The Space Station’s Vibrations: Are They Good for Science Experiments?
Media Credit: NASA
Hundreds of experiments are active right now on the International Space Station. They typically last a few weeks or months, before getting swapped out for new experiments that arrive on resupply vehicles such as Orbital ATK’s Cygnus cargo capsule that launched October 17, 2016.
This animation shows a Cygnus cargo spacecraft being captured by the Space Station’s Canadarm2 for docking.
Media Credit: NASANational Aeronautics and Space Administration
Experiments in the microgravityThe condition of perceived weightlessness created when an object is in free fall, for example when an object is in orbital motion. Microgravity alters many observable phenomena within the physical and life sciences, allowing scientists to study things in ways not possible on Earth. The International Space Station provides access to a persistent microgravity environment. environment of the ISSInternational Space Station can reveal surprising details about how things work. Combustion experiments showed materials scientists that some fuels continue burning with invisible “cool flames” even when their visible flames have gone out. Plant biologists were surprised to find that, in the absence of gravity, roots turned on light-sensing genes usually active only in leaves. Protein crystals grown in microgravity are easier to study than those grown on Earth, because space-grown crystals are bigger and have fewer structural flaws.
The Flame Extinguishment Experiment (FLEX) on the International Space Station yielded the surprising discovery that some fuels continue to burn even after the flame is extinguished.
Media Credit: NASA
Some microgravity experiments are extremely sensitive to tiny disturbances such as wobbles from a nearby astronaut using the exercise machines or vibrations from life support systems and other equipment running nonstop on the ISS, which you can detect as a constant background hum in any video shot aboard the Station. Debbie Wells, a science manager for the ISS U.S. National Lab, offered this comparison: “If you think about being in an airplane, all the noise and vibration that you feel—it’s like that, but worse.” Anything touching the Station’s walls, including racks filled with experiments, can be affected by these movements.
Until now, scientists have had difficulty judging whether the Station’s vibrations interfere with their experiments. But that’s about to change, thanks to technology developed through a partnership between Controlled Dynamics, Inc. and the ISS National Lab. The new Controlled Dynamics Locker (CDL) lets a small experiment float freely, isolating it from the Station’s movements. “To keep it from bouncing around in the locker, we apply tiny magnetic forces to keep it centered without jostling it,” said project lead Dr. Scott Green. This isolation feature makes the CDL sort of like a luxury car that offers you “an ultra-smooth ride,” Green added.
In this video, the small gold triangular box contains an experiment that needs to be isolated from vibration. That box is surrounded by electromagnets mounted to a round platform. During launch, the box stays firmly locked to the platform. Onboard the ISS, the electromagnets are turned on, causing the box to hover so it does not touch other surfaces.
Video courtesy of Controlled Dynamics/Scott Green
But the CDL does more than just isolate the experiment from the Station’s movements; it allows precise motion control within the locker. A researcher can program specific accelerations and vibrations to apply to an experiment. The customized movements can be repeated for several experimental trials, improving data quality. Continuing with the luxury car comparison, Green says this feature adds the option of enjoying a “programmable back massage” during your ultra-smooth ride!
The CDL will let scientists study how vibration affects their experiments. For example, biophysicists disagree about whether vibrations on the Space Station hurt or help protein crystal growth. Some think a crystal will grow larger and purer if perfectly isolated from any vibration, but others think certain vibrations could actually help the crystal grow by affecting the flow of dissolved chemicals near the crystal surface. A well-designed set of experiments in the CDL could help resolve this debate, leading to better crystals and a better understanding of protein structures.
Why does that matter? Many medical applications rely on understanding proteins. Disease-causing microbes have proteins that trigger an immune response, but some viruses and bacteria have surface proteins that let them hide from our immune system. Proteins in foods and other substances can trigger allergic reactions. Specialized proteins control the formation and breakdown of bone. Misshapen or tangled proteins are associated with diseases of the brain such as Alzheimer’s.
On October 28, 2014, an Antares rocket carrying an unmanned cargo vehicle exploded moments after it launched from NASA’s Wallops Flight Facility in Wallops Island, VA. The explosion didn’t hurt anyone, but it destroyed 5,000 pounds of supplies and equipment meant for the International Space Station.
Media Credit: NASA/Joel Kowsky
This week’s launch of the Cygnus capsule carrying the CDL used an Antares rocket for the first time in two years. After the last Antares rocket exploded in October 2014, Orbital ATK switched to Atlas V rockets until the new, improved Antares was ready.