. You need it to launch high enough to not wipe out the launch pad/facility with the bomb air blast.

3. In starship fashion, after reaching the minimum altitude required not to wreck the launch area, the orion will flip over with powerful RCS thrusters so that the pusher plate faces the bottom and the rocket end faces the top.

4. For the crew to be comfortable the ENTIRE crew habitat area must be a sphere that can rotate, like a gyroscope. Rotating within the ship so that down will ALWAYS align with ship thrust and planet gravity when landed. This is only an engineering issue that is also solvable.

5. Then the bombs release and blast and the Orion goes it's merry way to wherever it wishes in the solar system that it has enough nuke delta v for.

6. To return to Earth the orion could either:

A: Go to the moon and use leftover rocket propellant to land, flipping to present the rocket side and using landing legs to land. On the moon ideally a propellant depot with water available to pump into Orion would be great. Barring that the Orion would be forced to use onboard equipment/machinery to harvest moon ice and convert it to rocket propellant.

B: You could hunt down asteroids or comets for the same reason, but it may or may not pay off with the propellant you want most (likely water to do LH/LOX).

7. Once you have filled up your propellant tanks to enough to where you KNOW you can land in 1g on earth, you set a course for earth.

8. If you did NOT fill your tanks up enough enter low Earth orbit and request orbital refuling tank/tanks launched into orbit. Use them to fill up sufficiently and then you can reeenter the atmosphere and land back near if not on the site you launched from.

Hurrah!

And now you can analyze this if you like.

Pros: All the advantages of an SSTO combined with Project Orion. Self landing/launching. Perfect for exploration.

Cons: Gyroscopic rotatable habitate for entire crew is more complex than standard crew module decks. Project Orion nukes for radiation in the air during launch. Ship must be sturdy enough to hold it's own weight whether it flies forward with rockets or flips to use the pusher plate.

Good news:  All are only engineering challenges. It's not like trying to build a fusion reactor and physics keeps telling you "I'm melting! Too much heat...can't hold out...much longer."

What do you think?

 

EDIT:  I would love to see someone build this in KSP and show a video just to demonstrate viability. Any suggestions on who to ask? No I don't have KSP nor do intend to play it as I don't have the time as I have enough work on my plate.

 

I do enjoy the vids of people's creations and. Scott Manley of course!
 

Edited April 16, 2021 by Spacescifi

[MKI]

First lets assume the laws surrounding exploding nukes in space are removed for arguments sake.

Next, we can also assume all the nuclear fuel you need to detonate is available and there is no risk in its existence, as the threat of just having a bunch of nukes lying around is a problem in itself, let alone putting them all in one place on top of a freaken rocket. This would have insane geopolitical issues, but I'll brush all of that aside and focus on the rocket itself.

Finally, I'll also assume a few technical challenges are thrown out, like the physics of the pusher plate, or the economics of building the fuel for such a rocket, which would ultimately outweigh the cost of traditional spaceflight multiple times over.

 

For the concept itself, you probably start having problems around step 3. The same issue you have with normal rockets you have with an Orion Drive spacecraft, in that your rocket's main payload is more fuel. Last I checked you need multiple nuclear blasts to propel yourself through space. This would require you to carry a lot of explosive material, each being capable of igniting an isolated nuclear explosion in a controlled manner. I don't think we have anywhere near the technology to make this even close to feasible in terms of weight and cost, let alone make it safe.

Igniting nuclear explosions in the atmosphere, or even near space can have massive consequences to a large area. Never mind blasting the launch pad, you can easily black out half a country the moment you ignite your first explosive charge to get going, and that's if your out of the atmosphere. If your in the atmosphere you could basically drop radiation on a large portion of the globe! This is the reason why no one tests nukes in the atmosphere anymore, radiation carries to far, and most of these tests were near ground level.

So an Orion Drive SSTO is not feasible, as you need to get you to orbit using something other than the Orion Drive. Safety wise, a single launch can easily pollute a large portion of the globe with radiation. Making this more like something a Bond villain would try, rather than a launch system.

 

The Orion Drive is only close to sensible for deep space travel, where the consequences of an explosion are most minimal to those on the surface of Earth. Using such a drive closer to Earth hearkens back to large scale nuclear warfare in terms of its potential impact on Earth. However, in open space its vastly more reasonable as a primary "transfer engine". This still requires the same challenges as before in terms of getting the fuel, engineering the push plate, and carrying enough fuel to get where you want, but its way more reasonable. This then goes back to getting stuff to orbit, which is still the main challenge facing spaceflight today. Getting to orbit is more than half the challenge.

 

 

 

Edited April 16, 2021 by MKI

[kerbiloid]

Use the uranium in a powerplant to produce hydrogen and fuel a Nexus-szied liquid rocket with it.

P.S.
Who needs the tiny 9-m Starship when Nexus is at least twice wider.

[Spacescifi]

32 minutes ago, MKI said:

First lets assume the laws surrounding exploding nukes in space are removed for arguments sake.

Next, we can also assume all the nuclear fuel you need to detonate is available and there is no risk in its existence, as the threat of just having a bunch of nukes lying around is a problem in itself, let alone putting them all in one place on top of a freaken rocket. This would have insane geopolitical issues, but I'll brush all of that aside and focus on the rocket itself.

Finally, I'll also assume a few technical challenges are thrown out, like the physics of the pusher plate, or the economics of building the fuel for such a rocket, which would ultimately outweigh the cost of traditional spaceflight multiple times over.

 

For the concept itself, you probably start having problems around step 3. The same issue you have with normal rockets you have with an Orion Drive spacecraft, in that your rocket's main payload is more fuel. Last I checked you need multiple nuclear blasts to propel yourself through space. This would require you to carry a lot of explosive material, each being capable of igniting an isolated nuclear explosion in a controlled manner. I don't think we have anywhere near the technology to make this even close to feasible in terms of weight and cost, let alone make it safe.

Igniting nuclear explosions in the atmosphere, or even near space can have massive consequences to a large area. Never mind blasting the launch pad, you can easily black out half a country the moment you ignite your first explosive charge to get going, and that's if your out of the atmosphere. If your in the atmosphere you could basically drop radiation on a large portion of the globe! This is the reason why no one tests nukes in the atmosphere anymore, radiation carries to far, and most of these tests were near ground level.

So an Orion Drive SSTO is not feasible, as you need to get you to orbit using something other than the Orion Drive. Safety wise, a single launch can easily pollute a large portion of the globe with radiation. Making this more like something a Bond villain would try, rather than a launch system.

 

The Orion Drive is only close to sensible for deep space travel, where the consequences of an explosion are most minimal to those on the surface of Earth. Using such a drive closer to Earth hearkens back to large scale nuclear warfare in terms of its potential impact on Earth. However, in open space its vastly more reasonable as a primary "transfer engine". This still requires the same challenges as before in terms of getting the fuel, engineering the push plate, and carrying enough fuel to get where you want, but its way more reasonable. This then goes back to getting stuff to orbit, which is still the main challenge facing spaceflight today. Getting to orbit is more than half the challenge.

 

 

 

 

 

For what it's worth, in scifi I am partial to using currrently not possible pure fusion bombs.

 

Less adiation. No electromagnetic pulse.

 

But IRL all we have is nukes sooo......

 

 

[wumpus]

13 hours ago, Spacescifi said:

Now when you think of project Orion you usually think of it launching via a bunch of booster stages which it drops away and I presume also are obliterated when the orion begins blasting bombs out the back.

I've never thought of (nor heard of) Orion dropping booster stages.  Generally speaking, extreme mass is a bonus for pusher-plate designs, especially if using nuclear explosions (and moreso if using fusion explosions).  You take something the size of a battleship and not only blast it into orbit, but zip around the solar system with the whole battleship.  Smaller "boom-boom" craft using nukes would likely have to be unmanned, as the acceleration and pulses would be too high for a crew (or use extremely inefficient nukes).

Even if you built one out of "belter steel", you'd probably scale the thing up to handle roughly 1g acceleration for crew comfort and efficiency.  At that point neither the individual output of your nukes nor the mass of the craft would be a limiting factor (unless you want to scale it to nukes >>10Megatons or something like that).

[MKI]

17 hours ago, Spacescifi said:

For what it's worth, in scifi I am partial to using currrently not possible pure fusion bombs.

Less adiation. No electromagnetic pulse.

But IRL all we have is nukes sooo......

I'm not sure if its possible within the laws of physics to have a nuclear explosion of some kind without radiation. If there is, I'd assume the complexity is way beyond what we could harness and I also would assume there would be easier methods to getting to orbit making an SSTO concept moot. (Space Elevator anyone?)

[Spacescifi]

1 hour ago, MKI said:

I'm not sure if its possible within the laws of physics to have a nuclear explosion of some kind without radiation. If there is, I'd assume the complexity is way beyond what we could harness and I also would assume there would be easier methods to getting to orbit making an SSTO concept moot. (Space Elevator anyone?)

 

Not zero radiation but less and far more localized. Like you should not have been that close anyway.

Not like with a normal nuke and you live 25 miles away and STILL  might get cancer from it LOL.

[Spacescifi]

Right? For example, if you pulse every two seconds, that's two seconds of free fall inbetween.

You could hang a penny in midair for two seconds before it came crashing down.

 

And the rebounds! Coins would rebound more than usually but eventually settle down.

Bouncy balls? Take a while unfortunately.

 

Unless I got this all wrong, pulse propulsion with standard orion model won't be smooth uninterrupted 1g like on Earth.

So you may as well forget using it for that and instead use coasting and long tethers with modules with rotation spin gravity.

One could do higher g pulses to reach places faster anyway, since gravity interrupted every two seconds would get awkward fast.

 

What do you know and think on this?

Edited April 22, 2021 by Spacescifi

[SargeRho]

If the timing of the pulses is perfect, and the shock absorbers are adjusted perfectly, it would feel just like 1g.

But realistically, it's going to feel quite bumpy, at least like a fast elevator ride.

[Shpaget]

What exactly do you think is the main purpose of the pusher plate in Orion?

The acceleration profile would probably have a sawtooth component, depending on the spring constant.