The Skydweller drone was last visible on the flight-tracking service Flight Radar 24 north of Cancun, Mexico, in the early morning hours of May 4. The company described the drone as eventually performing a “controlled water ditching” around 6:30 am Eastern Time, but the aircraft “subsequently sank due to its non-buoyant composite structure.”

By the time it went under, the Skydweller drone had performed a record-breaking, solar-powered flight of eight days and 14 minutes—longer than any previous flights as either a drone or crewed aircraft. The company Skydweller Aero commemorated it as an “operational prototype” that had “validated the practical military utility of a persistent, medium-altitude solar aircraft” despite the loss at sea.

The aircraft’s earlier accomplishments will almost certainly endure in the public imagination. Solar Impulse 2 became the first solar-powered aircraft to circle the globe after completing a series of flights between 2015 and 2016. Along the way, it set a world record for the longest flight in a solar-powered plane when André Borschberg piloted the aircraft for 117 hours and 52 minutes—almost five days—during a 5,545-mile (8,924-kilometer) journey between Nagoya, Japan, and Hawaii.

Now, the crash of the Skydweller drone means that the Swiss Museum of Transport in Lucerne won’t get to display the historic aircraft per an original agreement with Skydweller Aero, according to SWI Swissinfo. That represents a blow for aviation enthusiasts unless future salvage operations can be carried out.

The pioneering design may nonetheless inspire future solar-powered aircraft for either civilian or military use. Skydweller Aero told Ars that it has no other prototypes immediately ready to replace the lost drone—but the company’s blog post described “planned upgrades using existing technology” that could enable future solar-powered drones to better withstand extreme weather conditions. Meanwhile, the Pentagon has proposed investing at least $54 billion into drone warfare systems.