Air Force Finds Way to Fold Space Telescopes

February 1, 2006

KIRTLAND AIR FORCE BASE, N.M. — Air Force scientists have figured out how to delicately fold a space telescope without mutilating it.

Scientists at the Air Force Research Laboratory’s Space Vehicles Directorate have spent years on a project to demonstrate how to place a large telescope inside a typical rocket body and prevent vibrations during launch or deployment that would keep the instrument from operating as intended.

“With the deployment of optics into space, the tiniest vibrations could impact mirror position and orientation, and thus, they must be canceled out,” said Michael P. Kleiman, a spokesman for the Space Vehicles Directorate.

The experiment was aimed at getting larger optics into space to provide better imagery for soldiers in the field.

The project began in 1995, when six researchers at the Space Vehicles Directorate proposed building a larger telescope for the Air Force, using the National Aeronautics and Space Administration’s school bus-size Hubble telescope as its model.

To cut costs, researchers began investigating how to house something that big into a standard rocket such as the Minotaur I, which is nearly 4 feet in diameter by 7 feet tall. The aim was to reduce the dimensions by folding the structure.

During the project’s first five years, researchers tested some of the technologies with a demonstrator, evaluating both software and structures. The demonstrator was not meant to fly into space but rather to prove the major technologies would work.

But the demonstrator lacked true optical mirrors – a crucial element.

A follow-up experiment, called the deployable optical telescope, had three optical mirrors, the lightest weight mirrors ever built. They are made of a special kind of glass called ultra low expansion glass, which is very thermally stable.

Teamed with industry, university professors and other government agencies, the Air Force lab spent four years of trial and error before the program was able to unfold the three delicate, circular mirrors to get an accurately focused image that could be updated a thousand times per second with positioning devices and a laser-based sensing system.

For the remaining nine months of the $40 million deployment optical telescope project, scientists assessed the correct location of the mirrors to ensure they would work correctly in space.

Kleiman said, however, such technology would not be put into use until early in the next decade.

In the meantime, NASA will use technology advanced by the deployable optical telescope program in a successor to Hubble.

The Air Force Research Laboratory has turned over the technology to large aerospace companies to develop systems for the Air Force, NASA and other customers, said Lawrence “Robbie” Robertson, chief of the research lab’s dynamics and controls group for the Space Vehicles Directorate.

On the Net:

Air Force Research Laboratory: http://www.vs.afrl.af.mil

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