The first spacecraft to orbit Mercury has been honored with a United States Postal Service "forever" stamp, issued on May 4, 2011. MESSENGER shares the honor with another space pioneer, Mercury astronaut Alan Shepard, the first American in space.
The stamp pair commemorates NASA's Project Mercury and Alan Shepard's historic launch on May 5, 1961, aboard the spacecraft Freedom 7, and the APL-built and operated MESSENGER, which went into orbit around Mercury on March 17 of this year. According to the NASA press release for the stamps, "The two missions frame a remarkable 50-year period in which America advanced space exploration through more than 1,500 manned and unmanned flights."
These images are from MESSENGER, a NASA Discovery mission to conduct the first orbital study of the innermost planet, Mercury. For information regarding the use of images, see the MESSENGER image use policy.