Private Team's Attempt to Move Vintage NASA Probe Hits Snag

International Sun-Earth Explorer-3 (ISEE-3)
This artist's rendition shows the International Sun-Earth Explorer-3 (ISEE-3) spacecraft, the which later became Interplanetary Cometary Explorer. A private team, called the SEE-3 Reboot Project, is hoping to restart the 36-year-old spacecraft's engines for a new science mission. (Image credit: NASA)

The quest to rescue a 36-year-old NASA spacecraft will go on for at least another day, as a private group controlling the probe achieved only partial success with an engine firing Tuesday (July 8).

The private team operating NASA's International Sun-Earth Explorer 3 spacecraft (ISEE-3) aimed to fire its engine numerous times to change the probe's trajectory and put it in a more stable position for communicating with Earth. But things did not go exactly as planned.

"The first segment was full duration but only partially successful," Keith Cowing, co-leader of the ISEE-3 Reboot Project, wrote in a blog post Wednesday (July 9). "The second and third attempts failed. Possible causes (under investigation) include valve malfunction and fuel supply issues."

Controllers in California, who are beaming commands to ISEE-3 via the Arecibo Observatory in Puerto Rico, tried the burns several times. After resetting the spacecraft and sending more commands, they stopped work for the day when their "window" of communication closed.

They noted that ISEE-3's thruster valve was opening and closing as expected, but the spacecraft wasn't accelerating.

"Either we are low on fuel in System A, or latch valve A is not working," the group said via Twitter, adding that the sun guidance sensor and accelerometers were not showing thrust.

"The ISEE-3 team is working [on] a strategy for tomorrow's pass. More to follow," the team concluded late Tuesday night.

The private group took control of the spacecraft several weeks ago after raising more than $150,000 via crowdfunding and obtaining permission from NASA, which retired the spacecraft in 1997. ISEE-3 launched in 1978 and worked as a comet chaser and sun probe, among other roles.

The team has not yet determined what to do next with ISEE-3 next, focusing first on making sure the spacecraft can consistently communicate with Earth. The clock is ticking for the Reboot Project to change ISEE-3's trajectory; Cowing has said that fuel consumption will become an issue by late July.

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Elizabeth Howell
Staff Writer, Spaceflight

Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, "Why Am I Taller?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: