Thruster glitch will stall SpaceX capsule arrival at ISS

James Dean, Florida Today | USATODAY

Show Caption Hide Caption Dragon capsule anomaly: what happened? After reaching orbit, a Dragon cargo capsule was unable to start three of four thruster pods, SpaceX CEO Elon Musk reports. FLORIDA TODAY's Todd Halvorson brings a wrap up report from Kennedy Space Center. By Caroline Perez. Posted 3/1/13

Liftoff occurred at 10%3A10 a.m.

SpaceX rocket launched for the first time last October

Current mission will deliver Dragon space freighter to International Space Station

CAPE CANAVERAL, Fla. — SpaceX appears to have salvaged an International Space Station cargo-delivery mission by fixing a problem that had temporarily crippled thrusters on the Dragon capsule.

Clogged pressurization lines had disabled the capsule's fuel tanks shortly after the spacecraft reached orbit following its 10:10 a.m. ET launch. Engineers pounded helium through the lines to clear debris that had disabled three of the four thruster pods for several hours and kept the capsule in a lower orbit.

The setback means the commercial resupply capsule won't rendezvous with the space station Saturday morning as scheduled, NASA said. Sunday is the earliest that the capsule could reach the ISS, space station chief Mike Suffredini said at an afternoon news briefing.

Shortly after 4 p.m., SpaceX founder Elon Musk tweeted: "Thruster pods one through four are now operating nominally. Preparing to raise orbit. All systems green."

"It was a little frightening there," Musk admitted during the news conference.

He had said the Dragon could begin flying toward the station with two pods. But NASA required that three thruster pods must be active for Dragon to be given permission to approach the station.

The ISS crew had been planning to grapple the Dragon with a robotic arm around 6:30 a.m. Saturday.

Musk said the Dragon could remain in orbit for at least a month, if needed, to sort out any issues before attempting to berth at the station.

"It's going to be up there for a while," he said.

Asked what caused the problem, Musk said it looks like "blockage" in oxidizer pressurization, meaning there likely was debris in propellant lines.

The spacecraft is carrying about 1,200 pounds of supplies and science equipment for the space station, plus another 600 pounds of hardware in its unpressurized "trunk."

After a successful launch, the Dragon separated from the rocket booster and its two solar array wings were deployed about 11 minutes into the flight.

That's when SpaceX first reported a problem from its mission control center in Hawthorne, Calif., near Los Angeles.

In a statement shortly after noon, SpaceX said Dragon experienced a problem with a propellant valve after reaching orbit, and that only one of four Draco thruster pods was functioning.

"We are trying to bring up the remaining three," the statement said. "We did go ahead and get the solar arrays deployed. Once we get at least two pods running, we will begin a series of burns to get to station."

Standing 157 feet tall, the powerful Falcon 9 rocket blasted off from Cape Canaveral Air Force Station with the Dragon freighter on top.

The launch, capping a five-month turnaround from a successful mission, was a dramatic demonstration of the vehicle's ability to survive an engine failure in flight.

The mission is the second of a dozen planned under a $1.6 billion NASA contract. Dragon vehicles successfully reached the station twice last year, once on a demonstration flight and once under the resupply contract.

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Musk is well known for proclaiming that the Falcon 9 is the first rocket designed with "engine-out" capability since NASA's Saturn V moon rocket.

Many at heritage aerospace industry companies scoffed. Nine Merlin 1C engines are linked together in a square at the base of the Falcon 9's first stage. Surely, an engine failure would result in collateral damage, leading to a catastrophic loss of mission.

But one-minute and 19 seconds into a brilliant night launch last October, a defect in a Nomex-and-Kevlar flak jacket around one of the rocket's engines triggered a depressurization within its combustion chamber.

The rocket's prime flight computer detected the problem and commanded an engine shutdown. The engine's protective fairing broke apart. Pieces of it were violently consumed in the fire-orange stream that trailed the rocket.

It looked as if the engine had exploded. But it didn't. It was shut down automatically, as intended under the circumstances. Nonetheless, the Falcon 9 delivered the Dragon spacecraft to orbit and it arrived at the International Space Station 30 minutes ahead of schedule. The first of 12 SpaceX cargo delivery missions under a NASA contract valued at $1.6 billion ended up a success.

"As a matter of fact, I have to tell you that I think the industry and the public was dramatically impressed by the fact that we had an engine issue, an engine shutdown, and still made mission," SpaceX President Gwynne Shotwell said Thursday.

"I want to point out that this vehicle has been designed to accommodate an engine out, and though you never necessarily want to see it happen, it's nice that we've demonstrated the vehicle (operates) as it was designed."

Over the past four months and 22 days, SpaceX engineers have been busy with an investigation into the engine failure — one focused on finding the root cause, fixing the problem, and flying again.

That's considered fairly fast in the U.S. aerospace industry.

"We did extensive analysis, obviously, to understand the problem, extensive assessment and testing on these particular engines," Shotwell said.

Investigations into engine failures typically involve what aerospace engineers call "Non-Destructive Testing." For example, ultrasonic examinations, radiography or thermography might be used to detect flaws on Nomex or Kevlar without destroying the material being tested.

NASA International Space Station Program Manager Mike Suffredini said the agency lent SpaceX a hand during its investigation into the October 2012 engine failure. But the company still is clearly looking for help in this discipline.

"It's as much an art as a science, and we certainly are getting much better at it as we mature here," Shotwell said. "But I am going to make a shameless call for any extraordinary NDE experts that want to come and change the state of science, or the state of the art, we're hiring you at SpaceX."