10 Benjamin Kustrin Can we create a self-sustaining space station, now or in the near future? Science Tharnan Nimalan

Benjamin Kustrin

Space stations are of huge importance to reaching out further in space exploration, but having a self-sustaining one could be potentially even better. In this project, I will discuss four main points – the benefits of having a self-sustaining space station, the engineering problems of making such a station, and considering both of these, is it feasible to create a self-sustaining space station, now or in the near future. The benefits of a self-sustainable space station Quoting NASA, the creators of the ISS (International Space Station) the purpose of a space station is to make it “possible for people to have an ongoing presence in space ... allow crew members to do research that could not be done anywhere else ... [and] to prepare for human missions that reach farther into space than ever before.”1

These main goals are already partially met by current space stations, the ISS, and the Tiangong Space Station. The ISS has continuously been inhabited by humans for more than 21 years 2, completing the first goal. The second goal, completing research that could not be done anywhere else, is being completed, shown by some of the experiments, for example ISS-RapidScat, which uses its unique position in orbit for mapping large areas with microwaves to predict weather patterns (900 km scanning radius3 compared to the range limit of similar ground-based versions which is a single spot4). It can also prepare for human missions into deep space, at least in part, by being a technology demonstrator for future outposts such as the planned Gateway station, which will be a “staging point for deep space exploration5”. If a non-self-sustainable space station can do all of that, why need a selfsustainable one?

Self-sustainable space stations have a few significant advantages. Revisiting the first goal, a self-sustaining space station would not only allow an ongoing presence in space, but it would also allow humanity to survive, should Earth be destroyed by a war or asteroid, as a selfsustaining space station would not require supplies from Earth. The second goal, allowing crew members to do research that could not be done anywhere else, would be even cheaper on a station whose payload can be filled entirely with experiments and not just supplies. Finally, the third goal, which is to prepare for deep space human missions, would also be improved by a large, self-sufficient station as one could utilise the large station as a ‘orbital construction shipyard’ for flights to Mars and beyond, as well as training astronauts to spend longer periods in space. Engineering of such a station To be completely self-sufficient is to “able to maintain oneself or itself without outside aid” 6 . When considering how to, we should take account the resources needed to keep a person alive. NASA7 states that “Human beings have certain basic needs. We must have food, water, air, and shelter to survive.” Considering this, we should think about ways we can create them. Our system will be based around the most important: air and its production.

Air production

One way to make oxygen, in a small space and with few moving parts or dependencies on plants and their survival, is a process involving Electrolysis and the Sabatier reaction. This process is currently being demonstrated on the ISS8 to produce breathable air, with this formula: 2H2O >electrolysis> O2 + 2H2 >respiration> CO2 + 2H2 + 2H2 >Sabatier reaction> 2H2O + CH4

This initially uses electrolysis to split two water molecules into oxygen and hydrogen. The oxygen is inhaled by humans and carbon dioxide is exhaled. The CO2 is added to hydrogen (half of which is from earlier, the other half is added). They are held at a high temperature, reacting to form two water molecules and waste methane.

Overall, it takes water, and adds carbon dioxide and hydrogen to create more water and methane9. The water is then fed to the beginning again. My diagram below illustrates the

process: When considering the self-sustainability of a station using this reaction, respiration would produce plenty of carbon dioxide, but hydrogen would still have to be added from tanks, as

on the ISS.

However, by using methane pyrolysis (heating the methane at 1200°C to get it to thermally decompose), 95%10 of waste methane could have its hydrogen recovered (shown above). These hydrogen atoms could be then inputted back into the Sabatier reaction, greatly reducing the hydrogen needed. The only waste product would be carbon forming on the sides of the methane pyrolysis reactor. This pyrolytic carbon could find use elsewhere on the station, either as a construction material, or it could be dumped overboard. The unreacted methane could be used for attitude control or reorbiting.

Food

There are three methods considered here in terms of feeding the crew – lab-grown meat, fungi, and plants. Lab grown meat is a method of making meat by taking a small number of cells from animals on Earth and growing them in special chambers to produce muscle and fat cells. A company, Mosa Meat, has managed to create a system that takes 0.5 grams of cells 15

and creates “80,000 burgers” from it12. However, this method requires a huge input of sugar and oxygen to feed off, as each of the cells still respires as usual. Also, the process is highly experimental, still in development, and also requires precise conditions to grow. Fungi is also used on Earth already, for example in Quorn, the common meat substitute. However, it also has waste products13 and requires a lot of glucose too. The third option is plants. Unlike the other options, plants actively scrub the air, and produce glucose for us to eat, without also needing air, so they could fit into the system well. See the below diagram:

This updated system would instead use plants to recycle human carbon dioxide, and the Sabatier reactor will finish what the plant does not take in through an electrically controlled valve. The plants would take in water from a water recycling system (which we will discuss next) and carbon dioxide from humans and

photosynthesise, creating glucose and oxygen. We will breathe the oxygen and eat the glucose (in the form of plant leaves or tubers). Then, when we excrete, water will be reclaimed from faeces, urine, and the water vapour we exhale, and carbon dioxide will be used by plants and the Sabatier system.

Water recycling

The water recycling system is also an important part of the station. Plants depend on it for photosynthesis, and we depend on it to survive.

Water from urine can be recycled, as around 91-96%14 of urine is water. Faeces are around 74.6%15 water, and so an efficient system would be able to reclaim a most of the water inside. This kind of system is already in place16 in the ISS WCS system, which recycles water vapour in the air, and all urine and wastewater from taps, sinks, etc. In terms of urine, it was designed to recover 85% of water from urine. However, a known effect of free-fall is that there is more calcium in astronauts’ urine meaning in practice it can only recycle 70% of water from urine. It works using distillation and uses a centrifuge to simulate gravity. All exhaled water vapour from is recovered as it has no contaminants17 and washing water recovery rates are also 100%18. About 93.5% of water is recovered by the ISS overall19. In a new mission, Nasa plan to send a “Brine Processor Assembly,” which will further remove water leftover from the from the WCS, meaning a 98% recovery rate of water20 .

is not recycled.

Power Production

Applying the technology to our space station, the mechanism would be quite simple. This would be especially true as the BPA was designed after the WCS and integrating the two would mean a simpler and lighter mechanism. However, there would still have to be a water tank to make up the 2% which

All of the other systems we have discussed require power. Power would be used to heat the Sabatier reactor, power the electrolysing process, grow the plants and spin the pumps of the water production system. Looking at different power production methods, there are a few main types used on spacecraft.

• Batteries • Fuel cells • Solay arrays • Solar dynamic devices • RTGs • Nuclear reactors.

Batteries are not sustainable, as they cannot be charged without one of the other methods. Fuel cells require hydrogen and oxygen to turn into water, however the Sabatier reactor depends upon using all of these, so we can rule the first two out.

Solar arrays are a generally light (in mass) method of getting electric charge, however their efficiency is often close to 10%21 and with a maximum of 1400 Watts per square meter falling on the panels22, only 140 Watts can be produced. The panels degrade over time - they can run at about 70% power output after 10 years23 in good conditions. They also only produce electricity in the bright side of an orbit and even then, the 1400 Watts available changes based on how the panels are angled (at the sun).

Solar dynamic devices are basically a large collection of lenses and mirrors that reflect and refract light into a sphere of water, which is turned to steam and drives turbines. This power method is more efficient and was considered for space station Freedom (the concept station that led to ISS, shown by this picture24).

However, Solar Dynamic Devices have a few problems – they weigh a lot, are flimsy, and also produce large amounts of drag.

RTGs are a reliable long term power supply. They are basically a casing for nuclear fuel, surrounded by thermocouples that generate electricity from the heat. However, they do not produce much electricity, suitable only for powering computers rather than powering high temperature reactions etc.

Space nuclear reactors are essentially like the nuclear reactors on earth, but scaled down and optimised for Zero-G. Their power production is in the thousands of Kilowatts25 However, they are very heavy, as well as needing many permits to launch nuclear fuel on a highly explosive carrier rocket.

Using a nuclear reactor would be ideal for the space station, as high power would constantly need to be produced. However, any reactor would need refuelling. A fuel pellet has 3,900,000 Megajoules of stored energy per gram26, as opposed to wood which has 16 Megajoules of stored energy per gram27. As a result, one pellet can produce heat/ electricity for one to two years28, requiring practically no refuelling.

What such a station might look like, if one is possible A station simply interconnecting all of these subsystems would not be complete, as we have only touched upon the main systems needed, and we have not considered the possibility of a failure in one of these systems. Neither have we considered other aspects, such heating, radiation, redundancy, a medical lab in case a crew member is injured. A station can never be truly self-sufficient, as all of the reactions are not 100% efficient. An example is the methane pyrolysis - 5% of hydrogen required would have to be added externally. Another example is the water recovery - 2% of water would have to be inputted from supplies, in a best-case scenario. So in conclusion, a completely self-sustaining station is not possible. However, our design can be expected to last about a year without a supply mission. This calculates as about 600% better than the ISS. Expanding on this, similar concepts utilising space mining for supplies and/or having the station on the planetary surface could increase this percentage.

1. Nasa.gov, audience/forstudents/5-8/features/nasa-knows/what-is-the-iss-58.html, 2020, “The space station has made it possible for people to have an ongoing presence in space. Human beings have been living in space every day since the first crew arrived. The space station's laboratories allow crew members to do research that could not be done anywhere else. This scientific research benefits people on Earth. Space research is even used in everyday life. The results are products called "spinoffs." Scientists also study what happens to the body when people live in microgravity for a long time. NASA and its partners have learned how to keep a spacecraft working well. All of these lessons will be important for future space exploration.”

2. Nasa.gov, oct-31-2000-launch-of-first-crew-to-international-space-station, 2015: “On Oct. 31, 2000, a Soyuz spacecraft lifted off from the Baikonur Cosmodrome”

3. Wikipedia.org, ISS-RapidScat, 2021: “It could collect data between 51.6 degrees north and south latitude, with a swath 900 km wide (560 mi).”

4. Wikipedia.org, Scatterometer, 2021: “Their main drawback is that the measurement is done over the very small volume of air between the transmitter and the receiver”

5. Nasa.gov, gateway/overview, 2021: “The Gateway will be an outpost orbiting the Moon that provides ... a staging point for deep space exploration.” 6. Merriam-webster.com, Dictionary/self-sufficient, 2021?: “able to maintain oneself or itself without outside aid : capable of providing for one's own needs.”

7. NASA, PDF 162514 on Human Needs, Unknown date: “Human beings have certain basic needs. We must have food, water, air, and shelter to survive. If any one of these basic needs is not met, then humans cannot survive.”

8. Nasa.gov, mission_pages/station/research/news/sabatier.html, 2017: “Currently in operation on the station, Sabatier is the final piece of the regenerative environmental control and life-support system”

9. Wikipedia.org, Sabatier reaction, 2021: “The Sabatier reaction or Sabatier process produces methane and water from a reaction of hydrogen with carbon dioxide at elevated temperatures”

10. Wikipedia.org, Sabatier reaction, 2021: “the loop could be further closed if the waste methane was separated into its component parts by pyrolysis, the high efficiency (up to 95% conversion) of which can be achieved at 1200 °C: (diagram)

11. Wikipedia.org, Sabatier reaction, 2021: “The released hydrogen would then be recycled back into the Sabatier reactor, leaving an easily removed deposit of pyrolytic graphite”

12. mosameat.com, growing-beef, Unknown date: “0,5 gram sample taken under anaesthesia Standardized veterinary procedure Selection of 33.000 myosatellite cells 80.000 burgers from one sample”

13. researchgate.net, figure/The-Quorn-fermentation-process-A-continuous-supply-ofmedium-is-fed-into-the-fermenter_fig5_340498918, 2008-2021 (?), (Diagram), also description: “The Quorn™ fermentation process. A continuous supply of medium is fed into the fermenter and the broth is harvested simultaneously. The harvested broth is heated to a temperature that destroys proteases but leaves RNAses active, allowing the RNA content of the mycelium to be reduced to less than 2%, which is a regulatory requirement. Once the broth has been heat-treated, the mycelium is spun down to form a paste, which is mixed with binders and flavouring agents before being shaped, cooked and frozen. The supernatant from the paste is currently sent for treatment as wastewater, but active research at Marlow Foods is looking into how the 1.5% solids in the waste can be recovered as a food grade coproduct.”

15. nih.gov, pmc/articles/PMC4500995/, 2015, “Feces had a median pH of 6.64 and were composed of 74.6% water”

16. Wikipedia.org, ISS_ECLSS, 20201, 2021, “The American segment has a Water Recovery System installed during STS-126[3] that can process water vapour collected from the atmosphere and urine into water that is intended for drinking.”

17. WIkipediea.org, Cellular_waste_product, 2021, “Cells undergoing aerobic respiration produce 6 molecules of carbon dioxide, 6 molecules of water, and up to 30 molecules of ATP (adenosine triphosphate), which is directly used to produce energy, from each molecule of glucose in the presence of surplus oxygen.”

18. nasa.gov, feature/new-brine-processor-increases-water-recycling-on-international-spacestation, 2021, “...processed through the Water Processing Assembly (WPA), which recovers 100% of the water it processes”

19. nasa.gov, feature/new-brine-processor-increases-water-recycling-on-international-spacestation, 2021, “As a result, our overall water recovery is about 93.5%.”

20. nasa.gov, feature/new-brine-processor-increases-water-recycling-on-international-spacestation, 2021, “With this new brine processor assembly, we’ll recover additional water from the urine brine produced by the Urine Processor, such that the overall water recovery is closer to 98%”

21. Graham Swinerd, How Spacecraft Fly, 2008, “Solar arrays for space ... have an efficiency of around 10%.”

22.drb-mattech.co.uk, uv map.html, Unknown Date, “The generally accepted solar constant of 1368 W/m2 is a satellite measured yearly average.”

23. Graham Swinerd, How Spacecraft Fly, 2008, “After 10 years of operation in GEO, the electrical output from a solar array can be reduced by around 20% of its beginning of life performance.”

24. The American Society Of Mechanical Engineers, Solar Dynamic CBC Power for Space Station Freedom, 1990, Picture (Cropped)

25. Graham Swinerd, How Spacecraft Fly, 2008, “They are used only for applications requiring large amounts of power – on the order of hundreds to thousands of kiloWatts”

26. energyeducation.ca, encyclopedia/Energy_density, 2021, (Table)

27. energyeducation.ca, encyclopedia/Energy_density, 2021, (Table) Uranium-235 Nuclear 3 900 000

Wood Chemical 16

28. xceed-eng.com, nuclear-reactor-refueling, 2021, “With Nuclear Power, sites generally refuel every 1-2 years, depending on the design of the plant.”

Who Were The Winners And Losers Of Covid-19?

Tharnan Nimalan

In December 2019 the Coronavirus emerged in Wuhan, China and rapidly spread across the world. It has resulted in 5.43 million deaths and has had many effects in the world, resulting in many winners and losers11. In this essay I will discuss several winners including IT, the environment, delivery services and gaming companies and the losers who were students, the economic sector, frontline workers, the tourism sector and patients. Firstly, delivery services were a winner of the Covid-19 pandemic because restaurants did not allow visitors during lockdown which increased the demand for online services through delivery apps. The four main services (Doordash, Uber Eats, GRUBHUB and Postmates) made 5.5 billion dollars in combined revenue from April to September 2020 whereas in 2019 during the same period, only 2.5 billion dollars were made. . In the short term, many restaurants shifted to an online delivery service with these apps so they could continue to make money. However, a Cowen & Co. survey of 2500 consumers showed that in July, 52% of people still said that they would not go to restaurants and bars even following the lifting of restrictions. This suggests that many people were scared to go to these places and this would now make restaurants reliant on the delivery apps over a long period of time and would result in delivery apps gaining even more revenue. Graph showing how much money each of the 4 main delivery services made(marketwatch.com)

Uber Eats was the biggest winner of the four main services where their bookings rose 135% , and its revenue increased by 125% to 1.45 billion dollars. Environmental benefits also emerged because people were not allowed to go outside, resulting in less travel which decreased emissions and air pollution due to lower fossil fuel emissions. As well as a reduction of fossil fuels, there is also a reduction in greenhouse gases such as nitrogen dioxide, sulfur dioxide and carbon dioxide3 .

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In addition, factories would not have been in work during the pandemic so harmful gases have not been going into the air and this would further improve the air quality. Despite these environmental benefits, the increased demand for delivery services has increased demand for materials to package items. These materials include single-use plastic and paper which are bad for the environment. The pandemic also lead to a demand in protection against the virus such as masks, gloves, gowns, hand sanitizer etc. and this would require lots of resources which are bad for the environment. Therefore these environmental benefits are slightly counteracted but there is still an overall environmental gain. Moreover, IT was a winner due to lockdown where there has been a surge in the use of electronic devices. During April 2020, adults spent an average of four hours a day online which is an increase from September 2019 when it was three and a half hours4. The use of IT would have increased greatly due to every school in the world doing their lessons online through apps like Zoom and Microsoft Teams. This would have caused these companies to gain lots of money. For example, Zoom’s owner Eric Yuan came into the ranking of top 100 richest people in 2020. His zoom shares are worth almost 17 billion dollars5 .

Apps used for entertainment also increased greatly such as Twitch which saw their visitors increase from 2.3 million in January 2020 to 4.2 million in April 20204. This would have given many streamers on Twitch an opportunity to make lots of money. For example, famous Twitch streamer Nickmercs made 1,737,535 dollars in 20206. This shows us that Twitch and many of their streamers would have made so much money due to the lockdown. Another winner from Covid were gaming companies. Due to people not being allowed to go outside, people have been bored at home and have decided to try new things like gaming. The global time spent on video games increased by 39% during the Covid pandemic7 and this would therefore provide more money for gaming companies and making companies more successful (statista.com). An example of a company is EA Sports which made 1.49 billion dollars in 2020 which is a 120 million dollars increase from the total revenue last year8 . There would also be a much higher demand for gaming consoles such as the Playstation or Xbox during the lockdown so children did not get bored as they had so much more free time. For example, the number of Nintendo Switches sold in 2020 was 9.37 million units9. This shows us that a great amount of money was made from the usage of console as well as the purchasing of consoles. Not only was time spent gaming on consoles but was also spent on Phones and PCs. There were 2.2 billion mobile gamers in the world in 202010. (techjury.net).

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On the other hand, frontline workers such as the NHS were losers during the Covid-19 pandemic. During the lockdown, these workers had to manage a huge influx of patients who had contracted the Covid-19 virus, causing them to work in very high-pressured environment. Despite the longer working hours and stress induced on the NHS, this was not reflected in the wages received by doctors and nurses as they earnt 8% less than the other employees12 . This shows us that the workers were not just doing it for the money but also to help and save lives and therefore makes the frontline workers heroes as you could say they were running the country. This high pressure environment also led to many workers having mental health problems due to the overload of work and stress and would have an effect in the long term. Another challenge the frontline workers had to face was delivering care without spreading the virus. This included having to wear lots of protective equipment such as masks and gloves and many other parts of equipment. Many frontline workers had to also work in wards which they had never worked in before therefore they would be in an unfamiliar setting and they would have to work in a different way. Not only did they have to work in unfamiliar wards, but they also had to work with a lack of equipment such as ventilators which would cause a rise in stress across the whole of the NHS. This would mean that some patients might have not been able to receive certain resources whereas others might have not. Across other countries, there was a growing incidence of stress, burnout, depression, drug and alcohol dependence and suicide across all groups of health professionals13 and this emphasises how difficult it was for frontline workers.

Secondly, students had a negative impact from Covid-19 because GCSEs and A levels were cancelled so teachers had to predict a grade in which their student would get. A student could have received a lower result when they might have got a higher result in the exam. This would have a long term effect as this might prevent a student from getting into a university which could further prevent them from getting a certain job in the future. This shows us that these skewed results could affect a student’s whole life. Another problem students have had to face is having their lessons online. This would disrupt their education and would mean they would miss out on learning opportunities. In the long term, this missed out education would not prepare them for future years of learning. Some people from a lower socio-economic background would have not received an education at all as they would be able to access ipads and laptops for online learning14. This increases global inequality. A child’s health would also be a worry during lockdown as some might be inside all of the time so they would not receive any vitamin D from the sun which is important for a child’s

cognitive development and academic performance and is essential for bones and teeth. Some children might not have a garden so they would not be able to engage in outdoor activities which would cause weight problems. A Chinese study by Chen stressed the need to maintain a regular physical activity to avoid behaviours that lead to inactivity15 . Furthermore, the economic sector was another loser of Covid-19. In 2020, GDP declined by 9.7%16. This means that the UK economy would have lost lots of money due to the market value of goods and services going down. Employment was down by 47%17 and this was caused by many businesses going out of business because their total revenue was less than the money they lost during the lockdown. An examples of a business which has closed down is Monsoon where 545 jobs have been cut and 35 stores are expected to close18. This indicates that many shop workers would have had a negative impact from the pandemic as they might have lost their job.

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Fourthly, the tourism sector was a loser. In July 2020, 20% of rooms were occupied whereas in 2019 in the same month, 90% of rooms were occupied20. The main reason for this is that there were travel restrictions therefore people were not allowed to travel and then stay in hotels. These travel restrictions have meant that tourism was one of the most affected sectors in the lockdown and has meant that the tourism sector has lost 935 billion dollars which is equivalent to a loss of 900 million visitors21. This shows us how much of a disaster Covid has been for the tourism sector economically. An example is Heathrow Airport where the passenger number have reduced by between 80%-90% a month and has led to Heathrow losing about 3.4 billion dollars22. Due to this loss in money, they have had to

change the way in which they did business and cut their spending. This shows us that this loss of money has caused airports to make even more changes. Finally, patients had a negative impact from Covid as many patients who did not even have Covid could not have a checkup. For example, if someone needed to check if they had cancer, they could not check and therefore the cancer could not be caught quickly. This means that the cancer would get worse and would not be treated at the beginning. This implies that the pandemic would not only cause deaths from Covid but it would also cause deaths from other illnesses. 10% of patients reported that they were unable to get an appointment23. Hospitals were focused on treating patients with Covid but they could not even treat all of them due to the lack of equipment such as beds and ventilators .In January 2020, there were 4.4 million patients on the waiting list and there were about 730,000 people who had to wait more than 18 weeks24 .

In conclusion, there were more losers than winners and I believe that frontline workers were the most affected. They had to work extra hours to not even get a fair wage and some were affected a lot mentally leading to depression. As a student, learning how to use new online platforms like Microsoft Teams was challenging at first but became easier and I felt that online learning was an interesting experience for me as we had to adapt to doing things such as homework in many different ways. However for many, I know that online learning has been a stressful experience for them, especially younger students who would have missed out on lots of education. Looking forward, I hope to see a world without a disease like Covid19 and to see a recovered economy. As well as this, I would want schools to always be open so many students do not need to struggle and feel like they have missed out on education so they can be prepared for the future.

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American sports combined, thanks to the pandemic 12. (2020) Should NHS Workers Be Paid Than A Footballer? 13. (2021) Improved Mental Health Support For Frontline Workers Urgently Needed 14. Montacute R. (2020) Implications for Covid-19 Crisis For Educational Inequality 15. Gupta S., Jawanda M. (2020) The Impacts Of Covid-19 On Children 16. Harari D., Keep M., Brien P. (2021) Coronavirus: Economic Impact 17. (2021) The Employment Situation 18. Grahns A. (2020)Monsoon Accessorize to permanently close 35 shops-full list of stores revealed 19. (2021) Coronavirus and the impact on output in the UK economy: August 2021 20. (2021) Coronavirus and the impact on the UK travel and tourism industry 21. (2020) Impact assessment of the Covid-19 outbreak on international tourism 22. Covid-19 Recruitment Impact at Heathrow

23. Charlesworth.A, Watt.T and Thorlby.R (2020) Early Insight Into the Impacts of COVID-19 on Care for People with Long-term Conditions 24. Charlesworth.A, Watt. T and Gardner.T (2020) The Health Foundation: The Scale of the Challenge Pre-COVID-19