New upgrades to a NASA radiation laboratory will let researchers explore the deadly environment astronauts encounter beyond Earth's magnetic field.
Radiation is the silent killer of space exploration. Astronauts can't sense their exposure to it, and over time it can lead to problems such as cancer or heart disease. Before humans can venture to Mars — a mission that NASA hopes to start in the 2030s — scientists will need to figure out how to protect the travelers on their long journey.
Martian astronauts will be unprotected by Earth's magnetic field, and therefore exposed to galactic cosmic radiation from charged particles (ions) emanating out of supernova explosions. They also will receive radiation doses from the sun — especially during coronal mass ejections that often happen with solar storms — and as they travel through the Van Allen radiation belts encircling Earth. [How Radiation in Space Poses a Threat to Human Exploration Explained (Infographic)]
NASA's Space Radiation Laboratory has already collected plenty of data on sources of Earth radiation, which ranges from X-rays to CAT scans to radon emissions in the house. (Radiation from space is deflected by our atmosphere and magnetic field.) But space radiation is different from Earth's electromagnetic radiation: It consists of a rain of particles that are traveling at close to the speed of light. Space radiation has enough energy to hit the nuclei in shielding material and human tissue, NASA officials have said, breaking these apart into new particles called secondary radiation.
"Where we lack data, and we have a large amount of uncertainty, is the biological consequences of space radiation. So really, the next steps and the ongoing steps are to try to understand those exposures better, and the biological consequences that follow them," said Tony Slaba, a research physicist at NASA's Langley Research Center in Virginia, in a video by NASA EDGE on YouTube.
Recently, NASA's Space Radiation Laboratory received upgrades that will help researchers better understand space radiation and its effect on biology. The NASA lab, which is located at the U.S. Department of Energy's Brookhaven National Laboratory on Long Island, can now better simulate galactic cosmic radiation. These upgrades were detailed in the journal ScienceDirect last year.
Researchers can now switch ion types and energy intensities within minutes to better simulate the conditions of outer space. This used to be hard to do in the lab, but a software control was added to make it easier to switch targets, NASA officials said in a statement. During the upgrade, engineers upgraded the cooling system in an electron beam ion source magnet for higher energy currents, and they added new probes to two of the beamline's magnets to make it faster to set changes.
The upgrades produce several benefits, according to the statement. The lab now covers more of the galactic cosmic-ray spectrum. The beam is larger, meaning it is easier to radiate several samples at the same time. Dose delivery is more accurate because of precision control, and experiments can provide a more uniform radiation field intensity.
"Imagine ion trajectories to be similar to rain; sometimes there is a downpour (solar particle event) and sometimes there is a light drizzle or heavy, sparse droplets (similar to galactic cosmic radiation)," Lisa Carnell, the lead of NASA's space radiation medical countermeasure team, said in the statement. "With the upgrades we can simulate different types of ion rain with multiple types of ions sequentially, versus only one type of ion at a time."
Preparing for Mars
NASA's Space Radiation Laboratory is just one of a few United States labs that can create heavier ions (charged particles). This is useful not only for cancer research, where heavy ion therapies can help eliminate tumors, but also for generating realistic exposures for an astronaut on a two- to three-year mission to Mars.
NASA can use this research to help establish lifelong radiation limits for astronauts, according to the statement. The current limit for low-Earth-orbit missions is a 3 percent increase in lifelong excess cancer risk. By comparison, measurements from the Curiosity rover suggest that a Mars landing and return mission of 860 days (2.3 years) would deliver a dose to astronauts of 1.01 sieverts, which is about a 5 percent increase in lifelong excess cancer risk. (The European Space Agency has a lifelong limit of 1 sievert.)
"[Our research] helps the astronauts not only from the short-term effects of radiation, but also the long-term health effects," Lisa Simonsen, a space radiation element scientist at the NASA Langley Research Center, said in another NASA EDGE video on YouTube. NASA studies lifelong cancer risk caused by radiation, as well as damage to the brain, central nervous system and heart, which can develop vascular disease with exposure to radiation.
NASA is also preparing several parallel technologies for better astronaut protection, the researchers said. This includes meters to measure radiation levels on the International Space Station, a hybrid electronic radiation assessor for the next-generation Orion spacecraft and the radiation assessment detector on the Curiosity rover.