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by sgt101 874 days ago
This surprises me, I have seen ground penetrating radar results that have shown buried items which have then been dug up, why is this result different?
1 comments

They’ve been calibrated on Earth for use on Earth.
What does it matter if it's calibrated on earth? If the problem is the antenna pattern, influence of the rover itself, etc, why can't it be calibrated with the exact duplicate of the rover we have?
different gravity
Oh interesting - so Earth calibrated systems expect... a specific density for display of signals?
Radio waves propagate at different speeds through different mediums so the GPR gain and time window have to be calibrated for each soil type and other environmental factors like how wet the ground is. Once calibrated, then any deviations become interesting. Otherwise it’s just a bunch of sensor noise.
Are you insinuating that NASA sent an incorrectly calibrated device? I know NASA has its flaws but this seems like a stretch no?
I think he means it would need to be calibrated on Mars as the exact ground density and composition isnt known from earth
Correct. The easiest way to calibrate a GPR is to stick a metal plate in the ground and cover it with a few feet of earth dug up on location. Can’t do that with some awkward rovers and an experimental helicopter.

NASA can do some fancy signal processing to get some useful data but until its properly calibrated, any interpretation of that data especially visual should be taken with a Phobos sized grain of salt.

NASA isn't doing anything here but providing the platform for the instrument.I mean, that's a lot but they are not the one in charge of running the instrument. The science teams are. GPR is a complex topic and *maybe* these signals contain the information that they think they do, but it's unlikely in my opinion.