Breakthrough Starshot – the third Breakthrough initiative in the past four
years – will test the knowhow and technologies necessary to send a
featherweight robot spacecraft to the Alpha Centauri star system, at a distance
of 4.37 light years: that is, 40,000,000,000,000 kilometres or 25 trillion
miles.
A 100 billion-watt
laser-powered light beam would accelerate a “nanocraft” – something weighing
little more than a sheet of paper and driven by a sail not much bigger than a
child’s kite, fashioned from fabric only a few hundred atoms in thickness – to
the three nearest stars at 60,000 km a second. Such a system
would allow a flyby mission to reach Alpha Centauri in just over 20 years from
launch instead of the best (but not existing) rocket ship that would probably take more than 30,000 years.
But falling costs and
increasing processing power mean that spacecraft could become ever smaller and
lighter: they could be launched by the thousand from a mothership and then
driven by the proposed Light Beamer, a billion-watt laser array, mounted
somewhere high and dry such as the Atacama desert in Chile.
“Nanocraft,” called StarChip: it fits between two fingers, attached to a giant sail.
By Kevin
Gill from Nashua, NH, United States - Solar Sail, CC BY-SA 2.0 https://commons.wikimedia.org/w/index.php?curid=42599221
This could multiply the
radiation pressure, and accelerate the space sailors to a significant fraction
of light speed. This would reduce such a journey to the timescale of one human
generation: some of the scientists caught up in the beginning of the project
could expect to see results within a working lifetime.
Nobody pretends that
any of it will be easy. Avi Loeb, of the Harvard-Smithsonian Centre for
Astrophysics, who heads the advisory board, said that to power the spacecraft,
researchers have to work out how to link lasers into one massive array. Since
the range of focus of a big laser on a small target would be no more than a million
kilometers, the fragile spacecraft must reach terminal speed in just two
minutes, and survive an acceleration of 60,000 times the force of gravity.
“Earth is a wonderful place, but it might not last forever. Sooner or
later we must look to the stars. Breakthrough Starshot is a very exciting first
step on that journey.”