Engineers at NASA are developing new smoke detectors for spacecrafts to prevent fires in space. And don't think that's easy. As smoke particles in microgravity are bigger than on Earth, they had to modify the smoke detectors installed in your kitchen. NASA designed two space stations experiments to test these smoke detectors. The goal of the first one, which was done in September, was to measure the size of the particles in smoke. The second one will be done next summer to ensure that the modified smoke detectors really work. I wonder how the astronauts survived all these years without smoke detectors, but read more...
Here is the introduction of this NASA news release.
Fires are no laughing matter on Earth, but in space they could be even more devastating. "If a chair is on fire in your home, you have time to get out. In a spacecraft, you don't," said NASA scientist Dr. David Urban. "You have to detect smoke in an early pre-fire state, so you can stop it before it starts."
And what is easily done with cheap smoke detectors in your home proves to be difficult in space because smoke particles in space are bigger than on Earth.
"Smoke particles form differently in microgravity than they do on the ground," said William Sheredy, project manager for the Smoke Aerosol Measurement Experiment (SAME). "When smoke is created in microgravity, the particles have more time to gather together, producing larger particles or particle chains than in normal gravity."
Not only smoke particles are different in space, but the combustion process is also very different. Below are two images of "a candle flame in Earth's gravity (left) and microgravity (right) showing that difference in the processes of combustion in microgravity" (Credit: SAME, NASA). Here is a link to a larger version.
Before building new smoke detectors, NASA engineers had to precisely measure the size of smoke particles in space. They designed another experiment, the Dust and Aerosol Measurement Feasibility Test (DAFT) to test if a modified version of a commercial particle counter worked correctly aboard the ISS.
In September, astronaut and Expedition 13 Flight Engineer Jeff Williams operated DAFT on the station. Urban, Sheredy and other DAFT team members watched in real time as Williams called in the recordings to Payload Communications. The results showed that the commercial particle counter works in space.
Now it remains to test if the modified smoke detectors also work in space. Here are the operational protocols which will be used by SAME during summer 2007.
SAME will use probes to heat a wire and drive the smoke onto a small collection grid (~1/8 in. diameter) as it flows past using an effect know as thermophoresis (what causes dust to stick to the wall behind a radiator). At each test point, two samples of the smoke will be taken: the first within seconds of its generation and the second after a defined aging period, during which the size and shape of the smoke particulates will have changed. These sample grids will be returned to Earth from the ISS and examined under a transmission electron microscope.
If the SAME experiment is a success, the smoke detectors developed for future spacecrafts will also be useful for "other extreme environments on Earth, such as submarines or underwater laboratories."
Sources: NASA's Glenn Research Center press release, September 29, 2006; and various pages at NASA
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