Demonstrator proves a big structure can fit snugly into a typicalrocket body (Forwarded)

Public Affairs
Air Force Research Laboratory
Kirtland AFB, New Mexico

Contact: Michael P. Kleiman
Phone: 505-846-4704

January 20, 2006

VS Release No. 06-03

Demonstrator proves a big structure can fit snugly into a typical rocket
body

Space Vehicles Directorate's research on the deployable optical telescope
validates the placement of a large system in a standard launch vehicle to
ultimately provide enhanced imagery to the joint warfighter

Positioning three delicate, circular mirrors to one one-thousandth of the
width of a human hair consistently challenged scientists at the Space
Vehicles Directorate, Kirtland Air Force Base, N.M., during their
five-year study of the deployable optical telescope (DOT), a 1.5 meter
(approximately 4.9 feet) in size demonstrator, which represents the future
of foldable, larger aperture optics housed in existing launch vehicles.

One year ago, the research team, however, discovered a breakthrough for
the complex experiment, which successfully ended last fall, and the
technology advancement will eventually produce significantly improved
tactical imagery supporting the joint warfighter on the battlefield.

"When all of us in the beginning saw what we had to do to get the DOT
study completed, there were some doubts to getting it done because it
might take too long, but we nailed it," said Dr. Lawrence "Robbie"
Robertson, chief, Dynamics and Controls Group, Space Vehicles Directorate,
Air Force Research Laboratory. "We wanted to give the warfighter better
tactical imagery."

In 1995, a group of six researchers serving at the Space Vehicles
Directorate desired to construct a larger telescope for the Air Force for
applications in the cosmos, and within a few months, they had completed a
conceptual design structure, conducted the required analysis, and
initiated the building of a test bed for their vision. Serving as the
experiment's model, the National Aeronautics and Space Administration's
Hubble Telescope, launched in April 1990 from the Space Shuttle
Discovery's cargo bay, and with a projected mission duration of 20 years,
measured 2.4 meters (8 feet) in diameter and resembled a large school bus.
On the other hand, for cost effectiveness, project personnel began
investigating the potential housing of a similar sized optical device in a
standard launch vehicle by reducing the apparatus' dimensions through
structural folding.

During the test program's first five years, a limited demonstrator, the
precision deployable optical structure (PDOS), exhibited, primarily
through software and structural evaluations, some of the intended
technologies, but did not have true optical mirrors, a crucial element.
The follow-up experiment, the DOT, comprised a scale representation of the
concepts developed by the six scientists five years earlier, and involved
a collaboration between public and private industries. For example, Kodak
constructed the three 60-centimeter mirrors, Shafer Corp. built the
three-meter deployable secondary tower, Boeing-SVS, Inc., and CSA
Engineering, Inc., integrated the demonstrator's components, as well as
assembled its control systems and the Space Vehicles Directorate provided
the primary main structure. NASA also served as a key program partner.

"The DOT project pulled together the best and brightest in AFRL today. It
really was an interdisciplinary team, and the project required one," said
Dr. Robertson. "Early on, we teamed with NASA because we realized that the
DOT project was not going to require just AFRL, but help from other
federal government agencies to make it happen."

Because of the sensitivity of its three optical mirrors, the DOT resided
in possibly the quietest confines in the country. To prevent minimal
motion and vibration, the laboratory's floor consisted of bedrock with 50
feet of concrete poured on top. During the telescope's inaugural tests,
the program added another control system to compensate for other
vibrations produced by a construction crew working several feet away from
the 1.5 meter structure. Nevertheless, another major challenge, arranging
the mirrors to the miniscule dimension of one one-thousandth thickness of
a human hair for sharper resolution, tested the researchers' resilience
and patience. After four years of trial and error in folding and unfolding
the three objects to the required placement specification, the program
finally reached the target benchmark by employing four optical sensors and
18 pointing devices, as well as a laser-based sensing system, which
measured the position at about 10,000 times per second. For the remaining
nine months of the $40 million DOT project, scientists continued to assess
the correct location of the mirrors to ensure proper functioning in the
space environment.

While the DOT experiment occurred, NASA started work on the proposed
successor to the Hubble, The James Webb Space Telescope, a projected 6.3
meter in-length folding optical device slated for operations early in the
next decade. Technologies advanced by the DOT have already been
transitioned to enhance the planned, high performance telescope.

"AFRL sees the DOT as technology complete and has been transitioned out to
large aerospace companies to develop and use to build systems for the Air
Force, NASA, and other potential customers," said the Dynamics and
Controls Group chief. "Academia was also involved with the DOT. We brought
in professors from around the country to help with the pointing
algorithms, and the result was a lot of new ideas and technologies for
accurate positioning of structures/optics were spawned."

For the DOT project team, the phrase "patience is bitter, but its fruit is
sweet," aptly describes the dedication, determination, and commitment
displayed during the past 10 years. Mission accomplished.

IMAGE CAPTION:
[http://www.vs.afrl.af.mil/News/Images/06-03.jpg (108KB)]
Photograph displaying the deployable optical telescope's three, 60
centimeter, optical mirrors with the laser-based sensing system. (U.S. Air
Force photo)