Interweaved tether for 'e-sail'

This scanning electron microscope image shows the new design of an ultra-thin and hopefully snap-proof solar sail tether soon to be tested on Estonia’s ESTCube-1, which is being launched into orbit along with ESA’s Proba-V satellite on the next Vega rocket in April. Harnessing manufacturing techniques from the microelectronics industry, this aluminium tether measures just 50 micrometres across – across half the diameter of the average human hair – with a smaller 25 micrometre wire interweaved onto it. Welding such small wires together was once considered impossible but a University of Helsinki team applied ultrasonic welding techniques. This interweaving technique will hopefully keep the tether intact to run an electric charge down it, even if all but one subwires in the tether are cut by micrometeoroids in orbit.