Does anyone know what material was used to construct the 8 cm square base of the MER calibration target? I'm guessing it could be either aluminum, titanium, or plastic, but after googling around I have not been able to track down anything definitive -- lot's of articles discuss the colors and sundial, but nothing more.

Hey Algorimancer,
This link has the info you are looking for...after reading it I would love to see a picture of the bottom! If you find one please post it.

http://www.news.cornell.edu/chronicle/03/6...03/sundial.html

You should contact Bill Nye--he must have a picture of the bottom.

Aluminum. Thank you -- this will keep me entertained for a bit.