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Jack and Jill on the Journey to Mars

Jack and Jill, the famous nursery rhyme couple, have come a long way since their tumble downhill. Today they’re part of NASA’s deep space human exploration program, serving as simulated stand-ins for the men and women who will work inside the Space Launch System.

The computer generated manikin program called ‘Classic Jack’ uses male and female models to represent a range of larger men and smaller women who will work inside the SLS rocket. Using computer models instead of humans during design and development saves time and money, while ensuring future crewmembers will be able to access all areas of the SLS rocket so they can maintain critical components.

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Screenshots of the Jack and Jill models working inside the Space Launch System rocket prior to launch.

Boeing human factors engineer Tom Hagale has worked for decades on ground systems, space systems, and military aircraft. He recalls when the first human modeling was done with paper cutouts or expensive full-scale mockups. Since then computer-aided design has given a better solution. Hagale and his team have applied their expertise to the assembly of the International Space Station, and now to the Space Launch System.

“Watching astronauts on an EVA (spacewalk), using the meticulously placed handholds and foot restraints we prescribed is great,” Hagale said.”We did that.”

Hagale added, “For me, the movie Gravity was very realistic. Those foot restraints and handrails are critical. Without them, in zero gravity, you’d turn a wrench and your whole body would rotate the opposite direction. You’d get nothing accomplished.”

Even in Earth’s 1-G environment, designing for human interaction is critical. On the SLS, the goal is to incorporate into the computer program every possible task needed to be performed by workers of all sizes inside the rocket from design to launch. “We can’t design for absolutely everyone, but we try to get as close as we can,” explained Hagale.

In the 1990s much of the aerospace industry used full-scale mockups or paper printouts of people, workspaces and hardware to accomplish human factors engineering. Boeing (as McDonnell Douglas) pioneered a computer aided design human modeling system. The technology has since matured and gone public, allowing Hagale to adopt an off the shelf tool for SLS called “Classic Jack” made by Siemens PLM.

“It’s an exciting time to do this kind of work – with new, more advanced, more affordable, simulation tech being developed every day. You can imagine how that will play out across all the elements we need for the journey to Mars.”