By Courtney E. Howard
SAN DIEGO, 1 June 2009. "Reliability is extremely important," described Ray Crum, Orion program technical director at Honeywell Aerospace in Phoenix, Ariz. "We have to focus on that in component selection." Crum described at length the technologies inherent in Orion during his talk, "Integrating Commercial Electronics into the Crew Exploration Vehicle (Orion)," during the Military & Aerospace Electronics Forum today at the San Diego Convention Center.
Orion is the vehicle that is going to take the crew, up to four people, back to the moon, Crum explains. NASA officials want not only to get to all geographic areas of the moon, which drives the propulsion requirements, but also to stay on the surface up to four weeks. Then it will orbit autonomously. "It's an ambitious program to set up a sustained presence on the moon," Crum continues.
Lockheed Martin Corp. in Bethesda, Md., is the prime contractor on Orion.
The crew module houses the avionics, and it is reusable. "There are tight constraints on size, weight, and power (SWaP)," says Crum. "We have done a number of design cycles to minimize SWaP while meeting all the performance requirements of the program."
Key features of Orion avionics include: a modern cockpit, IPv4 external communication, time-triggered Gigabit Ethernet LAN, fault tolerance, a dissimilar backup system, and autonomous navigation, rendezvous, and docking.
"There's a lot of software on board to support autonomy," Crum says. "The vehicle has to operate a lot like an unmanned satellite. We also have to provide crew situational awareness and the ability for the crew to manually take control and do so safely."
Video is another key feature. "More video is being processed on Orion than any other spacecraft," Crum explains. Further, NASA would like to get high-definition video out to the world. It is a lot of video bandwidth that has to be collected and routed.
Orion is a long lifecycle vehicle; its lifetime may span 20 years. Flexibility is, therefore, key. "We want to enable the ability to grow and change the spacecraft through flexible avionics," describes Crum.
"We want to use the best parts possible in this vehicle—we are flying humans and it's a long lifecycle vehicle—so our desire is the use the highest-reliability parts possible," Crum explains. "Our first choice is high-reliability, rad-hard parts. Next, we look at military-grade parts because we like the ruggedization; but, one of the concerns is the radiation effects, so we have to test those." Then, Honeywell engineers look at COTS (commercial off-the-shelf) parts. It's not simply a process of picking a part out of a catalog and plugging it in, he says. "Characterization data is required before COTS parts selection.
"The bottom line is there are key performance requirements on Orion that drive COTS part usage."
