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It’s August 1972 and Ian Richardson

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— a future NASA scientist -- is watching TV when the BBC announces:

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“The interference is caused by solar activity.”

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He didn’t know then, but the Sun had just erupted

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in one of the most powerful solar events ever recorded.

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There was no threat to humans because Earth’s magnetic field

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deflects much of the Sun’s radiation.

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But the explosions were so powerful that intense radiation

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disrupted TV signals and caused radio blackouts.

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So what if you were outside Earth’s magnetic field?

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On the Moon and beyond, astronauts face the risk of extreme radiation exposure.

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Luckily, the intense radiation in 1972 occurred right between

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Apollo 16 and 17 missions when no astronauts were in their path.

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As NASA plans missions to go back to the Moon and then on to Mars,

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predicting the Sun’s activity to protect astronauts from space radiation

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is one of our biggest priorities.

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One of the biggest unknown factors about going to space

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is the radiation hazard from the Sun.

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This is Ian today — studying the effects of the Sun, also known as the field of heliophysics.

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The Sun is always emitting radiation like the light we see.

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But solar energetic particles, like from the August 1972 events, can be far more harmful.

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To be able to forecast solar energetic particles, we need to know how the Sun energizes them.

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The Sun is made up of electrically charged particles called plasma.

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As this plasma moves, it builds up energy inside its massive magnetic field.

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This energy is usually released in two types of explosions.

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Flares are intense flashes of light.

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Coronal mass ejections are giant eruptions of solar material.

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These solar eruptions send shock waves across the solar system accelerating particles as they go.

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These are solar energetic particles, or SEPs.

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They consist mainly of protons and possess a lot of energy

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that can affect satellite measurements

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and humans.

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SEPs can bombard you with a lot of radiation in a short period of time.

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They can penetrate your skin, damage your DNA, and increase your chances of getting cancer and radiation sickness.

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But they don’t occur with every solar eruption.

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Only a small number of flares and coronal mass ejections create SEPs.

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So we’re trying to predict when SEPs form and how they travel through space.

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At NASA’s Goddard Space Flight Center,

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the Community Coordinated Modeling Center, or CCMC, is dedicated to testing prediction models.

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Working with global partners, they use data from NASA satellites at different vantage points

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and models to figure out how solar explosions behave

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including how shock waves energize SEPs.

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And as we get better at predicting, we get more time to prepare.

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Preparation for an SEP event -- of which you may know that is already coming

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and perhaps the magnitude as well --

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the technique that you would want is to use

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is to put as much mass between you and the source.

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On the surface of the Moon or Mars, astronauts can go underground or build shelter with local materials.

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But in transit, astronauts can only be protected with what’s on the spacecraft.

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which means that you might have elements on a spacecraft that have multiple purposes.

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NASA’s space radiation specialists are testing different ways to do this.

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One strategy they tested on the Orion spacecraft involves crew members

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barricading themselves with as much mass as possible in the center of the spacecraft.

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Other possible techniques in development include vests that add mass

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and electrically-charged surfaces that deflect particles.

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In terms of radiation protection and radiation mitigation, the factor of time is extraordinarily important.

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The Sun has a natural 11-year cycle that transitions through low and high activity,

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 which is indicated by the number of sunspots on the surface.

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More sunspots mean more eruptions resulting in a higher risk for SEPs.

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But during this increased solar activity,

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the Sun’s magnetic field strengthens,

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enhancing its shield against another important source of radiation --

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galactic cosmic rays.

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These are charged particles traveling at nearly the speed of light

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that are thought to come from supernova explosions from within our galaxy

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and possibly further out in the universe. 

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If solar energetic particles are intense, sporadic storms, then galactic cosmic rays are a constant drizzle.

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Galactic cosmic rays are more sparse, but also much more energetic.

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They include heavier elements that can penetrate through vast amounts of materials.

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Understanding the rate of galactic cosmic rays

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helps us determine how much time astronauts can spend in space safely. 

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To date, humans have only been on the lunar surface for a cumulative total of about 12 days.

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A trip to Mars will take 6-10 months each way.

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That means even more radiation exposure, and so NASA is doing the work to prepare for that.

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The Moon is going to be a testbed for us in order to be to prepare for Mars.

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The more that we understand the impact and the duration of radiation on the Moon,

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the more we can extrapolate that to the length of time that we will be spending in transit and on the surface of Mars.

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