NASA's solar-sailing spacecraft has a bent boom and is still tumbling in Earth orbit (photo)

Four black and white photos showing closeup looks at a spacecraft in earth orbit.

NASA's technology-demonstrating Advanced Composite Solar Sail System (ACS3) has a bent boom in Earth orbit, a newly released photo shows.

The ACS3 spacecraft launched April 23 to test key aspects of solar sailing, a next-gen propulsion strategy NASA thinks could greatly advance our exploration of the solar system. Solar sails harness the momentum of photons, using their subtle but constant push to cruise through the heavens like a boat through the ocean, without the need for propellant.