The Last Hurrah of Solar Cycle 23 with Lessons for Solar Cycle 25

In the final throes of solar cycle 23, complex Active Region 10930 appeared at the solar east limb with virtually no warning on 5 December 2006. Over the next 10 days it erupted multiple times, producing four X-class and three M-class flares and numerous solar energetic particle (SEP) events. One of the flares permanently damaged a GOES X-ray imager. The interval was further punctuated with solar radio bursts that twice shut down the GPS system on the Sun-facing side of Earth. By the time the active region reached central meridian it was classified as a β-γ-δ region. Sequential eruptions on 13 and 14 December produced ground level event (GLE) # 70, and then a ‘perfect storm’ scenario with a fast coronal mass ejection from the first eruption reaching Earth while SEPs from the second eruption arrived. Simultaneously, space-walking astronauts were re-wiring the International Space Station to channel power from a new solar array. I will present lessons learned from the chain of events and discuss challenges to maintaining control of the ISS during the time frame.