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Originally posted by Mclaneinc
NASA: Why call it space when you can fill it with crap!
Originally posted by Exuberant1
Here is another one of starshine - except it is strangely blurred:
Originally posted by watchdog8110
All of the Starshine objects have decayed from their orbits .
Orbital Debris Radar Calibration Spheres (ODERACS) experiment. ODERACS deployed spheres and dipoles from the Shuttle to calibrate the Haystack orbital debris radar measurements. An ODERACS sphere being deployed is visible just over the Shuttle's tail fin.
The Orbital Debris Radar Calibration Spheres (ODERACS) spaceflight experiments were designed to provide small, low earth orbiting (LEO) calibration targets for the ground-based radar and optical systems used for orbital debris measurements. The primary objective was to calibrate the Haystack Long Range Imaging Radar (LRIR) and validate the JSC Orbital Debris Analysis System (ODAS). These measurements and resulting data processing were a complete success.
The Haystack radar is used for orbital debris measurements in an unorthodox way. Instead of moving the radar dish to track satellites, the dish "stares" in a fixed direction. Debris objects that fly through the radar beam produce echoes that are recorded on magnetic tape. Analysis of the echo data must take into account that debris objects can fly through the radar beam from any direction and can cross the beam at any position. Entirely new analysis tools were developed to deal with this novel kind of data. Because of the complexity of this process, it was determined that an end-to-end calibration of the radar and the associated data processing system was essential in order to be confident that the debris data derived from the radar were valid. The question relating to radar operation was: Is the radar calibrated correctly, such that the measured radar cross section is the correct one? The question relating to the data processing system was: Are the physical sizes and orbital parameters calculated from the Haystack radar data correct?
The best way to do these calibrations was to place known objects into orbit and measure them with the Haystack radar. From a practical point of view, metal spheres were the best choice for test objects, since their radar cross section is independent of aspect angle, and their shape makes them easy to deploy from the Space Shuttle Orbiter bay. A problem with spheres is that they return only one polarization of radar waves, the Principal Polarization (PP). For this reason, the Haystack radar could be calibrated only for PP returns using spheres. Since irregular debris objects return both PP and Orthogonal Polarization (OP) signals, it was necessary to make an independent calibration of the radar for its response to OP returns. Wire dipole targets were used for this purpose, since they reflect exactly equal OP and PP polarizations.
ODERACS Sphere Delivery System
The best way to do these calibrations was to place known objects into orbit and measure them with the Haystack radar. From a practical point of view, metal spheres were the best choice for test objects, since their radar cross section is independent of aspect angle, and their shape makes them easy to deploy from the Space Shuttle Orbiter bay. A problem with spheres is that they return only one polarization of radar waves, the Principal Polarization (PP). For this reason, the Haystack radar could be calibrated only for PP returns using spheres. Since irregular debris objects return both PP and Orthogonal Polarization (OP) signals, it was necessary to make an independent calibration of the radar for its response to OP returns. Wire dipole targets were used for this purpose, since they reflect exactly equal OP and PP polarizations.