Russia's Space Research Institute has been studying the idea of a space-elevator cluster to economically deliver payloads from the Earth to the Moon and back.

According to Russian studies and experiments, the space-elevator cluster should consist of several cable systems. The first is in a low circular Earth orbit, and the second in a low elliptical Earth orbit. The third cable system would be in a circular equatorial lunar orbit. By adjusting the length of the tethers, it will be possible to change each orbital system's angular speed of rotation.

Mission payloads would be exchanged from one orbital cableway to another. Payloads from Earth to the Moon would be placed in first system, which would "sling" them higher to the second system, and then to the Moon, where payloads would be caught by the third system.

The intent of this system is to save on the huge energy costs of moving freight to the Moon. According to Russia's Space Research Institute, the new system will weigh 28 times less than the payload it will deliver to the Moon during its entire service life. In comparison, the fuel burned by conventional rocket engines will weigh 16 time more than their payload.

In reading about this, I found myself wondering where the energy for this will come from. Conservation of energy requires that the lowest tether, once it transfers energy to the payload, and boosting it higher, will fall to a lower orbit. How will it be raised again? One way is suggested by TUI, which is looking at using special tethers (cables) that can "push" against the Earth's magnetic field to move back up into position.

This "new" Russian technology is starting to look a lot like the MXER-Momentum-eXchange/Electrodynamic Reboost tether technology-now under development by NASA. MXER research is proceeding in five different research areas: aerocapture; advanced chemical propulsion; solar electric propulsion; solar sail technologies; and space-based tether propulsion.

With the entry of the Russians into this area, it sounds like the race to build a "space railway"-a system of cableways that can sling payloads to the moon-is underway.

Interested in space tethers? Check these out:

Read more about the Russian space-elevator clusters and NASA's MXER technology.

(This Science Fiction in the News story used with permission from -where science meets fiction.)