Breakthrough Starshot develops an interstellar solar sail powered by laser
– News of June 27, 2017 –
Breakthrough Starshot is a laser propulsion system project to send micro-probes to our stellar neighborhood at 20% of the speed of light. Huge technological challenges arise, which is why the research plan is spread over 30 years.
A micro-probe of a few grams is attached to a solar sail. But rather than letting the solar wind accelerate the probe very slowly, a very high power laser is focused on the sail to provide acceleration and thus achieve a significant fraction of the speed of light. The entire laser system is Earth-based and the space probe does not need to carry any fuel, just instruments and a small source of energy to use them.
This week, the Breakthrough Starshot Research Committee released its first conclusions about the shape of the sail. Unlike current solar sails in the form of a simple square or diamond, the sails of the project Breakthrough Starshot have a geometry a little more original. They must be able to withstand the very high accelerations due to the propulsion laser.
The space probe should indeed reach 20% of the speed of light in a few minutes, an acceleration of 10000 G. Early research on the shape of the sail suggest that the cone or balloon shapes are the most likely to resist this acceleration. This sail must also be able to reflect at least 99.9% of the light received, because with a laser of the order of 100 gigawatts of power, each small fraction of absorbed energy may melt the sail. Although the Breakthrough Starshot project needs to overcome many technological challenges, no fundamental breakthrough is needed. Technologies already exist, they now have to be able to improve them by several orders of magnitude.
Breakthrough Starshot has $ 100 million in private funding and heavyweight support : Stephen Hawking and Mark Zuckerberg are on board.
Image by Kevin Gill from Nashua, NH, Solar Sail [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons