EDITOR’S NOTE: The test occurred at 9:15am EST (1415 GMT). We’ll have an updated story shortly.

A Boeing Starliner crew capsule will fire off a stand early Monday at White Sands Missile Range in New Mexico on a mile-high test flight to validate the spacecraft’s emergency escape thrusters, a key milestone before human-rated Starliner ships fly astronauts to the International Space Station next year.

The capsule will not be flying any astronauts Monday when it launches off a pad at White Sands on a fast-paced test flight that will last just 95 seconds from liftoff until landing.

But a lot will happen during the flight, called a pad abort test, exercising the Starliner spacecraft’s abort engines, control thrusters, flight software, jettison mechanisms and parachutes.

Liftoff is set for the opening of a three-hour test window at 7 a.m. MST (9 a.m. EST; 1400 GMT) Monday from the same launch pad originally built for a pad abort test of NASA’s Orion crew capsule in 2010.

“I call this an ejection seat for a spacecraft,” said Chris Ferguson, a Boeing test pilot, astronaut and director of Starliner crew and mission systems.

The pad abort test will demonstrate the Starliner can “rapidly separate itself and gain distance from the launch vehicle should something go wrong,” Ferguson said Oct. 22 in a panel discussion at the International Astronautical Congress in Washington.

Ferguson will fly on the Starliner’s first crewed mission, a test flight that is expected to launch next year.

During a crewed launch, emergency escape engines on the base of the Starliner’s service module would propel the spacecraft off the top of its United Launch Alliance Atlas 5 rocket in the event of a failure on the launch pad at Cape Canaveral. The pad abort test set for Monday morning will prove the Starliner’s escape system is up to the challenge.

“We’ll go from zero speed, zero altitude, and safely demonstrate about a 1-mile-high, about a 1-mile downrange capability to remove the vehicle and safely bring it down in what will be a desert environment for the White Sands test, but what would be just off the coast of Florida if we, in fact, did have a launch pad abort.

“A lot of everything that we’ve been working on for the last eight years or so (is) all wrapped up in about a 90-second test, so it’ll be pretty exciting,” Ferguson said.

Boeing is developing the Starliner spacecraft under a $4.2 billion contract with NASA. The space agency also awarded a $2.6 billion contract to SpaceX for development of the Crew Dragon spacecraft, giving NASA two new commercial crew capsules to fly astronauts to the space station, ending U.S. reliance on Russian Soyuz vehicles for the job.

Monday’s pad abort test at White Sands will go by quickly, with a few flashes and bangs before three parachutes open and airbags inflate to bring the capsule gently back to the ground.

“This is a full-up Starliner,” said Alicia Evans, Boeing’s pad abort test flight director, in a NASA podcast last week. “It’s been built up specifically for this test. But because we were testing the integrated system, it has all of the systems required for the pad-abort test, and it’s full-up avionics capability, propulsion.”

On Monday morning, a command will trigger specially-designed valves to quickly open inside the Starliner’s service module, and a high-pressure mix of liquid hydrazine and nitrogen tetroxide propellants will rush into four launch abort engines, or LAEs. The chemical propellants will automatically combust when mixed together, generating 40,000 pounds of thrust from each of the Aerojet Rocketdyne-made engines.

The engines, coupled with thrust from smaller orbital maneuvering and attitude control rockets, or OMACs, will push the 16.5-foot-tall (5-meter) Starliner vehicle off the ground. A Boeing spokesperson said the capsule will experience a sustained force of 5 Gs for five seconds while the launch abort engines are firing, the same force astronauts would be under during a real abort off the launch pad.

The Starliner capsule slated for Monday’s pad abort test is mounted on top of the same type of adapter that will connect the real spacecraft to the top of ULA’s Atlas 5 rocket. When the craft ignites its four launch abort engines, vent doors on the adapter will open to prevent an over-pressure event.

“At the launch pad, you have the rocket standing next to its gantry,” Evans said. “You have a launch vehicle adapter, which is structural hardware that adapts the launch vehicle to the Starliner. So that’s how we interface to it. Then you have the Starliner sitting on top of the rocket. And we have a service module as well as a crew module, which is the (combined) Starliner.

“During an abort, if there was to be an accident with the rocket and we needed to save the crew, what would happen is we have four large launch abort engines that fire in conjunction with several more smaller thrusters, called our orbital maneuvering and attitude control thrusters,” Evans said. “And that combined collection of thrusters lifts the Starliner away from the rocket and outside of any debris or blast zone that might be created by a rocket.”

During Monday’s test, the abort engines will fire for 5.1 seconds, propelling the Starliner from zero to some 650 mph, a Boeing spokesperson said.

Then thrusters will pulse to flip the spacecraft around and fly tail first on an arc that will take the vehicle to a maximum altitude of approximately 4,426 feet (1,349 meters) above ground level around 18.6 seconds after takeoff.

The thrusters will stop firing 17 seconds after takeoff, and a series of pilot, drogue and three main parachutes will begin deploying at T+plus 20 seconds, according to Boeing.

The craft will jettison its service module at T+plus 34 seconds to fall to the ground. The crew module will then release its base heat shield, then inflate airbags to cushion the capsule’s landing at White Sands around 95 seconds after liftoff.

“This is a full demonstration of our landing sequence,” Evans said. “We have done a lot of subsystem tests of our landing sequence to show which component works individually, and in addition to showing that our propulsion system works to save the crew away from the rocket, the second half of the abort test is that it lands on land the way it would during an actual return from flight.”

On an actual space mission, the Starliner’s service module will jettison from the crew module in space, then burn up during re-entry into the atmosphere. Engineers will get video tracking of the jettison system’s function during the pad abort test, along with observations of the heat shield separation events.

The service module on Monday’s test flight will crash to the ground. Residual propellant inside the service module, which contains all the engines used for the abort test, could cause it to ignite on impact, Boeing officials said.

“We’ll get to actually see our parachutes deploy and billow out, as the reefers allow it to billow and see the crew module starting to float down,” Evans said. “As we get closer to the ground, we see the base heat shield separate, which exposes our airbags, and then, as we get closer to the ground, the airbags inflate.

“This’ll be the first time that’s demonstrated as on-flight hardware in the air,” she said. “So I’m very excited to watch all of that take place and then land under parachutes, on airbags, on land, which is the first American vehicle to do that.”

SpaceX completed the pad abort test for its Crew Dragon spacecraft at Cape Canaveral in 2015, and plans an in-flight abort test later this year at the Kennedy Space Center to verity the capsule’s ability to fire off a Falcon 9 rocket after liftoff. Boeing plans to bypass such an in-flight abort demonstration.

NASA gave both companies the option to decide whether or not to conduct an in-flight abort test.

“Boeing is not going to do an in-flight abort test,” said Jon Cowart, deputy manager of the mission management office for NASA’s commercial crew program. “They’re just going to do the ground one. They think that they can get enough data and then extrapolate that out, with good analytical techniques that we’ve endorsed. They will go and do it in that particular way, versus SpaceX, which is going to do both.

“We knew about this up front, both Boeing and SpaceX, when they proposed their contracts to us and said, ‘This is how we’re going to get to real flights,'” Cowart said last week in a NASA podcast. “We understood exactly, and we bought into it. We think, and we agree with them, that we can get all they need from a pad-abort test.”

Kathy Lueders, who manages the commercial crew program at NASA, called the Boeing pad abort “a huge test for us.”

“Obviously, it’s going to be important for us to understand how the separation works for the CM and SM (crew module and service module), checking out the chutes, making sure that the predictions are lined up right for us,” Lueders said Wednesday during a presentation to the NASA Advisory Council’s human exploration and operations committee.

Boeing is in the final stages of assembling and testing two space-ready Starliner vehicles inside a former space shuttle hangar at NASA’s Kennedy Space Center in Florida.

The first of the capsules is scheduled to launch as soon as Dec. 17 aboard an Atlas 5 rocket from pad 41 at Cape Canaveral Air Force Station for a week-long unpiloted test flight to the space station. That mission, called the Orbital Test Flight, will not have an active abort system, but Lueders said NASA wants to see how the Starliner performs on the abort test before going ahead with the OFT mission.

“OFT does not have the abort system on it because it’s an uncrewed mission, but obviously the way the system separates and everything else will reflect on our OFT progress, so it’s critical for us to get this test going and that we understand it prior to us doing rollout of the spacecraft (for OFT),” Lueders said Wednesday.

The Starliner’s Crew Flight Test to the space station will follow some time in the first half of 2020, with Ferguson joined by NASA astronauts Mike Fincke and Nicole Mann.

While final preparations for the pad abort test were underway this weekend in New Mexico, Boeing technicians at the Kennedy Space Center in Florida were readying the first space-ready Starliner spacecraft for fueling. Later this month, it will be installed on top of the Atlas 5 rocket at Cape Canaveral for final integrated checkouts and a full countdown rehearsal ahead of its scheduled liftoff in mid-December.

The new Boeing and SpaceX crew capsules could be ready to fly astronauts in the first half of next year, according to NASA officials.

The commercial crew program is a new paradigm for NASA. Boeing and SpaceX are in charge, but because NASA is the only customer for the new spaceships so far, the government still has a big say in how the contractors run the program.

“They own the flight tests,” Cowart said. “Even when they start flying up in the space station, they own the spaceship, they own the rocket. But these particular tests — they own them, which means we will consult with them, but in the end, they are the ones who own the tests and the results.

“It’s part of their certification,” he said. “They’ve got to bring the data from those tests to us before they can go fly our astronauts on-board. And we’ve got to say that, ‘Yeah, you’ve got the right amount of data and that the data is good and that the vehicle will perform correctly.’ But … this is the thing that’s kind of different from the way NASA has done business in the past. We don’t own the rocket. We don’t own the spaceship … It’s something more than consulting and something less than owning.”

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