The sign accompanying the spacecraft. It reads
This capsule served as the backup spacecraft for Wally
8 flight, known as Sigma 7. From 1959 to
1963, 20 Mercury capsules were manufactured by the McDonnell Aircraft Company
in St. Louis, Missouri. Some were modified after initial production and
received a letter designation after their number. Of the 20 capsules produced,
five never flew in space, including this one.