Space Elevator on Mars?

"Areostationary orbit. An areostationary orbit (abbreviated ASO) is a circular areosynchronous orbit in the Martian equatorial plane about 17,000 km (11,000 mi) above the surface, any point on which revolves about Mars in the same direction and with the same period as the Martian surface.Jun 19, 2016"

https://www.quora.com/What-is-the-Geostationary-mars-orbit

We don't have the capability to build a house on Mars. Building a space elevator there is definitely far in the future. I'm not sure, but it might be close to the orbits of Mars's two moons, Phobos and Deimos.

Phobos is a small moon of Mars in a close equatorial orbit. Deimos is a larger moon out a little bit beyond synchronous orbit. Both would likely be a hazard to a space elevator, but maybe Deimos could be repurposed as a counterweight.

"The motions of Phobos and Deimos would appear very different from that of our own Moon. Speedy Phobos rises in the west, sets in the east, and rises again in just eleven hours, while Deimos, being only just outside synchronous orbit, rises as expected in the east but very slowly. Despite its 30-hour orbit, it takes 2.7 days to set in the west as it slowly falls behind the rotation of Mars."

"Both moons have very circular orbits which lie almost exactly in Mars's equatorial plane,"

https://en.wikipedia.org/wiki/Moons_of_Mars#cite_note-burns-27

The close equatorial orbit would probably be the big problem as it would likely cut across the tether path. That kinda rules out a basic space elevator pretty quickly.

My next thought would be to have two tethers, one at or near the equator and a second at some latitude away from the equator such that it would pull the elevator far enough away from the equator so as to avoid collisions with the moons.

I think Phobos might be useful as the transfer station. Use a combinations of rockets to slowly move it out of its current orbit to the chosen stationary orbit point. Then carve it out to use as a staging facility and as the basis for construction and operation.

How about an elevator on the Moon? Could be a transfer point for workers and tourists. Would eliminate the need for rocket vehicles that can land and take off.

A lunar space elevator would be possible using available materials (e.g. Kevlar) because the lower gravity requires less strength. The elevator would stretch from the lunar surface to one of the Lagrange points L1 or L2, which are unstable, so the elevator would have to have some means of station keeping.

http://lagrangianpoints.com/lagrange-points-defined/

The elevator would have to be longer than an earth-based elevator. The distance from the moon to L1 is 56000 km versus 36000 km from earth to geosynchronous orbit. In both cases, the elevator would have to extend beyond that point for the counterweight.

https://en.wikipedia.org/wiki/Lunar_space_elevator

Unfortunately, a lunar space elevator would need to be set up for a 28 day rotation rate, which would likely make the elevator way too long to be practical.

How about "trying" the Space Elevator on our Moon first?

1. It's much closer to get to;
2. There's no atmosphere to contend with.
3. It's gravity is 16.6% of Earth; Mars is 38% of Earth.
4. We've already been there (and back) multiple times;
5. We (USA) plan to use the Moon as a 'way-station' anyway.

From above: https://en.wikipedia.org/wiki/Lunar_space_elevator

Thinner atmosphere might help a bit, but lower gravity helps a lot, certainly.

ISEC director Dr. Martin Lades has worked with our team to calculate some basics of a space elevator on Mars - his "Mars Lift" concept. We think it has some merits, notably:

- Martian partial gravity and relatively short tether length (areosync + 3k km) allow for use of materials that have the same order-of-magnitude specific strength as today's best, e.g., CNT film.

- Dr. Lades' off-equator base station allows the Mars Lift tether to bypass Phobos passively and safely, always, as below.

- Near-term, the only requirement is for cargo delivery to the martian surface, with no return cargo on the elevator. Therefore an unpowered, simplified, lightweight elevator transport - what we called a "rappeller" - should meet the need. Rappellers should be feasible with modest R&D.

- The warehouse dock in areosynchronous orbit - what we called an "Arestation" - would be close to Deimos. ~ 60 m/s delta-v can lift a spacecraft up to "Deimos Dock", where conceivably it could load Deimos ISRU propellant for return to Earth.

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We quantified some overall savings of this system: e.g.:

Earth launches:

The required number of Earth launches for cargo delivery (including tankers) is cut by 71%.

Propellant:

The required propellant load for cargo delivery (including tankers) is cut by 68%.

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We call this high-efficiency system concept the "Omaha Trail". We updated the Omaha Trail efficiency calculations to match SpaceX's 2017 spacecraft capabilities in our Nov. '17 press release.