SpaceX conducts successful Crew Dragon In-Flight Abort Test

by Ian Atkinson

SpaceX successfully launched a unique Falcon 9 rocket at LC-39A for the in-flight abort test of their Crew Dragon spacecraft. The uncrewed test flight saw the spacecraft demonstrate its ability to escape a failing rocket mid-flight. Sunday’s launch occurred at 10:30 AM Eastern, with a successful test resulting in the safe splashdown of the Dragon vehicle.

Abort test:

The In-Flight Abort (IFA) was the last major test of Crew Dragon before Demo Mission 2 (DM-2) – when astronauts will fly on Dragon for the first time. SpaceX performed the first abort test in May 2015- a Pad Abort Test from SLC-40 at Cape Canaveral Air Force Station.

Crew Dragon performing its Pad Abort Test in May 2015. Credit: NASA

The main objective of the IFA was to demonstrate Crew Dragon’s ability to escape a Falcon 9 rocket in case of an off-nominal launch. This could be caused by a wide variety of factors, including engine failures, tank ruptures, or a deviating trajectory. Like the two previous Crew Dragon test flights, the IFA carried no crew.

For the IFA, the Falcon 9 flew the same profile as a normal mission to the International Space Station (ISS). It launched from LC-39A at Kennedy Space Center, where all Crew Dragon missions will launch from.

The launch failure was simulated by shutting down the first stage’s nine Merlin 1D engines near the time of maximum aerodynamic pressure (Max-Q). This occurred around 90 seconds into flight.

Crew Dragon’s computers interpreted the engine shutdown as a loss of thrust, and activated its eight SuperDraco engines to carry it away from the uncontrolled rocket.

The Falcon 9, as predicted, did not survive long after the engine shutdown. Dragon was already a safe distance away from the rocket when it disintegrated. The second stage – still attached to the first stage’s interstage – survived the first stage’s explosion, and survived until impact with the ocean.

This was because Falcon 9 had no control after its engines shut down and broke apart due to aerodynamic forces.

Because of this, SpaceX did not attempt to recover the first stage. Had the vehicle not broken apart, it would have impacted the Atlantic Ocean further downrange. SpaceX has stated that they will attempt to recover all of the floating debris from the disintegrated Falcon 9.

Meanwhile, after its SuperDraco engines shut down, Crew Dragon coasted until apogee – the highest point of its flight. The small fins on its trunk – the cylinder with solar panels mounted under the capsule – kept Dragon stable and oriented forward. Once it reached apogee, the trunk was jettisoned and the capsule repositioned for descent.

As the capsule descended towards the ocean, its small drogue parachutes deployed to slow and stabilize its descent. The four main parachutes deployed, and slowed it to a safe speed for splashdown in the Atlantic ocean, about 31km downrange. SpaceX’s recovery ship GO Searcher was stationed nearby to retrieve the capsule.

The capsule’s fate following the test was unclear until recovery boats closed in shortly after splashdown. It was then revealed the vehicle was deemed to be in great shape.

Go Searcher then transported the vehicle back to Port Canaveral for closer inspections.

This specific capsule was serial number C205, signifying that it was the fifth Crew Dragon built. C204 flew on Demo Mission 1 (DM-1) – the first uncrewed orbital flight test for Crew Dragon – and was destroyed in a post-mission test. C202 was a structural and qualification test vehicle.

C204 was originally planned to be reflown on the IFA after DM-1. However, during a test firing of its Draco and SuperDraco engines at Landing Zone 1, the capsule suddenly exploded just before ignition of the SuperDracos. Following a long investigation process, SpaceX discovered that the explosion was caused by propellant leaking into a pipe. The “slug” of leaked propellant was then slammed into a titanium valve during pressurization. The propellant – nitrogen tetroxide, an oxidizer – reacted with the titanium and combusted, leading to the destruction of the capsule.

Prior to the failure, C205 was to fly on Demo Mission 2. After C204 was destroyed, all capsules were moved forward one mission. C205 would now fly the IFA, and C206 would fly Demo Mission 2.

Capsule C205 in assembly at SpaceX headquarters in Hawthorne, California. At this time, it was assigned to fly on DM-2. (Credit: Jack Beyer for NSF/L2)

The Falcon 9 flying on the test flight included the first stage B1046 – the first Block 5 booster. B1046 flew three previous missions, one from each of SpaceX’s launch pads. B1046 was also the first Falcon 9 booster to fly a third mission. Due to the near-certainty of the vehicle disintegrating after the abort – eliminating the possibility of a recovery attempt – B1046’s landing legs and grid fins were removed.

The IFA was B1046’s fourth flight. It was the third Falcon 9 booster to fly a fourth time.

In order to further represent a real launch, this Falcon 9 featured a real second stage – which was fueled. The only major difference is that the stage’s Merlin Vacuum engine was replaced with a mass simulator.

SpaceX originally planned to perform the IFA from SLC-4E – their launch site at Vandenberg Air Force Base in California – in late 2015. They would have reused the capsule from the Pad Abort Test in May 2015, which was a heavily-modified Cargo Dragon. The capsule would have been lifted by F9R Dev2, a three-engine first stage booster that was originally built to perform landing tests.

F9R Dev2 was to be the successor to F9R Dev1, an identical test vehicle lost during its fifth test hop at SpaceX’s McGregor, Texas facility. Dev2 would have carried out high-altitude landing tests at Spaceport America in New Mexico. However, due to everything learned from Dev1 and the actual first stage landing tests at sea, Dev2 was reassigned to launching the IFA.

F9R Dev2 laying in storage near LZ-4, SpaceX’s landing pad at Vandenberg Air Force Base. Credit: Jay DeShetler for NSF/L2

However, SpaceX later pushed the IFA further back, to between DM-1 and DM-2. They also moved the IFA’s launch site from SLC-4E to LC-39A, launching on a regular Falcon 9 stack. Dev2 was again left without a mission, but performed a tanking test on the launch pad in 2015. It was scrapped in late 2018.

Following the IFA, SpaceX and NASA will do a detailed review of the test data. The outcome of the IFA will help determine when DM-2 will launch – which is currently scheduled to fly no earlier than the first quarter of 2020. DM-2 may also be extended to a regular crew rotation mission length of 6 months at the ISS, per NASA approval.

Depending on when Boeing flies the Crewed Flight Test of their Starliner capsule, DM-2 may be the first crewed orbital flight from the United States since the final Space Shuttle flight, STS-135, in 2011.

Should DM-2 go well, Crew Dragon will begin flying operation crew rotational missions to and from the ISS once or twice each year. NASA has contracted six crew missions to SpaceX, with options to purchase more flights later. The first of these is planned for the end of this year, but that date is likely to be pushed back.

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