Humanity is about to return to the hottest planet in the solar system. BepiColombo is a mission to Mercury conducted jointly by the European and Japanese space agencies, due to launch from French Guiana at 6:45 PM Pacific time tonight aboard an Ariane 5 rocket. But while there’s just the one launch, there are two spacecraft. The broadcast starts at 6:15; you can watch the launch at this link or the bottom of this post. The last time we visited Mercury wasn’t actually that long ago.