Academy researchers go into zero gravity for science

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U.S. AIR FORCE ACADEMY, Colo. --  Academy researchers went into zero gravity Sunday to test a new patented optical telescope that can expand the capabilities of space-based imagery.

Cadet 1st Class Heather Nelson, 2nd Lt. Samantha Latch, Trey Quiller, Dr. Michael Dearborn and Dr. Geoff McHarg from the Academy went weightless to test payload deployment of the Academy's FalconSAT-7 satellite on board a NASA aircraft Aug. 26.

The zero-gravity test experience came courtesy of the NASA Reduced Gravity Research Program and the contract Boeing 727 it uses for research and astronaut training. The aircraft lifted off from Houston, and once over its test area, flew a series of parabolic arcs that produce periods of weightlessness at the top of the flight arc for 20 seconds at a time, and stronger gravity at the bottom of the airborne roller coaster ride.

Inside the aircraft's padded cargo bay, this was the first time the payload and Academy researchers have performed tests in less than full gravity.

"The Zero-G experience is unlike anything you can possibly describe to someone who has only ever experienced a 1-g environment," said Cadet 1st Class Heather Nelson, an astronautical engineering major from Cadet Squadron 16. "For the first parabolas, they have you lay back on your back so your inner ear has a better chance to adjust. When you hit the 1.8-g pullouts you feel like you are being pushed into the floor of the plane -- but not like you are being pressed, more like you sink in farther because you weigh more. When you hit the 0-g portions you just float off the floor, it's sort of like doing a deadman's float in a pool.

"It was as amazing as I had hoped it would be," she added. "I literally couldn't stop smiling. I am grinning ear to ear. Everyone I've been telling is super jealous and tells me that I got the coolest research project. I can't help but agree with them. I have had the amazing opportunity to work with a great team on a cutting edge program and for that I am very thankful!"

Once acclimated to the gravitational changes, the Academy research team was then able to test the Academy's latest satellite, FalconSAT-7, to see if it could successfully deploy its sole payload. That payload is a new optical telescope that known as a photon sieve.

"If we can demonstrate that this works, use of a photon sieve opens up the possibility of putting larger telescopes on small satellites," said McHarg, director of the Academy's Space Physics and Atmospheric Research Center. "This is critical for both NASA and the DoD because the resolution of a telescope is dictated by the size of the primary optic. Traditional space-based telescope optics are limited to the size of the host spacecraft. For instance, the Hubble Space Telescope is the size it is because it had to fit inside the Space Shuttle. NASA would have made a larger Hubble if they would have had a larger spacecraft to launch it."

The photon sieve was created and patented at the Air Force Academy's Laser and Optics Research Center.

"The photon sieve is a thin membrane with of billions of tiny holes, each of which causes diffraction," said McHarg. "The holes are cleverly arranged to add up correctly to make an image. The photon sieve is made from a very thin membrane material -- much like plastic wrap used in a kitchen -- that can be rolled into a small space, and stowed into our little spacecraft."

FalconSAT-7 is indeed small. The entire cubesat is 30 centimeters in depth and 10 centimeters in both length and width. Once in orbit, the satellite will open to release three arms that stretch the photon sieve's metal membrane out in only two seconds to deploy a 10-inch diameter telescope. This will become the world's first space-based membrane telescope, and it will be used to image the sun.

"The micro gravity flights made possible by the Space Test Program and the NASA Reduced Gravity Office were vitally important to our FalconSAT-7 program because it demonstrated that the basic deployment mechanism we have will work in a reduced gravity environment, and does not become fouled in the process," said McHarg. "On the technical side we found that our packing scheme does work, and that when the telescope deploys -- pops out like a jack in the box -- it does not make the spacecraft tumble."

FalconSAT-7 is a collaboration between National Reconnaissance Office, Defense Advanced Projects Research Agency, Air Force Office of Scientific Research, Air Force Institute of Technology, NASA, MMA Design and the Air Force Research Laboratory, and is slated for launch in 2014.

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