Student engineers from ETH Zurich are preparing to fly their world-record breaking solar plane over the Amazon rainforest.The team is fitting its AtlantikSolar unmanned aerial vehicle (UAV) for a 400 kilometer, 12 hour, flight as it seeks to push the endurance limits of solar planes.The fixed-wing 6.8 kilogram AtlantikSolar will be fitted with a variety of cameras and atmospheric sensors.AtlantikSolar's most recent landmark was achieved while carrying no payload this July. The team broke the flight endurance world record for any aircraft below 50 kilograms by flying continuously on solar powered batteries for 81.5 hours (over four days and three nights) in Zurich. The flight was also the longest-ever continuous flight of a low-altitude long-endurance (LALE) aircraft, the second-longest flight ever demonstrated by a UAV, and the third-longest flight ever demonstrated by a solar airplane. In addition, it was the fifth-longest flight ever demonstrated by any aircraft, both manned and unmanned.Team member Philipp Oettershagen, a PhD student, insisted that the concept of solar planes is relatively simple."In general it's a very simple thing," said Oettershagen. "What you have is batteries, very energy-dense batteries, and solar modules and the whole concept is that the battery basically gets recharged over the day and then supplies the whole energy during the night. That's the basic concept behind all these vehicles and then you basically have a standard configuration airplane that flies in that case autonomously, meaning that you have the autopilot that takes over the functions from the actual pilot." The team's ultimate aim is to prove solar planes worthy for use in large-scale disaster-scenarios or providing live-imagery during industrial sensing and inspection missions.According to Oettershagen, "What you want to have is a long flight endurance, so you want to be able to map the whole area and specifically a large area over a long time, in order to basically provide the rescuers with up-to-date imagery or, for example, information about obstructed roads, potential victims, etc - and because we need this long flight endurance we've decided to go into solar powered unmanned aerial vehicle research; the solar power giving us the long flight endurance and the unmanned aerial vehicles - so the autonomy of these systems - giving us ease of use of the systems in a lot of these different search and rescue scenarios." The AtlantikSolar project began a decade ago, led by Roland Siegwart, professor of autonomous systems. "We are now at a stage where we have built a couple of these airplanes where we are doing testing because the second goal is that they can fly at low altitude, close to the ground, so that they can perceive the ground with on-board cameras and then actually build a 3D map and then also do collision avoidance, for example, and explore different settings," he said.Siegwart believes that as the knowledge of solar planes increases and the cost of production falls, they could increasingly be used in bulk during rescue missions. "Imagine that you have an aircraft which we recently had, which is lost, in the ocean, you can imagine these are small airplanes, you have probably a fleet of them, 50, 100, and you really cover big areas. So you just fly them out in the ocean and then they can take images and then you can analyze images and then probably find people and find lost airplanes and so on," he said. Such UAVs could also be used for large-scale agriculture inspection.A five-person team - including four from ETH Zurich - led by Oettershagen, will arrive in Brazil on October 17. "We will fly for more than 400 kilometers straight, so continuously on solar power alone and autonomously too and we'll be mapping and recording atmospheric data during this time over the Amazon rainforest," he said.If weather conditions are favorable, AtlantikSolar will take off from the city of Belem on October 22.