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       article-tgtimes-what-on-mars.mw (2278B)
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            1 .SH tgtimes
            2 What really happened on Mars?
            3 .2C 34v
            4 .
            5 .PP
            6 What can possibly go wrong while sending a device entirely controlled
            7 by software on a remote location where noone would ever be able to
            8 go for a long while? The question opens a vast field of answers.
            9 .
           10 .PP
           11 1997, Pathfinder, a solar-powered ground lander and station, with
           12 VxWorks proprietary real time operating system onboard, embedding
           13 an 6-wheeled Sojourner rover with custom firmware, landed on Mars.
           14 .
           15 .PP
           16 During a field data collection mission a priority inversion did
           17 happen on the Pathfinder station total loss of control for the time
           18 of a reboot.
           19 .
           20 .PP
           21 The bug was reproduced on earth and patched, latter explained on a
           22 mailing list, published online.
           23 .
           24 .FS
           25 https://www.cs.unc.edu/~anderson/teach/comp790/papers/mars_pathfinder_long_version.html
           26 .FE
           27 .
           28 .PP
           29 At its core, most operating systems are built around a scheduler
           30 that orchestrates execution of many tasks onto one or several CPUs.
           31 It is a critical piece of software in the case of real-time operating
           32 systems, that must ensure to trigger some actions right on time.
           33 .
           34 .PP
           35 Complex systems may be unfit for such purposes, and software
           36 simplicity has found its way through experimenting how complex
           37 systems may end-up in difficult-to-debug situations.
           38 .
           39 .PP
           40 Imagine yourself in charge of reproducing a bug on earth for
           41 something that went wrong on another planet, with a patch expected
           42 for next Monday. A strong argument toward keeping systems simple
           43 and easier to debug.
           44 .
           45 .PP
           46 Although, the Mars operating system landscape is not all VxWorks and
           47 nothing else. For instance, the RTEMS system, Real-Time Executive
           48 for Multiprocessor Systems was open-sourced from US army 1993 and is
           49 today actively maintained by both corporations and the open source
           50 community.
           51 .
           52 .PP
           53 Being part of Google Summer of Code, it is also welcoming newcomers
           54 to real-time operating system development, who might be able to
           55 contribute to embedded software making its way onto space.
           56 .
           57 .FS
           58 https://www.rtems.org/
           59 .FE
           60 .
           61 .PP
           62 While the ISS project was put at threat by the current events in
           63 Ukraine involving all nations, outter-space still represents a middle
           64 ground where all sides have a same objective and can collaborate:
           65 extending the horizons above what could be reached before.