Orion wins big with software instrumental in executing its first flight test

On Dec. 5, 2014, Orion launched atop a Delta IV Heavy rocket for a four-hour-long two-orbit extended spin around Earth, testing many of the systems most critical to safety. One element that passed with flying colors and is now garnering extra attention is Orion’s Guidance, Navigation and Control (GN&C) software. This software is now officially award-winning, sharing the mantle of NASA’s 2015 Software of the Year (SOY) with Ames Research Center. (Ames is a co-winner with their NEQAIR v14.x, Nonequilibrium Radiative Transport and Spectra Program.)

As most people who witnessed the flight test know, it was a resounding success. What wasn’t seen, though, toiling in the background—was the GN&C software that helped make it happen.

“The GN&C software determines where a spacecraft is, the navigation function; determines the flight path the spacecraft will follow, guidance; and determines which thrusters should be fired to follow the guidance commands,” said Tim Straube, Orion Flight Dynamics System manager. “In other words, the software is 100 percent responsible for flying the spacecraft when it is not attached to the launch vehicle or upper stage.”

The software functioned flawlessly throughout Exploration Flight Test-1, without any ground commands, and landed the crew module within a half mile of the intended landing site in the Pacific Ocean.

The software was developed through a joint effort with two teams: the Orion GN&C team and the Orion Flight Software team.

“Both played critical roles in defining our process and executing the development,” Straube said.

Orion’s GN&C is unique. Government team members work with Lockheed Martin, the prime contractor, on badge-less co-led Multi-Organizational Development Engineering teams. This SOY award recognizes 82 engineers crucial in the maturation of the software, including members from JSC, both in Engineering and Flight Operations, Langley Research Center employees and eight other contractor companies.

The winning GN&C software exhibited innovation using a model-based design approach, which allowed for a lot of efficiencies.

“GN&C engineers implemented their algorithms as graphical models that a computer then auto coded into executable C++ flight code,” Straube said. “This allowed the GN&C team to directly implement the design without the need for a separate coding team, thereby eliminating errors during flight software development. Overall, the process speeds production and produces the flight software much earlier in development, allowing it to be tested more thoroughly.”

Though the process has been used before, it’s never been done to this scale — as in 28,000 lines of code — and for a NASA, human-rated mission.  

“We leveraged process elements from a number of sources, including the automotive industry, other aerospace programs and commercial tools from MathWorks, but had to invent and refine much of it ourselves to fit our unique mission and scope of the project,” Straube said.

The GN&C software also worked cohesively with Orion’s executive suite of software, flying the flight-test trajectory completely autonomously.

“We had to go from pre-launch, through ascent atop the launch vehicle, to orbital navigation … execute the separation from the upper stage, perform high-speed re-entry, and finally complete parachute sequencing to get to splashdown — without intervention,” Straube said.

Using software, NASA can build a virtual environment before flying it. Algorithms can be tested directly in a graphical world during development, allowing the team to develop tools and processes for continuous auto-code generation and testing for the evolving flight product.

Guiding a hypersonic, blunt body within a half mile of its parachute deployment target thanks to some pretty awesome software innovations? Yeah, we did it (and have the accolades to prove it).

Orion’s GN&C hopes to replicate its success on Orion’s Exploration Mission-1, a long-duration mission near the moon. Entirely plausible, because practice makes perfect. The beauty of this software is that it will allow the team to practice it over and over … and over again.

Catherine Ragin Williams

NASA Johnson Space Center