Pic The Planetary Society says its LightSail spacecraft has finally deployed its 32 sq metre solar sails. The Earth-orbiting craft is now harvesting energy from the momentum of the Sun's photons, we're told.
Motor is running! Sail is Deploying!!! 39 Years after Prof. Sagan spoke of it!— Bill Nye (@BillNye) June 7, 2015
It's been a tense time for the Planetary Society: this first experimental solar sailing craft has been plagued by difficulties since it was launched on May 20. The society – headed by TV's science guy Bill Nye – is a nonprofit organization bent on promoting space exploration.
Communications with the spacecraft have been patchy at best and there were problems deploying the solar cells to provide power, but the group reported that sail deployment began at 3:47pm. EDT (19:47 UTC) on Sunday.
"All indications are that the solar sail deployment was proceeding nominally," said mission manager David Spencer.
LightSail carries four triangular sails arranged in a square, and getting them unraveled successfully has been a key goal of the experiment. To save on weight, the sails are just 4.5 microns thick and are controlled by a solar-powered controller measuring just 30cm by 10cm by 10cm.
It's not the first time mankind has put a solar sail into orbit. Japan was the first to try the technology in 2010 and NASA had one up there for eight months a year later. But LightSail is the first attempt by the Planetary Society to make the technology work.
The next step is to monitor how the solar sails collect and power the spacecraft, in readiness for a much bigger version due for launch next year. The Planetary Society sought $200,000 on KickStarter for this project in May and it already has four times that amount in pledges. The fund will go towards building a spacecraft that can derive power from the Sun and be steered by altering the position of the sails.
The current orbital craft isn't going to be much good at that, since it was launched in very low Earth orbit. With the sails deployed, the amount of drag it's getting from the upper atmosphere will be increased dramatically and it will fall back to Earth relatively quickly.
But the hope is that the technology will allow space probes with huge range. The energy from the Sun might be small, but it's constant. In the almost frictionless reaches of space, once you have momentum, you keep it.
Solar sailing will never have the power of rocket engines, or even ion drives, but the advantages of fuelless propulsion are clear for certain missions and LightSail's success means we're much closer to, as Arthur C, Clarke put it, riding The Wind from the Sun. ®