By the late 2070s,*** following 15 years of construction,* a space elevator reaching from the Earths surface into geostationary orbit has become fully operational. The construction process involves placing a spacecraft at a fixed position – 35,786 km (22,236 mi) above the equator – then gradually extending a tether down to grow the cable towards Earth. It also extends upwards from this point – to over 47,000 km (29,204 mi) – a height at which objects can escape the pull of gravity altogether. A large counterweight is placed at this outer end to keep it taut. Locations that are most suitable as ground stations include French Guiana, Central Africa, Sir Lanka and Indonesia. As with most forms of transport and infrastructure in the late 21st century, the space elevator is controlled by artificial intelligence, which constantly monitors and maintains the structure throughout. If necessary, robots can be dispatched to fix problems in the cable or other components, from ground level to the cold vacuum of space. This is rarely required, however, due to the efficiency and safety mechanisms in the design. A major space boom is now underway, as people and cargo can be delivered to orbit at vastly reduced costs, compared with traditional launches. Over 1,000 tons of material can be lifted in a single day, greater than the weight of the International Space Station, which took over a decade to build at the start of the century.* Although relatively slow – taking many hours to ascend* – the ride is much smoother than conventional rockets, with no high-G forces or explosives. Upon leaving the atmosphere and reaching Low Earth Orbit, between 160 km (99 mi) and 2,000 km (1,200 mi), cargo or passengers can be transferred to enter their own orbit around Earth. Alternatively, they can be jettisoned beyond geosynchronous orbit, in craft moving at sufficient speed to escape the planets gravity, travelling onward to more remote destinations such as the Moon or Mars. In the decades ahead, additional space elevators become operational above Earth, the Moon, Mars and elsewhere in the Solar System,* with a considerable reduction in costs and technical risks. Construction is also made easier by lower gravity: 0.16 g for the Moon and 0.38 g on Mars. Further into the future, space elevators are rendered obsolete by teleportation and similar technologies.
Posted on: Wed, 30 Oct 2013 21:37:59 +0000
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