Additive manufacturing helps NASA develop the Do Everything Space Suit

Terry Persun, Technology Journalist

The transparent space suit built by Solid Concepts was used for static testing for many of the features the new NASA space suits will incorporate.

The US Space Agency has been working on their new Z1 space suit, and recently introduced some of the early prototypes now under test. Although several NASA groups joined to produce the suit, NASA Glenn’s past involvement in space flight software, power, and communications is a plus. Known as PAS (Power, Avionics, and Software), this group is developing the communications, avionics, and informatics (CAI), as well as the power subsystems for the next-generation space suit. Their efforts support the Advanced EVA Systems Development project, which is led by Johnson Space Center and supported by Glenn, industry, and academia.

Two entire Z1 Prototype Mark III Space suits, as well as a half-suit, from the waist up, were prototyped through services provided by Solid Concepts Inc. (Poway, CA). Engineers at Solid Concepts used their proprietary QuantumCast Cast Urethane process combined with complex soft tools and cores to produce the components needed to complete the suit. They used photo curable stereolighography resins as well as CNC machined parts for the patterns, Platinum Cured Silicone Tooling for the molds, collapsible foam and mold cores to handle the complex undercut geometry, rigid crystal clear urethane material for the actual finished product.

The space suit presents a few unique abilities that make it ideal for future missions. First and foremost, astronaut entry is located at the back of the suit to make it faster and easier to put on. Astronauts step into the full suit through the back port. Called the Suitport, it mates with the spacecraft, enabling an astronaut to enter the suit from inside the craft for extravehicular activity. An additional advantage is that the port conserves more air than a conventional airlock when used in low to no atmosphere.

This configuration requires no “prebreathing,” which involves using elevated oxygen levels to remove nitrogen from the bloodstream to prevent decompression sickness at lower pressures—which can take up to an hour to complete. The suit will automatically be at the internal pressure of the vehicle. So, by incorporating the rear Suitport, it allows future spacecraft and landcraft to use the airlock system only when suit maintenance is required or there is a problem with the Suitport.

 

In the prototype Z1 suit, astronaut entry is located at the back of the suit. This Suitport mates with the spacecraft, enabling an astronaut to enter the suit from inside the craft for extravehicular activity.

On the rear of the suit is a giant backpack, which doubles as a hatch that can latch onto another space ship or Rover-like vehicle. The backpack will carry all the life-support technology for a crew member and will provide oxygen, ventilation, and all the onboard electronics, such as in-helmet electronic displays, avionics systems, and special sensors to measure the metabolic rate of crew members during EVA activities and allow researchers to evaluate the data.

The new suit is expected to support an increase in the frequency and duration of EVAs for future exploration missions. The suit’s weight is only 158 pounds without the portable life support system backpack. Other features include bearings at the waist, hips, upper legs, and ankles to allow an astronaut greater mobility when performing tasks such as retrieving soil and rock samples in tough terrain.

The whole suits contained five urethane pieces each, while the half-suit contained four urethane pieces. The fourteen transparent components were used strictly for ground testing. NASA Glenn performed sound testing with the integrated audio system on the half-suit. Other tests, such as flow visualization tests, in which smoke is ventilated through the suit to mimic normal air ventilation flow to an astronaut, are expected to be completed by JSC. These tests will allow the designers to determine whether there is good uniform flow, or undesirable, stagnant areas within the suit.

The suits were not “ready for use” when they were delivered to the Glenn group. Some compression limiters still needed to be installed at the Johnson Space Center, which was planned prior to manufacturing the parts. At this point, the units were pressure tested after they were assembled. Only one unit was found to have a small crack due to a thin wall thickness, which Solid Concepts repaired.

Considerations for final suit components will include concerns about surface flatness and warpage under the stress and strain of outer space, which is why the suits were pressure and flow tested at an early stage of development. Along with these concerns are shrinkage and alignment. The suits produced by Solid Concepts are strictly used for testing purposes. They are rigid, not flexible like the final suits will be. The final suit has been designed to incorporate a provisional outer covering, which conceals the heavily engineered inner suits that will include a layer of urethane-coated nylon that is used to retain air, and a polyester layer that allows the suit to hold its shape.

With missions to Mars now on the horizon, an updated version of the older space suit was called for. The project was especially taxing for NASA engineers because they didn’t know where the suit would be used, meaning it had to be ready for anything—a trip to the moon, Mars, or an asteroid. The Z-1 prototype—currently being tested in a vacuum chamber—has been designed for versatility: to explore alien surfaces, float outside a space station, and even weather the radiation of deep space.

The Z-1 Prototype Spacesuit was completed in FY12, and the Portable Life Support System (PLSS) 2.0 will also be completed in FY12. A Z-2 Spacesuit and PLSS 2.5 system is expected to be fabricated in FY14. The combined system, known as the Advanced EMU (AEMU), is planned for flight in 2017, if proper funding is received.

 

Casting Difficulties
The challenges faced while building the Z1 Prototype Mark III Space Suits were many. Below is a list of only a few obstacles Solid Concepts (SCI) faced during the design and build process, many of which required proprietary design and manufacturing adjustments to solve:

Complex geometries:
Required that SCI make complex core components to create voids inside the uniquely shaped parts for the suits. Since each part was produced in one piece, there were no sectioning options available.

Varied thicknesses:
Not only did the components have to have varied wall thicknesses from as little as 0.030-in. to 3.00-in., but they also faced inaccessible 3-in. undercuts that traditional molding could not perform.

Long curing times:
Due to the weight and size of the parts, also caused hole alignments, mounting surfaces, and insert locations to be inaccurate when first cast.

Additional builds:
Core and molding stabilizers, as well as numerous other fixtures were created to hold flatness, accuracy of alignment, and full assemblies throughout the build.

Post processing:
Because of the nature of the tests being completed, every component had to go through a series of hand-polishing stages for maximum clarity and best surface finish.

Solid Concepts Inc.
www.solidconcepts.com

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