After a week of tests on the end of the International Space Station's robotic arm, the Roll-Out Solar Array (ROSA) was safely jettisoned. While the rollable solar panel unfurled successfully at the beginning of the experiment, the ground operations team was unable to retract it to stow.

ROSA is a flexible, lightweight unit that could someday help power solar-electric propulsion spacecraft for journeys far beyond Earth. It was released yesterday (June 26) according to a procedure developed before the instrument flew, in case of this contingency, NASA officials said in a blog post. NASA also released a video of the release.

"Once jettisoned, ROSA will not present any risk to the International Space Station and will not impact any upcoming visiting vehicle traffic," they added.

If it had been retracted successfully, ROSA would have been stowed in the trunk of SpaceX's Dragon spacecraft, which departs the space station in a week. But it still wouldn't have made it back to Earth: Dragon's trunk will detach and burn up in Earth's atmosphere as the cargo spacecraft returns.

During the week-long experiment, crews on the ground monitored how well ROSA deployed, observing via video from the space station, as well as measuring its performance over the course of the week as the assembly moved through sunlight and shadow. Its re-rolling marked the end of the instrument's in-space test, according to NASA.

The space station crew is busy packing Dragon for its departure Sunday (July 2); the departing spacecraft will bring cargo and experiments back from the station to splash down in the Pacific Ocean about 5.5 hours after its 11:38 a.m. EDT (1538 GMT) release from the station.

Email Sarah Lewin at slewin@space.com or follow her @SarahExplains. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.