— A new United States postage stamp features a colorful graphic of an astronaut carrying a postcard out on a spacewalk. Officially, the stamp celebrates the global hobby of "Postcrossing," but it also offers a welcome nod to the history of space mail.

The U.S. Postal Service (USPS) released the astronaut-themed stamp as one of four Postcrossing issues at the Boston World Exposition stamp show on Tuesday (May 26). The artwork, by illustrator Jackson Gibbs, was inspired by the international project that "enables participants to send and receive postcards from interested people around the world."

"Postcrossing began with a simple idea: Receiving a postcard in the mail could brighten someone's day," said Sheila Holman, the postal service's vice president of marketing, in a statement.

Created by Portuguese student Paulo Magalhães, whose Postcrossing website has resulted in more than 800,000 people in over 200 countries and territories sending over 85 million postcards since 2005. More than 300,000 Postcrossing postcards are on their way to recipients at any given moment. Germany has the most active senders, followed by the United States.

"What makes Postcrossing remarkable is not simply the number of postcards exchanged. It's what those postcards represent. Each one reflects time, effort and intention," said Holman.

The four triangular stamps were designed to highlight the joy that comes with getting physical mail, while also increasing an understanding across countries and cultures. The bring pink, purple, blue and green astronaut stamp also depicts starbursts, planets and a space shuttle, the latter soaring across the background.

In addition to the spacewalker, the other three similarly-styled stamps depict a rider on horseback in the American West, a scuba diver at the bottom of the ocean and a figure riding a motorcycle. Each person is shown holding a postcard that has one of the triangular Postcrossing stamps.

As Global Forever stamps, each may be used to send a postcard from the U.S. to any country to which First-Class Mail International service is available.

"What a fantastic system: free and fun to get mail from elsewhere!" said Antonio Alcalá, an art director for the USPS. The first Postcrossing postcard he sent went to China and the first card he received was from the Netherlands.

Alcala set out to make the U.S. stamps stand out from other nation's Postcrossing issues, partly inspired by their triangular shape.

Inadvertently, but likely to excite space-topical stamp and space mail collectors, the astronaut-themed Postcrossing stamp can also be seen as acknowledging the legacy of space mail. While no where near as accessible or inexpensive, stamp and space collectors have worked with orbit-bound crew members to send mail to space stations and return correspondence back on Earth.

Soviet-era and Russian cosmonauts in particular, have used unique philatelic devices on the Salyut, Mir and International space stations to postmark mail (and other items) dating back to the 1970s. Kits were also flown on NASA's Apollo 11 and Apollo 15 missions to the moon and the Chinese have set up a post office to send mail to its Tiangong space station.

Likewise, Club for the Future, the non-profit organization founded by Jeff Bezos' Blue Origin spaceflight company, has launched hundreds of thousands of postcards for free on the New Shepard rocket. The postcards are then returned to their senders with an ink stamp indicating they have been flown into space.

The Postcrossing stamps are for sale through the USPS's Postal Store or at post office locations nationwide. The service has also produced related collectibles, including First Day of Issue covers (stamped and postmarked envelopes) and postcards featuring the art from each stamp.