There have been 11 operational inhabited space stations since 1971. And this week marks 60 years since the first human in space - Yugi Gagarin. See my previous post covering his, and earlier animal flights into space that preceded him. That's 50 years of human science in Earth orbital laboratories. This article treats the main designs and governing principles which have shaped their development and deployment. Let's look at how those early designs have evolved and the near term expected developments in space station technology.
What is the Design Philosophy for a Space Station
Earlier space stations typically comprised a single pressurised unit launched to orbit atop a powerful rocket. They comprised a modified launch stage as a 'monolithic' single unit. These were subdivided internally with levels dedicated to different activities, experiments, living quarters, sometimes called Bologna sandwich structure. The main limitation to these early stations was the size of the rocket and the mass launch capability of the rocket sending the station to orbit.
This philosophy was propagated and refined with the Salyut series of stations from the Soviet Union. This line of orbital outposts ran from 1971 with Salyut 1 to 1986 with Salyut 7. The Salyut 1, more detail here, offered the first glimpse of orbital science and answered the question "can humans live in space for extended periods?".
This outpost in the heavens was a proof of concept. It helped demonstrate what are the key components of a space station:
Hatches/ airlocks - to enable crew and material transfer between transport vehicles and the station itself.
pressurised accommodation - The main accommodation section of the airframe
Space Observatory - The start of experiments and obersvation equipment aboard space stations. Modern contemporary of this is the Alpha Magnetic Spectrometer - A particle physics experiment mounted atop the main truss of the International Space Stations. This unit has observed upward of 90 billion cosmic ray events since its installation in 2011 as it hunts for dark matter.
How are Human Factors applied in Space Station Design
When I worked in HSSE design in Upstream Oil and Gas, I learned keenly the impact of human factors on the safe operations of a site. Bad ergonomics - relating to signage, or inherent safe design could result in heavy equipment trolleys being driven down un-rated walkways and falling through the floor. It can also result in the wrong 48" pipeline valves being closed because the operator isn't clear which valve needed to open/ close. Moreover not keenly understanding how humans experience sensory overwhelm can lead to poor control room design.
Human Factors Engineering/ ergonomics failures can result in simple injuries - valve handles sticking into the volume of space around head height can cause a head-strike. Instrument panels laid out poorly, or with awkward numbering or pointer design can make it difficult to get a good reading and cause eye/ neck strain. This has already caused prominent incidents in flight controls. This excellent book on human factors for pilots shows how things we take for granted have a deep impact on flight safety. This is my favourite book for relatable examples for ergonomics in real life.
A perhaps more relevant example from control room design maps onto the space exploration activities: careless alarm system design can easily not only overwhelm an operator, but also obfuscate the location and impact of that alarm, quickly leading to escalation through missed alarms.
However, the above examples go too far into the controls design of human factors in spaceflight vehicles. What I want to focus on is Human Factors of the habitat, to further explore the impact of design choices on human performance - situational awareness, fatigue, disorientation. These things can be less obvious and interesting in their solution.
Many significant Earth-based safety incidents occur because of failings in human factors. This has a more pronounced importance when living aboard a space station for months at a time, when trying to conduct safe operations day after day. This is part of the reason that an astronauts' day is planned down to 5 minute intervals, with backup and regular check ins with ground support operating around the clock in teams in Earth.
Below, I'll discuss some examples where earlier space stations appeared to lack the attention of ergonomics.
Skylab - Configuration and Locateability
The Skylab station showed an example of a design structure orientated in an up-to-down configuration irrespective of the fact of no gravity on the station. The astronauts onboard on the many Skylab missions made clear mention that their own eyes became their own personal reference system. Above their head was up, below them was down. Ed Gibson - one of the astronauts on the last Skylab mission before its re-entry, often discussed with ground control about the potential space station design enhancements.
Similarly, Pogue and the Mission commander Gerry Carr had a dim view of specific aspects of the design, namely the docking adapter and the location coding and numbering within the station.
However, Carr didn't simply sidle off after the mission ended on Skylab. He founded CAMUS inc. a human factors engineering firm specifically focused on space station design. This firm was a technical subcontractor to Boeing and an instrumental part of the effort to design the International Space Station. Furthermore, he was active even in 1991, working on Radiation shielding using animal models, submitting papers to the International Conference on Environmental Systems.
It is clear that Carr wanted to take his experiences and embed them to improve future off-world habitat design as even in 1991, he was named in the above paper as an active contributor. However there was no later mention of him in design documents or papers. Similarly, after delivering How Do You Go To The Bathroom In Space?: All the Answers to All the Questions You Have About Living in Space in (1991) and an earlier Primer for Astronauts in (1985), Pogue was also no longer active. Both gentlemen having retired from NASA, space design work at this time.
Interestingly enough, even in the 2014 NASA human integration Design Handbook, there are frequent references to learnings from Skylab. Data from studies which were conducted during Skylab tenure were called on. They ran from velcro-foot-fixing, to the awkwardness of showers onboard and how this impacted personal hygiene regimen. This modern NASA standard helped to learn the lessons from different eras in NASA space flight. But not only on NASA scope - for instance, the vacuum cleaner to contain crumbs, but also stray water was noted to have been a success in also cleaning filters of lint and dust during Skylab, Mir and also now on the ISS. Similarly, a review of house-keeping impact on operations was also noted.
Also in the above Human Integration Design Handbook was the pivotal decision to discontinue use of refrigerators tested onboard Skylab. This instead required all food to be 'shelf-stable', a legacy we live with today - any fresh produce brought to ISS must be consumed within 2 days to avoid spoilage and waste.
This last learning has proven not an obstacle to enjoying food in space though. See below video as Astronaut Chris Hadfield makes Space Tacos to a recipe from celebrated Chef Traci des Jardins.
Astronaut Chris Hadfield - an outspoken Astronaut who makes great effort to engage the public in the joy, importance and insight of extended human missions in space. Here he serves up Space Tacos under instruction from Earth. Credit: Adam Savage's Tested
Some other aspects of station design have come further since the earlier designs : notably internal structures to aid astronaut stability while on their work station.
On the ISS, there are grab rails on all surfaces (up, down, left and right) at fixed intervals, like the rungs on a ladder or steps on a staircase. This predictability helps the astronauts to gain the same confidence as climbing stairs without needing to focus so hard when getting the next grab rail.
An interesting part of this is the velcro attachments on many grab rails to enable astronauts to fix themselves to a position for an extended period so they can work at a fixed station. An uncanny point is that such 'docking' at a terminal can cause calluses to form on the top of the feet of the astronauts, the calluses normally present on the feet start to disappear because of the lack of use - feet require gravity to get the contact they need for use.
Salyut Series Space Stations 1-7 - Colour Coding
This is held in stark contrast to the earlier efforts of the Salyut 1 designers who tried to support cosmonaut orientation in zero gravity. The interior design engineers used a colour palette consisting of light-and-dark grey, apple green and light yellow to help the crew understand their new surroundings.
This kind of color-as-guide is an important concept in ergonomics called wayfinding as it helps communicate direction and orientation information embedded into the building design. This removes the need for overwhelming amount of written or obvious signage, in a stressful environment, where not all folks speak the same language. It uses the structure itself to answer the question "Am I going the right way?" It leverages the same brain centres communicating messages around red fruit = good to eat, yellow/black insect = poison. The more relatable example of colour as a guide are the coloured wayfinding lines on hospital floors and walls helping to guide to this place or that.
This sense challenge to find direction and location was reinforced in Skylab because of apparently confusing numbering of locations.
Additionally, ergonomics also treats the notions of human feelings within a space, or related to a device with a human interaction. Astronauts confessed that more secure and comfortable despite being in the cramped ' lower' decks - this due to the ease of re-orientating ones body within the space, even if it was awkward to move about.
Modularisation - The Future Now
A similarity to the development of off-shore and on-shore oil and gas infrastructure development came into the space exploration game: modularisation. In the early years of refinery, oil well structures and gas processing facilities construction, nearly everything was 'stick-built' on site piece-by-piece. Later, when the power of the large scale fabrication yards of South Korea came into prominence, and a suite of cash-conscious oil majors decided to challenge the costs of construction as margins put pressure on construction costs, modular design started to take form.
Offshore, modules became an efficient and lower risk way of deploying new equipment and upgrades on the platform. By conducting 'hot works' - welding, grinding, etc in a workshop on the land, away from the hazards of an oil and gas platform, the risk of fires and explosions from integrating new equipment was significantly lowered. Furthermore, due to the high cost to employ, train, transport, pay and retain talent in fabrication, it became attractive to complete more and more works onshore.
Why Bother with Modular Space Stations?
The similarity of modular oil and gas facilities with the space station construction is that all the construction is conducted on Earth. And also the modular concept endows power through expandability. Just like expanding oil processing infrastructure by adding extra 'trains' of equipment, staged, modular construction linked by airlocks, space stations can be expanded.
But why did the USSR and NASA bother, no longer to 'stop' with one monolith and simply use that facility? Firstly, limited space, means limited personnel - in the missions on Skylab and Salyut, most of the time, 3-person missions were carried out. By giving more modules, more sleeping berths and capacity to store all materials to accommodate more people, more scientists can live up there.
Secondly, the critical way to view the ISS is to look at purely square footage. It is widely touted that the structure covers the size of 1 football field, including the solar arrays. By deploying significant solar arrays, modules and storage, the facility can provide power, air, water and store enough spare parts to support more science payloads and fixed experiments. This greatly increases the amount of value that can be generated from the science up there.
As we can see in some plans, the use of the ISS as a staging and development area then cleaving into 'children' stations also presents itself as an opportunity.
Neither Mir nor ISS have undertaken such 'calving' to generate other stations, however this is discussed as a key lever to rapid development of more orbital infrastructure - other stations, more diverse structures and prototyping, as launch costs fall dramatically.
This then turned into multiple module structures when 'rapid' / successive launch became available - evidenced first through Mir - comprising 7 modules attached together:
Mir Core Module
Kvant - Astrophysics Module
Kvant-2 Augmentation Module
Kristall - Technology Module
Spektr - Power Module
Docking Module
Priroda - Earth Sensing Module
This was the first real full-scale demonstration of the viability of multiple module habitats in space. And it was a true success. I say this because the station was live for 15 years - this topped out at 3 times its original design life time, and survived a collision between the Spektr module and a Progress resupply vehicle. Above all, it proved the viability of a long-term orbital laboratory - completing over 23,000 experiments.
By moving from a single module to multiple modules construction joined together, the astronauts gain the opportunity to do more and more varied science - because of the greater space to deploy experiment rigs. Similarly, it also enabled to receive and stow greater payloads of food and water. This enables them to stay in space for longer and do more science, all while enjoying a more than spartan accommodation while there.
Further, the extra space provides greater opportunities for exercise and recreation - harking back to the earlier Skylab game of jumping 30 m through the core access way from one end to another, ISS cremates can somersault and perform all manner of acrobatics up there.
With space in space, comes increased personal space and time for reflection. I would argue that the single greatest enhancement to the ISS - from a personal wellbeing perspective - so far - is the deployment of the cupola.
The below reimagining of the Cupola over the blue south pole of Jupiter or that of the above blue Martian dunes above is a farce - there is no need for a station on Mars, as I had proposed in an earlier article. Indeed in the short to medium term, there will be no need for such infrastructure, the gravity well of Mars being so shallow that it is 'relatively' easy to escape Martian gravity - thus negating the need for a station there.
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