The repeated launch delays for the space shuttle Endeavour were not just frustrating, but expensive.

NASA estimates every launch cancelled after fuel tanking has begun can cost as much as $1.2 million dollars. Endeavour endured five liftoff scrubs before successfully launching Wednesday at 6:03 p.m. (2203 GMT), though some of these cancellations occurred before ground crews started loading propellant into the shuttle's external tank. The total price tag for this mission's postponements, which began in mid-June and ended with yesterday's liftoff, was less than $5 million, NASA spokesman Allard Beutel said.

Though NASA tries to operate as cheaply as possible, safety comes first, Beutel said.

"Nobody wants to waste any money," he told SPACE.com. "But those decisions made to not launch were for safety reasons and not for cost reasons. That has to win out. So the cost is not irrelevant, but it's not the reason that you launch or don't launch."

Ultimately, the extra money spent getting Endeavour off the ground is not a significant problem for NASA.

"These costs are absorbed as part of the overall budget," Beutel said. "We're not going to congress and asking for more money. There's always money to account for these kinds of things."

The high price tag of a scuttled launch comes from the expense of personnel, as well as the super-chilled liquid hydrogen and liquid oxygen propellant. Though NASA can recycle "the vast majority" of this fuel if a liftoff is cancelled, some boils away, Beutel said.

NASA estimates that each scrub costs $500,000 in lost fuel, and $700,000 to pay for the extra workforce needed for launch attempts. On these occasions NASA personnel are deployed around the world, including at various transatlantic abort sites where the shuttle might land in case of an emergency. The exact bill varies with factors like fuel commodity prices and whether the scrub took place on a weekday or a weekend.

Endeavour's seven-astronaut crew is flying a 16-day construction mission to the International Space Station. The astronauts will swap out one member of the station's six-man crew, deliver supplies and spare parts, and attach a large experiment porch to the exterior of the outpost's Japanese-built Kibo lab. Five spacewalks are planned.

Endeavour is due to arrive at the space station on Friday at 1:55 p.m. EDT (1755 GMT).

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