NASA technology may breathe life, safety into mines

The Cryogenic Refuge Alternative Supply System (CryoRASS) and a smaller liquid air-filled backpack under development in Kennedy Space Center's Biomedical Lab have the potential to store more than twice the amount of breathable air than traditional compressed gas systems.

Lead NASA engineer David Bush and teams from BCS Life Support, URS Corp. and InoMedic Health Applications began working on the two systems in September 2012.

The National Institute for Occupational Safety and Health (NIOSH) is funding both projects in the hopes that the liquid air-based systems could change the way coal miners seek refuge or flee from underground disasters. Bush and his team see far more potential for the cryogenic technology in terms of rescue operations, ranging from commercial applications to future crewed missions to space.

"We're excited about this cryogenic technology because it has the potential to save lives and improve safety in mines," Bush said. "Currently mines use big tube banks of compressed air with no cooling. Our solution uses smaller, lower pressure dewars of liquid air with cooling."

The agency has used the cryogenic technology in its rescue crew SCAPE suits, short for Self-Contained Atmospheric Protective Ensemble, since the Mercury Program in the 1960s.

The way CryoRASS and the backpack, called CryoBA, work is by drawing air into a closed environment, then vaporizing and circulating it back to the user. Bush describes the systems as "passive air conditioners" and said initial demos show a drop in temperature by about 15 degrees. Since many refuge chambers stand no more than 30 inches tall, cooling likely would be a welcome feature.

"When you get about 10 men in a small confined space, essentially laying down in tin cans, with their body heat, it can get really hot in there," Bush said.

Another advantage to the liquid air systems is improved safety.

"Compressed air has its own hazards because it's stored at a high pressure. It's also heavy and takes up a lot of space," Bush said, "Compressed 100 percent oxygen can present potential fire hazards."

Many refuge chambers are designed to provide up to 96 hours of breathable air, but Bush said CryoRASS could easily exceed the minimum requirements allowing more time for the miners to be rescued. Another plan being discussed is to build refill stations in mines spaced about 90 minutes apart, so that crews could walk out of a disaster situation with their personal CryoBA backpacks.

"NIOSH asked us to develop prototypes that we will test to their standards," Bush said. "The idea is that once we successfully test them, we can demonstrate the technology to commercial life-support providers for use in other applications, such as firefighting and military rescue operations."

As Bush and his team continue to advance and refine the cryogenic technology, they are gaining some attention from the agency's newest human spaceflight programs.

"In an emergency situation, rescue crews will have to go up some sort of launch structure, pull a crew out of a confined capsule, and get them to safety all within the span of their breathing device," Bush said. "We did a rescue dry run with a mock Orion capsule and, because the entryway is small, having a device with a smaller profile that is more efficient with the weight-to-space ratio is helpful."