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

121–130 of 216 posts

Re: Space Elevator

#121

Post by kbelder »

jackcviers3 wrote: post #104
millerm wrote: post #87

Earlier quoted context omitted.

Watching the countdown now! T-00:28:12! Will be spectacular no matter what happens! Yes, I'm excited. Not sure how the parent comment has missed what SpaceX has been doing with Dragon, Starship, Starlink, and all the rockets! Amazing.

It exploded when trying to orient for the first stage separation. And it appeared to have 5 of the 33 engines out during the first stage flight. This launch gave me very "Don't Look Up" ending vibes.

Just the opposite. This is engineer-driven testing.

Re: Space Elevator

#122

Post by NoMoreNicksLeft »

davidhyde wrote: post #2

At 74km/h you would reach space (100km karman line) in an hour and a half but you would need to keep going for another 20 days at that speed reach geostationary orbit in order to not fall back to earth when you exit the space elevator.

Can the speed be safely increased once you leave the atmosphere and there is no (appreciable) drag? With such a system in place, are there no other interesting places to stop along the way to geosync?

Re: Space Elevator

#123

Post by jackcviers3 »

kbelder wrote: post #121
jackcviers3 wrote: post #104

Earlier quoted context omitted.

It exploded when trying to orient for the first stage separation. And it appeared to have 5 of the 33 engines out during the first stage flight. This launch gave me very "Don't Look Up" ending vibes.

Just the opposite. This is engineer-driven testing.

[flagged]

Re: Space Elevator

#124

Post by neaden »

drtgh wrote: post #89
nivenkos wrote: post #56

Earlier quoted context omitted.

At that point gravity will act slower though, so it might be enough to take up a small liquid fuel craft too. Rockets will have abandoned solid fuel boosters long before then.

If you take a lift to a distance of 100 km and drop it, it will fall immediately reaching the ground in less than 10 minutes. Gravity remains strong. Satellites and space stations are always in free fall. The thing that keeps them in "space" is the velocity with which they were originally launched to orbit the Earth as centripetal force becomes the weight of the satellite, which slows down such falling process. Seein…

Yeah, the thing people miss about the space station isn't that it's high up, it is that it is fast. It orbits the earth roughly every 90 minutes! It is literally faster then a speeding bullet.

Re: Space Elevator

#125

Post by Retric »

Retric wrote: post #94
ta1243 wrote: post #76

Earlier quoted context omitted.

It would be cheaper to drop an equivalent massed object out of a plane. Or just use the plane as the weapon. You break a space elevator at the ground, it floats upwards. You break it at 30,000 foot then everything above the break floats away upwards, everything below "crashes" down, at a relatively low terminal velocity and thus with pretty low amounts of energy. An elevator isn't a tower, it's a rope handing from a…

That’s assuming you can’t say detonate a bomb inside the cargo thus resulting in vastly longer section falling down. Space elevators are inherently create a new safety risk as cutting them at geosynchronous orbit only takes compromising some security and building a modest bomb. Both of which are achievable by terrorist organizations.

Accidentally deleted a bit: Space elevators are inherently a means to reach orbit so they create …

PS: 911 didn’t happen because terrorists suddenly figured out how to build giant aircraft to douse buildings in tons of jet fuel they subverted an existing system that solved 99.9% of the technical problems. Thus by getting a few violent individuals on board with simple weapons simplified things to only needed to fly an aircraft that someone else built, got into the air, and filled with fuel.

Re: Space Elevator

#128

Post by marcosdumay »

midasuni wrote: post #99
Sharlin wrote: post #33

Earlier quoted context omitted.

Yes, it absolutely has to taper, with an exponential curve, to keep stress constant over the length of the cable. The taper ratio (in terms of cross-sectional area) for the best currently available engineering materials for an Earth space elevator would be in the tens to hundreds of millions, but a carbon nanotube cable might only require a taper ratio of around ten. (A steel cable would need a taper ratio on the ord…

I believe A taper ratio of 10 means a 5cm rope at the bottom would be 50cm at the top. A steel cable would be 1mm thick at the bottom and several light years* thick at the top. *hyperbole. Maybe.

> *hyperbole. Maybe.

A lightyear is around 10^19mm. Given that it's by area, a square lightyear is ~10^38mm^2. The cable is about 100 times thinner than it.

Re: Space Elevator

#129

Post by avhon1 »

jackmott42 wrote: post #109
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.

List of cool spaceships being worked on now or recently: * The Falcon 9, the first partially reusable spaceship that actually costs less than not re-using anything * Terran R - a fully reusable space ship in the works by relativity space * RocketLab Electron - an active rocket that is unique in its use of electric turbo pumps, 3d printed engines, and advanced composites use * RocketLab Neutron - in the works, a large…

Sierra Nevada Corporation's Dream Chaser - a reusable lifting-body spaceplane, currently slated to fly to the ISS on top of the Vulcan rocket in December 2023

Re: Space Elevator

#130

Post by marcosdumay »

MilStdJunkie wrote: post #23
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?

Space is big. 1) The cable's vibration resonance can be adjusted to avoid the bulk of larger objects, 2) new satellites can be mandated to have emergency maneuver systems (with larger objects not yet de-orbited cleared out by an elevator consortium), and 3) the cable will necessarily have close range defense systems probably at intervals for smaller objects that might be harder to detect at long range. The cable, als…

> In the long term, a space elevator is inevitable

There are plenty of zero-fuel launch possibilities and a few very high-ISP ones. On the long term one of them is inevitable, but it's pushing it a bit to claim that it will be the space elevator.

Post reply on HN