Open-Source Software and Its Role in Space Exploration
A software developer from JPL explains the reasons that NASA has embraced free and open source software in its application development process. Because, in a Mars launch, the term "mission critical" has a literal meaning.
The only way for the public to participate in seeing fresh images in near-real time is through an open architectures for public outreach.
FOSS develops the next-generation cutting-edge technology. Why can we put a man on the moon, but we still don't have robot cars? Some key challenges are:
- Robots have different physical characteristics.
- Robots have different hardware architectures.
- Contributions made by multiple institutions.
- Advanced research requires a flexible framework.
- Software must support various platforms.
- Lack of common low-cost robotic platforms.
- Software must be unrestricted and accessible (ITAR and IP).
- Software must integrate legacy code bases.
The Coupled Layer Architecture for Robotic Autonomy (CLARAty) project brings together folks from many institutions. They develop unified and reusable software that provides robotic functionality and simplifies the integration of new technologies on robotic platforms. (They also have some funky movies of robots doing funny things.)
Ubiquitous FOSS
Our dirty little secret is that space agencies are companies just like everybody else. We too (am I shocking you?) use e-mail, Web servers, and all the usual non-space-qualified suspects. Here are some examples:
- Operating Systems, Systems Management: Rocks (cluster Linux), Ganglia, amanda
- Software Management: Depot, Subversion, Trac, Bugzilla
- Communications: OpenSSH, Apache, Jabber, Firefox/Mozilla, Sendmail, Mailman, Procmail, CUPS, OpenOffice, wikis (various)
- Data Visualization: ImageMagick, GMT, MatPlotLib
- Compilers, languages, code checkers: SunStudio, splint, Doxygen, valgrind, Java, Perl (some JPL history there), Python, Ruby
- Databases: MySQL
The Open Advantage
OK, so given that our cultures are similar, how does that translate into our bottom line? Why does FOSS have such a large role in space exploration? Here's the top-10 list of what I see.
1. Schedule Margin
Planets move; launch windows don't. The Spirit and Opportunity Mars Rovers had to go in the summer of 2003 or never. They are simply too massive to throw that far, for that budget, unless the planets aligned just so. (Mars and Earth line up every 26 months or so, but in 2003 they were unusually close together.) Procurement cycles for spending lots of government money can be months long, and they can dominate critical paths.
Quickly obtainable FOSS relieves that pressure and gives us some elbow room. Bug fix turnaround times can be critical. If we can fix the source code ourselves, we can keep a whole team moving forward. If the fix is accepted by the open-source community, we avoid long-term maintenance costs and have it for the next project. Feature additions ("Gee, if it only did this, too...") have the same advantage but take longer to give back. Oddly, we can contract for new features but cannot easily give them away. The FOSS spirit hasn't yet pervaded government contracting rules.
