NASA confirmed on Friday that SpaceX’s Commercial Crew Dragon program successfully conducted a parachute test – as part of the Commercial Crew Integrated Capability (CCiCap) contract with NASA – in December. The test evaluated how the Dragon parachute system would function in the event of an emergency on the launch pad or during ascent.
Dragon Parachute Test:
SpaceX is currently preparing for their fourth Dragon mission to the International Space Station (ISS), the third under their Commercial Resupply Services (CRS) contract with NASA.
However, the company is also pushing forward with their aspirations to provide crew transportation to the orbital outpost via a crewed version of their Dragon spacecraft.
That effort is currently being conducted under the Commercial Crew Integrated Capability (CCiCap) contract with NASA.
SpaceX’s latest milestone – conducted in December, but only released to the media on Friday – continues to pace the company toward the completion of all 15 of its CCiCap milestones in 2014.
Dragon has already successfully used its parachute system when returning from its space missions to restock the ISS with much-needed supplies.
However, the crewed Dragon’s parachute system requirements stretch out into the realm of ensuring crew safety – even before the Falcon 9 launches off the pad.
The test of the parachute system was conducted at Morro Bay, in California, demonstrating how the parachute system would function in the event of an emergency on the launch pad or during ascent.
Traditionally, a crewed rocket in serious trouble at the pad would hold the option of triggering its Launch Abort System (LAS), pulling the capsule and crew safely away from the vehicle. Per tradition, the LAS have appeared as towers, pointing out on top of the vehicle stack.
These LAS towers were sported on even the early crewed launch vehicles, having first been tested in 1960 – when the “Beach Abort” practised the abort technique on the first production Mercury capsule at NASA’s test facility at Wallops Island.
The live use of the LAS during a pad abort event can be observed via footage on youtube – as the crew of Soyuz T-10-1 underwent a pad abort, just seconds before their failing vehicle exploded on the launch pad.
The video shows a line of the Soviet top brass witnessing the dramatic abort, acknowledged only by one General calmly adjusting his collar.
It was reported that the crew landed safely, just four miles away.
The tradition will continue with NASA’s new Orion spacecraft, with a tower LAS set to provide the escape system should the Space Launch System (SLS) suffer a serious issue late in the countdown or during the early ascent uphill.
However, SpaceX won’t be using a tower system, instead they’ll be using an escape system that is not only fully integrated into the body of the spacecraft, but one that also holds future uses, through to those that aren’t even related to launch abort.
The first major difference relates to the traditional use of solid propellant, mainly because of the speed it can ignite and reach full thrust – something highly desirable when moving human lives away from a failing rocket.
Instead, Dragon sports a series of eight liquid SuperDraco engines, built into the side walls of the Dragon spacecraft, capable of producing up to 120,000 pounds of axial thrust to drive the Dragon away from its failing launch vehicle.
Referencing back to the benefit of solid motor abort systems, SpaceX’s SuperDraco produced full thrust within approximately 100 milliseconds of the ignition command. It also fired for five seconds, which is the same amount of time the engines would burn during an emergency abort.
Advantages of the SuperDraco liquid thruster include how the engine can be put through a series of throttling ranges, in turn allowing for redundancy, with SpaceX claiming they could lose one of the eight abort engines and still recover the vehicle and crew successfully. The engines can also be restarted multiple times.
Another advantage is the fact it’s not a tower. The LAS tower normally requires jettison shortly after first stage flight. Any failure of this key sequence of ascent would end the mission, given the flight profile wouldn’t be designed for carrying the LAS along for the ride.
Because the system is integrated into the Dragon itself – as opposed to departing the spacecraft during jettison – the spacecraft can technically abort within much longer periods than the tower version. With Dragon returning with the engines on board, they can also be reused on future launches.
There is also a large amount of commonality between the 18 maneuvering engines built into Dragon and the SuperDraco LAS engines – bar the fact the SuperDraco engines would burn through propellant 200 times faster.
The biggest long-term advantage of this system is related to the potential use of the engines to land Dragon back on land propulsively, as seen via SpaceX’s Reusable Falcon 9 concept, which returns all of the launch vehicle and spacecraft hardware to the ground for reuse.
Parachutes will still be onboard the Dragon, for a contingency event resulting in problems with the SuperDracos, allowing the spacecraft to land on water, as it is currently designed to do.
Testing the parachute system – as carried out in December – is a key part of the CCiCAP requirements.
The test involved a 12,000-pound “Dragon Crew parachute drop test article” – a refurbished cargo parachute test vehicle -that was lifted 8,000 feet above sea level by an Erickson Sky Crane helicopter and flown over the Pacific Ocean.
“The parachute test is essential for the commercial crew effort because it helps us better understand how SpaceX’s system performs as it safely returns crew,” noted Jon Cowart, NASA Partner Integration deputy manager working with SpaceX.
“Like all of our partners, SpaceX continues to provide innovative solutions based on NASA’s lessons learned that could make spaceflight safer.”
Following Dragon’s release during the test, two drogue parachutes were released from the top of the spacecraft to slow its descent, before the three main parachutes deployed.
The craft splashed down and was quickly recovered by the Sky Crane and carried back to shore.
“SpaceX is working diligently to make the Dragon spacecraft the safest vehicle ever flown,” claimed Gwynne Shotwell, president of SpaceX.
“The parachute system is an integral part of Dragon’s ability to provide a safe landing for nominal and abort conditions – with this successful test we are well-positioned to execute a full end-to-end test of the launch escape system later this year.”
The pad abort test article Dragon is already being processed at SpaceX’s Californian base, ahead of its short flight in the latter half of this year.
(Images: via NASA, SpaceX and L2’s SpaceX Special Section, which also includes over 1,000 unreleased hi res images from Dragon’s three flights to the ISS.)
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