COLORADO SPRINGS, Colo. A program that gives U.S. Air Force Academy cadets a chance to fly their own satellites will put an experimental bird into orbit this fall carrying, among other things, an experiment from the Jet Propulsion Laboratory to study self-generated health-status reporting for a spacecraft, for potential use onboard a Pluto fly-by mission.
That satellite, called FalconSat-1, grew out of a program to design a small bird for collecting global-positioning satellite signals above the GPS constellation. The program is now a regular part of the curriculum at the USAFA, just north of here.
FalconSat-1, under development for a scheduled launch in September, is the first project to win official approval from the Defense Department's Space Experiments Review Board. If the effort is successful, several more sensor and communication experiments could be handed over to the undergrads over the next few years.
According to plans, FalconSat-1 will launch aboard a refurbished Minuteman II with Pegasus upper stages. Future development programs will involve more federal labs, as the missions become more experimental in nature. FalconSat-2, for example, may utilize a special "water rocket" developed in part by Lawrence Livermore Labs, using solar energy to perform electrolysis of water to provide propellants for main thruster control and altitude control thrust.
All the labs involved with USAFA's small-satellite program, from Livermore to Kirtland Air Force Base in Albuquerque, N.M., are learning lessons in reducing the cost of scientific missions.
"Larger missions can spend $1 million to $2 million per black-box component," said Emery Reeves, professor of astronautics who holds the Schriever Chair at USAFA. "By necessity, we have to aim far, far below that cost."
Reeves has been instrumental in defining missions and curricula to meet them. Ideally, he said, juniors and seniors would be taken through a four-course program that would take them from initial concept and design, to launching the satellite in their final year.
The academy is building its own dedicated ground station at the astronautics lab on the USAFA campus, with the help of another Air Force program, Picosat, and Surrey Satellite Technology Ltd. (Surrey, England). Industry helps out, too. In fact, Col. Michael Caylor, deputy for labs and research in the astronautics department, said word-of-mouth on the program has been so good that the department has more industry proposals than it can accommodate right now.
Corporate involvement has expanded as the initial project-the GPS-oriented Falcon Gold-was making the transition to the next-generation FalconSat. Navsys Corp., a GPS transceiver company just north of here, offered its popular "Tidget" (Tracking Widget) sensor for the Falcon Gold satellite. During a meeting at Navsys, the academy's GPS project manager, Gabriele Belle, struck up a conversation with Corey Miller, circuit-card assembly product manager at UTMC Microelectronic Systems Inc. That contact led to UTMC participating in the design of a standardized embedded controller for FalconSat.
The Falcon Gold GPS satellite, which Belle helped design as a student intern, had to be developed within severe size and power constraints, piggybacked on a Defense Satellite Communication System III satellite onboard an Atlas/Centaur. The satellite represented the first unclassified mission collecting GPS data in an altitude above the GPS constellation. It used amateur radio transceivers and nickel-metal-hydride batteries, which lasted for 15 of the planned 20 days of the mission.
Reliance on a Boulder ground station near the University of Colorado campus in that town underscored the need for a ground station on the USAFA campus. On the day of Falcon Gold's launch from Cape Canaveral, Oct. 24, 1997, a massive blizzard hit Colorado, preventing staff from reaching the Boulder site for several days. A Naval Academy facility in Annapolis, Md., collected the first few days' worth of data, a factor that pricked at interservice rivalries.
"Making this academy a learning facility for ground-station duties as well as satellite development will also simplify logistics," Caylor said.
Once Falcon Gold was flying, the department mapped out a three-year spacecraft-development program and worked with the physics department to define the mission for an Air Force project called Chaws (Charging Hazards and Wake Studies). Chaws studies charging of spacecraft in polar regions caused by dense plasmas that follow the earth's magnetic field lines. That study will join a JPL experiment, called JPL Beacon, on FalconSat-1.
The Chaws/Beacon satellite is designed for simplicity, using a combination of magnetic control and spin stabilization for rudimentary altitude control. Ground-station commands will be used to switch the satellite between magnet and spin control. The satellite's data-acquisition system had to be designed for easy readout when the track passed over Colorado, and simple analysis of the electromagnetic data. But at the same time, system design and development needed to be appropriately integrated into a learning program.
"We can't forget that the academy is first and foremost an educational undergraduate institution, and we have to meld experiment design into that mission," Reeves said. "Our technology base has to be more dependent on outside support, from private companies and government labs. I characterize this as 'CheapSat.' We have to depend on what government and private-industry support we can work into our curricula."
The undergraduate team designed a cube-shaped rack-and-stack set of ruggedized modules, with separate processing planes designed for such tasks as communications, control, telemetry and data acquisition. Miller and Tony Jordan of UTMC worked with USAFA department heads to define a standardized controller board based on a radiation-hardened C196 controller. Rather than use a standard MIL-STD-1553 bus, the academy used a 1553 protocol in conjunction with a special low-power 1-Mbit/second asynchronous serial bus for communications between the controller and the flight computer.
The controller card is a prototype, but UTMC will eventually offer it for use in commercial, NASA and military programs.