Philippa Flanagan-Smith
Tears held together by surface tension, zero-G tortillas, Star Trek cosplays — the International Space Station (ISS) has produced a plethora of entertaining and informing content about life in space since its launch in November 1998. A quick Google search brings up thousands of results about how astronauts on the ISS sleep, wash and use the toilet, or what the view of the Earth from above is like. But why are they up there to begin with? What actually happens on the ISS?
"There's coffee in that nebula"… ehm, I mean… in that #Dragon. pic.twitter.com/9MYrqIOXnI
— Samantha Cristoforetti (@AstroSamantha) April 17, 2015
The Station
The ISS is a 21-year (and counting) multi-national collaboration between 5 space agencies —NASA (USA), Roscosmos (Russia), JAXA (Japan), CSA (Canada) and ESA (Europe). Circling the Earth at a low Earth orbit of ~400 km (thousands of kilometres lower than satellites used for weather monitoring and GPS), the station is perhaps larger than one may assume from the videos. With an immense mass of 420,000 kg, the main body of the ISS is 109 m in length and has over 900 m3 of pressurised volume (about twice the length of an Olympic-size swimming pool and just over a third of the volume).
240 people from 19 countries have visited the ISS
The iconic T-shaped solar arrays have a combined area of around 2,500 m2 and charge the station’s onboard batteries to keep the power on when the station is in the Earth’s shadow. The station took 10 years and over 30 missions to assemble, with new modules continuing to be added to facilitate even more research.
The Astronauts and Their Research
240 people from 19 countries have visited the ISS. Among them is NASA astronaut Peggy Whitson who holds the American record of 665 cumulative days in space. During this time she contributed to hundreds of studies aboard the ISS, including research into the effects of microgravity (the apparent “weightlessness” experienced by objects in orbit) on the human eye, an investigation into using microgravity to grow human lung tissue, and research into chemotherapy drugs.
Tim Peake also remotely piloted a rover, still back on Earth, from the ISS
Whitson’s last mission, Expedition 52, which concluded on Sept. 2nd 2017, also included the installation of the Cosmic Ray Energetics and Mass Investigation (ISS-CREAM). Whitson’s journal of her time in space, documenting her experiences, her thoughts, and many of the day-to-day human moments shared between the crew (including origin of the crew’s motto “it’s all about the sauce”) can be found archived on the NASA website.
Another well-known visitor to the ISS is British astronaut Tim Peake, who spent six months aboard the station in 2015/16 as part of Expedition 46. During his time on the ISS, Peake contributed to several experiments, including investigations into the effects of microgravity on the growth of endothelial cells (cells found inside human blood vessels) and the effects of exposure to space on microbes. He also remotely piloted a rover, still back on Earth, from the ISS — a technique which could be used to safely explore Mars in years to come.
Tim Peake on a space walk outside the ISS
Perhaps the most well-known visitor to the ISS is Canadian astronaut Chris Hadfield, who also participated in an ISS assembly mission in 2001. Although Hadfield is most known for his outreach work, including appearances in the many videos answering questions about life on the ISS, he has also carried out much important research.
During his six month mission aboard the station in 2012/13, Expedition 34, Hadfield aided in the Radi-N2 experiment which investigated the amount of neutron radiation present aboard the ISS using “bubble detectors.”
These detectors are small tubes containing droplets of superheated liquid suspended inside of an elastic polymer (a type of very long molecule such as a plastic). When a neutron (a neutrally charged subatomic particle) passes through the liquid, a small bubble is produced and suspended within the polymer, allowing radiation levels to be tracked by simply counting the bubbles.
The Current Mission
The current inhabitants of the ISS are the crew of Expedition 63 — Russian cosmonauts Anatoly Ivanishin and Ivan Vagner, and NASA astronaut Christopher Cassidy — who’s mission began in April 2020 and is due to end this month.
From left are, NASA astronaut and Commander Chris Cassidy and Roscosmos cosmonauts and Flight Engineers Anatoly Ivanishin and Ivan Vagner
Among their other duties of station maintenance and science outreach, the crew has been operating several of the ISS’s on-board experiments. This includes the ACE-T-Ellipsoids experiment, which investigates ‘three-dimensional colloids’. A colloid is a suspension of particles within another substance (think of air inside shaving cream or the butterfat solids in milk).
The types of colloids being investigated could pave the way for the 3D printing under microgravity. Transporting cargo (such as replacement parts or tools) to the ISS is costly and comes with the risk of delays or failures. Being able to 3D print objects on the station itself would reduce the cost of missions and ultimately make them safer.
Along a similar, but more biological line, is the Space Organogenesis experiment. Cell cultures produced on Earth are limited to growing in two-dimensions unless some kind of artificial structure is used to help support and shape it. Under microgravity, the cultures could grow three-dimensionally without any additional structure because they are able to ‘float’ without gravity pulling them flat.
The Space Organogenesis experiment studies this 3D growth using human stem cells and looks at the effect of microgravity on human genes, potentially paving the way to growing artificial human organs.
The experiment is trying to determine whether supernovae (the superbright remnants of exploded stars) are the main source of observed cosmic rays
ISS-CREAM is an experiment that has been running on the ISS since 2017 and is due to conclude in 2021. It investigates cosmic rays (high energy particles which originate from the sun, as well as from sources outside of the solar system) without the interference caused by the Earth’s atmosphere.
In particular, the experiment is trying to determine whether supernovae (the superbright remnants of exploded stars) are the main source of observed cosmic rays and will hopefully give us a better idea of the history of cosmic rays in our galaxy. It also seeks to shed light onto one of astronomy’s ongoing mysteries – the cause of a sudden steepening of energy in the cosmic ray spectrum known as ‘the knee’.
What next?
Beyond ISS-CREAM, the ISS has a variety of on-going experiments that are still collecting data. Back on Earth, the ‘NASA Authorization Act of 2020‘ (sponsored by Democratic Congresswoman Kendra Horn) was introduced to the US House of Representatives in January 2020, seeking, in part, to extend NASA’s ISS operations through to “at least 2028.”
It’s clear that the ISS still has many years of service ahead of it, expanding human knowledge beyond the stars and, perhaps, providing even more entertaining YouTube videos along the way.
Expedition 64 is due to launch on 14th October 2020 and return in Spring 2021.
Philippa Flanagan-Smith
Featured image credit: NASA/Roscosmos. Image usage guidelines found here. No changes made to this image.
In article Tweet from @AstroSamantha
In article photograph of the Tim Peake by NASA Johnson from Flickr. Image license found here. No changes were made to this image.
In article photograph of the Expedition 63 crew by NASA Johnson from Flickr. Image license found here. No changes were made to this image.
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