After four launch attempts in four days, a Delta IV rocket and three military satellites remain right where they started -- on the launch pad.
But after a day off Sunday to give the launch team a break, United Launch Alliance and the Air Force will take another shot Monday, when the weather is expected to improve a bit. Launch on Monday is targeted for 6:43 p.m., the opening of a 65-minute window at Cape Canaveral Air Force Station.
There's a 60 percent chance of favorable weather -- the best odds yet since the mission began trying to get off the ground on Wednesday.
Technical problems scrubbed the first try, but thunderstorms and lightning washed out the next three countdowns on Thursday, Friday and Saturday.
There was some optimism the storms might clear before Saturday's window closed at 7:56 p.m., but a lightning warning never cleared. Several funnel clouds were spotted, and the Titusville area was under a tornado warning for about 30 minutes in the hours leading up to the launch window.
With the day off, the 206-foot Delta IV and its payload were returned to the shelter of a mobile service tower at Launch Complex 37. Atop the rocket are twin satellites that will look out for threats from other spacecraft orbiting more than 22,000 miles up, and a third experimental satellite.
The mission's delay to Monday has pushed back by one day, to Friday, the next launch on the Cape schedule: an Atlas V rocket carrying the seventh in a new series of Global Positioning System satellites. That launch is now planned at 11:23 p.m. Friday, with an 18-minute window.