Complex sentence: NASA officially suspended contact with ISEE-3 in 1997 and sent the shutdown command; though they discovered in 2008 that the probe had not actually shut down, NASA no longer had no means of communicating with it.
Split into simpler sentences: NASA officially suspended contact with ISEE-3 in 1997 and sent the shutdown command. In 2008 they discovered that the probe had not actually shut down, but NASA no longer had any means of communicating with it.