Session
Technical Session VII: New Mission or Bus Concepts I
Abstract
WITTEX, named in honor of E. Witte, who in 1878 first discovered the geostrophic current equation, is an acronym for Water Inclination Topography and Technology Experiment. WITTEX consists of three co-planar small satellite radar altimeters launched on the same vehicle into a GEOSAT -class orbit. The proposed satellite constellation would support measurement for the first time of both orthogonal components of the ocean's surface slope, rather than the single component seen by conventional instruments. The satellites are spaced by several kilometers along their orbit; Earth rotation causes their sub-satellite tracks to be laterally separated. Track separation can be readily adjusted by selection and autonomous control of inter-satellite spacing. If the satellite spacing were about 900 km, then the sub-satellite orbit tracks would fall approximately uniformly 53 km apart at the equator. This spacing is nearly optimal for observing oceanic eddy fields and surface energy transport. The enabling conceptual innovation is the delay-Doppler radar altimeter (DDA). Studies have shown that this technique yields more precise measurements than a conventional radar altimeter, yet it requires much less transmitted power. The notional instrument has two frequencies and an onboard water vapor radiometer, similar to TOPEX. The DDA approach, combined with recent advances in spacecraft technology, leads to substantial miniaturization; the goal is to use Pegasus as the launch vehicle. The enabling technologies include the Integrated Electronics Module (IEM), chip-on-board (COB), and the Command and Data Handling In-YourPalm (CDHIYP), all developed at The Johns Hopkins University Applied Physics Laboratory (JHU/APL). The WITTEX concept is a flexible, capable, unique, and cost-effective approach that will significantly advance the state of the art in both technical and scientific arenas.
WITTEX: A Constellation of Three Small Satellite Radar Altimeters
WITTEX, named in honor of E. Witte, who in 1878 first discovered the geostrophic current equation, is an acronym for Water Inclination Topography and Technology Experiment. WITTEX consists of three co-planar small satellite radar altimeters launched on the same vehicle into a GEOSAT -class orbit. The proposed satellite constellation would support measurement for the first time of both orthogonal components of the ocean's surface slope, rather than the single component seen by conventional instruments. The satellites are spaced by several kilometers along their orbit; Earth rotation causes their sub-satellite tracks to be laterally separated. Track separation can be readily adjusted by selection and autonomous control of inter-satellite spacing. If the satellite spacing were about 900 km, then the sub-satellite orbit tracks would fall approximately uniformly 53 km apart at the equator. This spacing is nearly optimal for observing oceanic eddy fields and surface energy transport. The enabling conceptual innovation is the delay-Doppler radar altimeter (DDA). Studies have shown that this technique yields more precise measurements than a conventional radar altimeter, yet it requires much less transmitted power. The notional instrument has two frequencies and an onboard water vapor radiometer, similar to TOPEX. The DDA approach, combined with recent advances in spacecraft technology, leads to substantial miniaturization; the goal is to use Pegasus as the launch vehicle. The enabling technologies include the Integrated Electronics Module (IEM), chip-on-board (COB), and the Command and Data Handling In-YourPalm (CDHIYP), all developed at The Johns Hopkins University Applied Physics Laboratory (JHU/APL). The WITTEX concept is a flexible, capable, unique, and cost-effective approach that will significantly advance the state of the art in both technical and scientific arenas.
