20/06/2024
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When hypersonic aeronautics and space exploration meet, European engineers dream of future fast return flights to space.
Momentum is building for a new generation of planes flying faster than the speed of sound and passengers hurtling from Brussels to Sydney in just three hours. However, we are still years away from civilians routinely traveling at the speed of sound again. The nascent revolution in air travel aims to reduce both time travel and fuel consumption.
Faster travel would make space closer. ESA addresses the challenges and opportunities in the aerospace industry in the production of vehicles flying at hypersonic speeds in and beyond the Earth’s atmosphere.
Fast future
Hypersonic speed refers to speeds greater than five times the speed of sound. Scientists measure it using the Mach number, named after the Austrian physicist Ernst Mach.
Nose-to-Tail calculations for a waverider-based vehicle at Mach 8
Sound has a speed of Mach 1, i.e. roughly 1235 kilometers per hour. While there is no clear physical definition of hypersonic speeds, vehicles traveling at Mach 5 or higher – around 6,000 km/h – are considered hypersonic.
European efforts
ESA continues to identify synergistic ticks and space sectors and determine technology locks for hypersonic vehicles on Earth and in space. A two-day workshop in Germany earlier this spring brought together experts from industry, academia and agencies from the aerospace sector.
“We did not aim to provide specific solutions, but rather to first identify challenges and technical dependencies between disciplines. This is the starting point to enable future reusable hypersonic vehicles for the node in orbit,” says Didier Schmitt, head of the ESA Future Preparation Group.
Hypersonic encounter
The combination of experts served as a technical jumpstart to the jump technologies for a vehicle carrying astronauts to low Earth orbit. Up to 70 experts asked key questions and challenges to overcome.
“We encouraged both industries to learn about who the other is. The key word for achieving transformational change is reuse. Concepts for hypersonic re-usable vehicles include lifting body designs for European crew access to space and landing on a runaway or landing pad,” Didier explains.
Hot topics
Workshop participants presented several topics on how to make a crewed low-Earth orbit vehicle a reality. Experts have identified eight areas of synergy:
– Air drive as the key to achieving hypersonic speeds.
– Wing body construction and morphing structures. Adaptable geometry combined with high temperature and lightweight materials for aerodynamic efficiency.
– Insulation and thermal management. Thermal protection systems, new materials and cryogenic propellants.
– Guidance, Navigation and Control (GNC). Specific challenges associated with high-speed flight, including precision.
– Reuse of lightweight high temperature materials. Evaluation of fatigue and re-flight capability for two different cases: controlled return and long-duration flights.
– Safety considerations specific to manned vehicles. There is a need to regulate human roles and responsibilities. This includes distinguishing between passengers, crew members, ground operators and environmental considerations.
– Crew survival systems. Crew safety and survivability systems for anomalies as major drivers in vehicle design.
– Cryogenic storage and distribution systems. Cryogenic fuel and oxidant storage technology and their management.
To orbit and back with Space Rider
Hypersonic ESA
This is not the first time ESA has explored hypersonic concepts.
Over the past 25 years, ESA has invested efforts in EU-funded studies of hypersonic materials, aerothermodynamics and propulsion concepts. Some of these studies are HEXAFLY, ATLLAS, LAPCAT, FAST 20XX, HIKARI and STRATOFLY.
Hypersonic financing
HEXAFLY, for example, has built up a fairly extensive knowledge of hypersonic capabilities since 2000. The Space Rider project, Europe’s first reusable space transport system, contributes to research into reusable launch vehicles.
ESA has also successfully tested critical reentry technologies. In 1998, the Advanced Reentry Demonstrator (ARD) made a controlled return back to Earth.
IXV during fairing encapsulation
In 2015, the Intermediate eXperimental Vehicle (IXV) reached a 25,000 km orbit and completed a scorching atmospheric descent and a safe splashdown at the target location in the Pacific Ocean.
“It is time for Europe to come of age and test these new concepts with breakthrough technologies on high-speed vehicles,” urges Didier.