There's a difference between "flight control software" and "laptop." I've seen some missions where mission-specific software is running on laptops but there's nothing going on with the laptop where the safety of the shuttle is put in jeopardy when the laptop crashes. This whole same conversation came up weeks ago on a battlestar thread here. The military HAS been known to do things inexplicably stupid like run a destroyer on NT. A computer crash there disabled the ship's engines. However, this is known as the BAD way of doing things and any engineer will tell you it's a sign of political interference with the design process or just plain stupidity. That is NOT the way things are supposed to be done. Yeah, well.. I know that! But the original comment was:
On NASA's manned space equipment you will find no software that is not controlled by NASA without respect of whether the aforementioned software might have been operational, personal, experimental or entertainment oriented.
I know that the Shuttle's and ISS' avionics systems are essentially custom made systems. And man, they should be ! for one, they're basically operating on the fringe or outside the Van Alen belt, so cosmic/solar radiation is a concern, and then in some aspects they are operating in life & death situations.. For example, the shuttle being a fly by wire flying machine, the loss of all GPCs while running OPS-1 (during ascent) or OPS-3 (descent-reentry) is a no-no (during OPS-2 (orbit coast), it's not THAT critical)
The older AP-101 were core based memory system (which is less influenced by radiation hits than CMOS or BiPolar semiconductors), but memory CRCs are a must anyway (although this is something usually available on off the shelf "server" class systems anyway).
Yeah.. But the original comment was that "(...) all manned spacecraft equipment (...)". So yeah... I know, it was a point of detail (does/doesn't astronauts personal computers account as spacecraft equipment ?) !
Anyway.. Now.. I'm not criticizing the quality of NASA produced software.. I'm fairly sure it is extensively tested ! But claiming that it is "mathematically proved" that a program is bug free (or at least works as intended under all conditions) was going a bit too far.. Hence my comment about Rice's theorem !
PS : At the time when the Shuttle's GPCs were IBM S/360 derivatives (the AP-101), it seems more likely that the OS controlling module loading (OPS1, OPS2, OPS3, etc..) was a TOS/360 derivative.. But that changed in the mid '90s (AP-101s).. The article at http://spaceflight.nasa.gov/shuttle/reference/shut ref/orbiter/avionics/dps/gpc.html describes fairly extensively the system and the fact that they were '70 era computers, the use of the word IPL (for boot), the fact that modules are stored on tape, would seem to substantiate the TOS/360 theory.. It also seems the AP-101s architecture is backward compatible with the AP-101 !
Finally, again, it seems the computers on the Russian side are NOT Russian "made" computers, but european built machines (c.f. last night's press conf.). And the US computers didn't take over.. The only thing that is happening is that the Shuttle is taking over the ISS' propulsive attitude control should the CMGs (Control Moment Gyroscopes) overload.. (note that the CMG computers seem to be OK so far !).. I very much doubt the Shuttle GPCs are equipped to perform the tasks of the ISS bound computers (that control Propulsive attitude control, the Elektron, humidity scrubbers, etc..)
The problem, of course, is that once Atlantis undocks, should the LANEs not be fit, the ISS won't be able to do its necessary attitude changes following the shuttle's undocking and *THAT* is a major concern !
First about the "all software is NASA controlled" assertion.. Well.. While I was watching NASA TV, I caught a glimpse of one of the astronauts obviously attempting to retrieve some e-mail from his laptop.. And then complaining over the com that he was getting a "you can only have one instance of Outlook running" - ground control advised for a laptop reboot, but the guy upstairs wasn't too keen on doing that (apparently, to him, this meant it was a server problem !) - the capcom person at that time then seemed to be taking the diplomatic side and answered : "lemme check" !
Second, you claim that NASA mathematically prove software correctness.. However, it is a known fact that this is an impossible thing to do (Rice's theorem)..
The fact that these system have no OS is debatable ! They at least need some system oriented code to interface between the hardware and the software (call it OS, library, firmware, whatever !) - but it seems that even getting the thing to initialize is failing..
Last, everyone is talking about the 'russian' computers.. Well, this guy last night in the press conference did state these were actually "western style" *european* computers !
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I know that the Shuttle's and ISS' avionics systems are essentially custom made systems. And man, they should be ! for one, they're basically operating on the fringe or outside the Van Alen belt, so cosmic/solar radiation is a concern, and then in some aspects they are operating in life & death situations.. For example, the shuttle being a fly by wire flying machine, the loss of all GPCs while running OPS-1 (during ascent) or OPS-3 (descent-reentry) is a no-no (during OPS-2 (orbit coast), it's not THAT critical)
The older AP-101 were core based memory system (which is less influenced by radiation hits than CMOS or BiPolar semiconductors), but memory CRCs are a must anyway (although this is something usually available on off the shelf "server" class systems anyway).
--Ivan
Yeah.. But the original comment was that "(...) all manned spacecraft equipment (...)". So yeah... I know, it was a point of detail (does/doesn't astronauts personal computers account as spacecraft equipment ?) !
t ref/orbiter/avionics/dps/gpc.html describes fairly extensively the system and the fact that they were '70 era computers, the use of the word IPL (for boot), the fact that modules are stored on tape, would seem to substantiate the TOS/360 theory.. It also seems the AP-101s architecture is backward compatible with the AP-101 !
Anyway.. Now.. I'm not criticizing the quality of NASA produced software.. I'm fairly sure it is extensively tested ! But claiming that it is "mathematically proved" that a program is bug free (or at least works as intended under all conditions) was going a bit too far.. Hence my comment about Rice's theorem !
PS : At the time when the Shuttle's GPCs were IBM S/360 derivatives (the AP-101), it seems more likely that the OS controlling module loading (OPS1, OPS2, OPS3, etc..) was a TOS/360 derivative.. But that changed in the mid '90s (AP-101s).. The article at http://spaceflight.nasa.gov/shuttle/reference/shu
Finally, again, it seems the computers on the Russian side are NOT Russian "made" computers, but european built machines (c.f. last night's press conf.). And the US computers didn't take over.. The only thing that is happening is that the Shuttle is taking over the ISS' propulsive attitude control should the CMGs (Control Moment Gyroscopes) overload.. (note that the CMG computers seem to be OK so far !).. I very much doubt the Shuttle GPCs are equipped to perform the tasks of the ISS bound computers (that control Propulsive attitude control, the Elektron, humidity scrubbers, etc..)
The problem, of course, is that once Atlantis undocks, should the LANEs not be fit, the ISS won't be able to do its necessary attitude changes following the shuttle's undocking and *THAT* is a major concern !
--Ivan
Wait a Minit !
First about the "all software is NASA controlled" assertion.. Well.. While I was watching NASA TV, I caught a glimpse of one of the astronauts obviously attempting to retrieve some e-mail from his laptop.. And then complaining over the com that he was getting a "you can only have one instance of Outlook running" - ground control advised for a laptop reboot, but the guy upstairs wasn't too keen on doing that (apparently, to him, this meant it was a server problem !) - the capcom person at that time then seemed to be taking the diplomatic side and answered : "lemme check" !
Second, you claim that NASA mathematically prove software correctness.. However, it is a known fact that this is an impossible thing to do (Rice's theorem)..
The fact that these system have no OS is debatable ! They at least need some system oriented code to interface between the hardware and the software (call it OS, library, firmware, whatever !) - but it seems that even getting the thing to initialize is failing..
Last, everyone is talking about the 'russian' computers.. Well, this guy last night in the press conference did state these were actually "western style" *european* computers !
--Ivan