Out of this world
The sky at night is both deceiving and fascinating – and its exploration is helping to save lives here on Earth.
On a clear night, you might spot the blips of light from the International Space Station, blissfully unaware of its scale or the cutting-edge scientific work it is doing.
It has returned to the headlines after celebrating two decades orbiting the Earth, and as part of renewed interest in space exploration that includes plans for manned missions to Mars and private space flights.
The images of astronauts floating in its cramped space belie the fact that the International Space Station is the largest artificial object in space – the size of an American football pitch. Yet it is ‘home’ to just six people at any one time.
So how does it keep that crew alive? And has there been any practical benefit from the work that has gone on?
The complexities of building it in low orbit were preceded by an equally challenging development. The Space Station had been the central aim of NASA’s early scientists but President Kennedy’s decision to land on the moon shelved progress.
The first section launched in November 1998 and the final section followed in May 2008. The station has been continually inhabited since October 2000.
It is made up of 14 elements with a mass of 900,000 lbm and is operated by 15 countries to provide a scientific laboratory dedicated to physical and biological sciences.
But in an age of computer simulation, why go there? NASA explains that by changing the environment, there’s better data.
The agency says: “Microgravity, or weightlessness, alters many observable phenomena within the physical and life sciences. Systems and processes affected by microgravity include surface wetting and interfacial tension, multiphase flow and heat transfer, multiphase system dynamics, solidification, and fire phenomena and combustion.”
Conditions in space include “exposure to extreme heat and cold cycling, ultra-vacuum, atomic oxygen, and high energy radiation”.
The biggest research area is on one of the simplest parts of our daily lives: generating heat – and emissions.
NASA explains: “For the foreseeable future the overwhelming majority of delivered energy in terrestrial applications will be from combustion or other chemically reacting systems. These energy uses cover the range from electric power and transportation to processes directly tied to manufacture.”
“These processes produce some of the most important environmental hazards currently facing humanity: global climate change, acid gas pollution, mercury contamination from coal, and wild-land fires.”
The agency adds: “Despite being the subject of active research for over 80 years, combustion processes remain one of the most poorly-controlled phenomena that have a significant impact on human health, comfort and safety.”
And all this research is happening at a speed of 17,500 mph. At 51 degrees inclination and an altitude of approximately 240 miles (400 kilometres), the ISS can orbit the Earth in 90 minutes with an orbital path covering 90% of its population.
And HVAC has a crucial role in making it all happen in a ‘shirtsleeve environment’.
The Environmental Control and Life Support System (ECLSS) provides a breathable atmosphere at a normal atmospheric pressure. This means the system provides oxygen (O2 ) and nitrogen (N2 ) at the same ratio as on Earth while removing contaminates such as carbon dioxide (CO2 ) and other impurities in the gas.
Ducting passes air between all the modules to ensure uniform mixing through High Efficiency Particulate Air (HEPA) filters. These have to be cleaned regularly as objects collect in the vents due to the lack of gravity.
Heating is critical as the temperature in Space is −270.45 °C. An active thermal control system uses heat exchangers and cooling loops filled with water to moderate temperature between 16.1 and 18.3°C. One section of pipes are filled with ammonia which has a lower freezing point at -77 °C. Two giant radiator panels outside the living section send excess heat into space.
Four tanks supply the oxygen and nitrogen needed for breathing. The tanks can either be vented directly to the cabin or stored. Transporting oxygen is expensive so generators produce it from water using electrolysis, which is the process of splitting water molecules into hydrogen (H2) and O2 using electricity. Having two independent systems provides redundancy if one suffers a problem.
But the biggest innovation is the water system used for rehydrating food, bathing and waste removal. Transporting water tanks is expensive and impractical. So water of every kind is filtered and reused.
Here’s how they do it:
“Using flush water, the Waste and Hygiene Compartment sends the urine to a unit (solids are retained in a tank to be disposed of later). It is treated with a chemical, called pretreat, to prevent the urea from crystalizing and potentially plugging the plumbing lines. A filter also removes any particulates that are left behind,” says NASA.
“It is pumped to the distillate assembly where the temperature is raised and the pressure is lowered to cause water evaporation. This evaporated water is compressed back into liquid form and is passed along to the WPA for further processing. The remaining fluid, called brine, is sent to the Advanced Recycle Filter Tank Assembly (ARFTA) where multiple filters pull out any particulates as the brine is sent back to the distillate assembly where it joins with more pretreat urine and more water is pulled out.”
But with just six people in space, who coordinates maintenance?
On the station, the Environmental and Thermal Operating Systems (ETHOS) flight controller is responsible for monitoring systems.
A NASA spokesman tells P&H Engineering: “In terms of who makes maintenance decisions, there are teams of flight controllers and program representatives constantly monitoring the station’s health and tasking astronauts for scheduled maintenance activities when appropriate.
“For larger maintenance activities, the International Space Station Mission Management Team consists of representatives from all space station international partner agencies and meets regularly to discuss and approve maintenance.”
Have there been any real-world benefits from all this work?
The ISS team has produced a 212-page dossier detailing the patents and projects that have resulted. And many of them involve creating safe water supplies around the world.
Among them is the Aquaporin Inside Tap Water Reverse Osmosis membrane for household purifiers.
The microbial water analysis kit – part of the space station’s environmental control systems – is being shared by mWater, a non-profit venture focused on providing low-cost test kits and monitoring software in support of the global Water and Sanitation for Health (WASH).
“Whether working to send the first woman and next man to the Moon or helping improve the technology that carries passengers from Portland, Maine, to Portland, Oregon, NASA innovators are constantly creating new technology,” said Jim Reuter, associate administrator of the agency’s Space Technology Mission Directorate in Washington. “Often these advances have wide-ranging benefits well beyond the need they were first imagined to meet.”
There’s another goal; in an era of fake news and conspiracy theories the scientists want to share the successful adaptations.
He adds: “Telling the public that story is one way we fulfil our mission to find homes for the technology beyond the agency for maximum benefit.”
Reuter says proudly: “Transferring NASA technology beyond the space agency is part of our culture and one of our longest-standing missions.”
Satellite TV anyone?
Looking for high-definition views of Earth from the space station? You can watch the ISS live on the Earth Viewing Experiment on UStream.
Spoiler alert: It’s only available when the space station is in contact with the ground.
Thinking of applying?
Astronaut training for a mission takes three years, depending on the tasks that will be involved. A scientific or aeronautical background is preferred. And all ISS missions require the ability to speak Russian – training is extended for this.
Want to stay more grounded? The UK has around 15 firms plus universities –including the University of Leicester – that build satellites. Dust particles can render the equipment useless so complex HVAC systems are needed for production facilities. Maintenance roles are specialist, but the market is expanding. A new £500m Deep Space research centre is set to be built in Leicester.