On Wednesday, May 21, it was announced that NASA gave a group of citizen scientists permission to contact the long-defunct International Sun-Earth Explorer-3 (ISEE-3) spacecraft in order to accomplish an extended science mission. In an unprecedented move, NASA signed a Non-Reimbursable Space Act Agreement with Skycorp, Inc., a company based in Los Gatos, Calif., which would allow them to “possibly command and control” the spacecraft, according to NASA. This is the first time the agency has signed such an agreement concerning a decommissioned spacecraft.
ISEE-3’s story began nearly four decades ago, before space shuttles were even a reality. The spacecraft was launched on Aug. 12, 1978, by a Delta 2914 rocket from the Cape Canaveral Air Force Station. The spacecraft went on to accomplish many firsts in spaceflight history. It was the first satellite to be placed in a “halo orbit” at the L1 Sun-Earth Lagrangian point; this allowed the satellite to investigate our planet’s interactions with solar wind. (The L1 point is where gravitational forces of the Sun and the Earth-Moon system balance out.) The initial science mission was performed by NASA and ESRO/ESA, hence the “international” moniker; it had two “sister” spacecraft, ISEE-1 and ISEE-2.
In 1982, ISEE-3 began its secondary science mission and was rechristened the International Cometary Explorer (ICE). In 1985, it became the first spacecraft to encounter a comet, when it passed through the tail of Comet Giacobini-Zinner; in 1986, it went on to transit between the Sun and Comet Halley. According to NASA, after being employed to accomplish a heliospheric mission in conjunction with “ground-based observations, continued cosmic ray studies, and special period observations such as when ICE and Ulysses [were] on the same solar radial line,” operations were ended on May 5, 1997. Its operational life was to span 10 years; it had survived for 19. Despite the spacecraft being retired, a 1999 status check revealed that nearly all of the satellite’s experiments were still operational, and it had leftover propellant.
However, this spacecraft’s life may have not ended 17 years ago. This year, ISEE-3 will make a close approach to Earth, which spurred the interest of Skycorp’s team of scientists and engineers. Due to budgetary constraints, reactivating ISEE-3 for an extended mission was not a priority for NASA, but Skycorp began a crowd-sourcing initiative to cover the cost of writing software and synthesizing hardware to contact the spacecraft. Interest in the project built, and, as of writing this, Skycorp has raised $159,602 (its initial goal was $125,000).
John Grunsfeld, former astronaut and current associate administrator for the science mission directorate at NASA, communicated his enthusiasm for this unique project.
“The intrepid ISEE-3 spacecraft was sent away from its primary mission to study the physics of the solar wind extending its mission of discovery to study two comets. We have a chance to engage a new generation of citizen scientists through this creative effort to recapture the ISEE-3 spacecraft as it zips by the Earth this summer,” he related.
However, some roadblocks remain for the ISEE-3 reboot team. On the crowd-sourcing website, the team announced: “ … During our listening sessions at Arecibo [Observatory, in Puerto Rico] the other day it became clear to us that the ISEE-3 spacecraft is not exactly where JPL’s database said it would be. After several decades, this is understandable. By adjusting the big dish we determined that the spacecraft is roughly 250,000 km from where is should be. Given that it is already on a lunar flyby trajectory – a close one at that – the error is such that there is a chance that it could hit the Moon – unless we fire the engines – and do so rather soon.”
The team intends to put the spacecraft back at the L1 Lagrangian point, taking it back to its 1978 roots. If successful, ISEE-3’s instruments will be made operational as originally designed, in hopes that it may chase another comet. According to the project’s website, the orbital maneuvers must be made no later than late June. In addition, if reactivated successfully, the spacecraft will be monitored concerning the effects of long-term exposure to the environment of space.
While ISEE-3 may have ended its primary and secondary missions long, long ago, the coming month will show whether this dauntless spacecraft still has some life in it yet. What a long, strange trip it’s been. …