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Computer Date Glitch May Limit Next Shuttle Launch
n3hat writes "Reuters reports that the next Space Shuttle mission may have to be deferred if it gets too close to the New Year because the onboard computers do not handle the changing of the date in the same way as the ground computers. From the article: '"The shuttle computers were never envisioned to fly through a year-end changeover," space shuttle program manager Wayne Hale told a briefing. The problem, according to Hale, is that the shuttle's computers do not reset to day one, as ground-based systems that support shuttle navigation do. Instead, after December 31, the 365th day of the year, shuttle computers figure January 1 is just day 366."
If they ran their shuttles on something like Debian stable it would be a rock solid platform and probably end up saving them lots of money. Or am I missing something here.
Yes, you are. Primarily the fact that Debian Stable isn't even Carrier Grade, and certainly not qualified for life support. Ie, "doesn't crash in the midst of re-entry."
Keep in mind that the shuttle computers are highly redundant (I believe there are three main computers, and three backups of each component?), monitor a HUGE number of sensors, control a large number of servos and other systems, do telemetry, etc.
Please help metamoderate.
Actually a lot of data is from that date. Navigation and other systems probably rely on the date being correct to give an accurate reading or reliable function.
You mad
The article is sparse on details, but it sounds more like a problem where the date on the shuttles computer does not match the date on the ground system's computer. That can be a problem.
Today's Sesame Street was brought to you by the number e.
Granted, the work they do is very impressive and the process is very exacting. But come on...they haven't been able to fix a simple year rollover event in 30 years?!?
From the Fast Company article:
I would say that requiring a reboot every year on December 31 is a pretty huge error. In this case, it is forcing NASA to launch earlier than they otherwise would wish. And this isn't the first time this type of problem has caused problems. The New Scientist has a similar article that goes into more detail:
The end-of-year rollover depends on the leap year and leap second (if any), and has traditionally been a source of problems.
Mea navis aericumbens anguillis abundat
That might work if the shuttle computers ran C. They run HALS. Also, in how many places does this code fragment need to be installed? How does the timing of the loop affect the rest of the code? Remember, the shuttle has multiple computers. If the timing is too different between them, they can shut down the mission.
It would be far safer to just delay the launch a few days.
When our name is on the back of your car, we're behind you all the way!
Perhaps the fact that the shuttle was being developed at the same time as ADA might have something to do with it. Or do you recommend using a not even fully designed, coded, and tested language for controlling the most complex piece of equipment that man has ever built?
I prefer the "u" in honour as it seems to be missing these days.
http://www.fastcompany.com/magazine/06/writestuff. html is a really good read on how the shuttle software is actually made. It's the most reliable software in the world with the most exacting design process.
How many other groups can deliver a half million lines of code with only 1 error (and no, not this issue. And as far as this being an error or bug, it really isn't. It's a know design restriction on a system that just works. Do you really want to go redesign a large chunk and possibly introduce life threatening bugs, or work within the known design window for the system.
"I want the cowboy astronauts back. The boys that few Apollo 13 and duct-taped their space craft together and rode it home."
Or maybe not. The Apollo Guidance Computer software had at least one serious issue in flight: the early versions allowed you to run the launch setup program in space and that would reinitialise the Inertial Measurement Unit so it forgot where you were. I believe someone did that by mistake on Apollo 8, fortunately NASA were able to send them the data to load into the computer to tell it where they were and the mission continued without a problem. Later versions had a 'we're in space, don't run program 01' flag to ensure it didn't happen again.
Actually, the estimated failure rate for the shuttle program was 1 in 35, though the shuttles themselves may have been designed to withstand 100 launch/landing cycles*. This was a bit of an issue when the 25th mission resulted in a failure (since most of the population does not understand statistics).
And, for the record, there have been 117 launches, according to wiki, which I will take as accurate enough for this discussion (far less than 200).
*yes, IWAAE (I was an aerospace engineer) working for NASA, and was involved with shuttle payloads and structural reliability analyses.
Is it just my observation, or are there way too many stupid people in the world?
Hundreds of comments and not a single one mentions that NASA is a CMMI Level 5 organization. For those that don't know (and apparently, that's a lot of you), CMMI, aka Capability Maturity Model Integration, is software ENGINEERING methodology for developing processes and technologies around IT systems. It is a very in-depth methodology for developing software and comes about as close to "engineering" as you can get in software development.
Here is a list of participants in this program.
And here is a general overview of what CMMI is.
And just to put it into perspective, when I was last working with CMMI, there were only 3 companies certfied at level 5. Nasa, Motorola, and another one I can't remember. I am sure that has changed but nonetheless, it's a big deal and shows a serious effort to do things in a controlled, measureable, testable, way.
I only bring this up to counter the ridiculous "solutions" that some have proposed on this site.
"I can fix that in 3 lines of code".
Well, great. That might work at YOUR company. But please don't do that at NASA. Despite what many think here, NASA is a top-notch software development house. And I would expect nothing less given what is at stake.