Spacecraft and
mission hardware designed by an artificial intelligence may resemble bones left
by some alien species, but they weigh less, tolerate higher structural loads,
and require a fraction of the time parts designed by humans take to develop.
“They look somewhat alien and weird,”
Research Engineer Ryan McClelland said, “but once you see them in function, it
really makes sense.”
McClelland pioneered the design of
specialized, one-off parts using commercially available AI software at NASA’s
Goddard Space Flight Center in Greenbelt, Maryland, through a process he has
dubbed evolved design.
To create these parts, a computer-assisted
design (CAD) specialist starts with the mission’s requirements and draws in the
surfaces where the part connects to the instrument or spacecraft – as well any
bolts and fittings for electronics and other hardware. The designer might also
need to block out a path so that the algorithm doesn’t block a laser beam or
optical sensor. Finally, more complex builds might require spaces for
technicians’ hands to maneuver for assembly and alignment.
Once all off-limits areas are defined, the AI connects the dots, McClelland said, producing complex structure designs in as little as an hour or two. “The algorithms do need a human eye,” he said. “Human intuition knows what looks right, but left to itself, the algorithm can sometimes make structures too thin."
Ryan McClelland displays a structural mount made of 3D-printed titanium. Credits: Henry Dennis
These evolved parts save up to two-thirds of the weight compared to traditionally designed components, he said, and can be milled by commercial vendors. “You can perform the design, analysis and fabrication of a prototype part, and have it in hand in as little as one week,” McClelland said. “It can be radically fast compared with how we’re used to working.”
Parts are also analyzed using
NASA-standard validation software and processes to identify potential points of
failure, McClelland said. “We found it actually lowers risk. After these stress
analyses, we find the parts designed by the algorithm don’t have the stress
concentrations that you have with human designs. The stress factors are almost
ten times lower than parts designed by an expert human designer.”
McClelland’s evolved components have been
adopted by NASA missions in different stages of design and construction,
including astrophysics balloon observatories, Earth-atmosphere scanners,
planetary instruments, space weather monitors, space telescopes, and even the
Mars Sample Return mission.
Goddard physicist Peter Nagler turned to
evolved design to help develop the EXoplanet Climate Infrared TElescope
(EXCITE) mission, a balloon-borne telescope designed to study hot Jupiter-type
exoplanets orbiting other stars. Currently under construction and testing,
EXCITE plans to use a near-infrared spectrograph to perform continuous
observations of each planet's orbit about its host star.
Ryan McClelland designed a titanium scaffold for the back of the EXCITE telescope planned for a test flight as early as Fall of 2023. The curved, criss-crossed reinforcing structures were designed to resist significant off-centered forces, and titanium 3D printing (rear versions) enabled a more rigid, stable structure. Credits: Henry Dennis
“We have a couple of areas with very tricky design requirements,” Nagler
said. “There were combinations of specific interfaces and exacting load
specifications that were proving to be a challenge for our designers.”
McClelland designed a titanium scaffold for the back of the EXCITE
telescope, where the IR receiver housed inside an aluminum cryogenic chamber
connects to a carbon fiber plate supporting the primary mirror. “These
materials have very different thermal expansion properties,” Nagler said. “We
had to have an interface between them that won’t stress either material.”
A long-duration NASA Super-Pressure Balloon will loft the EXCITE mission’s
SUV-sized payload, with an engineering test flight planned as early as fall of
2023.
Ideal Design Solution for NASA’s Custom Parts
AI-assisted design is a growing industry, with everything from equipment
parts to entire car and motorcycle chassis being developed by computers.
The use case for NASA is particularly strong, McClelland said.
“If you’re a motorcycle or car company,” McClelland said, “there may be
only one chassis design that you’re going to produce, and then you’ll
manufacture a bunch of them. Here at NASA, we make thousands of bespoke parts
every year.”
3D printing with resins and metals will unlock the future of AI-assisted
design, he said, enabling larger components such as structural trusses, complex
systems that move or unfold, or advanced precision optics. “These techniques
could enable NASA and commercial partners to build larger components in orbit
that would not otherwise fit in a standard launch vehicle, they could even
facilitate construction on the Moon or Mars using materials found in those
locations.”
Merging AI, 3D printing or additive manufacturing, and in-situ resource
utilization will advance In-space Servicing, Assembly, and Manufacturing (ISAM)
capabilities. ISAM is a key priority for U.S. space infrastructure development
as defined by the White House Office of Science and Technology Policy’s ISAM National Strategy and ISAM Implementation
Plan.
This work is supported by the Center Innovation Fund in NASA's Space Technology Mission Directorate as well as Goddard’s
Internal Research and Development (IRAD) program.
Banner image: Defined by a human designer, and filled in by an
artificial intelligence program, this spacecraft component was milled from a
solid block of aluminum and features connections for instruments and openings
preserved for laser light paths and human hands to attach and adjust sensors. Credit:
Henry Dennis
By Karl B. Hille
NASA’s Goddard Space Flight Center in Greenbelt, Md.
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