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Nasa: Artemis Moon rocket second launch attempt called off

todaySeptember 3, 2022 6

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By Jonathan Amos

BBC Science Correspondent, Cape Canaveral

SLS rocket

The launch of the US space agency’s most powerful ever rocket has been cancelled for the second time in a week.

The announcement came after a leak was found in the hydrogen tank of the Artemis I Moon mission.

Attempts to get it off Earth were thwarted on Monday by a mix of technical and weather woes.

Saturday’s leak was picked up as the rocket began to be loaded with super-cold propellants.

Controllers tried a number of fixes but without success.

The vehicle burns 2.7 million litres of liquid hydrogen and oxygen to provide the thrust needed to get off Earth.

But when the controllers sent the command to fill the hydrogen tank, an alarm went off, indicating there was a leak.

The problem is at the base of the Space Launch System, at the interface where a 20cm umbilical line brings in the hydrogen.

Saturday’s attempt to despatch the Space Launch System (SLS) rocket had been scheduled for the start of a two-hour window beginning at 14:17 local time (19:17 BST; 18:17 GMT).

The 100m-tall vehicle’s objective was to hurl a human-rated capsule in the direction of the Moon, something that hasn’t happened since Project Apollo ended in 1972.

Monday’s bid to fly SLS was ultimately scrubbed because controllers couldn’t be sure the four big engines under the rocket’s core-stage were properly prepared for flight.

The shuttle-era power units are chilled during countdown to -250C to prevent them being shocked by the sudden injection of cryogenic propellants at the moment of launch. But a sensor was indicating that Engine No 3 might be 15-30 degrees short of where its temperature needed to be.

Media caption,

Former astronaut Doug Hurley: “We’re building on safe, capable designs”

When the SLS does get away, it is sure to be a spectacular sight.

“It’s gonna be ‘shuttle on steroids’,” said Doug Hurley, who was the pilot on the very last shuttle mission in 2011.

The former astronaut now works for Northrop Grumman who make the big white solid boosters on the sides of the SLS.

“What I always thought was the coolest thing about shuttle launches was you saw it lift off and it was well clear of the tower before you heard anything, and then it was even a little longer before you felt it,” he explained.

“Thrust to weight-wise, SLS is pretty close to what shuttle was. Apollo’s Saturn V rocket was drastically different. I never saw it in person but it lumbered clear of the pad. For shuttle, it seemed like it was clear in an instant, almost as soon as the boosters were lit. SLS should be the same,” he told BBC News.

The first powered phase of the SLS’s ascent will last just over eight minutes.

This will put the upper-stage of the rocket, with the Orion capsule still attached, into a highly elliptical orbit that would see the two of them come crashing back to Earth without any further effort.

So, the upper-stage will have to raise and circularise the orbit before then boosting Orion in the direction of the Moon.

Confirmation that the capsule is on its own, on track and speeding through space at 30,000 km/h (19,000mph) should come two hours and five minutes after launch.

The planned mission length is just under 38 days. This would result in Orion returning to Earth for a splashdown in the ocean off San Diego in California on 11 October.

Thirty-eight days is much longer than the 21 days that capsule manufacturer Lockheed Martin says is the maximum time astronauts should spend in the spacecraft.

But Annette Hasbrook, senior advisor on the Orion programme at Nasa, said engineers wanted to stretch the spacecraft on this mission to understand its limits.

Image source, NASA

Image caption,

Artwork: The upper-stage of the rocket will put the Orion capsule on a path to the Moon

“You’re trying to test the edges of your boxes, not your nominal profile,” she explained.

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