This set of six mint stamp sheets, including four sheets with nine stamps each and two souvenir sheets with one high face value stamp each, were issued in 1990 by Sierra Leone to commemorate the coming exploration of Mars. Brief descriptions of the stamp subjects are included on the stamps. Extreme speculation has occurred with this set of sheets, centered around the Face on Mars stamp, which brought the asking price of the set to as high as $10,000. In reality, the retail value as based on asking prices from reputable stamp dealers, is $81 (Scott 2015 Standard Postage Stamp Catalogue).
The speculation (i.e., the purchase of the sheet with the belief that the value would soon rise far above the purchase price) in this issue arose from the touting of the issue by those who believed that the image of a face on Mars indicated that intelligent life likely exists or existed on Mars, and that this "fact" would make this large stamp set an extremely valuable collectible. The Face on Mars image was recorded during a Viking mission in the 1970s. The speculation was heavily fueled by the scientist Richard C. Hoagland (who offered the set for $10,000). Common asking prices (in newspaper adds, etc.) for the set were $2500 - $5000, and there were many takers. For additional information, simply search for the following in your browser: "face on mars Sierra Leone" or "Richard C. Hoagland face on mars."
We were fortunate to purchase a small wholesale lot of these sheets at a very good price and we are passing the savings on to our customers.
The actual size of the four 9-stamp sheets is 103mm x 145mm; the two souvenir sheets measure 87mm x 107mm.