Hopefully that bit of orange will not be too heavily silted or otherwise covered if it is lying free.
Then a good photo interpreter will have a fighting chance of picking it out.
There is enough steel in the DFDR that someone out searching for gold using a $50 inductive loop detector would find it 600mm (2 ft) under.
In all seriousness, the technique may need to be used if the the orange brick has gone and buried itself.
Substitute the person for a towed magnetic anomaly detection (MAD) device.
