by Zhen Zong Lim
Spurred by rapid advancement of technology and the entry of private companies in the space exploration race, space access is no longer confined to wealthy global superpowers. As a result of this democratisation of access to space exploration, the world is experiencing a renewed interest in space at levels not seen since the Apollo missions in the 1960s. With missions like NASA’s Artemis Program planned for the near future, humankind is once again looking to break free from our earthly tethers in search of answers in the cosmos.
Yet while we have long had the technical capability to transport probes and machinery far into deep space for extended periods of time, much work is still needed to be done before humankind is able to survive for extended periods in space, let alone achieve interplanetary status.
One of the most pressing concerns for human survivability is the effect of space radiation. While the Earth’s magnetosphere provides shielding against most types of space radiation, the space environment after Low Earth Orbit (LEO) consists of several type of ionising radiation. This includes a constant flux of low linear energy transfer (LET) radiation from solar wind, galactic cosmic radiation (GCR) ions originating from outside our solar system containing high-energy protons, alpha particles and high charge and energy nuclei, as well as large plasma clouds containing highly energetic protons and heavy radiation ions from solar particle events (SPE). Current shielding technologies provide limited protection against GCR, especially ionised transition metals, and SPEs with high density proton fluxes. Additionally, SPE protons and GCR particles can interact with spacecraft structures and shielding to produce additional radiation hazards that can have detrimental effects on astronauts1.
While there remains uncertainty of the morbidity risk and toxicity profiles of GCR and SPEs, it is known that space radiation exposure has a complex effect on multiple organ and physiological systems including degenerative vascular changes, genetic mutations, carcinogenesis, ionising damage to the CNS leading to decreasing cognitive functioning and fatigue1.
As a result, with the lack of sufficient knowledge about biological effects to space radiation, current space radiation guidelines are only relevant for LEO, making space radiation one of the most pressing risks to be solved to allow for long-term deep space travel1.
With NASA’s Human Research Programme outlining space radiation as a high-priority risk limiting successful human exploration beyond LEO, researchers have been looking into various ways to limiting astronaut space radiation exposure. Recently, a paper was published detailing the possible use of radiotrophic melanised fungi as a radiation shield.
In the paper, Cladosporium sphaerospernum (a melanised, radiotrophic fungus able to thrive in high-radiation environments) growth and ionising radiation attenuating ability was studied on the International Space Station (ISS) over a period of 30 days as an analogue of Mars surface habitat. The experiment showed a 2.17% decrease in radiation beneath a 1.7mm layer of fungus. Extrapolations with Martian radiation levels showed a 21cm layer of C. sphaerospernum required to shield against radiation. This opens the door for the possible use of metabolic engineering to increase the melanin content or integration of melanin with other materials to increase attenuation ability. This promising result serves to showcase such composites as a possible means to increase radiation protection with lesser mass (which is important as weight is an important launch factor) for future deep space missions2.
The future of space exploration is an exciting one. With the increasing cooperation between governmental and private sectors, we are seeing new scientific and technological innovations appearing at breakneck speed, allowing us to achieve what previously was deemed impossible. I believe that our generation is entering a revolutionary stage in space exploration, one that will delve deeper and longer into space than ever before, allowing us to make new discoveries, answer age-old questions, and lay the foundation for future generations to reach interstellar travel and humankind to attain multi-planetary status.
Hello readers! My name is Zhen Zong Lim and I am a third-year medical student at Imperial College London. I, along with a group of fellow Imperial students, united by our common interest in aerospace and extreme environment medicine, have gotten together to set up an (as of yet unofficial) Society of Extreme and Aerospace Medicine. Aerospace and extreme environment medicine is a highly niche field without a fixed path to entry. As such, we hope our society will serve as a platform to raise awareness of this field of medicine to potentially interested students and encourage them to get involved.
I hope that I might have sparked an interest in you, dear reader, in potentially dedicating your career helping humankind in its cause to unlock the mysteries of the cosmos. If you are indeed interested in finding out about what we do, please do hit us up on Facebook, Instagram or Twitter @icxspacemed. We believe the field of aerospace medicine is a highly inter-disciplinary field and our members come from a diverse background including medicine and computing. Additionally, we are organising a talk by Imperial College alumnus Dr. Mala Mawkin on 27th October 2020, 6pm – 7pm on Zoom. She will be sharing about her journey into space medicine as well as her research on glucose intolerance in spaceflight. Tickets are FREE and can be purchased at the following link: https://www.eventbrite.co.uk/e/merging-medicine-and-space-mala-mawkin-tickets-122863775861. We hope to be able to organise many more interesting talks and workshops to promote this field in the near future so do stay tuned!