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#11
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Operating systems used in spacecraft?
"Greg" wrote in
... Richard Kaiser wrote in message . .. I would try google on FlightLinux to see if its status is on the web. It may be hosts on sourceforge.org, look there too. If FlightLinux does fly it will probable be in an amature radio or university built satelite. I'm a big fan of open source etc. But even i would be very carful using it any of these applications. The problem is that too many people have writen the softwear. Some parts are writen very well, some are not. As you say, licence fees for these things are petty cash. It's not licence fee problems that makes people attracted by open source software. When using operating systems in particular you need to have access to the source code for debuging strange system behaviour. Anyone tried to do fault injection testing of fault tolerant computer without acess to the OS source code? It is a nightmare when the system dies, you don't know why and have no post mortem analysis possibilities. This fact for instance make the open source OS RTEMS a more suitable choice in space applications than for instance VxWorks (although I think Wind River has now realised the hard facts and makes the source available to licensees). Having access to the source code also simplifies additional testing on the product, something that definitely improves the quality of the final system. This begs the question-- perhaps a little OT. How is flight softwear, flight tested? In-flight testing is not the best criteria to "qualify" a product (look at for instance the first Ariane5 failure where a "flight-proven" software from Ariane4 was reused in a new application without proper system testing). Instead adequate design rules combined with carful testing both at module, software product and integrated system level guaratees a much more reliable function than showing that your software has flown once or twice. -- someguy |
#12
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Operating systems used in spacecraft?
And this is different from closed-source software... how, exactly?
I assumed that any FAA approved OS would have to document every line of code? Much like all FAA approved hardware. Otherwise my experience has been very good for some open source products (linux kernel ie without X11). Better support, easy to find out absolute limits etc While we have most commercial software will claim a lot more than they can deliver. greg |
#13
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Operating systems used in spacecraft?
Kevin Willoughby wrote in message ...
In article , gewi001 @phy.auckland.ac.nz says... This begs the question-- perhaps a little OT. How is flight [software], flight tested? Very carefully.... :-) In ordinary commercial software, the standard estimate is that a software product spends half of its budget during the testing phase. Apollo and Shuttle flight software spends 90% of its budget on quality assurance. Only half? Most projects i work on its a lot higher. I guess you could call it scope creep. But really it all still comes down to total cost of ownership. |
#14
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Operating systems used in spacecraft?
Henry Spencer wrote:
There are two possible answers. [Blink] 3) Redundant CPUs, one of which is running a different operating system, so if the other two get frotzed by Yet Another Windows Exploit in deep space, the Penguin can Save The Day. Or the Mac, as the case may be. There are always more possible answers. Aloha mai Nai`a. -- "Please have your Internet License http://kapu.net/~mjwise/ and Usenet Registration handy..." |
#15
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Operating systems used in spacecraft?
Grem wrote:
Which operating system/systems are used in spacecrafts? Has FlightLinux been implemented yet; and if not how far in the testing are they? Any information on these topics would be greatly appreciated. ... well, there is many open source aplication/systems in space, for example SSTL use RTEMS in his satellites. Flightlinux project was finished, but try to look at: ipinspace.gsfc.nasa.gov. there are also rumours about ST-7 (some technology from flight linux will be used). European use open source in Galileo Project (small costs) too. Sorry for my english. Some interesting pages: http://www.rocketforge.org/ or http://www.polsek.org.pl/ (polish only/english version in progress) Regards Adam Przybyla |
#16
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Operating systems used in spacecraft?
In article ,
Michael J Wise wrote: There are two possible answers. 3) Redundant CPUs, one of which is running a different operating system, so if the other two get frotzed by Yet Another Windows Exploit in deep space, the Penguin can Save The Day. Or the Mac, as the case may be. Only if the Windows machine(s) haven't already fired the pyros, left the gas valves open, pointed the camera at the Sun, etc. (Clementine's R3081 running C and VxWorks couldn't save the spacecraft when the antique 1750, that NRL had insisted on putting in, went berserk due to a software bug and left the thrusters on.) Yes, you can put in safeguards against such things... but if there is no way for a software malfunction to wreck the mission, then you don't *need* the extra computer at all -- you can rely on doing a reload from the ground if things go wrong. So in essence you're back to my answer #1, running the new experimental stuff as a secondary payload that is not crucial to mission success. -- MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer pointing, 10 Sept; first science, early Oct; all well. | |
#17
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Operating systems used in spacecraft?
"someguy" wrote:
It's not licence fee problems that makes people attracted by open source software. When using operating systems in particular you need to have access to the source code for debuging strange system behaviour. While that may be indeed what attracts some to Open Source, I suspect politics accounts for most of the interest in it. D. -- The STS-107 Columbia Loss FAQ can be found at the following URLs: Text-Only Version: http://www.io.com/~o_m/columbia_loss_faq.html Enhanced HTML Version: http://www.io.com/~o_m/columbia_loss_faq_x.html Corrections, comments, and additions should be e-mailed to , as well as posted to sci.space.history and sci.space.shuttle for discussion. |
#18
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Operating systems used in spacecraft?
Michael J Wise wrote:
Henry Spencer wrote: There are two possible answers. [Blink] 3) Redundant CPUs, one of which is running a different operating system, so if the other two get frotzed by Yet Another Windows Exploit in deep space, the Penguin can Save The Day. Or the Mac, as the case may be. You obviously have no idea how complex and difficult such a thing would be in practice. It's hard enough doing realtime control with one software / hardware system, it would be much more than twice as difficult with two different systems that had to mesh together and somehow magically share control and hand-off or assume control between each other when the other doesn't work right. "Nightmare" seems like a good enough first approximation for the problem, though it is not remotely sufficiently pungent a description to get across how difficult it would actually be. The Space Shuttle uses different control systems which back each other up but the software is very, very closely related to each other (the backup is a stripped down version of the original) and it all runs on the same hardware. |
#19
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Operating systems used in spacecraft?
You obviously have no idea how complex and difficult such a thing
would be in practice. It's hard enough doing realtime control with one software / hardware system, it would be much more than twice as difficult with two different systems that had to mesh together and somehow magically share control and hand-off or assume control between each other when the other doesn't work right. "Nightmare" seems like a good enough first approximation for the problem, though it is not remotely sufficiently pungent a description to get across how difficult it would actually be. ...yet all fliy-by-wire aircraft, and especially those from Airbus, do it every day. The Space Shuttle uses different control systems which back each other up but the software is very, very closely related to each other (the backup is a stripped down version of the original) and it all runs on the same hardware. That is not the case - the BFS is completely indepedant, in software development, tools and history - from PASS. Same hardware, though - and manual switchover. Jan |
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