CxP LOC/LOM Numbers

I wasn’t planning on doing any more blogging today, but I had a serious “what the hud!” moment earlier today, and thought it worth bringing attention to it. This is a presentation that was given by NASA back on July 2nd, and linked to by “” over in a comments section in Space Politics. brought attention to three rather troubling slides: pages 26, and 62-65.

Basically, unless this source is bogus, or I’m completely misreading things, it’s saying that even NASA admits that their odds of losing a crew or a mission using the Constellation architecture are far worse then they had originally claimed. In fact, at least for ISS missions, we’re talking almost an order of magnitude worse. For ISS, they’re claiming a LOC (probability of losing the crew on any given flight) of 1 in 231, with a LOM (loss of mission) of 1 in 19! If I’m reading this right, that means they expect right now that about 5% of missions to the space station will end up not making it to the station. For lunar missions, the LOC number is 1 in 170, and the LOM number is 1 in 9! That means of every multi-billion dollar mission, they’ve got an almost 11% chance of it being a failure. While some of these numbers have been improving, others have been getting worse.

To put this in perspective, the statistical reliability of most ELVs is rated at about 95-98%. One of the big selling points of Ares-1 was that it was going to be so much safer than any other vehicle that’s ever flown. The claim IIRC from ESAS was that the odds of losing a mission were going to be 1 in 460, which is about 9x more reliable than any other vehicle that’s ever flown. Not bad for a team that’s hasn’t designed, built, and operated a new launch in over 25 years. The Loss of Crew probability was supposed to be 1 in 2021 (both of these numbers can be found on the NASA ESAS Report website in chapter 6 on page 382). Now, I’ve made fun of them quoting four significant figures on reliability for something that hasn’t flown yet (though I apparently misremembered the numbers–I thought it was 1 in 2106…silly me).

In other words, it appears that NASA is admitting that the Ares-1 is not going to be any safer than an EELV/EELV derived launcher would’ve been, and in fact may be less reliable.

Am I misreading something? If not, why hasn’t anybody (other than been discussing this? While it’s true, things may get better with time, but so far the numbers have been getting consistently worse. And they’re currently over an order of magnitude worse than what “we” were “sold” on. What the hud?!?

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Jonathan Goff

Jonathan Goff

President/CEO at Altius Space Machines
Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and is the founder and CEO of Altius Space Machines, a space robotics startup in Broomfield, CO. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
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5 Responses to CxP LOC/LOM Numbers

  1. Swatch says:

    Jon, glad you pointed this out for me. I think you are absolutely right that they are predicting those extraordinarily disappointing numbers. This is serious cause for concern, and I have to wonder why it hasn't been brought to the public eye.

    <—has newfound fear for CxP

  2. Anonymous says:

    If you look at the charts, you’ll see this is not just an ares 1 reliability. it’s the reliability for the entire iss mission, which includes 6 months on orbit. the MMOD issues seem to be a large of this. In fact i see little that directly states that ares 1 is even a driver (though it may be, but i don’t see it in the charts). More likely, as the charts show, it’s the over all difficulty of making sure the cm/sm works after 6 months in orbit with mmod, etc.

  3. Karl Hallowell says:

    MMOD means micrometeor and orbital debris, right? Please explain infrequently used acronyms!

  4. Karl Hallowell says:

    Hmmm, another side of the coin here is why go for 1 in 400 LOM (loss of mission) and 1 in 2000 LOC (loss of crew) numbers for the launch vehicle when the overall mission is so risky? Assuming in an extremely generous manner that the launch vehicle can achieve those numbers when the total lifetime number of launches is around 100.

  5. Jon Goff says:

    Hmmm, another side of the coin here is why go for 1 in 400 LOM (loss of mission) and 1 in 2000 LOC (loss of crew) numbers for the launch vehicle when the overall mission is so risky?

    Bingo. That’s the point I’ve been trying to make for some time now. Spending tens of billions to make a new, supposedly “safer” launch vehicle, when it requires you to make compromises that cause the overall mission to be less safe is just plain retarded. Now, if NASA were doing something that could help industry develop vehicles that were both safe, cheap, and high-flight rate (like RLVs), it might be a more useful investment. But developing yet another NASA run ELV for that much when it isn’t even the main risk area in a lunar mission is daffy.


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