Rocket engines - from speculations to successful flights

[Loren Pechtel]

An insurmountable problem is heat. The shuttle had radiators in the cargo doors. It could not stay up if doors were not opened. The ISS has radiators.

ST never addressed the issue. Even at 99.9% efficient the waste heat of the power source would cook the crew. Place a box filled with air in deep space. Turn on a power source and the temperature will rise if the power exceeds the radiation from the box. It will keep rising until something failed.

It's a problem that must be accounted for, for sure; But, as the radiators on the ISS and in the shuttle's cargo doors demonstrate, it is not an insurmountable problem.

It's not insurmountable at the energy levels we operate at.

At Trek-level energy levels it is.

 

[Loren Pechtel]

The other three involve nuclear fusion, doing inertial confinement fusion on small pellets. This involves focusing some high-power laser pulses on a pellet, something that makes it implode and cause fusion in it. I'll call that the Daedalus drive, after where it was first proposed: Project Daedalus – Interstellar Mission. Icarus Interstellar is a successor project. Inertial confinement fusion has been worked on, and while one can get more nuclear-fusion energy out of a pellet than the laser energy put into it, the whole system has yet to demonstrate that it can power itself, and its lasers and other apparatus do not seem as rugged as some nuclear-fission reactors can be. So we are a long way from a workable Daedalus drive.

There's also a big yield problem with Daedalus.

Lasers can't actually squeeze anything. The pellets are being compressed by Newton's third law--apply a big pile of energy to the outside of the pellet. The outside departs at very high speed, the inside heads inward and meets the material from the other sides. Most of the mass of the pellet is lost before the fusion burn starts. For a power reactor this isn't a big deal, recover the waste stream and extract the good stuff. However, a rocket engine can't recover it. Most of your fuel goes out the back without ever being burned--and your I_SP goes in the shitter.

 

[Kharakov]

Missile technology has endangered all of humanity.

That's rather off-topic.

Let's get back to discussing the feasibility of different sorts of rocket engines and alternatives like space elevators.

That's mean. Everyone knows space is afraid of heights, which is why it seeks the lowest point in a gravity well.


In rocket news, my friend was honking as he pulled up today and yelled "get out here man, quick!!". There were contrails (another word for chem trails made of condensed dihydrogen monoxide) and rockets in the sky, flying north-northeast. Needless to say, none of us knew about the launch, and I said "thanks a lot President Trump".

Pretty cool. Neat to see something bright moving in the sky like that. I said "we're all going to die" and some little girl I forgot was there said "we're going to be fine silly", I lied and said "I was joking, everything is going to be all right", because I assumed that I would have read or heard about a SpaceX launch that was occurring so fricken close to us.

I was waiting for a bright flash for about 30 seconds as the rocket sped closer and closer (I mean, it was picking up speed, so to me it seemed like it was getting lower, which in hindsight.... it was fricken amazing).. then the girl's mom said "ohh, it's a Saturn 9 launch".

 

[steve_bank]

I can't remember the name to search, maybe someone knows it. There was something about an experiential NASA engine that had some risk of an effect, and it was going to be tested in space.