Bringing Generative Designs To Life

Sending a rover to Mars to collect rock, soil and atmosphere samples is challenging enough. Retrieving the samples and bringing them back to Earth has never been done.

To retrieve samples collected by the Perseverance rover and transport them to Earth for analysis, NASA and the European Space Agency jointly developed the Mars Sample Return mission. The robotic systems and Mars ascent rocket needed to complete the mission include multiple subsystems, and Newton LLC was tasked with delivering the capture lid mechanism (CLM), a subsystem of the capture containment and rendezvous system, said Alex Miller, mechanical engineer and deputy engineering lead for the Riverdale, Maryland, provider of “mission-critical components that advance science, exploration and humanity.”

For one component, the CLM arm, Newton designed it using the generative artificial intelligence tool within Autodesk’s Fusion 360, a CAD, CAM, CAE and PCB software platform, Miller noted. Using machine learning and an AI algorithm, an end user can, for example, define interfaces and loading conditions for a proposed part.

“It’ll spit out 30, 40, 50 different versions and tell you the performance characteristics of all those options,” Miller said, adding that the software also generates projected costs. “I can go in there and say, ‘This one looks to be the best option for the application. This has the best stiffness-to-mass ratio and it’s within our cost budget.’ It’s a pretty fascinating tool.”

In addition to reducing the design process time for such a complicated component from weeks to hours, the generative AI-designed part is at least 30% lighter than if a human designed it, according to Miller. The aluminum 606 part weighs 0.39 kg (0.86 lbs.).

Newton has its own machine shop, but scheduling constraints to complete other projects prevented the company from machining it in-house, he said. “We eally wanted to give it a try, but it was most feasible to go out of house for that specific part. Producing a part like this through CNC machining is not a trivial task.”

Baker Industries machined this CLM arm for Newton Industries, which attaches the circular lid to the capture lid mechanism subsystem of the capture containment and rendezvous system. Newton

Miller said Newton began its search for a machine shop to produce the CLM arm and selected Baker Industries, a Lincoln Electric company, in Macomb, Michigan, based on recommendations from research engineers at NASA’s Goddard Space Flight Center. One of the engineers was Ryan McCelland. “Ryan has been leading the effort at Goddard Space Flight Center to develop the processes to ensure that we’re reducing risk as much as possible when implementing this generative design technology.”

Newton provided Baker Industries with the CAD model of the CLM arm, which is essentially the hinge of the door, or circular lid, for the container that would receive the samples, Miller noted. In addition, Baker received the drawing that specified the dimensions and tolerances, which were as tight as 0.0254 mm (0.001") on standard geometries, such as straight cylinders, holes and flat surfaces, and 0.508 mm (0.020") on organic geometries. “They knew what they were doing and so we trusted them to go ahead and do what they felt was best to be able to produce the part.”

After machining, engraving serial numbers and hand finishing to remove machining marks and smoothen the organic geometry surfaces, MIL-SPEC surface treatments and coatings were applied, including a chemical conversion coating and anodizing. The chemical conversion coating protects aluminum from oxidation and rust, Miller explained, and an anodized coating covers most of the part with certain sections left exposed to maintain an electrical grounding path through the part.

Alex Miller, mechanical engineer – deputy engineering lead at Newton with the capture lid mechanism. Newton

To have a couple of spares, Newton ordered three CLM arms, which required two weeks to machine, Miller said. “They had the best lead time of anyone by far. This was a very tight schedule-driven project, and the only way for us to get our parts on time was to go with Baker.”

He added that Baker Industries even produced the parts ahead of schedule while meeting all the tolerance specifications. “We were very pleased with their efforts to communicate the status of the job with us. It’s not typical to get that kind of communication from a machine shop.”

Newton performed extensive vibration testing to ensure that the anodized coating adhered to the intricate organic geometries during launch and thermal testing across the temperature range the part would experience and still need to operate, Miller said. “It maintained its structural integrity throughout all the testing, and it works great.”

With the capture lid mechanism subsystem completed, it appears that the Mars Sample Return mission has a bigger obstacle to overcome than the average round trip distance of 508.8 million km (316 million miles) to travel to the red planet and back — that would be loosening the purse strings of the U.S. Congress. Budget cuts will essentially cancel the multiple-vehicle mission unless reversed.

“Unfortunately, the CLM arm, as of right now, is not going to Mars like we thought it would,” Miller said, “but there’s still a chance of it coming back.”