Posted 11 September 2023 in Blog, Concurrent Design, Engineering, Space.

Space exploration missions differ in many ways from other types of missions because they are typically unique, with no heritage to build on. Using a concurrent design approach can help, not only for specifying the various elements that go together to build a spacecraft, but also for assessing broader mission options, including human factors for crewed missions.  

OpenSpace spoke to Ilaria Roma, Head of the European Space Agency’s (ESA’s) Systems and Concurrent Engineering Section, to discover how the activities undertaken at the ESA Concurrent Design Facility (ESA CDF) contribute to making space exploration missions a success.  

This is an extract from an article in the current issue of OpenSpace magazine (issue 32). To read about issues raised by other aspects of space exploration missions, such as propulsion and radiation, read OpenSpace 32. 

What happens at the ESA CDF? 

As with many ESA spacecraft, its exploration missions typically start their lives in ESA’s Concurrent Design Facility (ESA CDF). Here, anything from top level concepts to more fully-fledged ideas are examined in order to identify what is feasible and where technology developments need to be implemented in order to enable a mission to progress.  

At the ESA CDF, experts in all the relevant key areas sit down together to establish the boundary conditions for a mission – such as its destination and target activities – and then pool their expertise to establish a mission concept and the required course of action to realise it. They may also investigate scenarios involving different partnership options, because cooperation with other space agencies can enable more ambitious endeavours; however, this can have a significant impact across the design, development, manufacture and operation of a mission.  

The design of space exploration missions includes a lot of unknowns. Thinking ‘out of the box’ and being creative is therefore valued much more than for other types of missions where the heritage from earlier missions and reuse of what we already know allows for faster and cheaper solutions. 

“Design teams have to make many assumptions, which are very attentively discussed, agreed and documented as they represent the conditions for the validity of the overall design. One crucial outcome of the CDF studies on exploration missions is the list of required technology developments, and this gets injected into the Agency’s plans, so everything can be ready on time.” 

How many studies are done for each exploration mission? 

The ESA CDF will celebrate its 25th anniversary in November 2023 and some current missions can trace their heritage a long way back in the Facility’s history. The second ever study at the ESA CDF, in 1999, was on Solar Orbiter, which was finally launched in 2020.  

“It is hardly ever that a single study leads immediately to a mission. For Juice, for example, there were studies done before the proposal was made, and then more afterwards because the scope changed and the mission itself changed, as well as the cooperation setting [who ESA was working with on the mission]. These modifications invalidated some of the aspects we had previously looked at. Similarly with crewed missions studied in the CDF – the plans have changed since we first looked at this from a European perspective, therefore additional studies had to be conducted to check design validity. Often we have to do multiple studies because if we look from the mission concept and architecture point of view, exploration missions are more complex than, for example, an Earth observation satellite (although Earth Observation missions instruments can be extremely complex!).

 Also, human missions and ones such as ExoMars or Mars Sample Return are extremely complicated, because we have to not only characterize the environment – which brings several uncertainties – but also work out how to land a rover safely or consider a whole range of extra parameters [specific to human needs].”  

What happens if something about the mission changes? 

Sometimes missions in development may find themselves back in the ESA CDF because the boundary conditions have changed. For example, the current ExoMars mission was due to use a Russian launcher and a Russian descent module to deliver the European rover to the Martian surface, but this was suspended due to the Russian invasion of Ukraine in 2022. This change meant everything about the design will have to be checked again, including the mission launch date. 

In addition, revising a mission’s launch date means the relative positions of the planets will have changed, which has an impact on the trajectories to reach a target and on the required amounts of propellant, which in turn affects the tank size and therefore the overall structure. And when a spacecraft’s structure changes, this may change its mass and thus its inertia.  

“Changes such as this have a cascading effect on the overall system. This is the kind of occurrence that is well addressed by the CDF.” 

ExoMars rover ESA
Artist’s impression of ESA’s ExoMars rover (foreground) and Russia’s science platform (background) on Mars. © ESA

Crewed mission essentials 

Missions that carry humans incur a much wider range of design considerations than uncrewed ones.  

The ESA CDF has been busy carrying out studies for human exploration missions.

“Sessions on these will include domain experts covering areas such as safety, environmental control and life support systems. We have to consider issues such as the crew’s health and performance.”

 There are standards for human spaceflight that dictate things like the redundancy required for environmental control and life support (ECLS) functions, and systems must be highly reliable. Then in addition to aspects such as crew hygiene, clothing and laundry, utensils and dishwashing, consumables, and water and oxygen recovery, we also have to look at areas such as medical, physiology and psychology aspects, which all affect the design.”  

ESA CDF studies have even considered the potential for hibernation, which would reduce the amount of resources needed as humans would need less food and water, help from a psychological point of view as astronauts would not have to be constantly awake, and mean a smaller area would need to be shielded.  

Find out more 

This is an extract from an article in the current issue of OpenSpace magazine (issue 32). Subscribe now to read the complete article, and others on using space to tackle climate change, physical security in critical infrastructures, Italy’s ambitions for space, and more. 

Main image ©  ESA – Jupiter and its moons