Demo-2.
It’s one of the most highly anticipated launches in SpaceX’s career.
Mostly because if all goes to plan, it’ll be the first private spacecraft to carry humans
to low-Earth orbit.
Back in 2014, SpaceX was chosen and given $2.6 billion as part of NASA’s Commercial
Crew contract.
A deal that would help NASA garner its independence from Russia and re-establish the United States
as a contender in crewed spaceflight.
But there’s been some delays, financially and technically, that have prevented the SpaceX
team in getting the Crew Dragon capsule ready for launch.
They did have a successful unmanned demonstration mission, Demo-1, in March 2019 showing off
their capsules capabilities to go to the ISS and back.
But they notoriously lost that first Crew Dragon
in a following static fire test in April.
As it turns out, rocket science is hard, but the team has been steadfast in a multitude
of tests to improve the capsule since.
Now, we’re just around the corner from viewing the company’s final milestone before a crewed
demo, the in-flight abort test.
It will be the determining factor in how soon SpaceX can get astronauts off the ground,
and into space.
Most of these final tests are extra safety demonstrations SpaceX wants to take
to showcase the functionality of the spacecraft during abort ascent, ensuring the security
of the astronauts onboard.
Meaning the parachutes, back-up engines, and detachment controls are all in working order.
Now in past months, NASA did express concern over parachute systems based on previous tests
where the spacecraft hit the ground harder than it should have and sustained damage.
And dang, did SpaceX take that note seriously.
At the end of October through November, the company completed an unprecedented 12 consecutive
and successful parachute drop tests, in a single week.
Starting with one-chute test with their new Mk 3 design, and then moving on to a multi-chute
one.
This drop particular drop test used 3 parachutes instead of the standard 4 to see how the capsule
would fair just in case one blew out.
Working with supplier, Airborne Systems, SpaceX improved these “Mark-3” parachutes by
integrating Zylon, a high performance polymer material that's lightweight and known for
its strength.
Elon Musk even suggests that the parachutes are possibly 10 times safer that the Mk2 versions.
The team is continuing to improve the quality of their design, but they earned their spot
to the next stage; the static fire test.
To start, the Crew Capsule is equipped with two distinct propulsion systems, one composed
of 16 Draco thrusters for on-orbit maneuvering, basically in space, and eight back-up SuperDraco
thrusters for use only in the event of a launch escape.
A static fire test, is when the rocket engine is strapped to the ground, and ignited.
Engineers can then observe how these thrusters would work during flight as well as showcase
that they operate smoothly.
This is where things went not so smooth in April.
A faulty valve let a liquid oxidizer leak into high-pressure tubes, and milliseconds
into the SuperDraco thrusters’ ignition, an explosive chain reaction occurred, completely
destroying the Crew Dragon.
This was a heavy loss for the team since that particular capsule had just successfully flown,
uncrewed, to the ISS and back.
But, although they’re starting from scratch, the company and NASA considers the anomaly
good testing; it was in a controlled setting, no one was hurt, and they could improve these
back-up thrusters.
The newest version has implemented burst disks that prevent a leakage from happening again.
The latest test that happened in November 2019 and it was a success, bringing us to
the highly anticipated in-flight abort test.
Now what should we expect when it happens?
Since the in-flight abort is a simulation of “the worst case scenario”, it’ll
look a little like this.
The Crew Dragon will sit atop a Falcon 9 rocket and launch into the air for almost a minute
just like in a typical launch.
Then after surpassing the speed of sound, the merlin engines will turn off, a feature
pre-programed before launch.
The computer onboard the Crew Dragon should detect the loss of thrust and trigger the
escape system (a.k.a the abort system), and this is where the previous parachute and static
fire evaluations will come into play.
The SuperDraco thrusters ignite, pushing the Crew Dragon half a mile away in just 7.5 seconds,
reaching a peak of 436 mph, then deploying its parachutes for a safe touchdown.
With every test, SpaceX comes one step closer to bringing crews onboard its capsule.
If the inflight-abort test goes well, the team can plan to have its first manned mission
in early 2020.
And this is a big deal not only for commercial spaceflight, but for everyone.
It opens the door to the endless possibilities that we can achieve.
Engineering that can get us outside Earth’s atmosphere, to the moon, to Mars, and maybe
even beyond.
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