NASA Administrator Jim Bridenstine announcing commercial crew in Houston

Jim Bridenstine speaks after he was sworn in as NASA's new administrator by Vice President Mike Pence, during a ceremonial swearing in, at NASA Headquarters on April 23, 2018 in Washington, DC. Jim Bridenstine speaks after he was sworn in as NASA's new administrator by Vice President Mike Pence, during a ceremonial swearing in, at NASA Headquarters on April 23, 2018 in Washington, DC. Photo: Mark Wilson, Staff / Getty Images Photo: Mark Wilson, Staff / Getty Images Image 1 of / 3 Caption Close NASA Administrator Jim Bridenstine announcing commercial crew in Houston 1 / 3 Back to Gallery

NASA Administrator Jim Bridenstine will be in Houston next week to announce the astronauts assigned to the first flight tests and missions of the two commercial spacecrafts currently being developed.

An announcement initially was scheduled to occur at NASA's Kennedy Space Center in Florida. But on Wednesday, Bridenstine tweeted that it would take place Aug. 3 at Houston's Johnson Space Center.

The Houston center is home to the nation's astronaut corps, where human space flight research and training take place. It is also home to the International Space Station's mission operations and the Orion program.

The astronauts named Aug. 3 will be "the first crews launching on American-made spacecraft from American soil since the retirement of the Space Shuttle Program," Bridenstine tweeted Wednesday afternoon. The space shuttle program ended in 2011, and the U.S. has since relied on the Russians to take our astronauts to the space station.

Vice President Mike Pence initially was supposed to make the announcement at Kennedy. He appears to have been removed from the scheduled speaker list with the switch to Johnson.

Both Boeing and SpaceX are developing commercial space flights in partnership with NASA.

"Commercial transportation to and from the space station will enable expanded station use, additional research time and broader opportunities of discovery aboard the orbiting laboratory," according to a NASA statement Wednesday. "The station is critical for NASA to understand and overcome the challenges of long-duration spaceflight, and necessary for a sustainable presence on the Moon and missions deeper into the solar system, including Mars."

Alex Stuckey covers NASA and the environment for the Houston Chronicle. You can reach her at alex.stuckey@chron.com or Twitter.com/alexdstuckey.