4 ms·

Probably the biggest barrier to space elevators is exactly what SpaceX and Blue Origin are doing - safe, reliable, and eventually (relatively) inexpensive rocke

by oliwaw 10y ago

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.

planteen 10y ago
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.
- oliwaw 10y ago
  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.
  - planteen 10y ago
    Yeah for cargo I agree. I was thinking more along the lines for human rating. 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.
    - hLHEDuYtSh 10y ago
      It actually would have helped on CRS-7 -- That capsule was fine until it hit the water. https://www.nasaspaceflight.com/2015/07/saving-spaceship-dragon-contingency-chute/ https://www.nasaspaceflight.com/2015/07/saving-spaceship-dra...
      - deleted 10y ago
        [deleted]
chriswarbo 10y ago
I think that the best long term way to spur investment in projects like a space elevator would be to make space as economically attractive as possible. In-situ resources, extracted/processed robotically and accessed via low cost rockets is the way to do that. 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.
HopDavid 10y ago
An elevator anchored to the earth and extending past geosynchronous orbit is wildly implausible. However orbital vertical tethers are doable with Zylon. A series of 3 orbital tethers could move stuff between LEO and the lunar neighborhood. http://hopsblog-hop.blogspot.com/2016/08/tran-cislunar-railroad.html http://hopsblog-hop.blogspot.com/2016/08/tran-cislunar-railr... Both Musk and Bezos seem well on their way to reusable boosters. But reusable upper stages is another story. An upper stage re-enters at around 8 km/s. An ~7 km/s delta V budget plus the need to carry a payload means a very slim dry mass fraction, an egg shell space craft. Recovering and reusing upper stages will be much harder than reusing boosters.

by oliwaw 10y ago

planteen 10y ago

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.

oliwaw 10y ago
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.
- planteen 10y ago
  Yeah for cargo I agree. I was thinking more along the lines for human rating. 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.
  - hLHEDuYtSh 10y ago
    It actually would have helped on CRS-7 -- That capsule was fine until it hit the water. https://www.nasaspaceflight.com/2015/07/saving-spaceship-dragon-contingency-chute/ https://www.nasaspaceflight.com/2015/07/saving-spaceship-dra...
    - deleted 10y ago
      [deleted]

chriswarbo 10y ago

I think that the best long term way to spur investment in projects like a space elevator would be to make space as economically attractive as possible. In-situ resources, extracted/processed robotically and accessed via low cost rockets is the way to do that. 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.

HopDavid 10y ago

An elevator anchored to the earth and extending past geosynchronous orbit is wildly implausible. However orbital vertical tethers are doable with Zylon. A series of 3 orbital tethers could move stuff between LEO and the lunar neighborhood. http://hopsblog-hop.blogspot.com/2016/08/tran-cislunar-railroad.html http://hopsblog-hop.blogspot.com/2016/08/tran-cislunar-railr... Both Musk and Bezos seem well on their way to reusable boosters. But reusable upper stages is another story. An upper stage re-enters at around 8 km/s. An ~7 km/s delta V budget plus the need to carry a payload means a very slim dry mass fraction, an egg shell space craft. Recovering and reusing upper stages will be much harder than reusing boosters.