Talk:Lacrosse (satellite)

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[edit] Similarities to Magellan

I believe that any statement that any Lacrosse constellation member is similar to Magellan are a complete fabrication.

Magellan is a probe whose SAR was designed to operate a long distance from a receiving station, where downlink windows are precious and, especially at the time, slow, and power is at a premium due to the number of instruments onboard. As such remote SARs are often designed to use burst-oriented chirp phases (this technique is associated with an imaging mode called ScanSAR in modern missions). While this decreases the size of data returned for ground processing, this comes at the expense of decreased resolution and increased doppler ambiguity for some parts of the image.

There are actually more reasons (I think, but cannot confirm, that phase information was not preserved as a part of Magellan's measured results).

As such, a "continuous" chirp SAR makes far more sense for an intelligence application such as that the NRO would be using a platform akin to Lacrosse as described around the web. Downlink from orbit is relatively fast (and has been for a long time), so compact data is not as necessary, as such at the expense of the amount of data to be downlinked the performance of the radar can be improved drastically.

As well, according to Cumming and Wong, Magellan was based on the Voyager bus and used a parabolic antenna (while images taken by amateurs of the satellite clearly indicate a planar antenna).

In summary, I believe that the likening of Magellan to an observation satellite in orbit to be false. SAR imaging man 17:34, 4 May 2007 (UTC)