It was one of three spacecraft, along with the mother/daughter pair of ISEE-1 and ISEE-2, built for the International Sun-Earth Explorer (ISEE) program, a joint effort by NASA and ESRO/ESA to study the interaction between the Earth's magnetic field and the solar wind.

[5][6] On 29 May 2014, two-way communication with the spacecraft was reestablished by the ISEE-3 Reboot Project, an unofficial group,[7] with support from the Skycorp company and SpaceRef Interactive.

[11][12] The project team initiated an alternative plan to use the spacecraft to "collect scientific data and send it back to Earth",[13] but on 16 September 2014, contact with the probe was lost.

ISEE-3 originally operated in a halo orbit about the L1 Sun-Earth Lagrange point, 235 Earth radii above the surface (about 1,500,000 km (930,000 mi).

It was the first artificial object placed at a so-called "libration point",[15] entering orbit there on 20 November 1978,[2] proving that such a suspension between gravitational fields was possible.

[16] Fifteen propulsive maneuvers and five lunar gravity assists resulted in the spacecraft being ejected from the Earth-Moon system and into a heliocentric orbit.

It defines a heliospheric mission for ICE consisting of investigations of coronal mass ejections in coordination with ground-based observations, continued cosmic ray studies, and the Ulysses probe.

It was determined to be possible to reactivate the spacecraft in 2014,[22] when it again made a close approach to Earth, and scientists discussed reusing the probe to observe more comets in 2017 or 2018.

A team webpage said, "We intend to contact the ISEE-3 (International Sun-Earth Explorer) spacecraft, command it to fire its engine and enter an orbit near Earth, and then resume its original mission...

[24] On 15 May 2014, the project reached its crowdfunding goal of US$125,000 on RocketHub, which was expected to cover the costs of writing the software to communicate with the probe, searching through the NASA archives for the information needed to control the spacecraft, and buying time on the dish antennas.

[31] They obtained the needed hardware, an off-the-shelf SDR transceiver,[32] and power amplifier,[33] and installed it on the 305 m (1,001 ft) Arecibo dish antenna on 19 May 2014.

[33][34] Once they gained control of the spacecraft, the capture team planned to shift the primary ground station to the 21 m (69 ft) dish located at Morehead State University Space Science Center of Kentucky.

[40][41] On 8 July 2014, a longer sequence of thruster firings failed, apparently due to loss of the nitrogen gas needed to pressurize the fuel tanks.

Instead, the team said, the ISEE-3 Interplanetary Citizen Science Mission would gather data as the spacecraft flies by the Moon on 10 August 2014 and enters a heliocentric orbit similar to Earth's.

With five of the 13 instruments on the spacecraft still working, the science possibilities included listening for gamma-ray bursts, where observations from additional locations in the Solar System can be valuable.

The spacecraft's post-lunar flyby orbit takes it further from the Sun, causing electrical power available from its solar arrays to drop, and its battery failed in 1981.