<p>Launch managers halted the countdown just minutes before Endeavour and seven astronauts were supposed to blast off Monday evening. The same thing happened Sunday. It was not immediately known whether NASA would try again today or wait until tomorrow.<br />This was NASA's fifth attempt to send Endeavour to the international space station with a new piece for Japan's massive lab. The shuttle should have flown last month, but was grounded by hydrogen gas leaks. Then storms interfered.<br /><br />NASA has until today or possibly tomorrow to launch Endeavour. After that, the mission will have to wait until July 27, so Russia can launch supplies to the space station.<br /></p>
<p>Launch managers halted the countdown just minutes before Endeavour and seven astronauts were supposed to blast off Monday evening. The same thing happened Sunday. It was not immediately known whether NASA would try again today or wait until tomorrow.<br />This was NASA's fifth attempt to send Endeavour to the international space station with a new piece for Japan's massive lab. The shuttle should have flown last month, but was grounded by hydrogen gas leaks. Then storms interfered.<br /><br />NASA has until today or possibly tomorrow to launch Endeavour. After that, the mission will have to wait until July 27, so Russia can launch supplies to the space station.<br /></p>