September 1, 2016 Zimmerman/Batchelor podcast

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Embedded below the fold. I am sure that no one will be surprised that the focus was the Falcon 9 launchpad failure. Talked about other stuff though, including some of the neat planetary discoveries this week.


  • Localfluff

    I wonder why SpaceX was fueling the upper stage before they test fired the first stage.

    Earth’s diameter is about 13 times that of Ceres, so 11,000 feet would correspond to ~45 km. It would be a great place for telescopes.

  • Localfluff: As to your question about the fueling, this was a dress rehearsal for launch. I think I’ve mentioned that in comments now about three times, as well as I think during my podcast. During the actual launch, they fuel the 2nd stage as well as the first. Thus, in the dress rehearsal, they do this as well, following exactly the same procedure.

    As to the relative height of Ahuna Mons on Ceres compared to Earth, if I remember right during the podcast I think I guessed off the top of my head, without doing the math, that on Earth it would compare to a mountain somewhere around 30 to 50 miles high. If my memory is right, than my guess was pretty close, since 45 km equals about 28 miles.

  • Dick Eagleson

    SpaceX static fire tests aren’t just about the 1st stage, they’re pretty much full dress rehearsals for launch up to, and including, ignition, but stopping without liftoff. So both stages are fueled as they would be for launch. Many times, the payload is also atop the rocket, though this is apparently the customer’s choice.

  • Localfluff

    Okay, empty tanks are vulnerable to vibrations, I read somewhere.
    A better question is why the payload was mounted on the rocket during the hot-fire test? It’s not really a test then, it is doubling the risk of losing the payload at launch like this.

  • Localfluff

    Because of horizontal payload integration? Still, if they want to “test” with a dumb weight as payload and then take the Falcon down to put the real payload on afterwards. For crewed launches, maybe the Dragon could be on during the test firing, and the crew enter it afterwards.

  • Localfluff

    Does the SpaceX pad explosion affect the sale of the Israeli company which lost the satellite? That deal was mentioned here recently. I heard that this satellite was theirs.

  • Edward

    You have confused this dress rehearsal for a hot-fire test. For these dress rehearsals if the engines are ignited then it is shut down almost immediately. They are not fired for a long duration. It does not double the chances for losing the payload, as the procedure for ignition should not be nearly as hazardous as an actual launch.

    Payloads on the rocket may be part of the dress rehearsal, as there is often a check to make sure the payload has not failed before launch. That check is part of the procedure. If the payload does not pass an aliveness test before launch, then launching it eliminates the opportunity to fix it. Payloads do not often fail, but then again, rockets rarely explode before first stage ignition.

    The only other time, that I recall, that a rocket exploded before first stage ignition was the Nedelin catastrophe, in which many engineers and technicians were working around the rocket at the time.

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