[oliwaw]

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.

[chriswarbo]

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]

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-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.

[planteen]

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]

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]

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]

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-dra...