Fire In Space

On Earth, fire provides light, heat, and comfort. Its
creation, by a process called combustion, requires achemical reaction between a fuel source and oxygen. The shape that fire assumes on Earth is a result of gravitational influence and the movement of molecules.

In the microgravity environment of space, moreover,combustion and the resulting fire behave in
fundamentally different ways than they do on
Earth—differences that have important implications for researchers. A group of engineering students from the University of California at San Diego (UCSD), for example, tried to find a method to make their biofuel combustion study (fuels derived from once-living material) free of thedrawbacks researchers face on Earth. The standard method involves burning droplets of fuel, but Earth’s gravitational influence causes the droplets to losespherical symmetry while burning.

This deformation results in subtle variations in density that both causes uneven heat flow and limits the size of thedroplets that can be tested. Specially designed “drop towers” built for this purpose reduce these problems, but they provideno more than 10 seconds of microgravity, and droplet size is still too small to produce accurate models ofcombustion rates. The UCSD students understoodthat these limitations had to be surmounted.

As partofthe program, researchers fly their experiments aboard aircraft that simulate the microgravity environment of space. The aircraft accomplish this feat by flying in parabolic paths instead of horizontal ones.

On the plane's ascent, passengers feel twice Earth’s gravitational pull, but for brief periods at the peak of the trajectory.