Author(s): Ashley Smith. Published on May 2, 2016.

FINAL FRONTIER

NASA plans a series of large-scale burn tests to determine how fire behaves in space.

BY ASHLEY SMITH

FOR THE FIRST TIME, NASA is planning to conduct a large-scale fire test in space to learn more about how fires burn in low-gravity environments and to collect data that could improve fire safety measures for future missions.

According to NASA, this will be the largest man-made fire ever in space. NASA has previously conducted small-scale tests at the International Space Station (ISS) and on the space shuttle, but it has never examined how large flames react in space.

The experiment will take place aboard the unmanned Orbital ATK Cygnus capsule, which is used to transport supplies to the space station. The capsule launched March 22 from the Kennedy Space Center in Florida; the fire test is scheduled for June 2, after supplies are dropped off and Cygnus has left ISS.

The Saffire I fire experiment being loaded into the Cygnus capsule

The Saffire I fire experiment being loaded into the Cygnus capsule. Photograph: NASA

“A lot of what we know about fires [on Earth] comes from full-scale testing rather than small-scale testing,” said Gary Ruff, manager of the Spacecraft Fire Safety Demonstration Project at NASA’s Glenn Research Center in Cleveland, Ohio. “We need this information to protect the crew on long-duration missions.”

Dubbed Saffire I, for “spacecraft fire experiment,” this is the first of a trio of fire tests in space that will take place this year. The goal of all three experiments, according to NASA, is to better understand how rapidly large fires grow in space, which materials will catch fire, and how those materials burn. NASA hopes to use the data to develop better materials, technologies, and procedures to reduce crew risk and improve space flight safety, Ruff said.

The fire will be monitored by cameras, computers, and a variety of testing instruments, including radiometers to record flame intensity and thermocouples to measure the temperature of the flame and gases.

The fires will not destroy the capsules—the flames will be extinguished by cutting the air flow when the tests are done—but the capsules will not return to Earth. After delivering supplies, Cygnus capsules are designed to burn as they reenter Earth’s atmosphere.

NASA approached Orbital ATK, a global aerospace, defense, and aviation-related technologies company, with the idea to conduct fire testing on its Cygnus capsules, and the company was on board. “We said, 'if you’re going to burn it anyway, let us mess it up a little first,'” Ruff said.

Previous fire tests in space have used centimeter-sized samples, but Saffire I and III will burn a piece of fabric about the size of a large t-shirt, Ruff said. The material is 75 percent cotton and 25 percent fiberglass by weight. Saffire II will test a variety of materials, including silicone, plexiglass, and Nomex, a flame-resistant fiber. Plans for additional Saffire missions are in development to further study flame spread, smoke propagation, and detection and suppression of fire.

Small-scale tests have shown that some materials are more likely to burn in space. “Something that might not burn at 25 percent oxygen [on Earth] could burn at 25 percent oxygen in low gravity,” Ruff said.

Current fire protection measures on manned spacecraft include restrictions on the types of materials and on how close certain materials can be placed to ignition sources or other flammable material. Spacecraft use smoke detectors and fire extinguishers to protect the crews from fires.

ASHLEY SMITH is staff writer for NFPA Journal. Top Photograph: NASA