From the position of the International Space Station, it’s not always easy to consider the implications of gravity as a continuum, but society meetings like the recent American Society for Gravitational and Space Research (ASGSR) in Cleveland help bring that into focus. Gravity isn’t just on or off, and it can be easy to forget that the space station is not the only place to go if you need a little microgravity.
Solutions for simulated microgravity like High Aspect Ratio Vessels (HARVs), clinostats and random positioning machines exist to confuse the gravity vector. Magnetic levitation can balance the gravitational force for small, water-containing objects. Short durations of 2-6 seconds can be achieved through drop tower experiments. Up to 20 seconds of microgravity can be accessed through parabolic flight, and new commercial and sounding rockets can deliver 2-6 minutes of microgravity exposure. These methods provide the tools to explore various levels of microgravity, and when you add in the laboratory centrifuge, we can even explore the effects of hypergravity.
Dr. Mark Weislogel’s opening talk at ASGSR gave us great insights into the behaviors of fluids and fluid/surface interactions that you can achieve in just two seconds of microgravity. Non-intuitive behaviors that provide the building blocks for ideas, inventions, and for applications that need to be proven, need exposure to the long-duration microgravity environment on the space station. In the realm of space biology, we see genetic changes – differential gene expression – that occur in the first few seconds of exposure to microgravity, yet comparisons between long-duration space station exposure and simulated or short-duration micro-gravity exposure show some of these changes overlap and some do not. Clearly there is more going on here that we do not understand at this time.
To be successful interplanetary explorers, we need to be able to know what will happen to our physiology and systems as we transition from one to zero to 1/6 or 1/3 Gs, and back again. Knowledge of gravity as a continuum is a must. On the ground, we can explore aspects of this through magnetic levitation and centrifugation. Hypergravity studies on the ground are pointing
to interesting effects that we may need investigate further in microgravity, like glucose metabolism effects.
A healthy research community is using all of these tools to investigate gravity and better prepare us to make the most of our space station research. Our success in helping humanity explore the solar system is built on their research successes, not only in space but in research labs across the world.
Kirt Costello, PhD
Deputy Chief Scientist for the International Space Station