Breathlessness has to be avoided at all costs. The astronauts are welcome to speechlessness when they see beautiful ol’ Earth from space but we really don’t want to take their breath away. How are we going to ensure that our astronauts have plenty of oxygen to get to Mars?
With over 7.5 billion people living on our planet a lot oxygen is needed to ensure that those 7.5 billion people aren’t dead. Where does it all come from?
50 to 85% of our oxygen comes from phytoplankton, oceanic, microscopic plants that live on the ocean’s surface (1). They photosynthesise like all other plants but their sheer number means they contribute a great deal to the overall volume of oxygen we breath. All plants photosynthesise which produces oxygen but also takes in carbon dioxide.
Using plants as the primary source of oxygen poses some issues. First, plants can only grow in the right conditions (Much like humans with their homeostasis). They require air, light, warmth, water and nutrients. On Earth this isn’t a challenge but, alongside the demanding needs of the crew, it’s naturally a lot harder in space.
One of the biggest problems about growing plants in space is that water doesn’t interact as well with soil in zero gravity. As a result, root systems can die which is never a good thing when you depend on the plant to survive (3).
That’s not to say it can’t be done. The ISS has seen a number of plants grown on board including basil, mustard, dwarf wheat, radishes and strawberries (2). The fact that plants have been grown and with such variety presents it as a possible solution but in conjunction with another system. Plants take time to grow so other systems would be required to bridge the gap.
Growing plants aboard the Erikson is a viable option for providing oxygen to our astronauts. It also offers the possibility of a source of fresh food as well as a system for removing waste gases provided it’s regulated (2). It does pose a problem with water society but it can be factored in if deemed good enough.
Electrolysis of water
On board the ISS they have water reclamation and oxygen generation systems. The former takes in astronauts’ urine, condensation on the wall and Extra Vehicular waste activity and ensures it can be reused on board the space station. We will have a look at that more when we discuss water (3).
Some of this recycled water is used to produce oxygen. Electrolysis, for those who don’t particularly like chemistry (Which used to be me, I’m exploring it more now I don’t have to do it as a compulsory subject (That being said, I’m far from an expert)), is effectively the breakdown of ionic substances into simpler substances with electricity (4). In this instance, an electric current, provided by the ISS solar panels, is passed through water from a positively charged anode to a negatively charged cathode. This breaks the water down where oxygen gas is produced at the positive anode and hydrogen gas is produced at the negative anode (3).
The astronauts can then breath in the oxygen whilst the hydrogen is combined with carbon dioxide, with the help of a catalyst (A component that basically speeds up the reaction without being used up, very handy), to form methane that is then filtered into space (Flammable gases are never a good idea aboard a space craft).
Would this work aboard the Erikson? Being a hypothetical spaceship we can make it a fair bit bigger than the ISS (Whether or not we can scientifically will be explored later) so we could house this system with ease, perhaps even increasing it’s capacity. It is definitely a more water-tight system than our forest and it helps that it has refined on-board submarines (3). Naturally, the need for water does raise a few problems but the crew size hasn’t yet been defined (I should probably do that soon…) so who knows how much urine we’ll have at our disposal (I bet you weren’t ever expecting to read that in your lifetime. You’re very welcome).
The excess hydrogen does come with some interesting possibilities as a fuel source. Noted, it is incredibly volatile but again, we already use it on Earth so whose to say we can’t use it in space?
In terms of realistic solutions, these two offer us the best chance of providing enough oxygen to our astronauts. Have any other suggestions for oxygen sources? Comment below. Any general thoughts or questions? Also comment below. Thank you.
- Earth Sky (2015), How much do oceans add to world’s oxygen? [online] Last accessed 13 August 2017, http://earthsky.org/earth/how-much-do-oceans-add-to-worlds-oxygen
- The Telegraph (2011), Plants growing in space [online] Last accessed 13 August 2017, http://www.telegraph.co.uk/news/science/space/8589849/Plants-growing-in-space.html
- Michelle Starr (2015), Breathe deep: How the ISS keeps astronauts alive [online] Last accessed 13 August 2017, https://www.cnet.com/uk/news/breathe-deep-how-the-iss-keeps-astronauts-alive/
- BBC Bitesize (2014), Electrolysis [online] Last accessed 13 August 2017, http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/acids/electrolysisrev1.shtml