Ikaros is hitching a ride into space aboard an H-IIA rocket, piggybacking with JAXA's Akatsuki Venus Climate Orbiter mission.

Once in space, the cylindrical, 677-pound (307-kilogram) craft will separate from the rocket and spin itself to unfurl its roughly 46-foot-wide (14-meter-wide) solar sail. (Related blog: "Tiny Solar Sail Pitched to Clean Up Space Junk.")

First proposed in the 1920s, solar sails are large reflective membranes that allow a spacecraft to be pushed by radiation pressure from sunlight, negating the need for heavy onboard fuel. (Explore a time line of space travel milestones.)

"It's the space equivalent of a yacht sailing on the sea," said