Students Help Shrink Satellite To Football Size

"I had no idea you could make these satellites so small. I was astounded," said Saman Kholdebarin, recalling his surprise when his Goddard mentors explained the project to him.

The pint-sized satellite will study lightning, when it launches from the Marshall Islands aboard an Air Force Falcon 1E rocket vehicle next year. In particular, Firefly will focus on Terrestrial Gamma-ray Flashes (TGFs), a little understood phenomenon first discovered by NASA's Compton Gamma-Ray Observatory in the early 1990s.

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Firefly will make simultaneous measurements of escaping energetic electrons accelerated over thunderstorms, the gamma rays produced by the electrons, and the radio wave and optical signatures of the lightning discharge.

The first hurdle to solving the mystery was building the spacecraft and its two experiment packages -- all for the budgeted amount of less than $1 million, which is about 100 times less expensive than what full-sized satellite missions normally cost.

In hope to answer what causes these high-energy flashes, Goddard scientist Doug Rowland and the Firefly team designed and integrated the spacecraft and its instruments with the help of 15 students from the University of Maryland-College Park, Siena College in Loudonville, New York, and other universities.

The team expects to ship the completed satellite to the Air Force sometime this fall in preparation for a March 2011 launch. Once deployed in its low-Earth orbit, Firefly will provide at least three months of data with a goal of up to one year to maximize student involvement in operations and data analysis.

Firefly is expected to observe up to 50 lightning strokes per day and about one large TGF every couple of days.

In 2008, the work on Firefly began shortly after NSF selected the mission concept for support under its CubeSat program, which launches mini satellites as stowaways aboard rockets carrying larger satellites in space, rather than requiring dedicated rocket launches. Firefly represents the second in a series of NSF-sponsored small satellites designed to study Earth's upper atmosphere.

Under the two-year collaboration, the Hawk Institute for Space Sciences provided the spacecraft, ground station testing and flight software. Siena College built a number of spacecraft components including one of Firefly's two experiment packages, the Very Low Frequency (VLF) receiver/photometer experiment.

This experiment combines multiple sensors to measure both VLF radio waves and optical light emitted by lightning. These measurements will corroborate the occurrence of lightning when the spacecraft observes gamma-ray flashes.

And the Goddard team built Firefly's Gamma-Ray Detector (GRD) instrument, which will measure the energy and arrival times of incoming X-ray and gamma-ray photons associated with TGFs.

Although Joanne Hill designed the instrument, the Goddard scientist assigned Ramsey and Kholdebarin the task of designing, building, and testing the instrument's power supply board, a component that monitors voltage levels that run the detector.

David Guzman, a student from the Universidad de Alcalá in Madrid, Spain, meanwhile, was tasked with applying his knowledge of computer microprocessors to enhance the instrument's performance.