How do humans interact in space? That’s what NASA is asking in anticipation of mankind’s next steps towards future space exploration goals. Large-scale experiments have been trying for years to shed light on human response, both physically and mentally. Results derived from the famous astronaut twins and simulations of missions to other celestial bodies may facilitate the design of… future expeditions.

The effects on humans in space for safer travel

A standard mission inside the International Space Station lasts about 6 months. After twenty years of continuous expeditions we have learned a lot about the psychophysical response of astronauts. Staying beyond low Earth orbit means a longer time frame: just think of the two to three years it takes to mission to Mars. The goal is to have more biomedical, behavioural and performance data that are valid for at least 400 days.

“To draw conclusions about the cumulative effects of space exposure, we need to observe more astronauts spending more time in the space environment. Scientists can use the information to predict trends in physical and behavioral health.”

John Charles, Ph.D., associate director for exploratory research planning for the Human Research Program at NASA’s Johnson Space Center

Teams around the world are already at work, and under NASA’s supervision have submitted study programmes for various areas identified for analysis: space radiation, isolation and confinement, interface with hostile environments, distance from Earth and gravity. That is what NASA’s Human Research Program (HRP) is all about: investigating human-focused methods and technologies for the next trips to the stars!

Results of the Kelly twins study

We previously reported on the groundbreaking NASA mission involving twin astronauts. The brothers Scott and Mike Kelly were selected for a comparative study: Scott spent a year on the ISS, while Mark remained on Earth as a control subject. The results are still partial, but let’s see what’s been discovered so far:

• Variation in the telomere size. Telomeres are the endings of chromosomes and tend to shorten with age. It seems that being in space increased the average length; the effect lasted up to 2 days after re-entry. The team is not yet sure about the effect because it could be due to the caloric balance during the mission.
• Effects on cognitive ability: the comparison between the cognitive abilities before, during and after the mission between the two brothers remained unchanged. Scott, the “space” sibling had a predictable drop in accuracy and speed due to the microgravity conditions.
• Immunological responses to the flu vaccine. The results produced similar effects in different environments for the two siblings: the immunostimulatory effects were the same on the ground as on the ISS.
• Interactions on RNA and DNA. Space conditions produced genetic responses: hyperactive immune activity, response to hypoxic states, altered DNA, blood coagulation and altered bone formation. 93% of gene expression appears to have returned to normal after re-entry to Earth.
• Influence on atherosclerosis. The team studied metabolomic and genomic markers of atherosclerosis. Scott’s markers were elevated, indicative of the inflammatory state that then involved vascular function. Studies need to determine whether this is a reversible state or an accelerated progression of atherosclerosis in Scott compared to Mark.
• Proteins in the urine. The variation of protein excretion allows us to understand the state of dehydration of the human body during the space mission.

HERA: Simulating a mission to Phobos, the moon of Mars

Since 1 October 2021, four volunteers have isolated themselves within a protected environment at NASA’s Johnson Space Center in Houston. The goal is to simulate a 45-day mission to Phobos.In this case, the primary objective is to test on-board operations following communication delays between Earth and the mission’s virtual position: up to 5 minutes. This is just one of 15 planned test campaigns.

Efforts are geared to support the technological advancement of the last decades, which in fact expands our potentially reachable boundaries. Therefore, a better understanding of how the human system reacts to extra-terrestrial stimuli is also needed. The HRP programme aims to deepen the relationship between humans and space: preparation for future missions continues.