SpaceX scrubs Falcon 9 launch again

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Update: It appears that they called the launch because of winds, though it also appears that the lower oxidizer temperatures have also reduced their weather margins.

In the heat of competition: For the second day in a row SpaceX has canceled a commercial launch of its Falcon 9 rocket because they were unable to get the oxygen in its tanks as cold as required.

The denser propellant gives the rocket added thrust, contributing to what SpaceX says is a 33 percent overall increase in its performance compared to the previous version.

But during countdowns Wednesday and Thursday, SpaceX reported trouble keeping the “deeply cryogenic” propellant cold enough. Although Thursday’s launch window lasted 96 minutes, it turned out SpaceX really only had one opportunity during that window. If any problem arose, SpaceX said the liquid oxygen would have to be drained and re-loaded, a process that would take too long.

This problem is troubling, suggesting that there might be a more fundamental issue here than they are saying. First, there was the significant delay since the last launch of this upgraded fueling system in December, implying that the data from that launch required some reworking. Now, they have scrubbed two launches in a row because they couldn’t get the oxygen cold enough to properly fuel the rocket. I also wonder if they need to reach a colder temperature in order to get enough fuel loaded to get the satellite to its proper orbit.

I generally trust SpaceX’s engineers to address a problem and fix it. Right now, however, they are under the gun. They need to get this working and begin launching rockets on a more reliable schedule. They have a lot of customers waiting in line.


  • Wayne

    Can they actually get a “33% improvement” using “deeply cryogenic” propellant?
    What sort of time-frame are they locked into, once they start to load the oxygen? I assume the rocket tanks aren’t “super” insulated.(?)
    –What sort of temperature differential is this, compared to “regular” LOX?
    -I understand (?) they had concerns about having sufficient fuel left in the first-stage to re-land it & to get the payload into the desired orbit.

  • PeterF

    I suspect that SpaceX is being highly cautious because they want this launch to absolutely perfect. I don’t fault them for being slightly gun-shy at this point. Criticism for several launch delays pales in comparison to booster recovery failure or even payload loss. IMO these delays cause me to be more confident in their capabilities and future success.

  • pzatchok

    I wonder if they are having trouble getting and keeping the tank down in the super cooled temperature?

    Maybe instead of just loading the tank and hoping they could cycle the tank during filling operations.
    Fill the tank once with coldO2 then start to drain that as they load in the super cold O2. letting it drain slowly as they keep filling it with thesupercoldO2 just before launch.
    Obviously recovering the draining O2 during the whole thing.

    That and add more insulation to the tank.

  • Wayne

    Yeah… tend to agree. No rush to blow up it, lose the first stage, or fail to insert the payload!

  • I wonder if one could have external insulation which could be removed prior to liftoff – thinking of a blanket.

  • mivenho

    They may be using vacuum jacketed tanks & delivery lines for the LOX. These can develop microscopic leaks if the welds aren’t perfect, causing heat leaks. Identification and subsequent repair is very time-consuming.

  • Edward

    We keep learning more and more about the Falcon.

    Now we know that the colder temperature (denser oxygen) helps with performance of the engine. I suspect that they have enough performance to get the payload to its proper orbit, but they are looking for optimum performance in order to have enough fuel left over to recover the first stage. They are likely learning the techniques and procedures needed to do this on a regular basis.

    I was wondering why they would have to drain the rocket and start again. It seemed like a bizarre thing for that one engineer to say, but now it makes sense.

    I agree, though, that at some point they need to stop making this an experiment and get their customer’s payload to orbit. The competition has the advantage of timeliness in their launch schedules, and SpaceX needs to keep that in mind as they improve their system.

    My father has long been concerned that rockets sometimes failed due to problems with incremental improvements, wondering if the small improvements were worth the loss. Not only do we have to worry about the loss of the spacecraft, with these changes in the rocket, but the customer’s revenue stream is also an important consideration.

    I once worked on a satellite whose owner had started training people to install the TV receivers on people’s houses, when we had a major setback with faulty equipment on the satellite. While we sent the equipment back to the supplier for repair, the customer had to fire all those people in training, because they could not afford to keep them on the payroll for the extended repair time. Although it did not affect my team directly, we learned an important lesson in the importance of schedule, and the effect on the lives of people who have no influence on the problem.

  • Edward

    Wayne wrote: “Can they actually get a “33% improvement” using “deeply cryogenic” propellant?”

    My father asked that same question, and I wrote to him:
    “I think that most of the 33% performance improvement is in other modifications, but that they are trying to eek out a little bit more so that they have just enough to land on a barge after doing a GTO (geostationary transfer orbit) launch.”

    Right now, if they cannot recover after a GTO launch, then the first stages for these launches will still be expendable and expensive. I suspect that the customer, SES, is willing to wait a little bit in order for future launches to be far less expensive than they are now. SES is a major satellite operator, and they would greatly benefit from lower launch costs.

    Eagerly watching SpaceX launch at T -3 minutes and counting, and hoping that the long hold did not warm the LOX too much for a successful barge (drone-ship) landing.

  • wayne

    They just scrubbed the launch for today.
    Hair-raising! You could see (at least some of..) the engines start up & then the on board computer cut off the sequence.

    Do you know what the difference is between regular LOX & the “deeply cryogenic” stuff?

    Spent a good long time at the SpaceX website yesterday– fascinating stuff.

  • Edward

    Wayne asked: “Do you know what the difference is between regular LOX & the “deeply cryogenic” stuff?”

    Cryogenic just means “really cold!” Maybe with a few additional “really”s in front.

    Liquid oxygen boils and condenses at -273F, at atmospheric pressure and it freezes at -361F, where absolute zero is -459.67F. So they are trying to get more oxygen into the tanks by cooling it closer to the freezing temperature. It looks like it has been quite a feat and problem.

    There is another form of oxygen, ozone, but they are not using that, just extra-cooled regular LOX.

    BTW: thank you for telling me about JPL’s von Karman lecture series. I am now spending (too much) time watching the archives.

  • wayne

    Thanks & you’re welcome.
    Good deal on the van Karman lectures! They have really interesting topics.
    -Gresham College (UK) has multiple interesting lecture series; Cosmology, Math, & Astronomy. (British Political History as well.)
    -Perimeter Institute in Canada (Theoretical Physics) has a very good annual public-lecture series.
    and for the more intense stuff;
    -Dr. Leonard Susskind from Stanford has 130+ of his physics-classes on line.
    (Personally– big fan of Dr. Roger Penrose & his Conformal Cyclic Cosmology.)

  • Edward

    There are plenty of lectures available, including SETI. However, be sure to watch Randy Pausch’s 1-1/4 hour “Last Lecture” for some excellent lessons on living life:

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