CAPE CANAVERAL, Fla. >> NASA’s next-generation space telescope has been delayed yet again at a staggering cost of $1 million a day.

For the third time in less than a year, the space agency announced a lengthy postponement Wednesday for the James Webb Space Telescope . The observatory will now fly no earlier than 2021; until last fall, it was on the books for a 2018 launch.

The telescope’s overall cost is now expected to reach nearly $10 billion. Development cost alone will exceed the $8 billion cap set by Congress by more than $800 million, and require reauthorization.

An independent review board cites worker error and embedded hardware problems for much of the escalating costs and delays. In an acoustic test of the telescope earlier this year in California by prime contractor Northrop Grumman, dozens of loose fasteners — some 70 pieces in all — came off. A few pieces are still missing and could well be inside the observatory.

In another mishap, an improper solvent was used to clean spacecraft propulsion valves. No one bothered checking to see whether the cleaner might damage the equipment, said review board chairman Tom Young.

NASA repeatedly was over-optimistic in the work schedule, especially given the complexities and unique features of the Webb telescope, Young said. Its sunshield, the size of a tennis court once unfurled in space, is needed to keep the infrared telescope cold and is a major risk area, he noted.

Despite the many problems, the review board urges that the project continue given its “compelling” scientific potential and national importance, according to Young.

Webb — considered a successor to the Hubble Space Telescope — is meant to peer farther into space and deeper into time than ever before. It will operate from a point 1 million miles (1.6 million kilometers) from Earth, unreachable by astronauts like the low-orbiting Hubble — launched in 1990 with a misshapen mirror — was.

“Make no mistake, I’m not happy sitting here having to share this story. We never want to do this. We always want to talk about the successes that we have,” said NASA’s science mission chief Thomas Zurbuchen.

Zurbuchen said NASA should have been providing better oversight and is part of the problem along with Northrop Grumman. Besides improved oversight, he said there will be more quality control and more NASA engineers will be taking part in everything moving forward.

“We have to get this right here on the ground, before we go to space,” Zurbuchen said. “Webb is worth the wait.”

The review board has issued 32 recommendations and NASA intends to implement them all, officials said.

Last September, NASA announced it was delaying Webb’s launch from 2018 to 2019. Then in March, the launch was postponed from 2019 to 2020. Now it’s March 30, 2021.

Young said if the board’s recommendations are “rigorously implemented,” then the new date is feasible.