MSc Space Physiology & Health; Human Performance Intern, McLaren Applied Technologies
With international space agencies and the real-life Tony Stark (Elon Musk) making huge advances in rocket technology, it is likely that within the next couple of decades humankind will touch down on Mars. However, this is only half the battle. The gravity on Mars is roughly one third as strong as Earth’s. You may be thinking “great, everything will require less effort”, and you’d be right, however, there is a huge caveat to that. As we’ve found from the results of time spent in space (the longest continuous period being 14.4 months), when people are exposed to levels of gravity lower than that on Earth, losses in muscle and bone occur; predominantly, in muscles which we continually use to walk and maintain our posture. You may have heard the expression ‘use it or lose it’ - hugely applicable here. These losses can increase astronauts’ risk of injury when returning to Earth by leaving them very weak and fragile. A return mission to Mars will take around 3 YEARS to complete, mainly because of the wait for the two planets to be close enough in proximity again to allow a relatively short journey home. That’s around 12 months in microgravity and around 26 months in Martian gravity. Now, it doesn’t take a rocket scientist to figure out that, based on the numbers, the outlook for muscle retention isn’t great. That being said, we‘re still pretty uninformed about the extent to which living on Mars will stimulate our muscles.
Recently, my colleagues and I conducted an investigation to try to shed some light on the matter. To do this properly, we needed to achieve two key things: 1) simulate walking in Mars gravity, 2) measure the activity in the muscles used for walking. With this, we compared the muscle activity produced while walking on Mars to that produced when walking on Earth, gauging the degree of muscle loss that we might expect for a mission to Mars and to inform countermeasures.
To simulate Mars gravity, we used a technique called lower body positive pressure (LBPP). There are a few different ways in which you can simulate partial gravity environments, but this one has fewer limitations than the rest. LBPP involves putting someone inside an air-tight inflatable box from the waist down. Through manipulation of the air pressure within, it can generate a lifting force, changing the weight of the person inside. Our device was designed and built by engineers at the John Ernsting Aerospace Physiology Laboratory at the Pontificia Universidade do Rio Grande do Sul (PUCRS) in Porto Alegre, Brazil. With a treadmill placed underneath, the participant could then walk in simulated Mars gravity. To measure the amount of activity inside the leg muscles, we then attached electrodes to the skin at each of the muscles we were interested in (a method called electromyography) which picked up an electrical signal that muscles give off when they are being worked. The more intense the signal, the more active that muscle is while walking.
What we found was quite unexpected. The results of our investigation suggested that there was no significant difference between the muscle activity observed while walking in Mars gravity and the muscle activity observed walking on Earth. If this were to be true, then it would not be foolish to think that we could use the 26 months on the Martian surface to reverse losses in muscle and bone suffered on the outward journey in preparation for the return trip. However, there were two important variables that we failed to account for in our experiment. These variables were stride length and stride frequency when walking.
The moon is smaller than Mars, and so there is even less gravity there, but the same principle applies. With this in mind, even if the results of our experiment were to be true and the walking muscles are getting just as much activity with each step on Mars as they are on Earth, theoretically, they will be used less often. Considering our ‘use it or lose it’ principle, this would still mean muscle and bone loss to a disabling degree in the absence of effective counter strategies; which are currently lacking. More studies need to be done around this area, accounting for all variables, to further our understanding of human performance on Mars and ensure the safety of our astronauts, or we’ll be keeping Elon Musk waiting at the launch pad!
Dr Andrew Winnard
Lecturer in Clinical/Musculoskeletal Biomechanics; Lead for the Aerospace Medicine Systematic Review Group; Chartered Physiotherapist; Faculty of Health and Life Sciences, Northumbria University
This was a question that the European Astronaut Centre space medicine office asked the Aerospace Medicine Systematic Review Group (AMSRG). With space agencies planning missions beyond low Earth orbit, in spacecraft that might not be as easy to exercise inside as the International Space Station, this question is becoming more relevant. While it is clear that countermeasures are needed to maintain muscle during microgravity exposure, there were questions such as ‘should we really be going to the Moon without exercising?’; ‘can we safely have pauses in countermeasures during Earth-Mars transits?’; and ultimately ‘how long can humans go in microgravity, without exercising, before the muscles seriously decondition?’.
There appeared to be some information available in the research base but no clear and transparent synthesis existed on which to make evidence based medical decisions. The AMSRG, led by Prof Nick Caplan, Dr Rochelle Velho and myself, based at Northumbria University’s Aerospace Medicine and Rehabilitation Laboratory, is all about working with spaceflight operations to provide high quality, evidence based medical guidance and, therefore, we took these questions on readily. It was determined that if data from inactive/no intervention control groups within any study done with astronauts or bed rest participants could be extracted, it would provide the evidence based information on which to inform the questions being asked. The team worked for almost two years, screening 754 potential studies, before extracting data from control groups of 75 individual included sources, to calculate 922 individual effect sizes, making this the largest review the AMSRG has conducted to date. All the included studies were from bed rest, ranging from 60-120 days, with mostly high risk of bias (using Cochrane’s risk of bias tool) and typically scoring 4 out of 8 for bed rest quality (using AMSRG’s bed rest quality tool). Across all the studies the team found that moderate deconditioning effects (effect size ≥0.6) occur between 7-15 days, with large deconditioning effects (effect size ≥1.2) occurring by 28 days.
Based on this, it seems that a 5 day Earth-Lunar transit period is probably safe to complete without exercise, at least for the skeletal muscle outcomes. However a Mars transit, that is likely to be 200+days, needs to counteract muscle deconditioning if the crew is to arrive and be able to function in a gravity loaded environment. Additional consideration was given to ‘worst case scenarios’, such as if there were a crew member more susceptible to low gravity induced muscle changes, for which the team used the most extreme negative end of the confidence intervals as a model. In these cases, a large deconditioning effect could be reached by 7 days and then even the travel time to the Moon could potentially become problematic. However, this model is rather crude due to large confidence intervals caused by the typical low sample sizes in human spaceflight research, and individual effects are difficult to determine in a way that is easily transferable to astronauts. Over the whole evidence base, there was great variety in outcome measures and time points evaluated across studies, along with limited data for all outcome measure subgroups, with research gaps highlighted in the published review’s results tables. No patient reported outcome measures of minimal clinical worthwhile changes were established that would help provide a more patient-centred approach to space medicine. This has been a common finding in AMSRG reviews. While space agencies require astronaut simulating bed rest studies to be done to set standards, it might be useful to try and establish a list of core outcome measures that would benefit human spaceflight operations, to become a foundation for patient-centred space medicine and to standardise the data presented to the field as a whole.
Dr Joaquim Ignácio S da Mota Neto / Dr Thais Russomano
Psychiatrist, Federal University of Pelotas, Brazil / Founder & Scientific Director, InnovaSpace
The brain is the prime and most complex organ of the human body and within it takes place the sophisticated phenomena that define us as human beings, enabling recognition of and interaction with our surroundings. Basic and primitive survival functions pass through the different formations and axes of the Central and Peripheral Nervous System, but far beyond this are the many other functions that differ in complexity and high degree of neural connectivity, such as those performed by the limbic system, containing the hypothalamus, hippocampus and amygdala.
These important structures are responsible for integrating and giving context to aspects of emotions, memories and learning, thus building our cognitive capacities. Therefore, it is essential to maintain the functionality of these cerebral regions that permit the acquisition, storage and recall of information, as together with the cerebral cortex, they are fundamental for several aspects of personal, social and professional performance.
The perception of potential fragility of these intricate brain structures is inevitable, when faced with extreme and unknown situations, such as one might encounter on a manned trip to Mars. The effects of different space features, such as radiation or microgravity, may pose a threat not only to the ability of an astronaut to perform both simple and complex tasks, but also to control emotions or react in an adequate manner to a new environment in which access to old memories may become essential.
A recently published article by Mike Wall of Space.com presented the issue of space radiation and how it can affect the brain function and psychological behaviour of animals, in research using a new scientific approach. The study conducted by Munjal Acharya & Janet Baulch of the University of California and Peter Klein of Stanford University, exposed mice for the first time to a continuous and chronic low-dosage radiation (1mGy/day). The idea of the research team was to mimic a manned trip to Mars, during which astronauts would be exposed to 6 months of low-dosage, deep-space radiation. This type of protocol differs from those previously used, in which animals were submitted to high-dosage radiation over short time periods.
The space environment is very unique and is full of radiation in the form of galactic cosmic rays, particles of high energy and charge, and solar particle events, which differ from the low-LET (X- or g-rays) radiation that is predominant on Earth. Radiation is known to affect humans in several ways, in three distinct phases: acute, latent and chronic effects. Chemical mediators are first released from damaged cells, particularly from bone marrow, lymphoid tissues and the gastrointestinal tract, leading to symptoms, such as nausea, vomiting and malaise. The latent phase is free of symptoms as it represents the time between the initial cell injury and manifestation of cell renewal. Chronic effects include a decrease in cell count, and increase in the risk of developing cancer, and degenerative and infectious diseases.
The negative impact of radiation on the Central Nervous System (CNS) has been considered relatively minor, as the CNS is formed of few actively dividing cells, which provides it with a type of natural resistance. Nonetheless, some studies have demonstrated that space radiation could potentially produce undesirable effects on the brain, including a decrease in function and neurodegeneration.
The results from the mice study would seem to corroborate the hypothesis that radiation can indeed cause deleterious effects on the CNS, perhaps due to the longer 6-month period of exposure to the low-dose radiation. These findings, published in the Society for Neuroscience's open-access journal, eNeuro, suggest that mice exposed to radiation had alterations in their hippocampus, the part of the brain responsible for learning and memory, and the prefrontal lobe of the cortex, dedicated to cognitive functions and social relationships. The neurological pathway has yet to be defined, but it is already of serious concern to the space scientific community, as such alterations could cause impairment in psychological performance, especially during stressful and critical situations, like those that could easily be experienced during an interplanetary trip, which is exactly the occasion when clear and immediate decision-making or problem-solving responses are needed!
Under normal conditions on Earth, the human cognitive and emotional processes can struggle to perform well enough to cope with the demands of everyday life, and therefore, the subjective and objective adversities of adapting to a long-duration trip to another planet could be a huge challenge. Even if we are able to control each one of the many physical or psychological variables that could impact on our relationship with the space environment, aerospace science still needs to deal with poorly understood aspects related to the interaction of executive memory with emotions, with experts having highlighted that what we remember is never the same as what was originally set to be fixed in our memory - the material undergoes change in the storage process as each individual adds personal characteristics to the stored element.
The peculiarities of the human brain and its crossovers between the acts of feeling, thinking, planning and performing have already led humanity to evolve, overcoming innumerous obstacles from the Stone Age to the Modern Era. However, even in a place with no palpable barriers, like the vastness of space, there will be invisible elements, such as radiation, that could be powerful enough to delay or impede human omnipotence and omnipresence in the exploration of the Universe.
Dr. Gabriela S. Pilo
Oceanographer, Institute for Marine & Antarctic Studies (University of Tasmania, Australia)
It is quite easy to draw a parallel between ocean and space exploration. Both require a ship, a large sense of adventure, and a love of discovery. But there are more similarities between the ocean and space than simply their ability to feed the imagination of writers, musicians, and curious minds.
The ocean, like space, is still unknown. Similarly to space research, ocean researchers are still trying to fill several knowledge gaps. We’ve advanced a lot since the beginning of modern Oceanography, attributed to the Challenger Expedition in 1872. We have now charted the main ocean currents, from the surface down to the bottom of the ocean, at 6000 m depths. We understand how and where surface waters become dense and sink, creating a conveyor belt that connects the whole planet, travelling for 1000 years before re-surfacing. We also understand that ocean currents interact with the wind, the ocean floor, and with each other, and break into several rotating bodies of water, known as ocean eddies. These eddies spin away, carrying their parent current’s water to distant parts of the ocean. However, as in space, there is still a lot we don’t know. Gaps in ocean research relate to balances of energy and of biogeochemical compounds, and to the response of the ocean to a changing climate.
Considering that there still so much to learn, we often find ourselves in the middle of the ocean looking for answers! This brings up the second similarity between ocean and space research: when you are out there, conditions can get harsh! Open-ocean Oceanographic cruises can last for up to 3 months, having only a few shore stops during this time. Therefore, like in space, an oceanographic vessel must be autonomous for a long period of time. During research cruises, scientists and crew members are putting all their efforts into sampling the water and measuring physical properties of the ocean. Sampling happens under all circumstances, in the middle of the night, in rain, snow, and under very high wave conditions! In addition, icebreaker vessels can go deep into an ice field, and reach the most remote parts of the world. Ocean-sickness, just like space-sickness, often kicks in, as your body gets used to the constant movement. You are also living in a confined space with like-minded people that have one goal: to do science!
But the ocean is not just a large body of water, flowing and crashing against the shore. The bathymetry of the ocean, the chemical elements dissolved in the water, and the animals, microbes, and algae that live in it, are equally important and fascinating! Oceanography is a highly multidisciplinary research field. Therefore, to fully understand the ocean, we need to collaborate. It takes a team of physical oceanographers, marine biologists, geologists, meteorologists, glaciologists, and several other scientists to put the pieces of the puzzle together. This team work builds up our knowledge of the ocean. Just like in the space sciences, collaboration is key! For example, the InnovaSpace Team is composed of experts in life science, telehealth, and engineering.
Finally, the ocean, like space, is vast. We cannot be everywhere, at all times to study it. To obtain global, constant measurements of the ocean we rely on state-of-the-art sensors, similarly to space research. The sensors to measure the ocean are either aboard a series of artificial satellites orbiting the Earth, or in instruments placed in the water. Sensors onboard satellites can measure the sea surface temperature, salinity, and sea surface height. In the water, sensors are aboard floats, mooring arrays, automated underwater vehicles, remotely operated vehicles, gliders, and seals (!). Operational oceanography is a fascinating field of research, and at its heart sits the Argo array, composed of 4000 Argo floats measuring temperature and salinity of the top 2000 m of the ocean since 2005. This array has helped oceanographers to answer important questions on ocean circulation and climate change.
Ultimately, the ocean - just like the space - brings fascination. The excitement of discovery is present both when exploring a deep canyon or a distant quasar. In the end, the ocean is also a final frontier. A frontier, however, closer to home!