Avionics News - September 2023 - 51

" L3HARRIS HAS SOPHISTICATED ENGINE CONTROLLERS ON
LUNAR LANDERS TO PROVIDE FUEL FLOW AND CONTROL ROCKET
THRUST. EVERY MISSION THAT IS MAN-RATED HAS A SET OF
QUALITY AND TEST REQUIREMENTS, WHICH ARE DESIGNED TO
KEEP THE ASTRONAUTS SAFE IN THE EVENT OF MALFUNCTIONS. "
MARK DAPORE
an engineering fellow and chief technologist at L3Harris
Photo courtesy of NASA
the challenges that space-qualified avionics must meet.
During launch, for example, if an explosion in the launch
vehicle is detected, the crew capsule is ejected off the
nose to save the lives of the astronauts as the launch
vehicle below them disintegrates. Avionics that can do
that automatically and reliably are special systems.
During weeks in space, avionics must be robust
enough to survive a single-event upset that occurs when
a heavy ion strikes a microelectronic device and causes
it to give an erroneous output. " So we test all of our
microelectronics to verify they are immune to these
upsets due to radiation and secondly, should a very low
probability upset occur, the fault tolerant system will
make sure the mission continues on, " Dapore said.
With quadruple redundancy, there is more fault
tolerance, and more malfunctions can occur, and the
system can still safely perform the mission. As with triple
inertial systems on commercial jets where an errant gyro
can be voted off the island, redundancy allows for voting
that refines the decision on which portion of the system
is defective. " If you only have a primary with a single
backup and they do not agree, it can be very difficult to
determine which one is good and which one is defective, "
Dapore said.
Today's advanced electronics have better self-test and
fault tolerance, and they are more reliable and lighter than
in the days of Apollo. Computers are orders of magnitude
more capable than those used in the Apollo program
spacecraft in terms of faster speeds and greater memory
capacity. The advances in computing make the spacecraft
much safer because issues and malfunctions are detected
sooner so corrective action can be taken to keep the
mission and the astronauts safe.
Space avionics are tested in the environments they
will experience in flight, including operation at freezing
cold temperatures, extremely hot temperatures and in the
vacuum of space.
During Artemis 1's launch, insertion into a trajectory
to the moon, passage around it, return to Earth orbit and
recovery all of L3Harris's avionics worked as expected.
" This doesn't mean NASA didn't learn some things that
they didn't expect, " Dapore said. " There were some
environmental aspects and the way the vehicle acted that
were a little different from what NASA expected. Our
avionics were able to measure the vehicle's performance
very accurately by digitizing sensor data and transmitting
it to mission control. Part of the whole mission was to
learn how does this vehicle fly, how does it perform, and
to gather as much data during the course of the flight as
possible so those performance items can be taken into
account once we get astronauts aboard. " The Artemis II
mission in late 2024 will have four astronauts aboard to
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Avionics News - September 2023

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