Shape of things to comeRotating space elevator propels its own load

As we place more systems in space — soon, perhaps, weapon platforms to counteract China’s growing anti-satellite warfare capabilities — there is a growing need to service and maintain these systems. As we wrote a year ago, one way to do so relatively on the cheap is to build a space elevator (see 2 April 2008 HS Daily Wire). The interest in space elevator is such, that the Mountain View, California-based Spaceward Foundation has been holding an annual Space Elevator Challenge competition in which teams compete with each other over concepts and designs to thrust the elevator skyward.

Now, traditional concepts of space elevators involved using rocket propulsion or laser light pressure to propel loads up a cable anchored to Earth, but a new study shows that a rotating space elevator could do away with engines or laser light pressure application completely. Instead, Physorg.com’s Lisa Zyga reports, the unique double rotating motion of looped strings could provide a mechanism for objects to slide up the elevator cable into outer space. The space elevator could launch satellites and spacecraft with humans, and even be used to host space stations and research posts.

Konstantin Tsiolkovsky, back in 1895, was the first to propose the idea of a giant string connecting the Earth and the skies. Until the latest proposal, however, all previous elevator ideas relied on internal engines, laser light pressure, or any kind of propulsion to propel the elevator and its load skyward. Now, in a study funded in part by NASA, theoretical physicist Leonardo Golubović and his graduate student Steven Knudsen at West Virginia University have explained that it is possible to conceptualize an elevator which propels its own load, at least in theory.

Golubović and Knudsen have elaborated the concept of Rotating Space Elevator (RSE), a rotating system of a floppy string that forms an ellipse-like shape. Unlike the traditional Linear Space Elevator (LSE) made of a single straight cable at rest, the RSE rotates in a quasi-periodic state. As the scientists explain, RSE motion is nearly a geometrical superposition of two components: its geosynchronous rotation around Earth (which has a one-day period), and the internal rotation of the string system that goes on around the axis perpendicular to the Earth (about a 10-minute period). This internal rotation of the string is especially important, as it provides a mechanism for objects to freely slide along the string, and also provides the dynamical stability to maintain the elevator shape.

“The idea