Nearly 40 large wildfires now burn across the United States.
Blazes are expected this time of year, with hot air, dry land, and gusty winds stoking big fires throughout the western U.S. But today, twice as much land is burned than in the early 1980s, when the U.S. Forest Service started keeping good fire records each year.
These firefighters are extremely well-trained, but sometimes the worst happens: Flames surround fire crews and force them to take cover under foil-like tents, called emergency fire shelters. Here, they wait for the scorching flames to pass overhead.
Although deploying this last-ditch option is rare, the results can be tragic. Five summers ago, 19 firefighters, battling flames in an Arizona area that had experienced extreme drought, perished inside their fire shelters. For this reason, the Forest Service has devised improved shelters over time, and this fire season, they’ve introduced robust prototypes, designed by NASA.
Scientists at the space agency, unsettled by the deaths of the 19 firefighters in 2013, decided to employ an inflatable heat-shield technology — meant to withstand the up to 5,000-degree-Fahrenheit temperatures spacecraft experience when falling through the atmosphere — to create more robust fire shelters.
In total, firefighters and fire equipment operators are now carrying around 40 of these prototypes into fire territory, in areas all over the country.
In laboratory tests, where researches shot fire at the shelters, the results show the NASA tents — which expand like a fluffy blanket when exposed to hot temperatures — can protect firefighters against deadly heat for considerably longer than the current shelters, designed in 2002.
“It is a marked improvement,” Tony Petrilli, the Forest Service’s Fire Shelter Review Leader, said in an interview.
The very first fire shelters, from decades ago, gave the firefighters inside about 12 seconds of lab-tested “survivability,” said Petrilli. The current shelters offer 54 seconds of survivability. And NASA’s prototypes lasted for about 90 seconds.
“It’s a very extreme test, but it does not necessarily reflect the most extreme fire in wild settings,” noted Petrilli.
But before the NASA shelters can replace the current shelters, Petrilli needs to ensure that they hold up in the real world, as the bundled and folded tents are lugged through rough terrain and tossed around.
“The biggest job the shelters have to withstand is being carried around,” said Petrilli.
The NASA fire shelters, like all fire shelters, must be pretty light, weighing in at around four pounds. Wildland firefighters are already burdened with heavy packs, and can’t take on much more baggage.
“Forty-five or 50 pounds is not unusual,” said Petrilli. “The vast majority of firefighters don’t want to carry more weight.”
This makes the NASA prototypes particularly well-suited for the task.
The thin fabric is embedded with pepper-like bits of graphite. When exposed to heat, this graphite makes the fiberglass insulation expand — so the material only gets bigger when exposed to scorching temperatures.
Still, said Petrilli, “There’s no guarantee of survivability in even the biggest, bulkiest shelters.”
The material can’t withstand long periods of direct contact with flames (not much can).
Before deploying the shelters, firefighters are trained to seek out an area where little fire will burn on the tents, such as ground with scarce vegetation. The idea is for the fire to burn around or near the tents — which still produces sizzling, deadly heat — but not directly on the tents, said Petrilli.
Even the earliest fire shelter, though inferior in many ways to NASA’s technology, has already proven quite effective in protecting professionals combating wild flames.
“That old-style shelter saved hundreds and hundreds of lives,” said Petrilli.
NASA’s formidable heat shields have protected astronauts and spacecraft from deadly heat for decades. Perhaps they’ll be equally effective at shielding firefighters.