<http://schema.org/alternativeHeadline>
"The historic first American spaceflight by astronaut Alan Shepard and NASA's Messenger Mercury mission are being honored as the faces of new U.S. postage stamps."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/earth-matters/space/stories/new-us-stamps-honor-astronaut-alan-shepard-and-mission-to-mercury>