ESTHER completes first test under real conditions
“Crossing mainland Portugal from north to south in just over five minutes.” This is how one can grasp the speed reached in the first hypersonic test carried out under real conditions by IPFN at the European Shock Tube for High Enthalpy Research (ESTHER) infrastructure, located at Técnico’s Loures Campus.
The test, completed on 19 November 2025, made it possible to generate a hypersonic flow in the facility at around 8 km/s (Mach 25), marking Portugal’s entry into the experimental capability to study such phenomena. This is a speed so high that the intensity of the shock is sufficient to raise the flow temperature to values exceeding those of the Sun’s surface, producing a bright flash reminiscent of the shooting stars occasionally visible in the sky.
“The test represents the culmination of 15 years of project development, initiated in 2010 within the framework of an international consortium led by IPFN,” explains Luís L. Alves, head of the N-PRiME group that hosts ESTHER. “The European Space Agency (ESA) awarded this consortium the contract to build an infrastructure to support future planetary exploration missions.”
For Mário Lino da Silva, Professor and researcher at IPFN and Principal Investigator of the project at N-PRiME/IPFN, this result constitutes “a direct contribution to Europe’s technological independence in the aerospace domain.”
Hypersonic flow corresponds to speeds above Mach 5, a regime where gases reach extreme temperatures and pressures, essential for studying phenomena associated with the atmospheric re-entry of space vehicles and the exploration of planetary atmospheres such as those of Mars, Venus, Titan or Jupiter.
“The success of this first test shows that Portugal and Europe now have a unique scientific tool to study phenomena that only occur when travelling several times faster than the speed of sound,” the researcher underlines. “The ability to generate and measure hypersonic flows places us within a very restricted group of countries with technological mastery in this field,” he adds.
Operation of the ESTHER shock tube involves demanding physical conditions, namely the use of mixtures of hydrogen, oxygen and helium at very high pressures. “The main risk is that of an uncontrolled explosion in a 50-litre combustion chamber at pressures of up to 100 atmospheres,” explains Mário Lino da Silva, noting the laboratory was designed to minimise these risks, with a reinforced structure, partially buried, and fully remote operation.
One of the main challenges of the project was the “validation of a prototype installation that implements several technological solutions unique in the world.” Since 2019, following assembly of the infrastructure, the different subsystems have been individually tested and validated, including the combustion chamber, the laser ignition system, the high-vacuum system, and the remote control and data acquisition systems.
The next steps involve progressively exploring the operational regime of the facility, reaching higher speeds and validating, in an integrated manner, the technologies developed. “This is a multidisciplinary operation that is only possible in institutions such as Técnico and IPFN, where specialists from different fields collaborate in an integrated way,” notes Mário Lino da Silva.
In the medium term, ESTHER is expected to directly support ESA mission planning and contribute to the development of national capabilities in the hypersonics field, through partnerships with academic institutions and Portuguese companies. The entry into operation of ESTHER, 76 years after the first hypersonic flight and on the 50th anniversary of ESA’s foundation, equips Europe with a facility that will enable (among other things) the fulfilment of European ambitions in access to and exploration of Space over the next 50 years.
In addition to ESTHER, the IPFN Hypersonic Plasmas Laboratory has participated in all ESA planetary exploration missions to date, including Cassini-Huygens and ExoMars. With the infrastructure now operational, tests of materials subjected to hypervelocity flows are planned.
“This successful test is a source of great pride for IPFN and for Técnico,” states Bruno Gonçalves, President of the research unit. “We honour the legacy of the navigators who gave new worlds to the world, now helping to open new pathways for space exploration and to write this new chapter in the history of Humanity.”
