WASHINGTON — NASA’s International Earth/Sun Explorer (ISEE)-3 will not be resuming its original mission after all, now that citizen scientists and engineers striving to rescue it discovered July 9 that the old heliophysics observatory’s propulsion system is not working. 
 
 “There was no burn and we detected no acceleration and nothing was coming out of the engines,” NASAWatch.com Editor Keith Cowing, who spearheaded the ISEE-3 Reboot Project along with entrepreneur Dennis Wingo, said in a July 9 phone interview. 
 
 “We really can’t do anything,” Cowing said. 
 
 The widely read blogger spoke to SpaceNews after a failed attempt to complete the remaining engine burns that project officials thought would be required to send the spacecraft, currently in a heliocentric orbit, back toward the gravitationally stable Earth-sun Lagrange Point 1. From that position, the 1970s-vintage spacecraft was expected to be able to resume observations of solar winds breaking against Earth’s magnetosphere. 
 
 “We’ve done our best, but we’re now looking at a flyby,” Cowing said. Controllers at the ISEE-3 Reboot Project’s main ground system at the Arecibo radio observatory in Puerto Rico have switched the craft over into science mode, which will allow its instrument to collect and beam data back to Earth for as long as anyone is willing to listen for it. 
 
 Practically speaking, that will be about three more months, Cowing said. After that, the spacecraft will have traveled so far away from Earth that communicating with it will require receiving stations so large that the expense would simply not be worth it. 
 
 Before the July 9 attempt, the ISEE-3 Reboot Project thought it had a chance of completing its planned trajectory correction maneuver. The spacecraft’s small hydrazine thrusters were spun up July 3, and systems appeared nominal, Cowing said. On July 8, the spacecraft even managed to perform one of the six multipulse burns that would have set it up for a return to the orbit into which it was launched in 1978. 
 
 But further attempts to activate the thrusters July 8 proved unsuccessful, as were all attempts the following day. After eliminating a malfunctioning valve as the cause of the problem, the ISEE-3 Reboot Project was forced to conclude that the satellite’s hydrazine fuel simply was not being pushed through its plumbing at the right pressure to conduct a burn. 
 
 The thruster firings that occurred July 3 and 8 were “probably the result of residual hydrazine that was already in the system that had pressure,” Cowing said. “We were a little misled that we got this perfect burn.” 
 
 The ISEE-3 Reboot Project efforts were funded with $160,000 raised on the crowd-funding website RocketHub.com. Another fundraising drive likely would have been required for the citizen science campaign Cowing and Wingo were planning. 
 
 “We did stuff that was widely seen as impossible, improbable, and impractical,” Cowing said. “You need to focus on the absurd things that are possible.” 
 
 Follow Dan on Twitter: @Leone_SN 
 
 
 
 
 
 RELATED ARTICLES 
 
 First Effort To Bring Old NASA Heliophysics Bird Back to Earth Orbit Is Cut Short 
 
 ISEE-3 Propulsion System Awakens at 11th Hour 
 
 Clock Ticking on ISEE-3 Reboot Project 
 
 Volunteers Take Command of Old NASA Craft, Which Might Crash into Moon 
 
 NASA Blesses Volunteer Effort To Bring Vagabond Heliophysics Satellite Home 
 
 Fundraisers Expect Green Light from NASA To Recover ’70s-Vintage Spacecraft ||||| 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. 
 
 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. 
 
 Follow Elizabeth Howell @howellspace, or Space.com @Spacedotcom. We're also on Facebook and Google+. Original article on Space.com.
– A long-dormant satellite is heading back toward Earth this summer after 31 years, and some "citizen scientists" want to try to wake it up and put it back to work, reports Motherboard. Cash-strapped NASA hasn't shown much interest in investing money in the idea, hence the move toward crowdfunding to get the job done. The plan revolves around a satellite launched by NASA in 1978 called the International Sun-Earth Explorer, or ISEE-3. It was supposed to permanently hang out in the orbit between the sun and Earth to monitor solar wind, but another team at NASA sort of hijacked the satellite five years later to go comet-hunting. While ISEE-3 did great in its new duty, it had to leave its old orbit to do so and has been looping around the sun ever since. But the spacecraft makes a swing by Earth in August, raising the opportunity for its reboot—assuming all the technical logistics can be addressed. "In order to interact with the spacecraft we will need to locate the original commands and then develop a software recreation of the original hardware that was used to communicate with the spacecraft," explains that crowdfunding plea at Rockethub. A blog post at Planetary.org lays out the difficulties. Still, it's worth a shot, concludes Ben Richmond at Motherboard. "Given NASA's success rate at using spacecraft beyond their mission—the Voyagers, Kepler, etc— why not try to wake up the ISEE-3 and see what it's got left?"