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Radio Amateurs Are Key Players in Effort to Maneuver 36-Year-Old NASA Spacecraft


Not even an earthquake kept the ISEE-3 Reboot Project from contacting the 36-year-old International Sun-Earth Explorer 3 spacecraft — later repurposed, redirected, and renamed the International Cometary Explorer (ICE) —on May 29 from the Arecibo Observatory in Puerto Rico. ISEE-3 Reboot Project is a private crowd-funded group of engineers, programmers, and scientists — including several radio amateurs — that is trying to fire the old spacecraft’s engines to redirect its path. And that has to happen by June 17, according to Dennis Wingo, KD4ETA, one of the team members and the CEO of California-based Skycorp Incorporated. Wingo has not ruled out the possibility that ICE could crash into the moon, but just commanding one of the spacecraft’s transponders on 2.042 GHz by radio marked a major milestone.

“[W]e have successfully contacted the bird!” Wingo enthused in a June 1 project update. Wingo was at Arecibo Observatory on May 29 when the magnitude 5.8 earthquake rattled the region. “I was on the central part of the Arecibo dish, 450 feet in the air…when it happened,” he said. “We had just chatted about how observations could be affected by vibrations in the dome structure…and then that happened! The azimuth tracking system…was slewing while we were there, as well as the dome.” Wingo said he and his colleagues were in a safe area when the earthquake occurred.

Surviving the earthquake experience aside, Wingo said, the “first miracle” was to command the spacecraft. The second task was to interpret data received back from ICE. The group is hoping to place ICE into a gravitationally stable spot some 930,000 miles from Earth — essentially its original orbit — where it could again study the effects of solar weather on Earth's magnetosphere (the project’s slogan is “Make me do science again!”). But, it has a lot of work to do before that is possible. The private group has obtained NASA’s approval to communicate with the satellite.

“One of the major problems that we have…is to update the range to the spacecraft, so that its position, velocity, and trajectory into the Earth-Moon system can be properly plotted,” Wingo said. If the team can fire the spacecraft’s thrusters this month, ICE will fly by the moon at an altitude of some 50 km on August 10. Wingo said the last trajectory solution from NASA’s Deep Space Network dates back to 2001, and it has been shown to be inaccurate when using the very narrow beamwidth signal from Arecibo.

“It is imperative that we get a ranging pass as soon as possible,” Wingo stressed. In the days ahead, the team also needs to evaluate the spacecraft’s health and analyze its propulsion and attitude-control systems, among other tasks.

Newer digital signal processing (DSP) techniques have made it possible to develop and apply software solutions to address problems that would have required extensive hardware a decade earlier. The project has purchased DSP peripherals from Ettus Research, founded by Matt Ettus, N2MJI, to implement modulator and demodulator programs.

Other team members have been working from the AMSAT-DL (Germany) Bochum facility. They include Achim Vollhardt, DH2VA, Thilo Elsner, DJ5YM, and Mario Lorenz, DL5MLO. More information and updates are available on the ISEE-3 Reboot Project Facebook page and the ISEE3 Returns Community Facebook page. The project also has a ISEE-3 Reboot Project Google+ page.





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