Space station no longer in the dark

Engineers at the University of Texas at Austin are working to solve a space age power problem currently encountered on the International Space Station (ISS).

The solar cells employed on the ISS are said to work efficiently in sunlight, but do not generate electric power in the dark. That creates a special engineering problem for cells on the ISS because it is powered by solar cells on a giant set of wings recently attached to it.

The space station’s orbit around the earth is 90 minutes long, cycling rapidly from the light to the shadow side of the planet.

‘Every time the station is in the dark – the equivalent of night-time – the solar cells do not generate electric power,’ said Dr Robert Hebner, director of UT Austin’s Centre for Electromechanics. ‘The station runs on power from batteries during these dark periods.’

Engineers at the Centre for Electromechanics are doing research that could lead to replacing the chemical batteries needed to operate the space station when it is in the dark with flywheel batteries, which store and release energy on a continuous basis.

If successful, Hebner said NASA estimates savings to the space station program of more than $200 million.

A flywheel battery, designed to fit in the existing space provided for a chemical battery, is said to have a greater capacity and could last the lifetime of the space station itself.

Current batteries weigh about 300 pounds and fit in a box about 12 cubic feet in size. Flywheel batteries are believed to be a cleaner and more economical source of battery power than chemical models. The flywheel that would be used in the battery on the space station is estimated to be about 1.5 feet in diameter and nearly three feet long.

The flywheel is made of a composite material, mounted on a titanium shaft and levitated on magnetic bearings, storing the energy from solar cells by spinning faster and slowing down as the energy is discharged.

The UT Austin program is being funded by the NASA Johnson Space Flight Centre in Houston, Texas, and managed by the NASA Glenn Research Centre in Cleveland, Ohio. UT Austin engineers aim to complete the project by the time the current space station batteries need to be replaced five years from now.