Composite Construction Under Consideration For Human Spaceflight

A NASA team looking into design concepts for future space capsules has successfully demonstrated that an all-composite structure is a feasible alternative to traditional metal capsules for carrying astronauts into space and returning them safely to Earth, the agency announced Monday.

The composite materials that make up the structure are basically the same as the tough, lightweight laminates used today for race cars, business jets and high-end sports equipment.

In combination with new space-age fabrication techniques, these advanced composite materials promise potential benefits over traditional metal structures. Among them is that they can easily be formed into complex shapes that may be more structurally efficient -- a desirable trait for future generations of spacecraft.

A team led by the NASA Engineering and Safety Center (NESC) developed and tested the capsule - called a crew module - in a series of full scale structural tests at NASA's Langley Research Center, Hampton, VA, over a several month period. The full-scale crew module was pressurized to design limits while critical interfaces - like the landing system main parachute fitting -- were pulled to simulate the combined loads a future crew module might see during launch and return to Earth. No trouble spots were detected.

Composite Crew Module

After passing those and other combined tests, follow-on tests checked for damage tolerance, a question of critical importance for composite structures. The crew module was subjected to measured impacts in multiple locations to simulate the kind of damage that might take place in the life of the structure - specifically, the equivalent of tool drops and routine handling damage. The module was then stressed to simulate the expected life cycle of a space-going composite structure. At points along the way, the damaged sites were inspected by non-destructive means, using both infrared thermography and ultrasonic techniques, to characterize subsurface damage and damage progression.

"Our tests showed that a composite module can 'achieve the mission' with damage that is likely to occur but could go undetected," said Mike Kirsch, manager of the Composite Crew Module (CCM) project. "The test article withstood twice the design internal pressures with known damage and then was subjected to cyclic testing to four times the design life with no detrimental damage growth," he added.

A follow-on round of impact assessments is planned to study the effects of higher impact energies. "We are very pleased with the entire test series. Throughout testing, there were no anomalies and performance aligned amazingly well with analytical predictions," Kirsch said.

FMI: http://www.nasa.gov/offices/nesc/home/index.html