Memory Overload

Digging through my files I recently found an email which caught my attention:


From:  Larry A.

Sent:  Thursday October 21, 2004 7:18 AM

TO:  A whole bunch of people who are probably retired now

Subject:  SMS Issue – SMS AR 018459 – Unexpected GPC Errors – 1141A T.L. – OI30 STS-114 BASE2 FSW (OF03.01) – Closure

After additional runs in the SMS and SPF and analysis of the data collected on those runs, FSW DR 121227 has been opened on the issue.  The SMS AR will be closed in reference to the FSW DR.  The description of the FSW DR reads as follows:

“In MM 104-105, 202, and 301-302 when an Item 22 (Load) is executed on the XXXXX YYYYY MNVR display, it is possible for 2 SQRT of negative number GPC errors to be generated.  This will occur when the TIG entered is not consistent with the PEG 4 burn targets.  The Orbital Altitude Time Task in the DIP computes the inverse of the mean orbital rate and the sine of the eccentric anomaly as a function of the square root of the semi-major axis.  Given the inconsistency of the TIG with the targets and the fact that the guidance converged to a solution, the semi-major axis is computed as a negative number.”


So here is my problem:  almost two decades later I completely understand EVERY BIT of this email!

How many of my memory cells are taken up with holding on to obsolete and totally useless information?  Is this why I can go down the hall to another room in my house and, upon arriving there, wonder what it was I came to do?


I imagine that there are dozens, if not hundreds, of former flight controllers, astronauts, trainers, software programmers, and trajectory analysts who were nodding their heads reading that email and saying ‘Yes!  I understand the problem!’

Some neuro-psychologist needs to explain to me how to clean out my memory cells of unwanted and useless information so that I don’t get confused looking for my car keys.

Oh well, its fun to remember the old days.

And my wish for you today is that your semi-major axis is never a negative number.






About waynehale

Wayne Hale is retired from NASA after 32 years. In his career he was the Space Shuttle Program Manager or Deputy for 5 years, a Space Shuttle Flight Director for 40 missions, and is currently a consultant and full time grandpa. He is available for speaking engagements through Special Aerospace Services.
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18 Responses to Memory Overload

  1. Ray Gedaly says:

    Many mornings I awaken from a vivid dream with new ideas on how to solve some difficult technical problem at my work. Sometimes I’ve even worked out the solution in my sleep. Funny thing though … I retired several years ago.

  2. Charley McCue says:

    Sorry, the person with the solution went down the hall to write it down, had to find a pencil but found the bread instead thought a sandwich would be nice couldn’the find the ham…uh, what were we discussing?

  3. Charlie Barber says:

    Good! Its not just me!

    • Jeff DeTroye says:

      Wayne – your posts are always a pleasure to read and (sometimes unfortunately) so relevant to the challenges in my life.

  4. Beth says:

    I love this, Wayne! If only we could re-image our brains like we do our computers.

    But then, of course, all the memory would be wiped, and I for one wouldn’t want to loose it all.

    Add a pager to the car key ring…and page it when you can’t find it 🙂



  5. DerekL says:

    Yep… Understand completely. The Naval Undersea Warfare Museum has a MK88/1 FCS (Poseidon) console on display. Though I was required to study it, I never actually sat that console (I was MK88/2 and MK98/0, Trident). Nearly thirty years on, I walked up to the display and realized I still knew what practically every button did and every indicator meant.

    Though the chair would do my back no favors… Give me a day or two in a 88/2 or 98/0 trainer to refresh my muscle memory, and I could probably run a countdown again.

  6. Spacebrat1 says:

    gotta stay away from those negative semi-major axes

  7. Mike Rodriggs says:

    I’m surprised this was found in 2004 and not earlier. Or was this due to an update? What was the final resolution, do you remember?

    • waynehale says:

      From a mutual friend:

      Item 22 is the LOAD entry for the OMS burn targeting section (either PEG 4..closed loop burn guidance…or PEG 7…external delta V burn guidance). The note indicates the flight software issue was probably discovered during a (training) session in the SMS when someone inadvertently entered the wrong TIG (time of ignition) for a Peg 4 burn target. Even so, guidance converged (fell within a tolerance error value), allowing calculation of a nonsense orbit.

      More than likely, this was the equivalent of shooting a bullet through the eyehole of a needle, which is why it took 23 years for someone to make the right mistake and trigger it. Software testing always goes after the “credible” errors, which never matches all the things someone CAN do…and was why the SMS was always a great software testing environment, despite the community’s naysaying.

      My brain cells are mine, packed or empty, to use as I please and am able until I’m dead; after that, you can have them.

  8. Dan Adamo says:

    Thanks for the trip down SMS/FSW memory lane, Wayne. Yes, I suppose all that mental detritus is with me until senility hits. But let me qualify your parting wish. In the context of FSW DR 121227, a negative semi-major axis is undeniably bad. But if you want to depart a gravity well (like Earth’s to reach Mars or the Moon’s to return to Earth) in a reasonably short time interval, you MUST tolerate a negative semi-major axis on your hyperbolic departure trajectory.

  9. Hank Jarrett says:

    Lord I miss all this from my days supporting launches for NESC. Reading it was like listening to the pre-launch telecoms all over again.

  10. Thomas Moody says:

    Hah! Same problem, different business Wayne! After more than four years away, I just recently got back into Nuclear Power plant operations, scheduling shutdowns for refueling outages in California. And when presented with the shutdown/cooldown procedure, I immediately flinched, thinking “I’m probably going to need someone to answer questions because it’s been so long…” But after digging in and reacquainting myself with “Set the Cooldown Steam Dump controllers 2225-2227 to achieve less than a 100 f/hour cooldown rate” and “Throttle RHR Heat Exchanger outlet valve 606 and monitor bypass valve 610 to achieve a uniform cooldown” and “LTOP arms at 350 f”, I was completely back in the groove. You’re absolutely right…many arcane things just seem to stick to you!

  11. Dennis says:

    I think it is probably related to those of us with a “technical mind” working on something that is all consuming. After over 35 years as an aerospace engineer, I’m sure I could go right back into the middle of an old problem and it would all come back. I still use my HP 11C calculator and will be sorry when it finally dies. I recently pulled out my Curta mechanical calculator that I got in college around 1968 and it was like talking to an old friend. I cranked (literally) through a few calculations and it was just like when it and my slide rule were still in use.

  12. Jeff Heitzman says:

    My semi-major (and semi-minor) axes will increase as positives to perpetuity. Here’s to hoping the same for human spaceflight.

  13. Dave H. says:

    I seem to have the opposite problem. When I review some of the many e- mails exchanged with Dr. Osheroff I find myself thinking “Did I write that?!”
    While I can still tell you how to calibrate a Hagan Ring Balance meter or how to neutralize the 6LQ6 finals in a vintage Swan 350, anymore I can see the faces but can’t put names to them.

  14. Neal, Valerie says:

    Wayne, I am happy to say that I have no idea what that message means and do not have a clue what the acronyms stand for, except GPC General Purpose Computer. I think SMS might be Shuttle Mission Simulator? Anyway, my mind is full of Smithsonian acronyms and I share your experience of forgetting where and why I am where I am. It must be information overload, if not aging.

    Looking forward to seeing you in a couple of weeks. Valerie

    Dr. Valerie Neal, Curator and Chair * Space History Department * Smithsonian National Air and Space Museum * P.O. Box 37012, MRC 311 * Washington DC * 202-633-2422 * ________________________________

  15. Heh. Probably the fact is that all these acronyms and jargon terms were so important and had so many lives depending on them that they were burned into your memory under: “Critical, Do not lose!”

    Compared to this, understandably your brain has probably not felt the need to prioritise remembering your wife’s second cousin’s third child’s name.

  16. Chuck Dusold says:

    After reading this I went to my book shelf and picked up a document I rarely look at anymore. I received it when I started on the Space Station Freedom program with MacDac in 1988. It is 585 pages of acronyms, in what appears to be about 6 point font, their meanings and source (covering all MacDac programs at the time). It brought back fond memories of the acronym bees we had at the local watering hole occasionally after work. I hadn’t thought about that in a while, thanks.

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