Internationally-renowned photojournalist Gerd Ludwig has spent years documenting the aftermath of the Chernobyl nuclear disaster. In 1986, errors at the plant in Ukraine led to an explosion that ultimately caused over a quarter of a million people to permanently evacuate their homes to escape the radiation and radioactive fallout. Over the course of several trips to the site and the region for National Geographic Magazine in 1993, 2005, and 2011, Ludwig has amassed a documentary record of a people and a place irreparably altered by a tragic accident. His 2011 trip was partially funded by a Kickstarter campaign. Now Ludwig has released an iPad app with over 150 photographs, video, and interactive panoramas.