Cape Canaveral, Florida - Mercury astronaut John Glenn wants Nasa's space shuttles to keep flying until their replacement is ready.
Glenn joined the national debate on Monday over America's future in space.
He issued a nine-page statement in which he questioned the decision to retire the shuttle fleet after two or three more missions.
The first American to orbit Earth - now 88 - says the shuttles are working extremely well right now.
He says little if any money will be saved by cancelling the shuttle programme, considering all the millions being paid to Russia to ferry US astronauts to and from the International Space Station.
He wonders what will happen if a Russian Soyuz rocket fails. He also worries scientific research in orbit will take a hit. - Sapa-AP