Eco-friendly and hypersonic—five times the speed of sound—sound like contradictions, but a Swiss aerospace startup took the first step towards combining the two, following a test flight of a prototype drone.

“The successful flight with hydrogen afterburners demonstrates the potential for high-performance propulsion systems that are highly efficient and reduce carbon emissions,” said Destinus CEO Mikhail Kokorich, following the event.

The unmanned Jungfrau prototype took off last Wednesday from an airport near Munich, Germany and successfully lit up the hydrogen-powered afterburners. It did several flights around the airport, reaching speeds of about 155 mph. While that’s a far cry from the 3,000-mph threshold where hypersonic flight begins, Kokorich said the experiments “showcased the functionality and efficiency of hydrogen afterburners in real-world conditions.”

The firm, comprised of aerospace experts from five European countries, developed the afterburner in house and paired it with a conventional jet turbine powered by Jet A fuel. The system injected hydrogen into the exhaust stream to generate a higher speed and climb rates. Combining hydrogen with conventional jet fuel will also reduce development time as Destinus strives to build a clean, hypersonic jet. Instead of carbon dioxide and nitrogen oxide, hydrogen emits only heat and water vapor.

Despite its initial success with the afterburners, Destinus won’t be moving up to a larger prototype jet just yet. The company is taking it a step at a time. Next year’s test will be “the world’s first supersonic drone powered by hydrogen,” said Kokorich.

The eventual goal is to build an aircraft that can move people and goods around the world in a matter of hours. Destinus says hypersonic flight from Memphis to Tokyo will only take three hours and 15 minutes, while flying from Memphis to Frankfurt will be an hour faster.