SEDSAT Puts Students Over The Earth

SPACEDAILY

Tucson - October 25, 1998 -

Tucson - October 25, 1998 - Students for the Exploration and Development of Space (SEDS) and the Amateur Radio Club (ARC) at The University of Arizona in Tucson will soon have command of an imaging satellite following the launch of SEDSAT as a secondary payload to the main Deep Space 1 payload on Saturday.

The UA students in Tucson will be the first to get science data from the satellite. They will archive its views of the Earth and be primarily responsible for making these images available to anyone with access to the Web.

The students got funding for, built and will operate the primary groundstation for SEDSAT-1, a microsatellite built by SEDS students at the University of Alabama in Huntsville.

SEDSAT-1, which will operate on amateur radio frequencies, was initially planned to be the end-mass for a tether-deployment experiment from the space shuttle. It developed instead into an amateur communications satellite with cameras. These are a multi-spectral telephoto camera and a 678 x 44 pixel (picture element) panoramic camera to photograph views of Earth and its atmosphere. It will also perform digital and analog amateur radio operations and conduct engineering studies in control, batteries and electronics technology.

All of the satellite's data will be loaded directly onto the Internet, and amateur radio operators can contact the satellite and download images while it passes overhead. A special mobile link to the satellite will provide near-continuous communications to the Internet, so that station operators won't have to wait for periodic downloads of satellite data. The UA students say they believe this is the first time the Internet has been used for this purpose.

The students in Tucson will be mobilized for action Sunday morning at their satellite control center, the UA ham radio club office in Old Engineering Room 303. The satellite will separate from the launch vehicle over Hawaii at about 83 minutes after launch, said Christopher A. Lewicki, a master's graduate student in aerospace engineering and driving force behind the project. According to his simulations, the satellite control team may send their first command 95 minutes or so after launch.

The UA team may be asked to run a simple telemetry uplink test on the first satellite pass, but SEDS students at Huntsville will make most of the initial uplinks to ready the satellite for operations, Lewicki said.

"The most interesting images will be when the satellite actually deploys from the launch vehicle, which will be the ones we try to download first," he added. "It will probably take the first several days to download the initial images. We'll start this process after the health of the satellite is verified during its first few orbits."

Lewicki coordinated construction of the station at the Old Engineering Building on the UA campus. The students spent about $12,000 to develop and build the station. They raised funds and support from the UA planetary sciences department, the UA electrical and computer engineering department, the Arizona/NASA Space Grant Program and from another UA student satellite project called "UASat," for which Lewicki is project leader. They also dug into SEDS and ARC club coffers. "We could really use a couple thousand dollars more to finish things up," Lewicki noted. Their station includes a 10-foot tower that supports three antennas which can be pointed at any spot in the sky and a feedline that runs radio signals through preamplifiers to the ham radio satellite control office. The heart of the satellite control system is a Linux server that will run terminals dedicated to various flight control operations.

Signals are received by the groundstation satellite radio and sent by modem to a computer. Students built the control box between the radio and the computer, as well as another control box between the computer and motors that point the antennas for tracking the satellite.

They also developed simple signal processing hardware and "much of the cobbled-together hardware to glue all these parts together into a cohesive unit," Lewicki said. " Most of our original contributions to this area is in the software, the first version to be done in time for launch," he added.

Checking equipment, checking satellite specifications and writing lots of software have consumed "tons" of time prior to launch, said Dana Irvin, a junior majoring in computer science and president of the UA Amateur Radio Club. Irvin also leads the Tracking Telemetry and Command Team on the UASat project.

SEDSAT station operators in Tucson will be able to contact the satellite directly in 10-to-15 minute bursts, for a total of about 30 minutes a day. Theoretically, they could "wormhole," or link through the Internet to other radio stations around the planet for continuous, 24-hour coverage. There aren't yet enough participating ground stations for 24-hour coverage, but the UA team should be able to contact the satellite two or three times during its global orbit to download all available data.

Once their station is fully operational, the students will automate it.

SEDSAT-1 could orbit Earth for years. Lewicki said, " These types of satellites have gone from lasting as little as a few days to as much as 15 years."

But it is worth the gamble because of the possible rewards, according to Lewicki and Irvin. It allows students the chance to take their own measurements, draw their own conclusions and gain their own insights into Earth and its atmosphere. It already has given students skills in amateur radio, satellite engineering, writing software, remote sensing and spaceflight operations.

"How many other students do you know who get to communicate with satellites on a regular basis?" Irvin said. " We aren't just talking about receiving a telemetry signal and passing it out. We will also be sending commands up to the satellite."

"It's fun because students have the opportunity to participate in the daily operation of something that is in space, and also provide the data from this satellite to the rest of the world," Lewicki said. "Student's don't have the opportunity to do this very often -- especially as part of an exclusively student project."

SEDSAT

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