Environmental
There are three mechanisms of degradation on EEE
components from ionizing radiation: total ionizing dose
(TID), displacement damage (DD) and single event
effects (SEEs).
The effects of SEE range from being a nuisance to
non-critical equipment to destroying critical hardware.
The scope of work to make electronics more resilient to
radiation is increasing for forthcoming missions to the
Moon and beyond, because the
environment is harsher in space outside
Earth’s magnetosphere.
Pesce says, “Contrary to TID and DD,
with SEEs a single ionized particle is
capable of depositing enough charge in
the device that can alter its operation
temporarily or permanently. It can occur
from the first second in-orbit and
throughout the mission duration.
“Total ionizing dose and displacement
damage are cumulative effects. TID
generates from electron-hole pairs
generated in the semiconductor oxides,
while for DD the cause is due to energetic
particles causing displacement of atoms
in the component’s material lattice.”
BIOLOGICAL EFFECTS
The longer a component is exposed to
radiation the more it degrades until
failure. Mitigate measures are put in
place by engineers, unless a component is
able to function correctly for the entire
duration of the mission.
Radiation shielding requirements thus
1 // Researchers perform
checks on equipment
before a proton radiation
test at the Paul Scherrer
Institute in Switzerland
2 // The use of commercial
off the shelf electronics in
applications such as small
satellites is increasing the
requirement for radiation
testing facilities
3 // The Berkeley
Accelerator Space Effects
facility provides beams of
protons, heavy ions and
other particles to simulate
the space environment
4 // The control room for
the 88-inch Cyclotron at
Lawrence Berkley National
Laboratory in California
where NASA conducts
radiation testing
depend upon the mission environment
and duration. Spacecraft for human space
flight also present another set of considerations. NASA
has been concerned about the negative effects of radiation
on spacecraft and astronauts for many years. Razvan
Gaza, ionizing radiation lead, Lockheed Martin says, “The
biological effects of ionizing radiation exposure constitute
the limiting factor in terms of mission duration. It is
unfeasible to deploy radiation mitigation strategies used
on satellites for human space vehicles.
“A single ionized
particle is capable of
depositing enough
charge in the device to
alter its operation
permanently”
66 MARCH 2020 \\ AEROSPACETESTINGINTERNATIONAL.COM
1
2
/AEROSPACETESTINGINTERNATIONAL.COM