The LRO orbiting the moon. (CREDIT: Audrey Quinn)

A NASA lunar probe is shedding light on the risks of radiation from space. The Lunar Reconnaissance Orbiter (LRO) is equipped with the Cosmic Ray Telescope for the Effects of Radiation instrument (called CRaTER). This instrument is designed to shed light on interstellar radiation near the moon and has materials on board designed to mimic human tissue or electronic parts.

Countdown before the moon conspiracy theorists go nuts in 3… 2… 1… (Note: before you start,you are absolutely required to read this before commenting)


Moving onward, outside of Earth’s protective atmosphere, astronauts are exposed to the wide spectrum of radiation that exists in space. These radiation sources include charged particles from the Sun and cosmic rays known as HZE particles (high mass and high energy) that originate from deep space. CRaTER is designed to measure these sources of radiation in order to improve the engineering and construction of spacecraft – making them both more efficient and more effective at blocking radiation for humans and computers alike.


Space radiation was a huge issue for the Apollo astronauts.

As far as measuring radiation for humans goes, the mission engineers use a plastic that mimics human tissue. They place radiation sensors behind the plastic (the sensors mimic bone marrow which is very sensitive to radiation) and measures how much radiation gets through. Even though the LRO found that HZE particles only make up about 1% of the radiation detected, about half of the radiation picked up by the CRaTER instrument was from HZEs. This is because, even though they are spars, HZEs pack a punch.


Mark Looper, a space radiation physicist, compared HZEs to other sources of radiation by saying, “It’s like the difference between getting hit with a bat or a bullet. Different kinds of radiation may deposit the same amount of energy, but they distribute it differently.”


By optimizing the construction and thickness of radiation shielding, engineers can design spacecraft so they block the radiation without making them too heavy. A heavy spacecraft means more energy to get it into orbit which means more fuel and less cargo… not to mention, a more expensive mission.


In addition to space-bound sources of radiation, CRaTER also found a shower of protons originating from the moon itself. These protons are blasted off the lunar surface as cosmic rays bombard our favorite natural satellite.

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