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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.