On November 5th, 2016 Stanford Student Space Initiative's Balloons Team launched a High Altitude Balloon named ValBal, short for "Valve-Ballast" - a novel platform that utilizes a gas venting valve and a ballast dispenser to zero its ascent rate and maintain a nearly constant altitude. Conceived in the winter of 2014, ValBal has been in development and testing for over a year and a half. This November, ValBal broke the world record for the longest duration flight of a latex balloon, flying from Modesto, CA to the outskirts of Quebec City, Canada.
This flight of more than 79 hours adds almost 10 hours to the previous world record, also set by SSI with an earlier version of ValBal in June of 2016. The ValBal platform is capable of autonomous and dynamic altitude control, a significant improvement over the passive control employed by the previous record holders. This capability allows ValBal to carry kilogram-scale research payloads for extended periods in the upper atmosphere, which SSI hopes to begin flying next year. The team will be presenting their work at the 2017 IEEE Aerospace Conference in March, 2017.