TOPEX Buoy Calibration Experiment

This Spring, The University of Texas Center for Space Research(UTCSR) and Texas SpaceGrant Consortium (TSGC) inconjunction with the Colorado Center forAstrodynamics Research(CCAR) and Colorado Space Grant Consortium solicited designs for prototype shallowwater buoy-type instrumentation platforms to carry satellite rangingequipment and other using satellite science instruments to betterunderstand the oceans and bays near Galveston, Texas. We solicited designs by teams of high school and middle school students for a buoycapable of supporting and protecting a GPS (Global Positioning System)receiver antenna and measuring other ocean properties which will be used to calibrate the TOPEX/Poseidon satellite.

Schools were asked to deploy their buoy designs at a site on Galveston Bay on Wednesday, May 15th of 1996. In all there were five buoys, three designed from students in the Houston area, as well as a buoy designed by Boulder Colorado high school students and a design from the University of Texas. Most of the designs incorporated a "wave rider" design, but were all different in many other respects.

Each student design was able to collect data using a single frequency GPS antenna for a period of fifteen minutes near the tide gauge at Eagle Point. The data was recorded at 30 second intervals, and will be prepared by CSR.

Two additional buoys, Colorado and UT, were also recording data at the "float off" with a dual frequency antenna at 30 second intervals. The "float off" was used as a demonstration of the actual data collection which took place later in the afternoon. Students were able to see several designs as well as understand various aspects and factors in an calibration exercise.

The two buoys built by Colorado and UT were used for data collection during the TOPEX/Poseidon overflight. A boat was chartered to position ourselves directly under the groundtrack of the satellite. The groundtrack is several kilometers out in the bay and it took quite a bit of time to arrive at the desired location. We arrived at the location at approximately ten minutes prior to the overflight.

To improve the data collection for the scientific portion of this experiment, we allowed for double redundancy with two base stations running both a Turbo-rogue and a Trimble SSE, as well as using a Turbo-rogue and Trimble in rover mode. The designs of the buoys were also identical, so that allowed for basically two sets of data at each collection site.

In all, we were able to record FIVE points along the groundtrack and an additional point at a selected crosstrack location. These additional points will help to better understand and map the geoid for Galveston Bay. At each site out in the bay, the GPS data was collected in one second intervals.

Two buoys recording positional data from the GPS satellites exactly when the TOPEX/Poseidon satellite passes directly overhead. Scientists will use the GPS data recorded from the buoys to calibrate the altimeter onboard TOPEX/Poseidon.

Background Information on Galveston Bay

UT Student Design

Float-Off Photo Gallery: Graphics Intense (680K)

Brought to you by...

Texas Space Grant Consortium
Colorado Space Grant Consortium

Colorado Center for Astrodynamics Research
University of Texas Center for Space Research

University of Texas at Austin
University of Colorado at Boulder

Last Modified: Aug 6, 1996
Comments or questions?
Amy Neuenschwander
Center for Space Research, University of Texas


Last Modified: Fri, Aug 20, 1998