WASHINGTON — An attempt to divert NASA’s venerable International Earth/Sun Explorer (ISEE)-3 satellite back toward Earth was suspended due to technical issues early July 8, but the all-volunteer team seeking to resurrect the 1970’s-era heliophysics mission expects to try again July 9. 

The ISEE-3 Reboot Project, led by space entrepreneur Dennis Wingo and NASAWatch.com editor Keith Cowing, must put the craft through a series of seven engine burns, each involving multiple pulses of its hydrazine-fueled thrusters, in order to nudge the satellite out of its heliocentric orbit and send it toward the gravitationally stable Earth-Sun Lagrange Point 1. 

“We did not do all seven segments today,” Cowing said in a July 8 phone interview. “We did one. We were going to try to do all seven today, but we originally figured this would take us three days, anyway.”

What happened was not immediately clear, Cowing said. One moment, the spacecraft was firing its thrusters as planned; the next, it did nothing at all. Leading theories are that a valve in the satellite’s fuel plumbing malfunctioned, or that hydrazine fuel delivered from the tank is not feeding through at the correct pressure.

ISEE-3 has two redundant sets of fuel plumbing, Cowing said, so in a worst case scenario, the ISEE-3 Reboot Project will command the satellite to switch to the backup system. 

The team will take another crack at its trajectory correction maneuver July 9, Cowing said. However, the clock is ticking, and the ISEE-3 Reboot Project must to get the spacecraft cruising back toward Earth soon, or retrieval may prove impractical.

“I can’t tell you exactly when it’s a no-go,” Cowing said. “If we’re towards the end of the month and we haven’t fired, then it starts to become an issue. August is problematical.”

ISEE-3 comes within range of its main ground station, the Arecibo radio astronomy observatory in Puerto Rico, for about three hours a day.

The Reboot Project aims to put ISEE-3 back into its original orbit to allow citizen scientists to resume the craft’s observations of solar winds breaking against the outer edge of Earth’s magnetosphere. The project is based at an abandoned McDonald’s restaurant on the campus of NASA’s Ames Research Center in Mountain View, California. 

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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...