Ex-News Junkie
Space Elevator with Graphene Ribbon
Sat Dec 2, 2017 2:23am
2001:1970:5c25:9400:94a2:9caa:3e13:4524

Referring to the Science Magazine article describing graphene as the strongest material ever measured, with an intrinsic strength of 130 GPa and elastic modulus of 1 TPa...

The technique (or similar) described in the previous post might enable manufacture of defect-free graphene tubing of 2-meter circumference which, when drawn & flattened by nip rollers, forms a 1-meter wide ribbon that can be continuously drawn to arbitrary length. Wide ribbon would be less likely to be severed by any one micrometeorite impact, and ideally would largely retain the 130 GPa tensile strength and 1-TPa elastic modulus of the laboratory specimen. Therefore a wide graphene ribbon would not only be damage tolerant, but the supersonic spray technique used to manufacture it also points to possible approach to repairing a damaged cable and restoring it to full strength in situ.

For modelling purposes it is also assumed that regardless of the final geometry, the graphene cable would have a mass of 0.004 kg per meter, so that a 10 km length would be 41 kg, and the length from Earth's surface to geostationary orbit (30630 km) would be 125 tonnes. A full conveyor belt loop would be 250 tonnes. For reference, the proposed SpaceX BFR rocket has a 250-tonne payload capacity to Low Earth Orbit when flown as an expendable rocket (source). When flown as an expendable rocket it would burn all of its fuel and therefore could not return to Earth to be re-used. However, it could be re-fueled by additional BFR rocket(s) and then boost its payload to geostationary orbit. Therefore the BFR would be a specific candidate to launch the first space elevator cable.

The first space elevator cable, when operational, would have a 0.3 margin of safety when lifting a 30.48-tonne 40-ft ISO container. Therefore, as many as eight BFR rocket launches would be required, each carrying an additional space elevator cable, before the payload capacity of the space elevator would begin to exceed the 250-tonne mass of the initial cable, and it could begin to "build itself" without additional rocket launches.

It is conceivable that with a dedicated 6-gigawatt power plant the space elevator could achieve speeds of several thousand km/hr vertically, reaching geostationary altitude in under 6 hours, including the 30-min acceleration & deceleration phases at the start & end of the journey. With a standard ISO container load adapter, the next payload could be racked & launched almost immediately, allowing up to four loads daily.

There is room in geostationary orbit for as many as 1800 space elevator installations. Each installation could drop as many elevator cables as needed to cities around the world. If each installation dropped just one cable to Earth, each with a dedicated 6-GW power plant, then as many as 2.628 million 40-ft ISO containers could be lifted into space annually. It is conceivable that these containers could be re-used to build habitats for millions, or even billions, of people. Therefore this is a way to move our entire civilization into space.

One significant geopolitical issue revolves around the need to de-orbit all satellites that are not in geostationary or geosynchronous orbits, since they would be at risk of colliding with the space elevator cables. Suitable replacements could be devised based, for example, on strata-lite technology.

  • Hypothetical technique for continuous room temperatureEx-News Junkie, Fri Dec 1 4:56pm
    production of defect free graphene film by bombarding a BAM-coated nickel cylinder with supersonic buckyballs or reduced graphene oxide droplets carried by standard atmospheric gas emitted from a... more
    • Space Elevator with Graphene Ribbon — Ex-News Junkie, Sat Dec 2 2:23am
      • It will never happen. I think that it is probably physically impossible let alone practically impossible. The "Royal Road to Space" is with the air-breathing "Space Plane" with ramjet for as high as... more
        • Why do you think I'm focusing on itEx-News Junkie, Mon Dec 4 5:10pm
          Because I KNOW it won't be done by anyone alive today. Which leaves it wide open.
          • It won't be done by anybody EVER. (nm)DFM, Tue Dec 5 4:28pm
            • e the idea of a space elevator. Rockets carrying an handful of astronauts will play a small role in the future I envision, but generally they will be obsolete.
              • Space Elevator cannot possibly be made to work. DFM
                • Rocket fuel is PH🚀🚀EY, Mon Dec 11 7:15am
                  destroying ozone. We need an alternative means of propelling our ephemeral-everything into space.
                • Elevators pre-date rockets by a centuryEx-News Junkie, Sun Dec 10 9:07pm
                  Rockets didn't launch from Cape Canaveral until 1950. The technology is dangerous and closely guarded due to the potential for weaponization. Due to cost, complexity, and high risk, few countries in... more
                  • https://www.grc.nasa.gov/www/k-12/TRC/Rockets/history_of_rockets.html The date reporting the first use of true rockets was in 1232. At this time, the Chinese and the Mongols were at war with each... more
                  • FurthermoreEx-News Junkie, Tue Dec 12 11:18pm
                    Rocket technology is not guarded merely due to its potential for weaponization. Rockets were originally intended, built and used, as weapons. Peaceful uses came later, much later. Large rockets, for... more
                    • A space elevator could clear orbital debrisEx-News Junkie, Tue Dec 12 11:28pm
                      As a static structure, a space elevator could be used to collect or de-orbit space junk. With an appropriately designed Whipple Shield that can move up & down, a space elevator could absorb... more
        • Whoops.DFM, Mon Dec 4 4:51pm
          I wrote "(which HAS been achieved)" too many times. It should only be at 3km/sec. Higher speeds have NOT yet been achieved, or at least not published. DFM
      • Global Space Elevator Ring ConstructionEx-News Junkie, Sat Dec 2 3:52am
        The Global Space Elevator Ring construction would roughly follow this sequence: - BFR rocket #1 launches to low-earth orbit (LEO) carrying one 250-tonne space elevator cable spool. BFR rocket #2... more
        • Massaging the numbers a bitEx-News Junkie, Sat Dec 2 11:14am
          - (edit) After 10 years of operation, the first space elevator could lift 14,400 cable spools to GEO. Concurrently, the cable spools could be assembled in groups of eight, and each group moved into... more
          • Geometric GrowthEx-News Junkie, Sat Dec 2 12:11pm
            If each space elevator could launch enough cable spools to build an other space elevator every two days, then the number of space elevator installations would double every two days... The time to... more
            • What hasn't been improved by electrification?Ex-News Junkie, Sat Dec 2 3:29pm
              1. gas lights --> electric lights (ubiquitous) 2. wood stoves --> electric stoves (ubiquitous) 3. abacus --> electronic computer (ubiquitous) 4. sun dial --> digital watch (ubiquitous) 5. astrolabe... more
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