Recent comments in /f/space

lilrabbitfoofoo t1_j6ny0aw wrote

> We are currently evolving in space.

We are not.

>Evolution never stops.

This is true.

>Technology is a part of our evolution.

It is not.

Machines (or human consciousness in machines) is the future of all space exploration beyond this solar system.

−2

McCaffeteria t1_j6nxmyv wrote

I think you are just missing one important detail about Project Orion that would clear up you confusion: they theorized used a series of smaller nuclear explosions in order to continuously propel a spacecraft.

This video is a great visual example of the project, I highly recommend you watch it if you haven’t already. Honestly his whole channel is great.

We can make materials that can “withstand the ablation of a nuclear explosion,” but we can’t make materials that can withstand the force of any arbitrary explosion, nuclear or otherwise. We have to limit the size of the explosion to the material properties of our pressure plate and our spacecraft. There is an upper limit in terms of instantaneous G-forces that our constructions can withstand and that prevents us from just building a canon as you suggested (not to mention you would still have to do another burn once you are in space to actually circularize your orbit otherwise you’ll orbit once and hit the ground where you launched from lol).

Someone else mentioned Spin-launch in the comments and they are right. The whole point of spin-launch is to generate the kinetic energy and momentum you would have had to generate to get into space, but they are doing it over a longer period of time to protect the payload. Same concept with project Orion: they are distributing the total energy over many separate explosions so that the ship would actually be possible to build with real materials.

0

TheBroadHorizon t1_j6nvlha wrote

Nope. The Partial Test Ban Treaty bans atmospheric testing. The Comprehensive Test Ban Treaty of 1996, while it has never entered into force, has been signed and de-facto adopted by all nuclear powers except for India, Pakistan and North Korea. It "bans nuclear weapons test explosions and any other nuclear explosions, for both civilian and military purposes, in all environments".

5

A_Vandalay t1_j6nv9xt wrote

Yes, but we have good tools to solve this now. NASA has put a lot of research into designing space craft in such a way as to utilize all required mass as shielding. Furthermore SpaceXs starship that is actively being designed with lunar/Martian landings in mind and the sheer scale of this spacecraft gives you a lot of capacity to bring mass only as shielding. While this is a problem it’s absolutely a solvable one and far from the greatest hurdle to a mars mission.

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A_Vandalay t1_j6ntmh2 wrote

This is one of the primary advantages starship will have over other lunar landers. The sheer mass of the ship will allow you to devote a significant amount of payload as primarily a radiation shelter.

29

PandaEven3982 t1_j6ntm34 wrote

Who told you this? Are we discussing Nerva/Heavy Orion, as proposed by Dr. Pournelle and Dr. Kingsbury? Yes they discussed quite a few multistage designs, yes the SatV was the obvious choice of system. No. They never got comfortable enough with the Murphy factor to move forward. There was no acceptable design when the treaty showed up.

3

zolikk t1_j6ntj8h wrote

Hmm, I guess it's possible? But then it requires quite a lot of constant fuel for your orbital retrieval vehicle. I suppose you could also "shoot" fuel up with the cannon constantly.

I'm not convinced it could be worth it. From the construction and maintenance of the cannon to the reliability of the method, even if possible, where if you don't catch a payload perfectly it just falls back to earth... rocket launches are probably more worthwhile for all this.

Since you need fuel to get into orbit you're still beholden to the rocket equation where you're using fuel that you catch to put the payload you also catch into orbit... I don't think you're necessarily that far from just using rockets, except the reliability problem.

2

New_Acanthaceae709 t1_j6nt3f2 wrote

Moving an airplane sized thing that's already in orbit, any push makes it go faster.

Moving it from the ground, you don't just need shielding from the blast, but also shielding from the *air* in front of you.

https://nuclearweaponarchive.org/Usa/Tests/Brownlee.html

This is a manhole cover going 75 kilometers a second; it went too fast to burn. But human beings and most cargo can't possibly survive going from 0 to escape velocity instantly; the speed you'd have to fly would, well, have the time to burn through most things.

1

zolikk t1_j6nso2v wrote

You have to make a rendezvous with the ISS which means you have to have propulsion on your "vehicle", it can't just be a "cannonball" fired from the ground once. And the engine and other delicate components necessary wouldn't survive being fired out of such a cannon.

To put it simply, you cannot shoot an unpowered object into orbit. Its path intersects the earth again, or it attains escape velocity and leaves earth permanently, but neither path makes an orbit.

2