The space agency made it official Thursday after weeks of hints of launch delays: More time is needed to get the cargo ready for the final two shuttle flights. What's more, a decision regarding a possible third - and really last - mission is off until at least next month.
Managers agreed to postpone the next-to-last shuttle launch until Nov. 1. Discovery had been scheduled to fly to the International Space Station with a load of supplies in September.
The very last mission now has a Feb. 26, 2011, launch date. Endeavour will close out the 30-year shuttle program by delivering a major scientific instrument to the space station.
The Alpha Magnetic Spectrometer - a particle physics detector - is getting a makeover in Europe to ensure a longer working life once it's attached to the space station. The extra work repeatedly has delayed the Endeavour flight, which initially was targeted for this month and then slipped to November.
As for the possibility of an extra shuttle mission, NASA officials said no decision is expected before August. The space agency would like to fly Atlantis one more time, next June, before the fleet is retired. Officials had hoped for an answer by now to start training a crew and preparing the payload.
The White House would need to sign off on any additional mission. NASA estimates it could cost as much as $200 million a month to keep the shuttle program going beyond 2010. The original plan - set forth in 2004 by President George W. Bush - was to quit flying shuttles this year.
Regardless of the outcome, shuttle Atlantis is being prepped to be on standby for a potential rescue mission for Endeavour's crew.
Earlier this week, the Obama administration released its official space policy. President Barack Obama wants future exploration to be more global, with multiple countries teaming up to send astronauts to an asteroid by 2025 and, after that, to Mars.
Obama has directed NASA to focus on those long-range goals, with private companies eventually taking over the business of getting cargo and astronauts to the space station. The California-based Space Exploration Technologies Corp., or SpaceX, successfully flew its Falcon 9 test rocket last month.
Until a commercial rocket is ready to start hauling passengers, American astronauts will continue to hitch rides to and from the orbiting station on Russian Soyuz spacecraft. Each seat costs NASA tens of millions of dollars.
Mercury astronaut John Glenn, a retired senator and one-time shuttle flier, said last week he'd rather see that money go toward keeping the shuttles flying until there's a reliable replacement.