And the Chinese have an idea to saving us. 2029 is projected the year a massive asteroid - Apophis - will pass close to the Earth. Close enough to scare some very serious people, astronomers. It will, because life is funny this way, enter what is called a keyhole and come for another close pass in 2036. Or it will hit us. The good news is if it hits us in 2029, we don’t have to worry about 2036. Whatever happened to Halley’s Comet? Now there’s something you can set your watch by.

Propellant-free system could accelerate a 1000 kg spacecraft to more than 67,000 miles per hour in one year

Artist’s impression of an electric solar wind sail (credit: Alexandre Szames)

The Electronics Research Laboratory at the University of Helsinki has successfully constructed a 1-km-long electric sail (ESAIL), which would interact with the solar wind (charged particles from the sun) to produce long-distance propulsion power for a spacecraft.

Using ultrasonic welding, the feat proves that manufacturing full-size ESAIL tethers is possible. Experts previously considered it impossible to weld together such thin wires.

Invented by Dr. Pekka Janhunen at the Finnish Kumpula Space Centre in 2006, the ESAIL consists of long, thin (25–50 micron) electrically conductive tethers manufactured from aluminum wires. A full-scale sail can include up to 100 tethers, each 20 kilometers long.

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