Potential next step in space travel gets deployed
The ability to sail across the cosmos, powered by the energy of the sun, is finally becoming a reality.
Engineers in California pressed a button on Tuesday that unfurled the sail on a satellite that can be steered around Earth, advancing long-held hopes for an inexhaustible form of spaceflight and expanding the possibilities for navigating the voids between worlds.
For centuries, it was only a dream: traveling through space propelled by the solar wind. It was first imagined in the 1600s, and Carl Sagan, the cosmologist, believed it could be more than a speculative fantasy and in the 1970s began promoting the building of solar sails for space exploration.
After 10 years of planning and more than 40,000 private donations worth $7 million, that idea took flight Tuesday, as Lightsail 2, a spacecraft built for the Planetary Society cofounded by Sagan, began what its creators hope will be a year of sailing around Earth.
“This is still one of the most feasible pathways to have real interstellar space travel in the future,” said Sasha Sagan, a writer as well as the daughter of the astronomer.
If it succeeds in its mission, it will contribute to overcoming one of the greatest limitations on the outer bounds of space travel — that the power that steers spacecraft, usually hydrazine fuel, eventually runs out.
In contrast, the sun is a source of constant energy. It is always releasing photons into space. Although these particles don’t have mass, they have momentum. Solar sailing relies on the ever-sogentle nudge of photons to push a sail forward, moving whatever is attached to the sail in the desired direction.
Other fuel sources, such as solar power and ion propulsion, can power spacecraft for decades, but solar sailing could eliminate their need for fuel.
Lightsail 2, a cubesat that is about the size of a loaf of bread, was launched last month by a Spacex Falcon Heavy rocket and has since been orbiting Earth while its managers on the ground prepared to unfurl its sails like a space-lotus.
The sail is formed by four triangular sheets of extremely thin, reflective Mylar that form a square totaling 344 square feet.