21–30 of 41 posts
Ah, the benefits of not having to listen to shareholders. SpaceX can take long term bets, for example moving capital into exploratory programs including the proposed Mars missions, without having to justify it by profit.
Earlier quoted context omitted.
Probably the biggest barrier to space elevators is exactly what SpaceX and Blue Origin are doing - safe, reliable, and eventually (relatively) inexpensive rockets will make the large fixed costs of setting up a space elevator uneconomical.
It seems like there is a wall in reliability with getting chemical rockets much more reliable than about 99% - 99.5%. SpaceX and Blue Origin are doing cool things, but I don't see them being any more reliable than previous generations of chemical rockets. If an elevator could provide more 9s of reliability, that could be huge.
And when we're talking about human spaceflight, consider the work SpaceX and Blue are putting into in-flight abort and propulsive landing - SpaceX's Crew Dragon should be much safer than the Space Shuttle, for example.
In some ways, not a good sign. Space-X can't make and launch Falcon boosters fast enough now. They're not a big enough company to do many things in parallel. Their unfinished, and late, projects include the Falcon Heavy, the Brownsville TX launch facility, and the crewed Dragon, all of which were supposed to be working by now.
I do wish that Falcon Heavy would finally launch though.
Earlier quoted context omitted.
It seems like there is a wall in reliability with getting chemical rockets much more reliable than about 99% - 99.5%. SpaceX and Blue Origin are doing cool things, but I don't see them being any more reliable than previous generations of chemical rockets. If an elevator could provide more 9s of reliability, that could be huge.
But cost is also at issue. For cargo, it might make sense to take on 0.5-1.0% risk versus the massive investments necessary for the development of a space elevator. And when we're talking about human spaceflight, consider the work SpaceX and Blue are putting into in-flight abort and propulsive landing - SpaceX's Crew Dragon should be much safer than the Space Shuttle, for example.
Propulsive landing helps for some failure modes but not all. Like I don't think it would have helped the CRS-7 failure had that been manned.
Ah, the benefits of not having to listen to shareholders. SpaceX can take long term bets, for example moving capital into exploratory programs including the proposed Mars missions, without having to justify it by profit.
Bezos has been doing this for decades.
Completely off-topic, but what's the latest thinking on space-elevators? Is there any active research on them? I thought that carbon nanotubes or diamond nanothreads were likely candidates for the cable material.
Probably the biggest barrier to space elevators is exactly what SpaceX and Blue Origin are doing - safe, reliable, and eventually (relatively) inexpensive rockets will make the large fixed costs of setting up a space elevator uneconomical.
Once we have a rocket-powered transport network between, say, Earth-orbiting space stations, a moon colony, some near-Earth asteroid mines, fuel depots at lagrange points, a Phobos outpost and robotic factories on Mars, the economic payoff of a space elevator will be more immediate. Plus we could try them out on less massive bodies first, like the moon.
https://m.reddit.com/r/spacex/comments/4y0z6e/toray_carbon_f...
My only issue with carbon fiber is that it is not very easily recycled. Aluminum, on the other hand, is quite trivially recycled. So while spaceships made from CFRP are great in the short-to-medium term (a single spaceship can get a lot more use), I hope that we figured out how to recycle CFRP sooner rather than later.
Aerospace aluminum isn't as easily recycled as beer cans. If you're building a space ship you have very tight tolerances and specifics needed for the alloying of the metals you use. The aluminum in aircraft is full of strange things that need to be removed for general use aluminum and definitely need to be removed for building new aircraft. You're right that melting and re-casting aluminum is really cheap and efficie…
[0] Aircraft grade aluminum alloy's composition roughly includes 5.6–6.1% zinc, 2.1–2.5% magnesium, 1.2–1.6% copper, and less than a half percent of silicon, iron, manganese, titanium, chromium, and other metals.
[1] Aluminum cans are typically 1% magnesium, 1% manganese, 0.4% iron, 0.2% silicon, and 0.15% copper.
There are a lot of metrics that determine the appropriate use of various grades of aircraft level alloys [2]. I guess from the outside some big considerations are how the metal reacts to temperature change and how well a metal cylinder can handle stress while staying light.
[0] https://en.wikipedia.org/wiki/7075_aluminium_alloy [1] http://www.madehow.com/Volume-2/Aluminum-Beverage-Can.html [2] https://en.wikipedia.org/wiki/Aluminium_alloy
Earlier quoted context omitted.
Aerospace aluminum isn't as easily recycled as beer cans. If you're building a space ship you have very tight tolerances and specifics needed for the alloying of the metals you use. The aluminum in aircraft is full of strange things that need to be removed for general use aluminum and definitely need to be removed for building new aircraft. You're right that melting and re-casting aluminum is really cheap and efficie…
I never thought about it but I became curious as to what the differences are, here's what I was able to find: [0] Aircraft grade aluminum alloy's composition roughly includes 5.6–6.1% zinc, 2.1–2.5% magnesium, 1.2–1.6% copper, and less than a half percent of silicon, iron, manganese, titanium, chromium, and other metals. [1] Aluminum cans are typically 1% magnesium, 1% manganese, 0.4% iron, 0.2% silicon, and 0.15% co…