SpaceX has successfully pulled off a test mission it hopes it will never again have to execute for real: the catastrophic high-altitude failure of a Falcon 9 booster at one of its most critical phases of flight—the period of maximum aerodynamic turbulence, colloquially known as “Max Q”—and the separation and parachute-aided return to Earth of a Crew Dragon spacecraft.
Launched from historic Pad 39A at the Kennedy Space Center (KSC) in Florida at 10:30am EST Sunday, 21 January, 2.5 hours into a six-hour “window”, the mission was a great success, but spelled a sad end for SpaceX’s long-serving B1046 booster core, which was intentionally destroyed as part of the test.
“This critical flight test puts us on the cusp of returning the capability to launch astronauts in American spacecraft on American rockets from American soil,” said NASA Administrator Jim Bridenstine. “We are thrilled with the progress NASA’s Commercial Crew Program is making and look forward to the next milestone for Crew Dragon.”
Described by NASA as one of SpaceX’s “final major tests” as the Commercial Crew Program gets ever closer to launching U.S. astronauts aboard U.S. spacecraft, atop U.S. rockets, and from U.S. soil, for the first time since the 2011 retirement of the Space Shuttle fleet, the In-Flight Abort Test on Sunday, 19 January, also carried an unhappy element of déjà vu with harrowing memories of the first time that a Falcon 9 flight went awry on the CRS-7 mission in June 2015.
“As far as we can tell thus far, it’s a picture perfect mission. It went as well as one can possibly expect,” said Elon Musk, Chief Engineer at SpaceX. “This is a reflection of the dedication and hard work of the SpaceX and NASA teams to achieve this goal. Obviously, I’m super fired up. This is great.”
The In-Flight Abort Test was one of the last significant milestones to be overcome before SpaceX receives clearance to launch NASA astronauts Bob Behnken and Doug Hurley on the Demo-2 mission of Crew Dragon at some point later in the spring. Ironically, just one year ago, the very spacecraft launched this morning was expected to be theirs to fly. In March 2019, they watched as the first Crew Dragon flew a virtually unblemished Demo-1 mission to the International Space Station (ISS). Upon its return, Demo-1 was slated to undergo a static test of its powerful SuperDraco thrusters, before being put to work on the In-Flight Abort Test. Then Behnken and Hurley would fly the next available Crew Dragon off the production line for their Demo-2 mission to the ISS.
Unfortunately, fate had other ideas. Last April, just six weeks after returning from its mission, the Demo-1 spacecraft blew itself to pieces on the test stand.
The cause was traced to a leaky valve in the SuperDraco system which caused nitrogen tetroxide oxidizer to enter high-pressure helium tubes and trigger an explosion. With Demo-1 already booked for the In-Flight Abort Test, SpaceX and NASA suddenly found themselves without a spacecraft to execute this critical milestone. The second Crew Dragon off the production line—what would have been Behnken and Hurley’s ship—was reassigned to the abort test and the astronauts were correspondingly bumped onto the next one.
So it was that the spacecraft intended for these two Space Shuttle veterans wound up flying a mission which would duplicate a dire eventuality that nobody ever wants to see unfold in real life. As outlined in AmericaSpace’s preview article, the three-times-flown B1046 core stage assigned to the flight—together with a sparkling-new second stage, minus its Merlin 1D+ Vacuum engine—was trundled out to Pad 39A last week and performed a customary Static Fire Test on Saturday, 11 January. It was then returned to the horizontal integration facility for the integration of Crew Dragon and taken back to the pad on Thursday, 16 January.
When elevated to the vertical, the stack stood about 215 feet (65 meters) tall. The Launch Readiness Review (LRR), also conducted on Thursday, declared an unequivocal “Go” for Saturday’s opening launch attempt.
That proved just as well, for Saturday’s predicted 90-percent-favorable weather conditions were expected to take a significant downturn to only 30 or 40 percent in the event of a scrub and delay to Sunday or Monday. “Winds will become southeasterly on Saturday, forming some shallow coastal showers,” noted the 45th Weather Squadron at Patrick Air Force Base. “The primary weather concern is flight through precipitation with those showers.” With a frontal system due to move into the Panhandle later in the weekend, conditions would deteriorate markedly, potentially threatening SpaceX’s scheduled Monday launch of another batch of Starlink low-orbiting internet communications satellites from Space Launch Complex (SLC)-41 at neighboring Cape Canaveral Air Force Station.
However, late Friday, SpaceX tweeted that the In-Flight Abort Test would be targeted to occur late in Saturday’s window. “Latest weather data suggests sustained winds and rough seas in the recovery area during the top of tomorrow’s four-hour launch escape test window,” it was explained. “Now targeting toward the end of the window. Will continue to monitor weather and update the T-0 accordingly in the morning.”
Unfortunately, Saturday was not to be SpaceX’s day. “Standing down from today’s in-flight Crew Dragon launch escape test attempt, due to sustained winds and rough seas in the recovery area,” SpaceX tweeted early Saturday morning. “Now targeting Sunday, 19 January, with a six-hour test window opening at 8 a.m. EST.” Sunday’s weather outlook was predicted to be marginal, with a 60-percent chance of acceptable conditions at the start of the window, deteriorating markedly to only 40 percent near its end.
To keep the In-Flight Abort Test a close analog of the real thing, SpaceX and NASA teams worked in close co-ordination for launch-day end-to-end operations, including the final inspection of the Crew Dragon and the closeout of its side hatch. At the instant of liftoff, the trusty B1046 rose smoothly into the clear Florida sky to become only the third orbital-class rocket stage to record a fourth launch. It had previously boosted two geostationary communications satellites and Spaceflight Industries, Inc.’s SSO-A SmallSat Express payload into orbit within the span of seven months, back in 2018.
But today’s flight was its last.
A minute and a half into the flight, its nine Merlin 1D+ first-stage engines were programmed to shut down, simulating an in-flight booster failure and loss-of-thrust situation. Immediately, the Crew Dragon’s launch escape system was triggered, the eight SuperDraco thrusters mounted in its sidewalls roaring to life with a combined impulse of 120,000 pounds (54,400 kg) to pull the spacecraft clear.
Burning to completion, after the SuperDracos shut down, the Crew Dragon passively coasted to its peak apogee, discarding its unpressurized trunk on the way. Alone now, the pressurized capsule—which on piloted flights will house the crew—inexorably began its descent back towards the Atlantic Ocean. Six miles (9.6 km) above the ocean, the drogue parachute was successfully deployed, followed by the main trio of red-and-white canopies at one mile (1.6 km).
Splashdown occurred some ten minutes after liftoff. Today’s successful test clears an important milestone as SpaceX strives to return U.S. astronauts to space, launched atop its Falcon 9 rocket, perhaps as early as this spring.
“The past few days have been an incredible experience for us,” said astronaut Doug Hurley. “We started with a full dress rehearsal of what Bob and I will do for our mission. Today, we watched the demonstration of a system that we hope to never use, but can save lives if we ever do. It took a lot of work between NASA and SpaceX to get to this point, and we can’t wait to take a ride to the space station soon.”
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Current plans call for Behnken and Hurley to fly in the next few months, with NASA Commercial Crew Program manager Kathy Lueders explaining that a significant amount of work still remains to be done—including additional parachute tests and analysis of data from today’s mission—before humans can be trusted aboard the vehicle.