Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Space Elevator

neal.fun

Post reply on HN
Print view View original

151–160 of 216 posts

Re: Space Elevator

#151

Post by burnished »

avmich wrote: post #5

I don't understand why so many seemingly educated people keep discussing Earth space elevator. For a long time there is a conclusion that the elevator is incompatible with Earth satellites, which mostly fly below GEO, and elevator will collide with satellites, with all negative consequences. The inherent elevator problem has nothing to do with the material of the cable. Am I missing something?

Cause they are fucking rad! Its grandiose and big but plausible, its like some one heard of archimedes lever and took it as a challenge. Basically it sparks the imagination :)

Is that sort of collision inevitable or can you have parallel orbits that don't collide? I'm ignorant and this is the first I'm hearing of this issue. Last I heard the material science part was the heartbreaker.

Re: Space Elevator

#152

Post by seabass-labrax »

Ah yes, I thought, scrolling past the Learjet 45, the de Havilland Vampire, the Caproni Ca.161, all high-tech jet aircraft of the space age... hang on, the Ca.161?! I must say I'm sceptical that such a single-engined biplane could reach 50000 feet. The most advanced piston-powered aircraft, the four-engined Lockheed L-1649 Starliner, had a cruising altitude of no more than 30000 feet.

Re: Space Elevator

#153

Post by red-iron-pine »

midasuni wrote: post #90
hammyhavoc wrote: post #52

Earlier quoted context omitted.

That all assumes that it got loose at the base and not part way up within the atmosphere. If 9/11 can happen, this can happen. All that cable and kinetic energy has to go somewhere.

If your bad guys can get high enough to sever your cable, they can get high enough to do a kinetic or powered bombardment and cause magnitudes more damage.

¿Por qué no los dos?

Plus accidents are more likely than you think. A rocket just exploded this morning, and read up on rates of railroad or shipping screwups. A train full of apples and pallets of kleenex going over ain't a big deal but the same containers falling out of the sky will certainly cause more damage.

Re: Space Elevator

#154

Post by pavon »

davidpronk wrote: post #49

Very very nice. Love the details and the °F/°C toggle. "...above this altitude your saliva and tears will boil if you don't have a pressure suit." :-$

And it puts a suit on for you if you don't select one. No stickman snuff animations here.

Re: Space Elevator

#155

Post by [deleted] »

csomar wrote: post #62

Couple of things I learned from this: 1. Some birds go really high into the sky. Not sure how they evolved to tolerate such a hostile environment. But it seems that Duck-like birds are able to handle very high altitude. 2. There are lots of cool spaceships that man has made. But it seems most of these were made in the 1950-1990 era. It's a shame that we are no longer doing that.

[deleted]

Re: Space Elevator

#156

Post by jandrese »

metalliqaz wrote: post #135
midasuni wrote: post #93

Earlier quoted context omitted.

Getting to 100km or even 200km is easy. Staying there is hard. 80% of the energy in a rocket goes to adding sideways motion. An elevator upto GEO adds enough energy (taken from the earths rotational energy) to your payload to get it into orbit. If you let go lower down you need to add sideways velocity. In LEO you on an elevator would be travelling about 1,400mph and need to get to 18,000 to get into orbit. Sure ther…

> 80% of the energy in a rocket goes to adding sideways motion. I have not researched this at all, so I'm not doubting you, but doesn't most of the energy go into accelerating the remaining fuel? So, by the rocket equation, shouldn't you be way ahead of the game by starting at the edge of space?

You still need to accelerate the fuel at that point. Free travel up to LEO doesn't buy you much.

There is an excellent What-if on this: https://web.archive.org/web/20230211050159/https://what-if.x...

Re: Space Elevator

#157

Post by trey-jones »

outworlder wrote: post #134
jackcviers3 wrote: post #123

Earlier quoted context omitted.

[flagged]

Yeah. It's one thing to blow up during test firings, or when trying completely novel maneuvers like the belly flop. It's another thing entirely to do that during stage separation. Sure, historically separation has been risky, but it's nothing novel. They didn't seem to expect the vehicle to survive past that anyways. There would be a delay even if another vehicle was ready to go - the launch site is a wreck.

If you were thrown by the explosion (automated termination, not some catastrophic failure), then you weren't listening to any of the media around the launch. This was a successful mission, gathering data for future launches. Expectations were set appropriately, so I think it's really just your problem for not listening.

In addition, this isn't publicly funded, so it would seem if some of the people get spooked by not understanding the goals of a launch correctly, then it doesn't really matter that much.

Re: Space Elevator

#159

Post by lastangryman »

gibolt wrote: post #13

A key point with space elevators is that they aren't limited to Earth. The solar system has plenty of celestial bodies that could benefit (us) from having one. It may not be as significant as the impact of an Earth-based one, but any propellant savings is a win.

A martian space elevator is explored in Kim Stanley Robinson's Red Mars trilogy, definitely worth a read.
Post reply on HN