Press release 23.3.2020

Scientists discovered inexpensive method to make E-sail tether

Thin metallic tether for Coulomb drag devices of satellites and spacecraft can now be produced simpler than before. Scientists of the Finnish Meteorological Institute developed method to produce multi-wire tether by twisting hair-thin metal wires.

The solar wind electric sail (E-sail) enables transportation in the solar system without propellant. Likewise, the plasma brake eliminates the orbital debris problem by providing low-cost reentry at end of satellite mission.  Both utilise the plasma Coulomb drag effect. They require multi-wire tether made of hair-thin metal wires.

Scientists at the Finnish Meteorological Institute have now developed a new method to produce Coulomb drag tether. Earlier, the Electronics Research Laboratory of the University of Helsinki has produced tether successfully using ultrasonic bonding. The new method is simpler and is based on twisting metal wires. The method resembles the industrial production of hexagonal chicken wire mesh. It produces a 4-wire tether from 0.05 mm thin metal wires. The tether must be made of multiple wires so that it is not broken even if micrometeoroids cut the individual wires every now and then.

"Four subwires give sufficient micrometeoroid tolerance even for full-scale E-sail and plasma brake," says Dr. Petri Toivanen of the Finnish Meteorological Institute.

Dr. Petri Toivanen and the tether factory.

The tether and the plasma brake are to be tested on the FS-1 nanosatellite of the Finnish Centre of Excellence in Research of Sustainable Space.

Further information:

Dr. Petri Toivanen, Finnish Meteorological Institute, tel. +358 50 380 3417,

Dr. Pekka Janhunen, Finnish Meteorological Institute,

The Coulomb drag propulsion research of the Finnish Meteorological Institute is part of the Finnish Centre of Excellence in Research of Sustainable Space which is funded by the Academy of Finland.

Resulting 4-wire tether made of 0.05 mm wires. Human hair below for comparison. Pictures taken by Petri Toivanen.