WASHINGTON — Rebounding from a failed attempt the day before, an all-volunteer team managed July 2 to activate the propulsion system on NASA’s International Sun-Earth Explorer (ISEE)-3 , setting the stage for a down-to-the-wire attempt to return the vagabond spacecraft to Earth-sun Lagrange Point 1.

With the old spacecraft’s propulsion system functioning, and with the spin-balanced satellite now rotating at the correct rate for a planned trajectory correction in mid-July, the ISEE-3 Reboot Project led by serial space entrepreneur Dennis Wingo and NASAWatch.com editor Keith Cowing is rushing to prepare for a second engine burn that will send ISEE-3 flying by the Moon for a gravity assist designed to knock the craft out of its heliocentric orbit and back toward the stable storage orbit it left in 1982 to chase comets.

Time is of the essence. If the ISEE-3 Reboot Team misses its window, the spacecraft will hurtle back out into space, not to return for thousands of years.

Wingo, reached by email July 2, said ISEE-3 is now spinning at 19.76 revolutions per minute, up from the 19.16 revolutions per minute it was making prior to the 11 combined pulses its two hydrazine thrusters made in the July 2 spin-up maneuver. 

Wingo and Cowing are now rushing to put paperwork together to show NASA the spacecraft’s engines are functioning as intended, and that the team is ready to reel ISEE-3 back to Earth-sun Lagrange Point 1 to resume observation of solar winds — charged particles emitted in bursts from the sun.

NASA officials and ISEE-3 Reboot Project representatives are scheduled to meet the week of July 7, when the team will ask the agency for an all-clear to bring the spacecraft home.

“They want approval to do a trajectory maneuver in the next couple of weeks,” Geoffrey Yoder, NASA’s associate administrator for programs, said in a July 1 phone interview.

Yoder, chief government gatekeeper for the ISEE-3 Reboot Project under a Space Act Agreement inked May 19 with Wingo’s company Skycorp Inc. of Los Gatos, California, said the team must demonstrate not only that the satellite’s propulsion system works but that there is a real plan for science operations. 

That plan, Yoder said, should include not only technical things such as end-of-mission spacecraft shutdown procedures but also the ISEE-3 Reboot Project’s strategy for education and public outreach — the same sort of plan a new NASA science mission would have to draw up before receiving authorization to proceed. 

“So far they’re doing pretty much what they said,” Yoder told SpaceNews. “It’s not easy for them; they’re working hard.”

On July 1, the ISEE-3 team struggled to communicate with the faraway spacecraft as it flew over its main ground station at the Arecibo radio observatory in Puerto Rico.

“The spacecraft has taken more than five times its design radiation dose,” Wingo wrote in a July 1 email. “The receiver on transponder A has problems locking to our transmitted signal.”

If ISEE-3 makes it back to Earth-sun Lagrange Point 1, Cowing and Wingo plan to command the spacecraft from mission control McMoons: an abandoned McDonald’s on the Campus of NASA’s Ames Research Center in Mountain View, California. Besides raking in more heliophysics data, Cowing and Wingo want to give the general public, students in particular, a chance to learn firsthand about Earth-sun interactions, and spacecraft operations. 

That will likely require another crowdfunding campaign, Cowing has said. Just to scrape together the equipment, personnel and operating budget required to reactivate the spacecraft — which NASA shut down in 1997 — the ISEE-3 Reboot Project raised some $160,000 from about 2,200 donors on RocketHub.com. The monthlong fundraising campaign wrapped up May 23.

Follow Dan on Twitter: @Leone_SN

Dan Leone is the NASA reporter for SpaceNews, where he also covers other civilian-run U.S. government space programs and a growing number of entrepreneurial space companies. He joined SpaceNews in 2011.Dan earned a bachelor's degree in public communications...