August 28, 2012

Unlike Earth Space elevators, Lunar space elevators look feasible and economic

Lunar space elevators are flexible structures connecting the lunar surface with counterweights located beyond the L1 or L2 Lagrangian points in the Earthmoon system. A lunar space elevator on the moon’s near side, balanced about the L1 Lagrangian point, could support robotic climbing vehicles to release lunar material into high Earth orbit. A lunar space elevator on the moon’s far side, balanced about L2, could provide nearly continuous communication with an astronomical observatory on the moon’s far side, away from the optical and radio interference from the Earth. Because of the lower mass of the moon, such lunar space elevators could be constructed of existing materials instead of carbon nanotubes, and would be much less massive than the Earth space elevator. We review likely spots for development of lunar surface operations (south pole locations for water and continuous sunlight, and equatorial locations for lower delta-V), and examine the likely payload requirements for Earth-to-moon and moon-to-Earth transportation. We then examine its capability to launch large amounts of lunar material into high Earth orbit, and do a top-level system analysis to evaluate the potential payoffs of lunar space elevators.

A flat ribbon of M5 material, 30 mm wide and only 0.023 mm thick, similar to aluminum foil, could support a mass of 2000 kg at the lunar surface, or 100 cargo vehicles of 580 kg each spaced evenly up the length of the elevator ribbon. The average velocity of the cargo vehicles might be reasonably maintained at 100 km/hour for the ascent, without producing undue wear on the elevator ribbon.

A lunar space elevator system with a mass of 6,100 tonnes including a massive counterweight would be capable of lifting or depositing loads of 2,000 newtons (450 lbf, or at lunar surface gravity, masses of 1233 kg / 2700 lbm) at the base. The counterweight could potentially be lifted from the lunar surface.

A lunar space elevator can be made with current materials which exist in sufficient commercial quantities and an entire system could be delivered in one rocket launch. The materials and rocket launch will provide benefits that will pay for themselves by supporting lunar development and to lower costs for operating in earth orbit by delivering fuel and supplies from the moon at lower cost than materials from earth going to earth orbit.

Pearson had a 71 page NASA study of a lunar space elevator

A lunar space elevator using existing high-strength composites with a lifting capacity of 2000 N at the base equipped with solar-powered capsules moving at 100 km/hour could lift 584,000 kg/yr of lunar material into high Earth orbit. Since launch costs may be about $1,000/kg then, this material would be worth more than half a billion dollars per year, resulting in greatly reduced costs and creating a new paradigm for space development.

Private Fund Raising on Track

The Liftport lunar space elevator kickstarter has raised over $27,000 and has 15 days to go. They have raised over $10,000 from yesterday to today. They should get well over $100,000 and could reach $250,000 assuming they can maintain the fund raising pace.

$50,000 - new robot and at least 3 to 5 kilometer
$75,000 - transition from altitude to endurance
$100,000 - back in business for real
$250,000 - try for to climb to the limit of balloon technology , about 20 miles / 30 kilometers
$500,000 - tests with plants and animals at 30 kilometers

Liftport have a proposal for a one launch deployment of a prototype lunar space elevator

LADDER is a mission to deploy an operational prototype Lunar Space Elevator (LSE) using currently available technology. The LADDER mission would erect a 264,000 km space elevator from the Lunar surface, past the L1 Lagrange point, to a counterweight deep in cislunar space. The LADDER mission is intended to gain experience with the deployment and operation of a space elevator, deploy scientific
instruments and other equipment to the Lunar surface, and return samples of the Lunar surface from Sinus Medii to Earth.

LADDER is intended to achieve both a functioning LSE and to provide a solid scientific return in the same mission, based on one launch from an existing or planned Heavy Lift Launch vehicle. LADDER currently is planned to be executed in a single Discovery class mission, starting with the delivery of 11,000 kg of Zylon HM fiber plus associated equipment to the L1 Lagrange site. While the fiber could be changed if better choices become available, Zylon is sufficient for LADDER, and is also commercially available in sufficient quantities for the LADDER LSE.

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