Spacecraft, heal thyself!
Press release issued: 26 January 2006
A material that could enable spacecraft to automatically "heal" punctures and leaks is being tested in simulated space conditions on Earth. he self-healing spacecraft skin is being developed by Ian Bond and Richard Trask from the University of Bristol, UK, as part of a European Space Agency project.
The self-healing spacecraft skin is being developed by Ian Bond and Richard Trask from the Department of Aerospace Engineering, University of Bristol, UK, as part of a European Space Agency project.
The researchers have taken inspiration from human skin, which heals a cut by exposing blood to air, causing it to forms a protective scab. In humans, the air chemically reacts with the blood, hardening it. In the airless environment of space, mechanical ‘veins’ have to be filled with liquid resin and a special hardener that leak out and mix when the fibres are broken. Both must be runny enough to fill the cracks quickly and harden before it evaporates.
The researchers fabricated a composite laminate material containing hundreds of hollow glass filaments 60 microns (thousandths of a millimetre) wide, each with an inner chamber of 30 microns in diameter. Half of the filaments are filled with an epoxy polymer or resin and the other half filled with a chemical agent that reacts with the polymer to form a very strong and hard substance.
The glass filaments are designed to crack easily when the overall composite material is damaged, which causes both chemicals to leak out and rapidly plug the resulting crack or hole. "We've demonstrated we can restore strength by doing this," Bond says, "and that it can stand the space environment."
He imagined such cuts as analogous to the 'wear-and-tear' suffered by spacecraft. Extremes of temperature can cause small cracks to open in the superstructure, as can impacts by micrometeroids – small dust grains travelling at remarkable speeds of several kilometres per second. Over the lifetime of a mission the cracks build up, weakening the spacecraft until a catastrophic failure becomes inevitable.
The pair have successfully tested the self-repairing material in a vacuum chamber to see whether it would work in a space-like vacuum, and also investigated the effect of gravity on the skin's protective properties when covering the top or the underside of a craft. They now plan to develop stronger materials containing the healing filaments and to test them in even more extreme conditions, such as very high temperatures.
The promise of self-healing spacecraft opens up the possibility of longer duration missions. The benefits are two-fold. Firstly, doubling the lifetime of a spacecraft in orbit around Earth would roughly halve the cost of the mission. Secondly, doubling spacecraft lifetimes means that mission planners could contemplate missions to far-away destinations in the Solar System that are currently too risky.
In short, self-healing spacecraft promise a new era of more reliable spacecraft, meaning more data for scientists and more reliable telecommunication possibilities for us all.