It is hardly a fitting end for such finely engineered, expensive and energy-intensive vehicles. What if they could instead return to Earth to launch again on another mission – or even carry out further missions in orbit before returning? SpaceX has repeatedly demonstrated the return of first-stage ‘booster’ rockets, so why not second-stages too? A new project from the National Manufacturing Institute Scotland (NMIS) explores that possibility.
The University of Strathclyde-operated centre unveiled a demonstrator vehicle at the Space-Comm Expo at the Excel centre in London on Tuesday (11 March). Drawing on techniques used in the construction of Formula One cars, the concept design integrates novel composite materials to add extra functionalities and payload while limiting additional mass.
The project aims to make better use of the huge amount of energy expended to reach orbit, while also taking advantage of Scotland’s upcoming rocket launch capacity.
“Satellite assembly is a really important aspect of the Glasgow city region; we make more satellites in Scotland than the rest of the UK,” Professor Iain Bomphray, director of the Lightweight Manufacturing Centre (LMC) at NMIS, told Professional Engineering. “But with SaxaVord in Shetland, we have an opportunity to have the vertical launch capability, and we want to support vertical launch.”
The NMIS display featured a large model of the vehicle’s concentric liquid oxygen and propellant tank, including multi-functional design features such as anti-slosh fluid transfer channels. A smaller model showed how the tank would be integrated into the second stage, as well as the composite heat shield and a combined systems bay for recovery, guidance and control. Digitally enabled and additive manufacturing techniques would be used for high-rate production and adhesive-free joining, according to the display.
“We felt it was too simple to make a round tube to demonstrate having a bigger first-stage rocket,” said Bomphray, speaking at the UK’s largest space industry event. “Nobody really recovers the second stage at the moment. SpaceX are very successful in recovering the first stage, but we thought, ‘Hey, once we've got an asset in space, that's taking a lot of energy to get it there, so it's a valuable asset – let's try to do something useful with it while it's there.’”
Those tasks could include servicing or recovering satellites, or deorbiting them to prevent additional space debris.
The vehicle has an aerodynamic profile to provide spin stability, according to Bomphray, enabling a controlled return to Earth. Other elements that are not normally needed include heat shields and deceleration mechanisms. The craft includes thrusters to manoeuvre in orbit, and parachutes for the eventual landing.
Together, these features could risk adding significant weight to the vehicle, reducing the potential payload and increasing costs – but the LMC is using its lightweighting specialism to reduce the craft’s mass with composite materials. Thermal protection is also optimised by the aerodynamic profile, which would enable it to enter the atmosphere at a certain angle to avoid burning up.
“It's always going to be a trade-off [between] the amount of fuel and the operations that we can do in space, because that's a mass penalty as well,” said Bomphray. The ability to complete extra missions would be an attractive way of improving the economics of a launch.
‘We have to be ambitious’
With British rocket firms such as Skyrora and Orbex already developing their own multi-stage rockets, it might not initially be clear who the reusable concept is aimed at. But for NMIS, part of the government-founded High Value Manufacturing Catapult, the project is not just about advancing engineering concepts that could one day reach space.
“For the Glasgow region, we want to demonstrate that we are a credible R&D partner, that people can come and spend their R&D money,” said Bomphray.
According to Space Scotland, the sector contributes more than £4bn to the economy each year, with almost one-fifth of all UK jobs in the sector based in Scotland.
“We have to be ambitious,” said Bomphray. “We can't let this opportunity go. The space sector is growing exponentially – we want to be part of that.”
NMIS also hopes to “catalyse” industries providing certain materials, such as ceramics and silicon carbide fibres, which currently come from outside the UK.
The concept was developed as part of the Stratellite Space and Photonics project, which is part-funded by the Glasgow City Region Innovation Accelerator programme led by Innovate UK.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.