Additive Manufacturing used for Earth Re-entry Capsule

Original article written for QM Magazine by John Challen

Magna Parva were contracted by ESA to develop a additive manufactured (3D printed) material for a crushable thermal protection system for the Earth re-entry capsule, the capsule will hold a 500g Martian soil sample, and was subjected a number of tests and analysed at various facilities.

Engineering challenges:

In order to transport 500 grammes of Mars soil safely back to earth, the Mars Sample Return capsule must be:

  • Strong enough to withstand freefall impact on re-entry
  • Crushable enough to reduce impact shock for its contents
  • Heat proof to keep the sample below a specified temperature

Part of the project involved investigations into additive manufacturing, as a suitable crushable material will very likely be based on cellular material and additive manufacturing is a means to tailor crush properties to be used within the capsule’s structure. Magna Parva used the Manufacturing Technology Centre in Ansty (MTC) for their additive manufacturing expertise to assist with the manufacturing process.

Material challenges

Having put in a bid for the project in 2012, Magna Parva started working on the thermal protection system in January 2013. The development of a crushable material for the system had a number of objectives. The material needed to be attached to an ablative material forming the heat shield that burns during re-entry to the Earth’s atmosphere. It also needed to be attached to the much cooler structure of the sample container, while limiting its acceleration level on landing. Finally, the material needed to provide thermal insulation between the hot ablative material and the cold structure.

“The difficult thing is that you are bringing a sample from one planetary body into another and this causes issues with bioburden control”
Zeshan Ali, Magna Parva design engineer

To these mechanical challenges to the design must be added that of protecting against ‘bioburden’, or the bacteria that may be present in an unsterilized sample. “The difficult thing is that you are bringing a sample from one planetary body into another and this causes issues with bioburden control,” explains Magna Parva design engineer Zeshan Ali. “Whatever we send to Mars has to be sterilized. you have to take a sample that is clean, get it into a sealed biocontainer, and then get it back to Earth.” The challenge here, for Magna Parva, was ensuring that the soil sample stays at the permitted temperature, and that the bio-container is not crushed when it lands. “You have to protect it very well, and this means the dual challenge of thermally protecting it and impact-protecting it,” confirms Ali.

Within the Earth re-entry capsule, the volume in between an ablative material and the bio-secure container – where the Mars sample soil will be stored – is where Magna Parva is developing a crushable material as part of the thermal protection system. The outside of the capsule is covered in the ablative material, which burns off during re-entry. “For that material, you have to work out the exact thickness you will need, considering its job is to protect the internals from high temperatures,” explains Ali. ” It can reach above 2000 Celsius on the outside, dependant on the re-entry capsule design, but the objective is to also protect the inside. As the material burns off, it is also transmitting heat towards the bio-container that we are trying to protect. so, thermally, we are trying to protect the bio-container with the crushable material because if the sample gets too hot, it might burn off imported chemistry. Crucially, we need to protect the integrity of the container by not allowing any ingress or egress,” says Ali.

Crush testing

Although they form part of the same structure, the design of the crushable Earth re-entry capsule and the selection of the material itself were two different parts to the project. On the materials side, says Ali, work started by looking at available materials that were used for energy absorption, such as crushable damping systems for cars, and trains. “We looked at a number of different materials, such as RVC (Reticulated Vitreous Carbon) foams, hollow titanium spheres, and aluminium sandwich panels. We concentrated on a lot of foam systems – such as copper, silicon carbide, corecell and aluminium – but didn’t look into polymers,” he adds. “A target requirement of the material was a service temperature of up to 600 Celsius, which ruled them out.”

The decision was taken to go with a titanium lattice that was constructed using additive manufacturing ” because it ticked all the boxes of our criteria, and it also provides design flexibility,” comments Ali. “You can develop something that is electron beam-melted, or selective laser-melted. Material trade-offs were performed for each material, using criteria such as energy absorption; maximum component dimensions; yield strength; thermal conductivity; relative density and oxidation resistance. The ability to tailor properties such as yield strength and thermal conductivity made the titanium lattice material high scoring in the trade-off,” confirms Ali.

The MTC then looked at what additive manufacturing methods were available. This extensive list included Selective Laser Melting (SLM), Electron Beam Melting (EBM), Digital Part Materialisation (DPM), Laser Metal Deposition (LMD), Plasma Transfer Arc (PTA) and Ultrasonic Consolidation (UC). “We eventually chose SLM and EBM as the best routes forward,” says Ali.

Integration and joinability of the new material

On the grounds of availability and cost, component and powder removal, heat treatment, and parent material properties, as well as the availability of a machine at the MTC, EBM was selected for material development. “We then designed the crushable cell geometry required, and worked out how we would bond the material to itself, because currently the machines aren’t large enough to build a whole structure,” explains Ali. “The earth re-entry capsule is roughly 1.5 m in diameter, so we would need to build it in sections, and then join them together. The protective material also had to be joined to a cold structure – representing the biocontainer – and the ablative material. This configuration meant reviewing and trading-off several methods of joining the three interfaces – crushable material to the bio-container; crushable material to itself, and crushable material to the ablative material.”

After designing test samples to characterise the material, the next challenge was to manufacture the samples. “We need to conduct various tests on the manufactured samples in order to characterise the crushable material allowing correlation of the empirical data and design analysis,” explains Ali. “The MTC was able to provide knowledge of the additive manufacturing tooling capabilities and detail exactly what happened during the manufacture phase, so we could record and review the process as well as the design methodology for further development. It is this advancement that is helping the technological process, and giving us the manufacturing input we need.”

“A crushable thermal protection system is seen as a more reliable solution than parachutes, and offers a mass-saving opportunity.” says Ali. “We calculated an impact energy based on a general earth re-entry capsule design, entry trajectories, ballistic and drag coefficients to work out our material strength requirement – it can’t be too weak, or else it won’t damp the impact energy enough, but can’t be too strong because there will be too much g-force transmitted into the container.”

The proposed – or earliest possible, depending on how it is viewed – date for launch for the Mars sample return is 2025. This is a long way to go in terms of time, but also in the amount of development work that is required. In the meantime, Magna Parva will look at how it can exploit the technology elsewhere. “One of the key advantages of additive manufacture exploited in this project is the ability to incorporate features into the crushable material design which allow the integration of different components. This enables the attachment of ablative and cold structure components, as well as additional sections of crushable material, onto a single processed part,” concludes Ali. “It is a small part of a big mission, but it is an essential part.

 

Magna Parva start the move onto Leicester’s Pioneer Science Park

The company has started a year long transition to a brand new office and laboratory facility next to the National Space Centre on Leicester’s Pioneer science park. The new facility will be part of a development called DOCK 2 due to be completed at the end of 2016.

During the 2016 transition period the head office, design and lab functions will move from our Meridian Business Park industrial unit to DOCK (photo) which overlooks the site of the new building. This temporary accommodation move will enable oversight of the build, improved facilities and improved links to the city’s Science and Space communities.

The Meridian industrial unit will be maintained until the lease expiration for large workshop & test facilities.

For the DOCK 2 new build, Leicester-based rg+p Ltd have been contracted as project managers and quantity surveyors, with international firm Idom appointed as lead consultant and architect by Leicester City Council. With headquarters in Spain, Idom was also executive architect for the stunning Guggenheim Museum in Bilbao. Javier Quintana, architectural director of Idom, said: “Dock 2 is a very exciting project for us to be involved in. We look forward to creating a building of which Leicester will be proud.”

The Leicester Pioneer science park is part of a range of redevelopment activities based around the National Space Centre including plans for the University of Leicester to develop a National Space Park.

Our new address and contact details are:

DOCK, 75 Exploration Drive, Pioneer Park, Leicester, LE4 5NU

Switchboard phone: +44(0)116 2688708

 

In-Space Manufacturing Prototype

We have launched a dedicated In-Space Manufacturing microsite, please visit it here (opens new tab)

Magna Parva has produced a prototype in-orbit manufacturing system that should provide a method of producing huge carbon composite 3D structures in space. A prototype COPMA system has been successfully built and tested under ‘near space’ conditions at Magna Parva’s Leicester development facility. It demonstrates the potential for the production of assemblies, equipment or even buildings from fully cured and consolidated carbon fibre materials, potentially miles in length.

Magna Parva’s innovative technology enables the deployment of extremely large, repeatable, composite structures. Radio antennae, synthetic aperture radar systems and radio / optical interferometers are examples of items that are feasible to make in space using the COPMA system.

The new precision robotic technology manufactures 3D space structures using a supply of carbon fibres and a resin that are processed by pultrusion through a heat forming die in a continuous process, producing cured carbon composite elements of extraordinary length. As the resin and materials behave differently in space, the development has included testing under both ambient atmospheric and vacuum conditions. While pultrusion itself is an established manufacturing process, it has now been scaled down to a size where the equipment can be accommodated on spacecraft, and further work is under way to advance the technical readiness of the concept.

COPMA stands for ‘Consolidated Off Planet Manufacturing and Assembly System for Large Space Structures’, and allows the fabrication in space of large structures that would be difficult to produce on Earth due to limitations at launch. Current pre-manufactured structures designed to go into space are high in mass and volume and have specific launch environment requirements. By manufacturing in space, many of these requirements are eliminated, allowing the production and deployment of extremely large composite structures. They can be made much thinner, larger and use less material than they would need if terrestrially produced, avoiding the rigours of launch.

For more information on this development please get in touch..

Successful Flight Hardware Installation

The Mercury Imaging X-ray Spectrometer (MIXS), with the optics structures designed and supplied by Magna Parva in collaboration with the University of Leicester, has been successfully installed on the BepiColombo Mercury Planetary Orbiter (MPO).

MIXS is a University of Leicester instrument, and was until his untimely death led by Professor George Fraser who is greatly missed by all at Magna Parva.

The BepiColombo mission is one of ESA’s cornerstone missions in cooperation with Japan and will provide the most complete exploration of Mercury to date. The mission will consist of two separate spacecraft that will orbit the planet. ESA is building one of the main spacecraft, the Mercury Planetary Orbiter (MPO), and the Japanese space agency JAXA will contribute the other, the Mercury Magnetospheric Orbiter (MMO). BepiColombo will help to reveal information on the composition and history of Mercury, as well as general information on the formation of the rocky planets, including the Earth.

For further information on the work Magna Parva provided for the instrument please see our project case study page.

Sepsis diagnostic tool tested

Sepsis, a potentially life-threatening inflammatory condition triggered by infection, kills 1400 people every day worldwide and over 500,000 people annually in the western world. It is common, it is deadly and it is expensive; responsible for more deaths than HIV, breast and bowel cancer combined, it costs the UK/US ~£20Bn annually. However, if it is caught early, it can be treated, but for every hour that sepsis remains undiagnosed, the risk of death increases by 8%.

 The RAPPIDS disgnostic tool is a fully-integrated, rapid multiplexed pathogen/biomarker immunodiagnostic device for rapid detection (<15 min) of sepsis at the point-of-care. The technology will accept blood samples as collected by a doctor/nurse, remove blood cells, and concentrate the remaining plasma for subsequent immunosensor detection, all within a single, automated, self-contained process.

 RAPPIDS development is led by Magna Parva and is part funded by the Technology Strategy Board in collaboration with Cardiff University, AET and Chelsea Technology.

Zero-g fuel manipulation tech developed

Our Acoustic Fuel Manipulation (AFM) technology development has culminated in the achievement of controlled movement and positioning of fluids using acoustic waves. This technology could be applied to fuel on board Spacecraft to save significant mass by reducing waste fuel and ancillary fuel tank elements such as baffles.
Space missions depend upon various fuel systems to work and in microgravity environments the fuel used is dominated by capillary forces which cause them to coalesce into large droplets or cling to tank walls, which means that optimum fuel usage cannot be achieved. Magna Parva’s AFM development aim was to investigate and demonstrate methods that use acoustic streaming to trap propellant in predetermined locations. This would enable maximal fuel usage allowing optimisation of the fuel mass providing more efficient overall systems. The project achieved this through a number of tasks; acoustic modelling (a computer model examining the interaction between the acoustic waves and the liquid it’s travelling through), analysis, and implementation of a ground test bench that works at both room and cryogenic temperatures.

Using sound energy in unique developments is proven to be one of Magna Parva’s key strengths. If you would like any more information, or think we could help you, please contact us!
The technology development project was funded by the European Space Agency and supported by Cranfield University.

The video below shows the movement by using coloured dye to highlight the fluid flow.

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Spacecraft protection ESA contract win

Magna Parva Limited has been awarded a contract by the European Space Agency to develop novel materials for use in space which will provide improved protection against radiation and micrometeorites. The increasing need of a new low-cost hybrid material has arisen to help protect spacecraft and the safety of its crew. Astronauts and satellite electronics can suffer subtle damage from radiation in orbit and the satellites themselves can be damaged by natural interplanetary dust particles or by small pieces of orbital debris. The project will develop laminated materials which provide more protection per kilogram than current options.
Spacecraft in orbit around the Earth continually sustain damage from hyper velocity impact, colliding with micrometeoroids and orbiting debris (MMOD). Travelling at orbital velocities reaching speeds of 8km/s, the possible impact is unthinkable. To put this into perspective; ballistic objects fired from firearms on Earth travel around 0.3km/s. Whilst the majority of orbiting debris and micrometeoroids are small enough to not be a worry, a need for protection is established. A small fraction of the MMOD population is large enough to cause potentially catastrophic damage. Large objects in orbit around Earth are tracked such that space craft can be manoeuvred and collisions can be avoided.
The second motive behind the development of the ‘Low Cost Hybrid Materials’ is radiation. In the space environment radiation takes the form of energetic particles; these originate from supernova explosions and other high energy events outside the solar system. There are also Solar Energetic Particles which originate from the sun. The Earth’s magnetosphere blocks out the majority of radiation, but at increasing altitudes, and beyond Earth orbit, exposure levels increase. The risk of collision with MMOD and increasing exposure to radiation needs to be mitigated.
Magna Parva will be supported by the expertise from a number of high technology companies and universities from across the UK, showing the strength of this sector. Director Andy Bowyer said “This provides an exciting step for the company into a new business area. The materials we develop in this contract will be particularly useful in deep space missions such as those planned for the Orion capsule”. Magna Parva is supported by their subcontractors Fluid Gravity, TISICS, RadMod and Kallisto.