As we recently reported, we are getting telemetry from ISEE-3 indicating that its entire suite of science instruments is powered up and has been powered up since NASA last commanded the spacecraft many years ago. We are getting data back from the magentometer that indicates that science data is coming back. We now have a growing team of former ISEE-3 investigators, their colleagues, and successors working to make sense of what the spacecraft is sending back.
Just because an instrument is powered up doesn’t mean that it is functioning normally – just that it is powered up. Based on some historical references, some of the ISEE-3 instruments had begun to fail or become partially functional as early as 1982. See “Data from ISEE-3 for the IMS Period“, T.T. Rosenvinge, The IMS Source Book AGU, 1982. (click on image to enlarge) By 1993, the Cosmic Ray Isopes experiment was having significant issues according to “Cosmic Ray Composition Investigations using
ICE/ISEE-3“, M.E. Wiedenbeck, Final Technical Report, NASA-CR-192808, 1993.
Given that so many other things on board ISEE-3 have been operating since 1978 and are still doing quite well, it would not be at all surprising if some of the science package remains operational as well. We’ll be posting updates on the science instruments soon.