In the near future, crews will embark on multi-month missions to the Moon, and eventually Mars and beyond. All incredible adventures, however, have their hazards, and a major one for crews on long-duration spaceflights is the space radiation they will be exposed to during their missions.
A new experiment aboard the International Space Station, The Growth of Large, Perfect Protein Crystals for Neutron Crystallography (Perfect Crystals) study, aims to help scientists find a way to deal with the problem using a protein that is already at work in our bodies.
The Perfect Crystals experiment flew to the orbiting laboratory on SpaceX’s 16th commercial resupply mission (CRS-16), and is led by principal investigator Gloria Borgstahl, lab technician William Lutz, and doctoral graduate student Jahaun Azadmanesh from the University of Nebraska Medical Center.
Shedding Light on the Problem
Exposure to space radiation can create dangerous chemical compounds in the body called reactive oxygen species (ROS).
“Radiation from space is a big problem — especially for crew members,” said Azadmanesh. “ROS damages our DNA and contributes to the development of many diseases here on Earth, including heart disease and cancer.”
This serious health threat means NASA must devise ways to protect astronauts from radiation. Figuring out how to deal with the damage from ROS could also help scientists treat and prevent cancers back on our planet.
The answer may come from the way our bodies already deal with the low-level radiation that sneaks through our atmosphere and reaches us on Earth. The protection is provided by a naturally-occurring protein in our cells called manganese superoxide dismutase (MnSOD), which breaks ROS down into more benign substances the body can safely process.
“Everyone on Earth is constantly bombarded with solar radiation, and superoxide dismutase helps us deal with that,” said Lutz. “Since NASA is dedicated to traveling to the Moon and Mars, we are hoping to help find a way to protect astronauts from this harmful radiation, and we think superoxide dismutase could help.”
The first step is finding out how MnSOD works — all the way down to its atoms.
The method the team wants to use to study the atomic structure of MnSOD is a very powerful technique called crystallography. To use crystallography, researchers must employ liquid chemistry to get molecules of MnSOD to stack themselves in a very uniform way, like bricks in a wall, until they form crystals that are similar to a grain of salt. They can then take the crystals into a special laboratory, where they expose them to intense blasts of neutrons and track how the neutrons bounce off them using surrounding detectors. The way the crystals diffract the neutrons could tell researchers a lot about the shape and position of atoms in the stacks of MnSOD, providing clues about how it functions.
The problem is that growing proteins into crystals that are large and uniform is difficult to do on Earth. Vibrations from machines, the presence of impurities, and even gravity can interfere with how well crystals grow. Consequently, an imperfection in a crystal, such as a speck of dust or molecules that are stacked in a sloppy way, can throw off how a crystal bends the paths of neutrons, yielding inconclusive results.
Finding the Perfect Solution
The space station, with its ultra-clean microgravity environment, could be the ideal place to grow crystals of MnSOD that are large enough and ordered enough to show scientists how they really work.
“It is ironic that the problem of space radiation could be solved with the aid of space,” said Azadmanesh. “The microgravity environment the space station provides significantly lessens the intensity of vibrations, which promotes an environment where crystals can grow with the fewest imperfections.”
To try out the idea, the investigation is testing different approaches to growing MnSOD crystals over weeks and months aboard station. After the SpaceX resupply vehicle arrived, cushioned boxes filled with vials of MnSOD crystal-growing solution were unpacked from the Dragon cargo craft and placed in an EXPRESS locker inside the orbiting laboratory to insulate them from possible vibrations. The vials, which contain different formulations of the solution, will begin growing crystals at varying times.
“About half of the vials will grow crystals after arriving at the station and within 30 days,” said Borgstahl. “The other half will take a few months to grow. We’ll see which approach works best.”
When the crystals are ready, they will be brought back to Earth on later cargo return flights. Azadmanesh will then take the best crystals to Oak Ridge National Laboratory in Tennessee and analyze the MnSODs’ atomic structure using the facility’s crystallography equipment. The findings of his analysis will be used in medical applications and shared with other researchers to help explain how MnSOD functions and potentially create methods to help spaceflight crews manage the hazards associated with radiation and stay healthy on their missions.