SpaceX In-Flight Abort Test

SpaceX in-flight abort (artist's conception)Tomorrow, SpaceX is planning to conduct what promises to be a spectacular test flight of the crew escape system for their Crew Dragon spacecraft.  If successful, this should clear the launcher for the first crewed flight to the International Space Station later this year.  The launch is scheduled for a four-hour launch window which opens at 13:00 UTC on 2020-01-18.  At this writing, there is a 90% probability of acceptable weather for the test.   Update: Saturday test scrubbed due to high winds and rough seas in the recovery area.  Now re-scheduled for a six-hour launch window beginning at 13:00 UTC on Sunday, 2020-01-19.

If all goes as planned, the flight will be brief.  At the moment of maximum dynamic pressure (when the combination of velocity and air density produces maximum stress on the vehicle [“max q”]), the capsule’s Super Draco thrusters should fire to carry it away from the booster, whose engines will be cut by the abort system.  This is expected to occur around 84 seconds after launch.

After separating, the capsule will deploy its parachutes and splash down in the ocean to the east of the launch pad.  The rocket, without a payload or guidance, is expected to tumble and break up from aerodynamic forces. As both first and second stages will be fully fueled (although SpaceX did not bother installing an engine on the second stage), this may result in an impressive explosion or, as NASA prefers to say, “propellant dispersal”.

Rather than trying to embed players, here are links to Webcasts which should cover the flight.  Coverage will start around 12:45 UTC or earlier on some channels.

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Author: John Walker

Founder of Ratburger.org, Autodesk, Inc., and Marinchip Systems. Author of The Hacker's Diet. Creator of www.fourmilab.ch.

20 thoughts on “SpaceX In-Flight Abort Test”

  1. Here’s an idea for Elon. They already include one instrumented dummy on each flight. How about filling the other 3 seats with Japanese sex robots and then auction them off?

    They can also fill the cargo area with compressed T-shirts decorated with the slogan: “The Japanese sex robots had a suborbital kaboom and all I got was this lousy T-shirt.”

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  2. ctlaw:
    Here’s an idea for Elon.

    Anyone know how to reach him with this idea?  Just crazy enough to be worthy of his attention.  Probably too late to print the tee shirts, but I bet he could borrow the three robots from his California acquaintances. (:

    (If he doesn’t have one or more himself, of course.)

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  3. Note that the test is to be conducted at the most challenging point of the flight.  If you can make it there, you can make it anywhere.
    imagine a series of these tests, all at max Q, wherein 50 of 100 tend to break up rather than escape.
    Would this mean that the system has only a 50% reliability?  No, because the system is expected to operate most of the time in a far less challenging environment.
    Keep this in mind next time you hear about a zillion dollar military system that only works half the time. We don’t test the easy cases, especially when it costs real money.

    If the rocket is twice as likely to need escaping from for ten seconds around max Q, and there are 100 seconds in which escape can be done at all, then the system has a fifty percent chance of failing ten percent of the time, and a twenty-five percent chance ninety percent of the time.  A little math in my head tells me that this is a 27.5% chance of failure.  Naturally, there will be a distribution curve which will yield a more realistic value than our arbitrary ten percent of the time block, but even in this oversimplified math, the documented fifty-fifty result *taken in context* clearly indicates a much better than 50% performance.

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  5. Haakon Dahl:
    Would this mean that the system has only a 50% reliability?  No, because the system is expected to operate most of the time in a far less challenging environment.

    Estimating the reliability of a crew escape system can be a subtle and controversial business.  Rand Simberg goes into this in some detail in Safe Is Not an Option, and this was a bone of contention throughout John Paul Stapp’s career in developing and testing ejection seats and survival equipment.  I summarised the argument from Simberg’s book in my review:

    Suppose we have a launch system which we estimate that in one in a thousand launches will fail in a way that kills its crew. We equip it with a launch escape system which we estimate that in 90% of the failures will save the crew. So, have we reduced the probability of a loss of crew accident to one in ten thousand? Well, not so fast. What about the possibility that the crew escape mechanism will malfunction and kill the crew on a mission which would have been successful had it not been present? What if solid rockets in the crew escape system accidentally fire in the vehicle assembly building killing dozens of workers and destroying costly and difficult to replace infrastructure? Doing a total risk assessment of such matters is difficult and one gets the sense that little of this is, or will, be done while “safety is our highest priority” remains the mantra.

    This was written in 2014, and it came more sharply into focus when on 2019-04-20, during a static test of the SpaceX Crew Dragon launch escape system, the spacecraft was destroyed by an “anomaly”.

    Since the Crew Dragon and Boeing Starliner both take their crew escape systems to orbit, as opposed to jettisoning them during the launch process, as on the Mercury, Apollo, and Soyuz capsules, the possibility of such an “anomaly” exists during the entire mission, including when the spacecraft is docked to the International Space Station, where a detonation of this kind could conceivably kill everybody on board the station and result in a write-off of the whole US$ 150 billion facility.

    The key thing is that the launch escape system is another high-energy rocket component which is as prone to failure as any other, and the possibility of its failing catastrophically on one of the (presumably) large majority of missions on which it won’t be used must be taken into account when estimating total risk.

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  6. John Walker:
    Since the Crew Dragon and Boeing Starliner both take their crew escape systems to orbit, as opposed to jettisoning them during the launch process, as on the Mercury, Apollo, and Soyuz capsules, the possibility of such an “anomaly” exists during the entire mission, including when the spacecraft is docked to the International Space Station, where a detonation of this kind could conceivably kill everybody on board the station and result in a write-off of the whole US$ 150 billion facility.

    If they take it into orbit, I presume that they plan to bring it back for use in future launches.

    Do they remove the escape system and store it in the cargo bay for return to earth?   Can they disarm it while getting it secured for the return?

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  7. MJBubba:
    Do they remove the escape system and store it in the cargo bay for return to earth?   Can they disarm it while getting it secured for the return?

    The escape system is integrated into the capsule.  SpaceX was originally planning to use it for a propulsive precision landing on land (with parachutes for backup), but NASA nixed that proposal.  The escape system is disarmed at all times except during the launch phase but, as the explosion last March showed, valves and other components can fail, and you’re still carrying all of that hypergolic propellant around during the entire mission.  (Of course, both Soyuz and the Space Shuttle also had hypergolic propellant on board while docked to the Station.)

    The Boeing Starliner has its launch escape system built into the service module, which will be kept attached while docked to the Station, but discarded prior to return to Earth.

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  8. Here is the SpaceX Webcast of the test.  A NASA/SpaceX press conference to discuss the test is expected at 16:30 UTC, which should be covered on the SpaceX and NASA TV links in the main post.

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  9. I managed to catch it live just before leaving for church….  impressive.  I wasn’t expecting to be able to see the separation from the ground camera, but it was clear as day.  Lucky break in the clouds, perhaps.

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