Portugal is now at the forefront of hypersonic research following a prosperous November test at the Instituto Superior Técnico in Lisbon. The experiment, conducted at the European Shock Tube for High Enthalpy Research (ESTHER), marks a critical step in developing thermal protection systems for spacecraft re-entry and advancing understanding of extreme flight conditions. Officially funded by the european Space Agency, ESTHER is uniquely positioned to support planetary exploration and secure European independence in space access and descent technologies.
Researchers at the Instituto Superior Técnico (IST) in Lisbon, Portugal, have successfully completed their first hypersonic test, achieving speeds capable of traversing the Portuguese mainland from north to south in just over five minutes. The November 19 experiment, conducted at the European Shock Tube for High Enthalpy Research (ESTHER), marks a significant step forward in understanding the extreme conditions experienced during hypersonic flight.
The ESTHER facility, described by IST assistant professor Mário Lino da Silva as “a kind of 20-meter-long cannon,” doesn’t fire projectiles, but rather “shoots air at speeds of several kilometers per second.” These velocities, reaching between 6 to 8 kilometers per second, are difficult to grasp, he explained. “It’s like flying from here to Setúbal in three seconds, or going from here to Porto, about 200 kilometers, in around 30 seconds.”
At these extreme speeds, the friction between the air and the atmosphere generates what Lino da Silva calls “a huge ball of light,” a phenomenon readily observable in nature as shooting stars. When a meteoroid enters the Earth’s atmosphere, “it enters at a minimum of 6 or 7 kilometers per second, and even tens of kilometers per second,” he said. The intense friction completely disintegrates these meteoroids, providing a natural protective barrier.
This principle is directly applicable to spacecraft design. Just as a meteoroid, “a spacecraft with astronauts or robots, if not properly protected, will completely disintegrate in the atmosphere.” The IST laboratory is focused on replicating this phenomenon in a controlled environment to improve spacecraft thermal protection systems. “We reproduce these fireballs and adjust the heat they emit to allow spacecraft to be designed with adequate thermal protection, so they don’t burn up completely in the atmosphere,” Lino da Silva stated.
Funded by the European Space Agency (ESA), ESTHER replaces a similar facility that operated in France during the 1990s. The new installation is now “the official facility for testing spacecraft entering planets,” according to Lino da Silva, and holds strategic importance in the current geopolitical landscape. The facility’s capabilities are crucial as nations invest heavily in space exploration and defense technologies.
“It ensures European independence in access to space,” the researcher indicated, emphasizing that Europe must master not only launch technologies but also “the technologies that guarantee we descend safely.” The Laboratory of Hypersonic Plasmas (HTL) at IST is specifically focused on the re-entry phase of space travel. “As everything that goes up must come down, we here deal with the phenomenon of descent.”
While other shock tubes exist globally – including facilities in the United States, China, Russia, Japan, and India – ESTHER is unique in being “officially funded by the European Space Agency” and directly supporting its missions. “In terms of shock tubes, worldwide, there are about 10 to 15 facilities, more or less of this category, because each country or block of countries has to have an installation like this.”
Lino da Silva clarified that while other shock tubes exist in Europe, they aren’t designed for the same level of hypersonic testing. “This one is for reaching hypersonic velocities. There’s another shock tube in Germany that’s more for aerodynamics, but it doesn’t reach this range of speeds.” The recent test generated a hypersonic flow, corresponding to speeds five or more times the speed of sound – or Mach 5 or higher – subjecting the gases to “extreme temperatures and pressures.”
The successful test represents a key milestone in the development of materials and designs capable of withstanding the extreme conditions of hypersonic flight, a technology with implications for both space exploration and potential future defense applications. The research underscores Portugal’s growing role in cutting-edge aerospace engineering and its contribution to European space independence.
