[ExI] Obayashi Space Elevator

[Keith Henson]

I have not really been advocating an elevator project. The strength of even
nanotubes is not high enough. But I did come up with a way to start with a
relative thread. Using motors and pulleys, you use the elevator to raise
the rest of it. Made the background for a story, https://htyp.org/UpLift,
but the unsolved problem is that every satellite runs into the cable
eventually. Moving cables to supply the lift energy makes a lot more sense
than climbers. I once worked out that a laser powering climbers is so big
that you can use it as a launching laser.

A lunar elevator makes a lot more sense. It competes with mass drivers, but
even using a moving cable at 1000 km/hour, it takes 50 hours to reach L1.
It has to hang down well beyond that point in Earth's gravity to stay in
tension. If you make it 190,000 km, a payload just dropped off the end is
in a Hohmann transfer orbit to GEO.

Keith


On Mon, Jun 8, 2026 at 5:56 AM Stuart LaForge via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

> The Obayashi Corporation, one of largest publicly-traded Japanese
> construction companies, has plans to complete a space elevator by the
> year 2050.
>
> https://www.obayashi.co.jp/en/thinking/detail/space_elevator.html
>
> "The space elevator is planned to be built by the year 2050 with a
> capacity to carry 100-ton climbers. It is composed of a 96,000-km carbon
> nanotube cable, a 400-m diameter floating Earth Port and a 12,500-ton
> counter-weight. Other facilities include Martian/Lunar Gravity Centers,
> an Low Earth Orbit Gate, a Geostationary Earth Orbit Station, a Mars
> Gate and a Solar System Exploration Gate.
>
> The construction process consists of deploying the cable and
> constructing the facilities. It is necessary to analyze the cable
> dynamics in order to estimate the characteristics of the cable,
> counter-weight, facilities and climbers, and in order to determine the
> construction procedures. Parameters for the cable dynamics include
> tension, displacement and elongation of the cable due to ascending
> climbers, masses of counter-weight and cable, wind, and fixed loads of
> facilities. With the help of a computer simulation of the equations of
> motion, we designed the system and determined the construction process.
>
> Based on the results, we conclude the following: construction will be
> technically feasible with an assumed cable tensile strength of 150 GPa,
> it will take roughly 20 years to construct the cable, the impacts of
> wind or Coriolis force on cable displacement are small, and it is
> essential to fix one end of the cable to the earth's surface, always
> applying pre-tension at the ground end. According to the plan, a 20-ton
> cable is deployed initially, and is reinforced 510 times by climbers up
> to 7,000 tons, ascending in succession over roughly 18 years. The
> facilities are then transported and constructed within one year."
>
> By my estimation, this is so far the largest, most serious attempt at
> building such a structure. Keith, it looks like the years of advocacy by
> you and the others might be paying off.
>
> Stuart LaForge
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