The Cooperative Astrophysics and Technology SATellite (CATSAT) project is a collaborative effort between the ECE Department, UNH Physics Department, Weber State University, and the University of Leicester. The mission of the satellite is to detect the origin of Gamma Ray Bursts (GRBs). There are two very important aspects of this project:

• the scientific goal - try to determine the source of Gamma Ray Bursts
• the educational objectives - graduate and undergraduate student teams will design, fabricate, test, and operate the satellite under supervision from faculty and scientists.

GRBs were discovered accidentally twenty years ago by the Vela satellites while attempting to verify Soviet compliance with the Nuclear Test Ban Treaty. Their existence was a complete surprise and in spite of extensive experimentation has remained one of the most mysterious of astrophysical phenomena. Mechanism(s) that produce GRBs are among the most violent and energetic processes known to exist in nature, emitting the majority of their luminosity at gamma-ray wavelengths. During the time of an outburst it is usually the brightest object in the gamma-ray sky. GRBs typically last from a fraction of a second to about a minute. About 400 GRBs are reported each year but it has not been possible to identify quiescent counterparts at other wavelengths or establish a correlation with a specific class of astronomical objects.

CATSAT is a small space flight mission specifically designed to solve the problem of finding the origin of GRBs using an innovative multi-observation approach. CATSAT uses an array of cooled silicon detectors to measure the spectra of GRBs at energy levels down to 500 eV for a field of view that is nearly 360 degrees. This will allow the use of soft X-ray cutoffs, generated at energies below 2 keV by photoelectric absorption in the interstellar medium, to estimate burster distances. None of the burst experiments that have flown or are currently under construction have the ability to make such a distance measurement. CATSAT uses the innovative technique of imaging the earth's albedo flux to study the polarization properties of the incident burst radiation. The large field of view afforded by this technique makes it the first practical method for measuring burst polarization.

Increased economic pressure (caused by shrinking government budgets) has caused a revolution in thinking about space missions. The emphasis is on the increased use of smaller satellites for commercial and scientific applications. There are two major categories of small satellites: microsatellites and lightsatellites. Microsatellites are the very smallest, least complex craft, generally massing less than 10 kg. Lightsatellites are defined with specific limitations in terms of size, cost, and development time. For example, the Lightweight Satellite Systems conference found the maximum weight of a lightsatellite to be 500 pounds. The CATSAT satellite will be 250 pounds, 91 cm in height, and 76 cm in diameter, for a total volume of approximately 0.41 m3. Prior to 1985, the performance and flexibility of lightsatellites had been limited by their design and integration path, which was unable to utilize advanced technologies developed for large satellites. With the development of newer smaller technologies and microsystems, small satellites appear to be on the brink of performance breakthroughs. These new technologies open up small satellites for increasingly complex missions, formerly limited to their larger cousins.

The Student Explorer Demonstration Initiative (STEDI) mission, which was announced in May of 1994, sought to facilitate support for space science, support for educational involvement, and the demonstration of small satellite technology. Space science support incorporates a broad range of activities: astrophysics, earth sciences, life and biomedical sciences, microgravity sciences and applications, and solar systems. Educational involvement is emphasized as a major factor in the downselect process, with requirements for active mentoring of student participants. The technology development objective is to conduct in-flight test and demonstrations of new and improved technologies in space systems, space communications and other space operations, and other areas of advanced space technologies.

Combining the requirements for the scientific mission and the smaller satellite initiated with the STEDI program, UNH's Institute for the Study of Earth, Oceans, and Space (EOS) received a grant from NASA to start the development of CATSAT. ECE students started working on the project last summer. Students from the ECE Department logged some 3341 hours, of which 2186 were undergraduate student hours, on the CATSAT project during the fall semester. Sixteen students in Dr. Rucinski's Introduction to VLSI class designed and implemented a major portion of the Digital Electronics Unit (DEU). Other students, supported through the Research Experiences for Undergraduates (REU) grant and the phase I CATSAT grant, designed the soft X-ray sensor circuits, the portion of the analog electronics that interfaced the sensors to the DEU, and a part of the high voltage power supplies. Students were grouped into Student Engineering Teams (SET), a concept that teams undergraduate and graduate students with faculty and scientist mentors. A number of quality management procedures were initiated to insure the quality and reliability of the project.

First, students had to become familiar with the overall goals of the satellite's mission. Dr. David Forrest from the UNH Physics Department, who is the principal investigator of the project, and Mr. Ken Levinson, who is the project manager, conducted a series of lectures to introduce and explain the scientific and system goals. Richard Harrison, an ECE graduate student, developed systems level specifications for the DEU. These specifications were then partitioned into manageable subsystems and assigned to SETs. Each SET was assigned a subsystem to design and test, with the understanding that all subsystems had to be integrated together and function as part of the entire satellite system. Since space system electronics provide interesting challenges not normally associated with earth bound electronic systems, students had to become familiar with such issues as reliability, radiation hardness, fault tolerance, stringent power and layout requirements, and heat dissipation under nonatmoshperic conditions. The students also had to prepare extensive documentation, part of the quality management procedures, and present their subsystem designs to the NASA project review board which visited UNH in February.

CATSAT currently has four funded ECE graduate students working on the satellite systems: Dino Milani, Glenn Forrest, David Geary, and Steve Lynch. This summer there are also four REU funded undergraduate students working on CATSAT along with two mechanical engineering students and a visiting student from France. This fall Dr. Rucinski's Collaborative Engineering (see related article in this issue) and Introduction to VLSI classes will continue with CATSAT development.