In this blog series on the second campaign of NASA's sensorimotor countermeasures (SMC) bed-rest study, researchers from the DLR Institute of Aerospace Medicine present the key experiments and people behind them, showing how they develop measures to prepare humans for safe space exploration – while also advancing medical care here on Earth.
When we think of space travel, space stations, rockets and rovers come to mind. However, a large part of space research is devoted to life sciences such as medicine, biology and human adaptation to extreme conditions. Long-duration missions to space challenge nearly every physiological system of the human body: our muscles and bones change, as do our balance and circulation – even the way we perceive our environment is altered in space.
Exercise while lying down
One of the countermeasures being tested in the bed-rest study against the negative effects of weightlessness during space missions combines 'proprioceptive' training with strength and endurance exercise.
Preparing astronauts for these adaptations is essential. When humans land on the Moon or Mars after months in microgravity, they won't have the luxury of recovery time. They will need to exit the spacecraft under unfamiliar gravity, walk across uneven terrain, operate equipment and make critical decisions. To be fully functional on arrival is mission critical. That's why we are developing targeted strategies – countermeasures – such as exercise protocols and stimulation techniques to preserve astronauts' performance in this novel, high-risk environment.
Precise bed adjustment
Spirit levels mounted on each bed confirm whether they are precisely adjusted at a six-degree head-down position.
But how do we test the effectiveness of these countermeasures before a mission? The number of people who get regular exposure to space is too small for the reliable, timely testing of new training methods. This is where 'space analogues' on Earth come in. Using special equipment, researchers can simulate specific aspects of space exploration here on Earth, under controlled and repeatable conditions. By isolating their effects as much as possible, the impact of countermeasures can be assessed.
Do not disturb
Privacy is important when using the ensuite toilet and when changing clothes, and subjects' rooms should also not be entered during certain experiments.
One of the most established models is head-down bed rest, where healthy volunteers lie in a bed tilted at minus six degrees towards the head for weeks or even months. This position mimics the fluid shifts, muscle and bone loss, and sensorimotor challenges that astronauts experience in microgravity. A head-down tilt study also allows us to recruit more subjects and systematically test more countermeasures than would be possible with 'real' astronauts.
At the DLR Institute of Aerospace Medicine, we are studying sensorimotor countermeasures in cooperation with the US space agency NASA, using this exact model. Across four campaigns, with 48 participants in total, we are investigating how various training methods can preserve coordination, balance and motor control. Every variable – including diet, sleep and exercise – is rigorously controlled to ensure scientific accuracy.
