The wrong kind of cloud (too low) over Florida has prompted NASA's shuttle mission managers to postpone the next launch until Saturday. It was due to blast off yesterday, but the bad weather meant the launch could not go ahead.

Although NASA says the weather should improve by the weekend, the news that the launch date has slipped is never good. Postponing a launch is an expensive business: the costs can quickly head toward to million dollar mark.

On this occassion, the costs are not the only concern. If Discovery does not take off by 18 December, a computer bug could keep the 12-day mission grounded until January next year.

Earlier this year, space shuttle program manager Wayne Hale explained: "The shuttle computers were never envisioned to fly through a year-end changeover."

This would mean the onboard computers losing synch with ground control, and could force a mid-flight reset. This would leave the shuttle flying blind until all the systems came back online, a scenario NASA would naturally prefer to avoid.

Launch of Discovery is now scheduled for 8:47pm, EST, 9 December. ®