carl sagan talked about a visionary mission using a solar sail, which is pushed through space by nothing but sunlight. it never flew, so today, 39 years later, the planetary society, i'm very proud to say, is launching our lightsail spacecraft. thank you all very much. here you go, jeff. so in 2005, we launched the first solar sail spacecraft, and it crashed. if this doesn't work, i'll be very disappointed. [cheering] this chemical reaction is making water vapor. yes. nye, voice-over: we believe that by the successful launch of our lightsail spacecraft, we will advance space science for the betterment of human kind. man on phone: indications are that an rf signal is being received. that would indicate that the antenna deployed successfully. awesome news. nye, voice-over: you and i are made of the dust of exploding stars, we are stardust, and so we are at least one way that the universe knows itself. that fills me with reverence. that is astonishing. [applause] if the past few decades have taught us anything, it's that science alone isn't enough to combat climate change. in fact, science