NASA's Mars Pathfinder mission

Students from Sierra College in Rocklin, Calif., have delivered their very own creation -- "Mr. SunSensor" -- an engineering model of a sun sensor to be used this week in a Mars Pathfinder spacecraft operations simulation at NASA's Jet Propulsion Laboratory.

The students are part of a special student-industry- government team which has spent the last two years building their own miniature spacecraft. In a unique collaborative arrangement, JPL and industry representatives have been providing technical assistance to the team effort, while NASA and the Advanced Research Projects Agency (ARPA) furnished the funding.

"We met recently with the team for a technical review and learned that they were designing a sun sensor for their own spacecraft that could also be used for a specific Pathfinder test," said Dr. Dankai Liu, a lead engineer on the Pathfinder attitude and information management subsystem team at JPL. "So we suggested integrating their sensor on the Pathfinder spacecraft and inviting them to watch the simulation."

Ordinarily, a sun sensor would have been purchased or built by JPL to perform the test, Liu said. JPL's partnership with Sierra College, industry and ARPA made the hardware delivery possible at no cost to the Laboratory.

The students' project managers, Mike Dobeck and Stan Spencer, both instructors at the Northern California community college, jumped at the opportunity to get students involved in the Mars Pathfinder mission. JPL representatives Dave Woerner, manager of the Pathfinder attitude and information management subsystem team, and Brian Muirhead, flight system manager, agreed whole-heartedly to the collaborative arrangement. Dobeck also enlisted the participation of a group of high school students enrolled in a spacecraft design class at Colfax High School, near the Rocklin-based college.

"This antenna-pointing test is a critical step in the final months of Pathfinder testing and we're very glad to be able to use the students' sensor," Liu said. "One of the first tasks the Pathfinder spacecraft will have to perform after it lands on the surface of Mars is find Earth and point its high-gain antenna toward us so we can communicate with the craft."

To demonstrate Pathfinder's pointing capability, engineers will mount the sensor on the spacecraft, then ask the spacecraft to find the sun and track it as it moves across the sky. Liu's attitude subsystem team will measure errors in the lander's guidance system to determine Pathfinder's "marksmanship," or how accurately the spacecraft is pointing its antenna.

Attitude testing will take place during a two-day spacecraft operations simulation to be held at JPL on May 7 and 8. Other testing, including electrical, acoustic and thermal vacuum testing, will continue at the Laboratory through the summer. Pathfinder is scheduled to be shipped to Cape Canaveral, Florida, on Sept. 1, where it will be integrated on a Delta 2 launch vehicle and prepared for a Dec. 2 launch.

The Mars Pathfinder mission is the first in NASA's Discovery program of low-cost planetary spacecraft with highly focused science goals. The mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, D.C.

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