Dec. 13, 2010

Student-built satellite scheduled for rocket launch

It was a waiting game not unlike a marriage proposal -- expected, yet unclear in timing. But finally, the CUSat team gets to set a date.

The student team, which has built an experimental satellite equipped with sophisticated GPS technology, has been "manifested" for flight -- that is, the satellite is guaranteed a spot on a rocket bound for space, where it will conduct experiments in low-Earth orbit.

In 2007, CUSat won the U.S. Air Force-sponsored University Nanosatellite Program's Nanosat-4 competition, and the prize was a flight worth millions of dollars. Just recently, their satellite became a confirmed passenger aboard the Falcon 9, which will head to the International Space Station sometime between October 2011 and January 2012.

"We knew we were in the hopper," said Mason Peck, associate professor of mechanical and aerospace engineering and CUSat principal investigator. "It was just a matter of waiting long enough."

Falcon 9 is a rocket built by the company SpaceX, and it will carry routine cargo to the space station during that mission. The payload will be integrated and flown under the management of the Department of Defense Space Test Program.

"The rocket is basically like a subway," said Adam Yozwiak '11, co-team leader. "The SpaceX satellite will get dropped off last at the space station orbit -- we are just hitching a ride on the way."

Since their Nanosat-4 win, the mostly undergraduate student team has been working to improve the software aboard CUSat, which is actually a pair of twin satellites that will separate in space to perform experiments involving orientation and location. The system is capable of circumnavigating space relative to each other, using a code called Carrier-Phase Differential GPS (CDGPS) developed by Mark Psiaki, Cornell professor of mechanical and aerospace engineering. The algorithm he developed is accurate to within centimeters.

"With that type of accuracy, future missions can use the technology to do, for example, close proximity maneuvers," said Mike Goetz '11, co-team leader.

Most or all satellites today use gyroscopes or accelerometers to determine their orientation in space, Yozwiak said. But CUSat can use the CDGPS algorithm to do it autonomously.

The mission will set out to prove the robustness of this new GPS technology, Peck said. "It's very rare for spacecraft to cooperate with each other," he said. "It's usually a cowboy thing -- one spacecraft does its thing. But if you ever hope to have more than one, they have to navigate relative to each other."

These days, the CUSat team spends a lot of time at mission control in Ward Hall. Their satellite has spent the past year at Kirtland Air Force Base in Albuquerque, N.M., for a battery of required environmental tests, which include thermal vacuum chamber testing and vibration testing. These procedures are meant to ensure their hardware will survive the harsh conditions of space.

The team is also busy configuring ground stations that will help them talk to the satellites once they're in orbit. There's one in Ithaca at the Mount Pleasant observatory, and others will be located in the Marshall Islands and in Redondo Beach, Calif.

Another team under Peck is working on a high-agility technology demonstrator satellite called Violet. Violet team members are preparing for the Nanosat-6 competition, and their flight competition review board will meet in January.