Military Embedded Systems Spring 2005 Volume 1 Number 1

Hardware
MILITARY EMBEDDED SYSTEMS Resource Guide
Space-ready, radiationtolerant
processor modules:
A COTS technology strategy
By Anthony Lai
The processing power available from today’s off-the-shelf
embedded technology and boards far exceeds that available
only two years ago. However, in space-based applications,
technology that is five and ten years old is commonplace. The
requirement to survive the rough trip into space, and the incessant
radiation of in-space service has often necessitated using
older and lower-performing radiation-tolerant electronics.
But that’s begun to change. COTS modules loaded with leadingedge
components are finding their way into orbit and deep space
missions. Radiation-tolerant processors are now available, and
board-level design techniques such as redundancy and voting
logic can be utilized to bring desktop performance to space applications.
A careful design strategy – tailored to the end application
– can yield high performance in high-radiation systems.
Now that President Bush’s space exploration vision is receiving
initial funding, NASA is gearing up to realize the Administration’s
mandate to explore Mars and beyond. NASA is preparing a host
of options and plans, the likes of which the space industry has
not seen since the Apollo program. As before, technology will be
the cornerstone and the space community is in search of a nextgeneration
processor module that can meet the immediate and
future demand of the country’s return to space.
Furthermore, design engineers want processing power and I/O flexibility
that meets or exceeds what is available on their desktop, and
capabilities that are at least on par with contemporary benign environment
embedded processor modules. And with the requirement
for maximum technology reuse across multiple systems in satellites
and space vehicles – from the avionics suite to payload packages
– settling on a processor module that meets multiple system
requirements simplifies the overall design task and maximizes the
investment against the harsh nuclear and particle effects of space.
The good news is that unlike the Apollo program, where
proprietary processors and subsystems were designed from
scratch, modern Commercial Off-the-Shelf (COTS) technology
can meet NASA’s space demands. However, this is only true as
long as appropriate design attention is paid to mitigate the space
environmental effects of Total Ionizing Dose (TID), Single Event
Effects (SEEs), and induced data errors.
Basic requirements
Any new processor design must target the needs of affordable, yet
high-performance open-architecture avionics to field in Low-Earth
Orbits (LEO), Mid-Earth Orbits (MEO), Geosynchronous Orbits
(GEO), and deep space missions. An open architecture enables
modularity and flexibility in a system of systems design. With
NASA planning to launch human exploration missions to planets
such as the moon and Mars, a launch vehicle developed under the
Evolved Expendable Launch Vehicle (EELV) program will provide
a larger payload capability to succeed in these missions.
The survival and operational environment experienced by space
electronics will also become much more severe as the EELVs
penetrate deeper into space and rely on nuclear power to operate
electronics. Furthermore, the aerospace industry is hard-pressed
to provide more onboard processing and data storage capabilities
for high bandwidth real-time data from various types of advanced
remote sensors. Some general space-requirements for an openstandard
processor module are shown in Table 1.
Typical mission-critical space system applications that require a
next-generation processing element include:
■ Mission computer with redundancy
■ Flight guidance and navigation computer
■ Solid state recorder
■ Health monitoring computer
■ Robotic manipulator controller
General Requirement
Performance
Open architecture
Low- and Mid-Earth Orbits,
Geosynchronous Orbits,
deep space, and the
terrestrial environment of
moons and other planets
Nuclear-powered
vehicles
Multisystem use/reuse
Traveling in space requires
a launch and a re-entry
with possible intermediate
docking in space
Comment
Processor module needs
unparalleled processing power
to handle complex tasks for
challenging missions.
Allows multiple vendors, standard
interface electronics, modular I/O,
longer life cycle.
Processor module must
evolve to offer various levels of
radiation hardness to survive and
operate missions in many space
environments.
Deep space applications and habitats
in other planets may not rely on
solar/battery power; instead, an
onboard nuclear unit supplies power.
Electronics must withstand close
proximity to the nuclear unit.
Processor module must be useable
in multiple roles on the vehicle:
from avionics to payload to general
housekeeping (such as mass
storage). Also, specialty applications
such as a robotic arm should benefit
from the same processor module.
Processor module must be able
to survive and operate through
the severe launch and re-entry
environments for multiple planets.
Table 1
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