Then ISEE-3 was recruited to a different mission. With a serpentine do-si-do around the moon and Earth, it was aimed at Comet Giacobini-Zinner, passing through the tail in September 1985.

NASA used ISEE-3 for a few more observations of interplanetary space before retiring it in 1997. Since then, the craft has been looping around the sun on a 355-day orbit. Like a faster racecar lapping the rest of the field, ISEE-3 will catch up to and pass Earth in two months.

That is exactly what Robert W. Farquhar, the craft’s flight director, intended.

Dr. Farquhar, known for devising clever ways to move a spacecraft from Point A to Point B, came up with the intricate orbits that moved ISEE-3 to various locations in the solar wind, and then with the idea of using ISEE-3 to visit Giacobini-Zinner.

That angered the solar scientists, who accused him of stealing their spacecraft. But Dr. Farquhar won the support of NASA leaders. He also said he was just borrowing the craft and would return it.

After the successful Giacobini-Zinner flyby, ISEE-3 still had ample fuel, so three rocket burns in 1986 set it on a course to zoom about 30 miles above the surface of the moon 28 years later, on Aug. 10, 2014. The gravitational pull of the lunar flyby would swing ISEE-3 into orbit around Earth. Dr. Farquhar suggested that a space shuttle could bring it to the ground. NASA even signed an agreement to donate the craft to the National Air and Space Museum.

The rest of NASA, however, was not looking that far ahead.

In 1999, the agency upgraded its Deep Space Network, the system of radio telescopes that communicates with distant space probes. The old transmitters that could talk with ISEE-3 were thrown away.