One small step for NASA, one giant running leap for Stephen Colbert.

NASA announced Tuesday that it won't name a room in the international space station after the comedian. Instead, it has named a treadmill after him.

NASA earlier held an online contest to name a room (or "node") at the space station. With write-in votes, the name "Colbert" beat out NASA's four suggested options: Serenity, Legacy, Earthrise and Venture.

On Tuesday's "The Colbert Report" on Comedy Central, astronaut Sunita Williams announced that NASA — which always maintained it had the right to choose an appropriate name — would not name the node after Colbert.

Instead, Node 3 will henceforth be called Tranquility, the eighth most popular response submitted by respondents in the poll. The node's name alludes to where Apollo 11 landed on the moon — the Sea of Tranquility.

NASA and Colbert compromised by naming a treadmill used for exercising in space after Colbert. NASA, itself an acronym (National Aeronautics and Space Administration), often names things so they spell out something fun. And that's what they did with the Combined Operational Load Bearing External Resistance Treadmill (COLBERT).

Sophisticated treadmills are crucial for living in space for long periods of time, as astronauts do on the space station; they help keep astronauts fit and their bones from losing strength. Williams ran a marathon on one while living at the space station in 2007, jogging in place to coincide with the Boston Marathon.

The COLBERT treadmill is a new version that will be operational in August, NASA spokesman Mike Curie said.

"We don't typically name U.S. space station hardware after living people and this is no exception," Bill Gerstenmaier, NASA's associate administrator for space operations, said, adding: "We have invited Stephen to Florida for the launch of COLBERT and to Houston to try out a version of the treadmill that astronauts train on."

AP Science Writer Seth Borenstein in Washington contributed to this report.