In 2014, a team of independent scientists, engineers, and programmers successfully reactivated NASA’s long-retired ISEE-3 probe, firing its thrusters for the first time in 27 years—but a critical maneuver to return it to an Earth-Sun observation point failed due to depleted nitrogen for its propulsion system.
The ISEE-3/ICE mission, originally launched in 1978, was a pioneering effort to study the sun-Earth relationship and comets. Initially named ISEE-3, the spacecraft was later renamed the International Cometary Explorer (ICE) after a series of complex lunar flybys redirected it to encounter Comet 21P/Giacobini-Zinner in 1985. This encounter confirmed that comets are dirty snowballs
, a key finding that shaped planetary science.
ISEE-3 was designed to investigate the solar wind and Earth’s magnetosphere. After its primary mission, NASA redirected the spacecraft through Earth’s magnetic tail and toward a comet, a maneuver that required five lunar flybys. By 1985, ICE became the first spacecraft to fly past a comet, flying within 7,862 kilometers of Comet Giacobini-Zinner’s nucleus. The data it collected, including measurements of plasma and magnetic fields, provided critical insights into comet composition and solar wind dynamics.
ISEE-3/ICE – NASA Science
The spacecraft’s trajectory eventually placed it in a heliocentric orbit, where it continued to transmit data until NASA terminated operations in 1997. Despite this, ISEE-3 remained active, its transmitter left on for tracking. By 2014, its path brought it back toward the Earth-Moon system, creating a narrow window for reactivation.
The ISEE-3/ICE mission was part of a joint program between NASA and the European Space Agency (ESA). NASA built the first and third spacecraft while ESA built the second. The three spacecraft were to simultaneously investigate a wide range of phenomena in interplanetary space. ISEE-3 was launched on August 12, 1978, aboard a Delta 2914 (no. 144 / Thor no. 633) rocket from Cape Canaveral, Fla., Launch Complex 17B. Its mass was 1,056 pounds (479 kilograms), and it carried 14 scientific instruments, including the Solar Wind Plasma Detector, Vector Helium Magnetometer, and Energetic Particle Anisotropy Spectrometer (EPAS).
Key milestones in ISEE-3’s history include its entry into a halo orbit at the Sun–Earth L1 Lagrange Point on November 20, 1978, and its movement into Earth’s magnetic tail on June 10, 1982. On September 11, 1985, it became the first spacecraft to fly past a comet, passing within 7,862 kilometers of Comet Giacobini-Zinner. In 1986, it provided solar wind data on Halley’s Comet before NASA terminated operations on May 5, 1997. The spacecraft continued in heliocentric orbit, with its transmitter left active for tracking.
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In 2014, a group of independent engineers, scientists, and programmers led by Keith Cowing and Dennis Wingo sought to reestablish contact with ISEE-3. With NASA’s permission, the ISEE-3 Reboot Project used modern software-defined radio technology and global radio telescopes to communicate with the spacecraft. On July 2, 2014, the probe fired its hydrazine thrusters for the first time in 27 years, restoring its spin stability. However, a larger maneuver to adjust its trajectory for an Earth-Sun observation point failed. Telemetry indicated that the spacecraft had lost the nitrogen gas needed to pressurize its fuel system, preventing the thrusters from receiving propellant.
The reboot team’s success in reestablishing communication demonstrated the potential for private initiatives to extend the life of aging space assets. However, the inability to fully restore ISEE-3’s mission underscored the technical and logistical hurdles of such efforts. The spacecraft’s original design, developed in the 1970s, lacked modern redundancies and had no built-in mechanisms for long-term reactivation. NASA’s decision to terminate support in 1997 reflected the agency’s focus on active missions, but it left the spacecraft’s fate in the hands of future opportunities.
The 2014 effort, funded by public crowdfunding, became a landmark example of grassroots space exploration. Despite the partial success, the mission’s limitations were clear. The spacecraft’s systems, including its propulsion and communication equipment, were not designed for such a long-term hiatus. The failure of the 2014 maneuver meant ISEE-3 remained in a heliocentric orbit, unable to resume its original scientific role.
Citizen scientists revived NASA’s long-retired ISEE-3 probe in 2014
The story of ISEE-3/ICE and its 2014 reboot highlights the enduring value of legacy space missions and the growing role of citizen scientists in space exploration. While the probe’s future remains uncertain, its history and the 2014 effort have inspired new approaches to spacecraft longevity and public-private collaboration in space science. NASA’s ISEE-3/ICE mission details and the 2014 reboot effort provide further context on this unique chapter in space history.
ISEE-3’s original mission included conducting the first deep survey of Earth’s magnetic tail and supporting the theory that comets are dirty snowballs.
Its observations contributed to the understanding of the solar wind and its interaction with planetary magnetospheres. The spacecraft’s journey from the L1 Lagrange Point to a comet encounter and its eventual return to heliocentric orbit marked a series of firsts in space exploration. The 2014 reboot attempt, though limited, showcased the resilience of both the spacecraft and the teams dedicated to its revival.
On July 8, 2014, the ISEE-3 Reboot Team attempted a longer thruster firing to reshape the spacecraft’s path through the Earth-Moon system. This maneuver failed, with telemetry indicating that the spacecraft had lost nitrogen gas used to pressurize its propulsion system. Despite this, the team successfully communicated with the probe and gathered data, demonstrating the feasibility of reactivating aging spacecraft. The effort also highlighted the challenges of operating a 1970s-era probe without original command infrastructure.
ISEE-3’s trajectory after the 2014 attempt brought it close to the Moon on August 10, 2014, and it continued in heliocentric orbit. The spacecraft’s legacy endures through its contributions to solar and planetary science, as well as its role in inspiring future missions. The ISEE-3 Reboot Project’s work remains a testament to the potential of collaborative, non-traditional approaches to space exploration.