'Solar Impulse 2' completed its circumnavigation of the planet, which included a flight over Giza's pyramids, in 2016. Credit: Jean Revillard / Solar Impulse 2 via Getty Images Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. The groundbreaking experimental aircraft known as Solar Impulse 2 has met an untimely end. According to a National Transportation Safety Board report , the completely solar-powered plane crashed into the Gulf of Mexico during an autonomous test flight on May 4. While there were no injuries or fatalities, the wreck of the Solar Impulse marks an unfortunate end for one of the most impressive and inspirational planes in aviation history. Solar Impulse was first conceptualized in 2003 by Bertrand Piccard, the grandson of Swiss deep sea pioneer Auguste Piccard and the son of Jacque Piccard, the first person to reach the Mariana Trench.…