Engineers at Cal Poly San Louis Obispo test the LightSail's solar sail deployment. Credit: The Planetary Society

WASHINGTON — Despite earlier optimism, the Planetary Society postponed the planned June 5 deployment of the LightSail spacecraft’s solar sail after communications with the craft fell silent for the second time June 4. 

Jason Davis, a spokesman for the Pasadena, California-based Planetary Society, said late Thursday evening that LightSail’s batteries are struggling to store power. The craft likely entered a safe mode-like state in order to protect its electronics, he said. 

Mission manager David Spencer wrote the afternoon of June 3 that the team observed a problem with LightSail’s batteries after the craft’s hinged side solar panels opened to make way for the possible deployment of the craft’s solar sail.

“Following solar panel deployment,” Spencer wrote, “it was noticed that all of the battery cells were drawing near zero current. This indicated that the batteries were likely in a fault condition stemming from the solar panel deployment event.”

The ground station last heard form LightSail June 3 at 4:40 p.m. EDT. 

“When contact with LightSail is reestablished,” Davis said, “the sail deployment sequence will likely be triggered as soon as battery levels are heathy enough to proceed.”

LightSail first went silent May 22 after a software glitch crashed the computers just two days after after a successful deployment from the Atlas 5  rocket launched the U.S. Air Force’s X-37B. On May 31 ground stations reestablished contact with the spacecraft. A cosmic ray had hit the LightSail, causing the computer to reboot.

When the LightSail project began in 2009, San Luis Obispo, California-based Stellar Exploration, Inc. was in charge of building the craft. But in 2014 Ecliptic Enterprises Corp. took over the integration and testing of LightSail, working out of Cal Poly San Luis Obispo. Borealis Space also worked on LightSail as a subcontractor to Ecliptic.

The project is crowdfunded on Kickstarter with the help of the Planetary Society’s chief executive, Bill Nye, who is known to millions thanks to his long-running television show “Bill Nye the Science Guy.”

If LightSail manages wake up and deploy its sails, the Planetary Society will be be in a good position for the launch of its next solar-sail vehicle in 2016 aboard SpaceX’s Falcon Heavy rocket. This vehicle will be put in a higher orbit that the current one, allowing it to use the solar sail for propulsion unencumbered by Earth’s atmospheric drag.

Jonathan Charlton is a editorial intern who has been logging a bunch of solo hours at the controls of The Boston College senior is majoring in political science with a minor in hispanic studies.