CAPE CANAVERAL, Fla. -- NASA is pressing ahead with Monday's planned launch of a supply ship despite a critical computer outage at the International Space Station, promising the situation is safe.

Mission managers decided Sunday to proceed with the countdown for the SpaceX capsule, Dragon, already a month late in delivering more than 2 tons of cargo.

"We're good to go," said NASA space station program manager Mike Suffredini.

Suffredini noted the many important supplies aboard the Dragon, including a new spacesuit and repair parts for the older spacesuits already in orbit. Much-needed food is also packed away.

"There's a certain amount of urgency to go ahead and get these vehicles" at the space station, he told reporters. These shipments have to fit around other space station operations, like crew comings and goings.

"Things start to bunch up," Suffredini said, "and so we're just trying to fly as soon as we safely can, which is what we believe we're doing."

This backup computer, located on the outside of the space station, mysteriously failed to work when activated Friday. The main computer kept operating perfectly, and the six-man crew was never in any danger. NASA debated whether to delay the SpaceX mission and, on Sunday, determined the station has sufficient redundancy to safely support the visiting vessel.

A spacewalk will be required, meanwhile, to replace the bad computer. Engineers don't know why it failed.

Suffredini said the spacewalk will be conducted by a pair of astronauts on April 22, using suits outfitted with new fan components to avoid the near-disaster that occurred last summer. An Italian astronaut almost drowned when his helmet flooded with water from the suit's cooling system.

An April 22 spacewalk will give SpaceX two chances to get its unmanned Dragon capsule flying. Good weather is forecast for Monday's 4:58 p.m. launch. If that doesn't work, the next launch attempt would come Friday.

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NASA approves space station visit despite dead computer