How NASA Will Protect Astronauts From Space Radiation at the Moon

How NASA Will Protect Astronauts From Space Radiation at the Moon

August 1972, as NASA scientist Ian Richardson remembers it, was hot. In Surrey, England, where he grew up, the fields were brown and dry, and other people tried to remain indoors — out of the Sun, televisions on. except for several days that month, his TV picture kept ending . “Do not adjust your set,” he recalls the BBC announcing. “Heat isn’t causing the interference. It’s sunspots.”

The same sunspots that disrupted the tv signals led to enormous solar flares — powerful bursts of energy from the Sun — Aug. 4-7 that year. Between the Apollo 16 and 17 missions, the solar eruptions were a mishap for lunar explorers. Had they been in orbit or on the Moon’s surface, they might have experienced high levels of radiation sparked by the eruptions. Today, the Apollo-era flares function a reminder of the threat of radiation exposure to technology and astronauts in space. Understanding and predicting solar eruptions is crucial for safe space exploration.

Almost 50 years since those 1972 storms, the data, technology and resources available to NASA have improved, enabling advancements towards space weather forecasts and astronaut protection — key to NASA’s Artemis program to return astronauts to the Moon.

Space radiation may be a key factor for astronaut safety as they venture to the Moon. NASA is exploring a spread of techniques and technology to mitigate differing types of radiation during spaceflight .

Credits: NASA’s Goddard Space Flight Center/Joy Ng

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Space isn’t empty

Today, Richardson may be a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. He studies high-energy particles that burst from the Sun within the wake of giant solar eruptions.

In addition to flares, huge clouds — called coronal mass ejections — containing a billion plenty of solar material occasionally blast from the solar surface. Increasingly, scientists think coronal mass ejections play a dominant role in driving the Sun’s most powerful radiation: solar energetic particles, or SEPs.

astronauts 

Earth is at the middle of a huge blue, comet-shaped bubble. 

Earth’s magnetic bubble, called the magnetosphere, is illustrated in blue. The magnetosphere provides natural protection against space radiation, deflecting most charged solar particles from Earth.

Credits: Andøya Space Center/Trond Abrahamsen

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SEPs are most protons, flung at such high speeds that some reach Earth, 93 million miles away, in but an hour. “When a high-speed boat goes through water, you'll see the wave before it,” Richardson said. “The shock waves before fast coronal mass ejections accelerate particles before them.”

Radiation is energy packaged in electromagnetic waves or carried by particles. The energy is handed off when the wave or particle runs into something else, like an astronaut or spacecraft component. SEPs are dangerous because they pass throughout skin, shedding energy and fragmenting cells or DNA on their way. This damage can increase risk for cancer later in life, or in extreme cases, cause acute radiation syndrome within the short-term.

On Earth, humans are safe from this harm. Earth’s protective magnetic bubble, called the magnetosphere, deflects most solar particles. The atmosphere also quells any particles that do make it through. The International space platform cruises through low-Earth orbit, within Earth’s protection, and therefore the station’s hull helps shield crew members from radiation too.

But beyond Earth’s magnetic reach, human explorers can face the tough radiation of space.

“The danger of radiation is usually present, whether you’re in orbit, in transit, or on a planetary surface,” said Ruthan Lewis, a Goddard architect and engineer for NASA’s human spaceflight program. “From mitigation techniques to protection and enclosures, we’re considering this in every environment astronauts are going to be in.”

Space lifeguards 

Two women wearing hard hats are in small bay of a spacecraft, surrounded by storage bags. 

Jessica Vos (foreground), deputy health and medical technical authority for Orion, and astronaut Anne McClain (background) demonstrate the radiation protection plan during a representative Orion spacecraft. During an SEP event, the crew will use stowage bags on board Orion to make a dense shelter from radiation.

Credits: NASA

Orion Backstage: Evaluating Radiation Protection Plans for Astronauts

In a room crammed with expansive computer screens and blinking lights at NASA’s Johnson Space Center in Houston, scientists work daily shifts to watch space weather for astronauts on the space platform . referred to as space environment officers, they’re the lifeguards of space: rather than tidal waves and rip currents, they keep await the ebb and flow of space radiation.

Each day, the scientists — who are a part of Johnson’s Space Radiation Analysis Group — check the space weather outlook from the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center. They alert mission control of potential solar activity. If solar energetic particles are ramping up and therefore the space platform happens to be passing outside Earth’s magnetic protection, they could recommend postponing activities that need leaving the security of the station. Anywhere astronauts go, the group will keep watch their space environment. 

During a future Artemis mission, if a radiation squall were to occur while astronauts are beyond Earth’s magnetic bubble, they could tell the crew to create a short lived shelter. “Our strategy in space is to form use of whatever mass is out there ,” Johnson scientist Kerry Lee said. “We’re redistributing mass to fill in areas that are thinly shielded and getting crew members closer to the heavily shielded areas.”

The more mass between the crew and radiation, the more likely that dangerous particles will deposit their energy before reaching the crew. On the Moon, astronauts could pile lunar soil, or regolith, over their shelters, taking advantage of their environment’s natural shielding materials. But where spacecraft design cares , counting on sheer bulk for cover soon grows expensive, since more mass requires more fuel to launch.

The Johnson team works on developing shielding methods without adding more material. “It’s unlikely that we’re getting to be ready to fly dedicated radiation-shielding mass,” Lee said. “Every item you fly will need to be multi-purpose.”

For the Orion spacecraft, they’ve designed an idea for astronauts to create a short lived shelter with existing materials available , including storage units already on board or food and water supplies. If the Sun erupted with another storm as strong because the Apollo era’s, the Orion crew would be safe and sound.

Other teams across NASA are meeting the radiation challenge with creative solutions, developing technology like wearable vests and devices that add mass, and electrically charged surfaces that deflect radiation.

Here come the Sun’s energetic particles

Protecting astronauts from solar energetic particle storms requires knowing when such a storm will occur. But the particle flurries are fickle and difficult to predict. the character of the Sun’s turbulent eruptions isn't yet perfectly understood.

“Ideally, you'll check out a lively region on the Sun, see how it’s evolving, and check out to predict when it’s getting to erupt,” Richardson said. “The problem is, albeit you'll forecast flares and coronal mass ejections, only alittle fraction actually spawn the particles that are hazardous to astronauts.”

A close-up of the Sun during a flare shows a seahorse-shaped, orange region lighting up against boiling red.

The Aug. 7, 1972, flare was captured by the large Bear Solar Observatory in California. This particular flare — referred to as the seahorse flare for the form of the brilliant regions — sparked a robust SEP event that would are harmful to astronauts if an Apollo mission had been ongoing at the time.

Credits: NASA

https://solarscience.msfc.nasa.gov/flares.shtml

And, if SEPs do come, it’s hard to predict where they're going to go. magnetic flux lines are a highway for the charged particles, but because the Sun rotates, the roadways spiral. Some particles are knocked off-road by kinks within the field lines. As a result, they'll spread far and wide through the system , in a vast, nebulous cloud. 

“We still have an extended thanks to attend get to an equivalent position as meteorology on Earth,” said Yari Collado-Vega, a scientist at the Community Coordinated Modeling Center, or CCMC, which is housed at Goddard. The CCMC may be a multi-partnership agency dedicated to space weather modeling and research. “This has got to do with the very fact that we just don’t have as many data sets on the Sun.” 

Models to predict when SEPs arrive are within the early stages of development. One uses the arrival of lighter and faster electrons to forecast the torrent of heavier protons that follow, which are more dangerous.

Scientists depend upon NASA’s heliophysics missions to advance their space meteorology models. It helps to possess spacecraft at different vantage points between the Sun and Earth. Launched in 2018, NASA’s Parker Solar Probe is flying closer to the Sun than any spacecraft before it. The spacecraft will track SEPs near their origins — key to solving how solar eruptions accelerate particles.

Timing may be a factor too. The Sun swings through 11-year cycles of high and low activity. During solar maximum, the Sun is freckled with sunspots, regions of high magnetic tension that are ripe for eruption. During solar minimum, when there are little to no sunspots, eruptions are rare.

While scientists still improve their models, NASA’s heliophysics spacecraft do currently provid