Thunderstorms have prevented space shuttle Atlantis from returning to its home base in Florida for a second straight day.
Atlantis's seven astronauts, who were supposed to land on Friday, are now having to keep circling the Earth.
The astronauts had been repairing and upgrading Hubble Space Telescope, an exercise that lasted 12 days.
On Saturday, offshore storms forced Nasa, the US space agency, to skip both morning landing attempts at Kennedy Space Centre.
As Atlantis soared overhead, right around what would have been landing time, commander Scott Altman called down that he saw a "pretty solid mass of clouds".
"It looks to us like maybe it is starting to break up and move out, so we're hopeful to get home tomorrow," he said.
"We're sharing your optimism," Mission Control replied.
Despite an equally dismal forecast for Sunday, Mission Control opted to wait out the bad weather rather than move the landing to California.