The prospect of human life on Mars is one of the perennial staples of science fiction, but transforming fiction into reality now lies well within the realm of modern engineering.
To test the suitability of rover vehicles for celestial conditions, Space Agencies have long used simulated terrain in so-called ‘Mars Yards.’ Sonila Kadillari, a fifth year Master of Architecture (MArch) graduate at UCL Bartlett, has collaborated with Max Fordham engineers to take this a step further.
Pre-Ecopoiesis Mars Yard (PEMY) is a site where a number of simulations of the planet Mars are created. These include light, topography, temperature, atmosphere, gravity and wind simulations. Each simulation is designed to provide scientifically reliable testing facilities as well as to provide educational interest to the public.
“Having visited the Kennedy Space centre in Florida, I was inspired by the vast landscape provided for NASA’s programmes and its top secret nature,” said Kadillari. “I began to think about how scientific facilities could be designed more specifically for testing procedures and how they could potentially become part of the society. “
Terraforming, the engineering of a planet to make it inhabitable for humans, became the key concept in Kadillari’s research. Terraforming has many stages, the first of which is Ecopoiesis, where the atmosphere of the foreign planet is engineered to be similar to Earth’s.
Kadillari proposed a scenario where this terraforming would have a new phase, that of Pre-Ecopoiesis, where environmental engineering occurs on Earth rather than on another planet.
Consultation with Max Fordham was integral to the design development as Kadillari sought to gather and offer advice relating to solar radiation characteristics, gravity and concentrated solar power. Techniques used included simple analytical methods, raytracing and computational fluid dynamics.
“On Mars, the surface gravity is 60 per cent weaker than on Earth. In practice, what is required to simulate Martian gravity on Earth is to reduce an object’s effective weight by 60 per cent,” explained Tom Greenhill, an engineer at Max Fordham. “Using simple force vector diagrams along with research of existing methods of simulating gravity environments, we analysed the ways we could replicate the effect of Martian gravity on people as well as objects like Mars Rovers."
The team produced three entirely different proposals: a lift which could move vertically at a constant rate of deceleration for a period of time, a truck that moved along a parabolic track around the site and a system involving a suspension tether running around a conical “walk” surface with this final solution being chosen.
The design uses an approach previously demonstrated by Australian Artist Adam Norton.
“The apparatus is designed to rotate the object/person and the ground surface (the cone) that supports it until the vertical component of the object’s / person’s weight is reduced to the desired amount,” said Greenhill. “By doing this, a horizontal component of weight is introduced, but if this is counteracted with an equal and opposite force (the tether) it has no effect on the object.”
“Like fast spinning clothes sticking to the outside of a washing machine, Norton’s simulation suffered the effects of centrifugal force: the faster Norton rotated around the cone, the effective gravity acting on him was reduced. To eliminate this during the simulation of movement, in our proposal the object / person remains stationary and the ground surface (the cone) rotated.”
Greenhill has postulated as to whether the cone and tether apparatus could be applied elsewhere.
“A low gravity simulator built within a conventional lift would be a fun and interesting feature in a tall building,” he joked.
To simulate the conditions that might be encountered during entry through an atmosphere, a method was needed to create intense heat and radiation conditions using solar power.
“We drew upon our experience of using concentrating solar power plants in the Sahara Forest Project to produce a concept design for a huge parabolic reflector that could be used to focus the sun’s rays to produce a patch of super-heated terrain,” said Hareth Pochee, a physicist at Max Fordham.
The team used 3D CAD and simple raytracing techniques to design a simple, static, 3D parabolic reflector that for a large part of the year would focus the sun’s rays onto an area of land 20 metres in diameter, situated at the focal point of the parabola. The concept reflector is fairly sizable at 100m in height, and is predicted to have a concentrating power factor of about 10.
“In normal, non- concentrating conditions we might expect incident solar radiation intensity at the surface of the earth to be around 1000 W/m2, in which case ground temperatures reach a maximum of about 60°C,” said Pochee. “We used simple steady state heat transfer theory to show that at the focus of the parabolic concentrator the average incident radiation intensity would be more like 7000 W/m2 producing ground temperatures of 200-300°C.”
About half the heat from the super-heated patch of terrain is predicted to be lost via radiation to the sky while the other half is dissipated upwards in a thermal plume formed by natural convection. Using computational fluid dynamics (CFD) the team investigated and visualised the hot plume - in particular its interaction with the ambient wind conditions.
Parabolic reflectors are already in use in telescopes, solar power plants, and concentrating solar cookers.
Pochee is currently using a similar bespoke CAD raytracing technique to optimise building forms in response to the solar radiation characteristics of different climates on Earth.