It is not NASA commanding the spacecraft now, but a group of civilians working in a former McDonald’s in California taking advantage of technological goodies of the 21st century, including Skype, Twitter, laptop computers and crowdsourcing.

ISEE-3 is still about three million miles away, but is closing in quickly on Earth’s neighborhood. It will pass close to the moon next month, and if the team can complete the course correction, the pull of the moon’s gravity will sling ISEE-3 into orbit around Earth, where it will await commands for a new mission.

Launched in 1978, the craft made some of the first measurements of the solar wind — the stream of particles ejected from the sun — before it reached Earth.

A few years later, ISEE-3 was redirected to fly through the tail of Comet Giacobini-Zinner. Then, in 1986, it was put on a course toward home. NASA, however, retired the spacecraft in 1997 and soon after dismantled the transmitters that could talk to it. As ISEE-3 approached, the agency decided it would be too expensive to build new transmitters to get back in touch.

Mr. Cowing, the editor in chief of the website NASA Watch, and Dennis Wingo, an engineer and entrepreneur, jumped in to fill the void. A crowdfunding campaign raised nearly $160,000. In May, they re-established communications with the spacecraft. NASA agreed to help, offering time on its Deep Space Network of radio telescopes to fine-tune measurements of the spacecraft’s trajectory.