As the launch date for Exploration Flight Test -1 (EFT-1) closes in, the Orion team conducted the final major parachute testing ahead of gaining data from an actual return from space. The latest parachute drop test was the “sportiest” of the series so far – pushing the system through several failure modes to see if Orion could still land safely. The test has been deemed a success.
Orion Parachute Tests:
Dropping a boilerplate Orion spacecraft out of the back of a plane at the U.S. Army’s Yuma Proving Ground in the Arizona desert has been going on since the days of the Constellation Program (CxP).
The tests use a Parachute Test Vehicle (PTV) system that consists of numerous additional parachutes, required to drag the test vehicle out of the C-17 aircraft via a sledge or pallet system at 25,000 feet, providing the correct orientation, altitude and speed, whilst also allowing for the pallet to land safely on the ground under its own dedicated parachutes.
As per the reason testing is conducted, the program has suffered from a couple of failures.
The Orion PTV (Parachute Test Vehicle – first generation) suffered a failure back in 2008, when the programmer chute failed to inflate after deployment, critically removing the requirement for the vehicle’s descent rate to be slowed down and to be correctly orientated for drogue chute deployment.
This failure resulted in the vehicle falling upside down at high speed and the increased velocity. When the two drogue chutes deployed, they were ripped off almost immediately due to the higher loads. The three main parachutes then deployed – again subjected to the higher loads – ripping two of them away from the vehicle.
The one remaining parachute valiantly remained attached, but was obviously unable to stop the vehicle crashing to Earth at high speed on its own, resulting in the destruction of most of the test hardware.
Another failure in 2010 was believed to be the fault of the pallet system itself, which allows the test vehicle to slide out of the back of the C-17.
The pallet apparently remained attached to the test vehicle, causing the duo to crash into the ground, again destroying most of the hardware.
The 2010 parachute test failure occurred during the period Orion was being cancelled by President Obama’s FY2011 budget proposal, prior to being fully reinstated, primarily as a Beyond Earth Orbit (BEO) vehicle, by the 2010 Authorization Act.
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Testing has proceeded with numerous successes since Orion was placed under its new role as an exploration vehicle, with objectives ranging from drop tests that examine how Orion’s wake – the disturbance of the air flow behind the vehicle – impacts the performance of the parachute system, through to examining the effects of one main parachute skipping the first reefing stage.
Testing even included how Orion would cope during a return with only two of its three main parachutes.
Tuesday saw test 14 of 17 of the developmental series conducted in Arizona, with NASA classing this test as the most ambitious so far.
With the C-17 aircraft 35,000 feet above the drop zone – only the third time Orion has been dropped from such a altitude – the test included 10 nervous seconds of freefall before Orion’s first parachutes were finally deployed.
Those 10 seconds allowed Orion to build up more speed and aerodynamic pressure before the first of the parachutes were released, placing the maximum amount of stress on them.
These under-stress parachutes will have the role of pulling away the forward bay cover – a shell over the top of the vehicle that protects the top of the crew module as it reenters the Earth’s atmosphere. A failure at this stage would result in Orion’s two drogue and three main parachutes being unable to deploy.
The test was successful, with the Orion going through all stages of parachute deployment, with an additional failure mode test involving a skipped stage in the chute reefing – for good measure – also included.
“We’ve put the parachutes through their paces in ground and airdrop testing in just about every conceivable way before we begin sending them into space on Exploration Flight Test (EFT)-1 before the year’s done,” said Orion Program Manager Mark Geyer.
“The series of tests has proven the system and will help ensure crew and mission safety for our astronauts in the future.”
The test marked the last time the entire parachute sequence will be tested before Orion launches into space in December on its first space flight test.
A partial Orion’s parachute test is set for August, which will include combined failure of one drogue parachute and one main parachute, as well as new parachute design features. This test does not need to be completed before Orion’s first flight later this year.
While the tests are ultimately designed to complete the safe conclusion of the first crewed mission during what is officially still called Exploration Mission -2 (EM-2) in 2021, the first return from space for Orion is now just months away.
EFT-1 will mimic Orion’s return from a Beyond Earth Orbit (BEO) mission, proving a critical test for both the Thermal Protection System (TPS) and the parachutes. Orion will splashdown in the Pacific Ocean.
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