Commercial aircraft avionics leveraged for next-generation NASA spacecraft

Avionics for the follow-on to the space shuttle are based on systems used in commercial aircraft and adapted for space to help guide the pilots of NASA's next generation spacecraft – the Orion Crew Exploration Vehicle.

By John McHale

For nearly three decades the space shuttle carried NASA's astronauts to space and was the forefront of America's space program.

It is set to retire in 2010, still flying with some of its original 1970s technology – technology developed long before NASA and the U.S. military looked to buy commercial-off-the-shelf (COTS) technology wherever and whenever possible.

Following on the heels of the successful Apollo program, which landed astronauts on the moon, the space shuttle was well funded and could afford to design systems from the ground up.

The shuttle's successor, the Orion program, is modernizing spacecraft cockpit avionics. The new Orion Crew Exploration Vehicle (CEV) will have a technology roadmap that ensures the latest technology will have an upgrade path for the next 30 years.

Orion is part of NASA's Constellation Program, which has a goal is to send humans back into space in a cost effective manner, according to the NASA Constellation homepage.

"The technology going into Orion is amazing," says Rick Kasuda, Orion avionics and software director for Lockheed Martin Space Systems Co. in Littleton, Colo. This is the best technology astronauts have ever had in the cockpit and "quite different from what they had in the space shuttle," he adds.

"Orion is flexible," Kasuda says. It can dock with the International Space Station, bring crew to the lunar surface then autonomously orbit the moon, he continues. Eventually it will also fly crew to Mars and even visit an asteroid if need be, Kasuda adds.

The CEV will launch on the Ares I rocket and the Ares V cargo launch vehicle will serve as the heavy lift vehicle for NASA, Kasuda says. The space shuttle carried both crew and cargo.

NASA is still defining requirements for the Ares V spacecraft, Kasuda says.

Crew and cargo vehicles were separated for the safety of the astronauts, says Mitch Fletcher, chief systems engineer for human space business at Honeywell. Orion was designed with safety first, "after the shuttle program lost two spacecraft and 14 astronauts," he says.

Lockheed Martin is the prime for the Orion CEV and together with Honeywell in Glendale, Ariz., is designing the avionics for the spacecraft.

The first launch of the Orion CEV will be in 2015, to dock with the International Space Station, Fletcher says. However, these times may be negotiated as the program moves forward, he adds. NASA is also planning to add a second docking station to the International Space Station instead of designing a crew escape vehicle, Fletcher notes. "They find this solution more economical."

The space shuttle may also get a one or two year extension to "fill the gap" between now and 2015, says Dennis Donati, director of human space business for Honeywell.

The space business is quite robust, Donati says. "We are involved in the avionics suites of the space shuttle, International Space Station, and the Orion CEV," he adds. "If you look at the total avionics for the Orion, the lion's share is Honeywell's."

"We will also be designing the avionics for the Lunar Lander and Lunar Base Surface System," Fletcher says.


Using existing, proven technology

As a systems integrator Lockheed Martin tries to subcontract out as much as possible, Kasuda says. We liked the Honeywell approach of using their existing technology and adapting it for space."

The Orion spacecraft drives the packaging of that technology through its unique requirements, he adds.

We looked throughout our organization for current technology that could be reused and repackaged for space, Donati says. "However, I prefer the term non-specific design technology to COTS (commercial-off-the-shelf)," because it more accurately defines how Honeywell designed the avionics for the spacecraft.

"It is a low risk approach and NASA liked it," he adds. It helps keep pace with standards and technology and "NASA does onto have to flip the bill."

NASA's requirements are always unique, but using proven avionics systems helps mitigate risk, Donati says.

Honeywell has avionics technology in Boeing 777 and 787 jets as well as the Embraer business jets, Fletcher says.

Specifically Honeywell engineers looked at the avionics used in the Embraer jets and how they stayed cost competitive while maintaining top-level performance, Fletcher continues. For their high-integrity flight computers they used one third the hardware at one third the cost by putting all the capability into one box instead of using multiple boards and components from multiple third party vendors, he explains.

Honeywell developed their computers in house and on the Orion are designing the "primary and secondary high-integrity flight computers," Fletcher says.

The Honeywell computers use a PowerPC 750 processor based on silicon on insulator (SOI) process, Fletcher says. The SOI material is inherently radiation tolerant, he adds.

There is a third computer that is used is a backup and produced by Lockheed Martin, he says. It will have a separate design separate manufacturer so that if something goes wrong with the first two that is related to their design, it will not affect the third since it is a different make and model, Fletcher explains.

If both boxes fail the third computer will enable the astronauts to use it to restart the mission or fly home, Kasuda says. The back up flight computer contract has yet to be awarded, he adds.

CEV designers are also developing "a prototype network router card that is Internet Protocol-based, giving the CEV its own local area network," Kasuda says.

Honeywell also looked to its commercial aircraft avionics and space shuttle experience for the Orion CEV's cockpit displays.

They will have a glass cockpit with very few switches and be able to see everything through the glass display, Kasuda says. Information provided by gauges and dials are now accessed through the display, he adds.

It has the newest glass that goes in the Boeing 777 cockpits, and is twice the size of the Multifunction Electronic Display Subsystem (MEDS), which was the display upgrade for the space shuttle, Fletcher says. The Orion CEV's three displays are 8 inches by 10 inches or the size of a sheet of paper, he explains.

In contrast the MEDS displays were only 5 inches by 7 inches, Fletcher adds.

The MEDS upgrade swapped out the old shuttle cockpit's mechanical and analog instruments and cathode-ray-tube displays and replaced them with software-driven multifunction liquid-crystal displays (LCDs). Nine displays made up the MEDS upgrade, while only three will be used in Orion, Fletcher notes.

The new display system will bring state of the art situational awareness to the astronauts, Donati says. It has excellent brightness and clarity, which is typically what the astronauts care most about, he adds.

"However, sometimes you can bring 150 astronauts together for a review and get 150 different answers," Donati notes.

Honeywell is also looking at ways make this display capability portable for use in the astronauts' space suits, Fletcher says.

"Other aspects are still being worked out and defined by NASA as we go along in this process, Donati says. The displays may have other unique features based on future mission requirements, he adds.


Guidance and navigation

Lockheed Martin is also providing the guidance and navigation instruments to the Orion CEV, Kasuda says. They awarded Ball Aerospace in Boulder, Colo., a contract to provide the boxes for the Star tracker, visual navigation sensor, and docking camera, Kasuda says.

"The star tracker triangulates the position of the stars to measure absolute attitude," Kasuda says.

The visual navigation sensor uses flash lidar (light detection and ranging) to guide the spacecraft into dock on the International Space Station, he says. The docking camera provides the crew with a visual of the process, Kasuda adds.

Lockheed Martin is also designing a phased array antenna for the communications system, Kasuda notes.

Obsolescence

The high performance commercial electronics bring many benefits but also create major headaches for designers who need to manage their inevitable obsolescence.

"Obsolescence is a huge challenge for us," Kasuda says. "We are looking at spacecraft that will last 30 years with products that become obsolete in five years."

It is "the biggest problem we face" with the new technology, concurs Fletcher. Life cycles can last only 18 months, which is much shorter than NASA design cycles, he adds.

Fletcher notes that the original Honeywell avionics and other components for the space shuttle "were quite robust as well so there are still tons of spares available." Fletcher worked on the original shuttle program back in the 1970s. There are less than a handful of those experts still on the job, he says.

Today it is about implementing open architectures and remaining cost competitive, Fletcher continues. "Technology wise we implemented an open system based on standards for the computers and the software," he adds.

Each can be upgraded without changing the other pieces, he says. "In other words each module of the system is independent and abstract from the others."

It is a similar concept to secure portioned operating systems, Fletcher says. They separate applications so that if one is adversely affected it doesn't affect the rest of the operating system, he explains.

Lockheed Martin manages the life cycle by buying parts block by block, Kasuda says. We have blocks for each schedule such as schedule A (design), schedule B (production run), a Lunar block, and so on, he continues.

We set the estimated number of parts needed for each block, Kasuda says.

When one goes obsolete, a new one is integrated, Kasuda says. It should not affect the rest of the system as it is open architecture process, but in a rare case a significant part of the system could be redesigned to handle a life cycle problem, he says.

"Most of our boxes have plug and play capability, so that scenario is unlikely," Kasuda says.

"When we go through the selection process we make sure the supplier will still be around in 20 years," he says. "The open architecture should help with most bumps in the road."


Radiation, shock, and vibration

The displays and computers are high-performance, but still need to be modified to meet the harsh environment of space.

Making electronics radiation resistant for space is traditionally a labor-intensive, multi-year process, but that is cost-prohibitive in today's funding environment, Kasuda says.

Microprocessor cores have helped shrink the design time because they can be bought and put on a custom ASIC (application specific integrated circuit), Fletcher says. The process now is at about two years, he adds.

In the old days of the shuttle program, electronics had to be completely resistant to radiation, now they need to be more radiation tolerant than radiation-hardened, Fletcher says.

We search for parts that have inherent radiation tolerance, then upscreen them for space, Kasuda says. "Upscreening dramatically cuts back on design time," he adds.

It is a more practical approach, Kasuda continues. When you build a satellite and put it into space it has to last 10 years. "We only have to stay in space for consecutive days, not consecutive years."

Radiation-tolerant parts will do the job, he adds.

Electronics in space suffer more severely from shock and vibration than radiation, Kasuda says. It is the G force from the vibration of the rocket motor and its acoustics, he adds.

On an aircraft they only have to withstand 2 Gs, but on a spacecraft its 17 Gs, Fletcher says.

The CEV's launch abort system alone generates five seconds of thrust, which violently shakes the electronics, Kasuda continues. The system is designed to lift the crew module away from the launch vehicle to save the crew in case of an emergency, he adds.

It was based on a similar system for the Apollo program, Kasuda notes.

According to a Lockheed Martin release the abort motor "utilizes a composite case, and exhaust turn-flow technology rather than a tower, which results in weight savings, improved performance and improved success in crew survival during an abort. Instead of the rocket plume exiting straight out a nozzle at the aft end, the manifold is placed at the forward end of the motor. The rocket thrust enters the manifold and is turned 155 degrees exiting out the four nozzles, creating a forward-pulling force."

Alliant Techsystems (ATK) in Promontory, Utah, designed the launch motor under a contract to Orbital Sciences Corp in Dulles, Va. Alliant officials performed the first test of the motor in November. It was the first test of such a system since the Apollo program performed its test of a launch abort system in the 1960s.

Orbital is responsible for integrating the LAS motor for Lockheed Martin. The Orion Launch Abort System (LAS) program is managed out of NASA's Langley Research Center in Hampton, Va.


SIDEBAR

Software most expensive factor in avionics

"It is really software and the maintenance of software that drives the cost of avionics," says Mitch Fletcher, chief systems engineer for human space business at Honeywell.

The goal is to reuse as much software as possible to make it easier to certify for NASA and to cut down on the development costs of writing new code, he continues.

For the real-time operating system (RTOS), the Orion Crew Exploration Vehicle (CEV) avionics will use ARINC-653 system from Green Hills Software in Santa Barbara, Calif., Fletcher says. The Green Hills avionics platform includes their Integrity and Integrity1-78B operating systems.

The RTOSs will be used in the CEV's "Flight Control Module (FCM), Spacecraft C3I Communication Adapter (SCCA), and Backup Emergency Controller," says Gary Shubert, Orion flight software manager for Lockheed Martin. "It was determined to be the most technically mature and offered a more economical commercial off-the-shelf solution."

The Green Hills toolset has support for the standard ARINC-653 application software interfaces, and the documentation and services required for U.S. FAA DO-178B Level A safety certification, according to a Green Hills release. Integrity's partitioning features allow developers to deploy multiple applications on a single processor, at multiple safety certification levels, which enables developers to reduce the number of on-board computers needed to support multiple software systems, Green Hills officials say.

According to the release, the solutions are also certified for multiple languages, including Ada, C, and Embedded C++. Integrity is also used for the avionics on the F-35 Joint Strike Fighter and flight controls for the Boeing 787 Dreamliner.

As long as you do not change the operating system you do not have to recertify," Fletcher says. Honeywell also has a middleware that has been re-used many times over the years, and it will have to be recertified for NASA, but because "we've done it before the process is much simpler," Fletcher says.

Other middleware vendors do not have that history and would require greater effort and expense toward certification, he adds.

In addition to what Honeywell is integrating, Hamilton Sundstrand in Windsor Locks, Conn., implemented the software for the electrical power subsystem and the environmental controls and life support system or ECLSS, says Rick Kasuda, Orion avionics and software director for Lockheed Martin.

Hamilton Sundstrand also will provide the CEV with the fire detection and suppression system, carbon monoxide removal/humidity control system, pressure control system, atmospheric monitoring system, cabin air ventilation, and potable/cooling water storage as well as perform as a systems integrator in the development of extra vehicular activity interface systems.

Aside from outsourcing, most software development "is something we do in-house integration wise," because the requirements are so unique, Kasuda says.


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