Radiation hazards for manned missions beyond LEOReferences
An astronaut on a mission to Mars could receive radiation doses up to 700 times higher than on our planet – a major showstopper for the safe exploration of our Solar System. A team of European experts is working with ESA to protect the health of future crews on their way to the Moon and beyond. 1)
Figure 1: Earth's protective shield. The magnetic field and electric currents in and around Earth generate complex forces that have immeasurable impact on every day life. The field can be thought of as a huge bubble, protecting us from cosmic radiation and charged particles that bombard Earth in solar winds (image credit: ESA/ATG medialab)
Earth’s magnetic field and atmosphere protect us from the constant bombardment of galactic cosmic rays – energetic particles that travel at close to the speed of light and penetrate the human body.
Cosmic radiation could increase cancer risks during long duration missions. Damage to the human body extends to the brain, heart and the central nervous system and sets the stage for degenerative diseases. A higher percentage of early-onset cataracts have been reported in astronauts.
Figure 2: Cosmic radiation could increase cancer risks during long duration missions. Damage to the human body extends to the brain, heart and the central nervous system and sets the stage for degenerative diseases. A higher percentage of early-onset cataracts have been reported in astronauts (image credit: ESA)
“One day in space is equivalent to the radiation received on Earth for a whole year,” explains physicist Marco Durante, who studies cosmic radiation on Earth.
Marco points out that most of the changes in the astronauts’ gene expression are believed to be a result of radiation exposure, according to the recent NASA’s Twins study. This research showed DNA damage in astronaut Scott Kelly compared to his identical twin and fellow astronaut Mark Kelly, who remained on Earth.
A second source of space radiation comes from unpredictable solar particle events that deliver high doses of radiation in a short period of time, leading to ‘radiation sickness’ unless protective measures are taken.
Europe's radiation fight club
“The real problem is the large uncertainty surrounding the risks. We don’t understand space radiation very well and the long-lasting effects are unknown,” explains Marco who is also part of an ESA team formed to investigate radiation.
Since 2015, this forum of experts provides advice from areas such as space science, biology, epidemiology, medicine and physics to improve protection from space radiation.
“Space radiation research is an area that crosses the entire life and physical sciences area with important applications on Earth. Research in this area will remain of high priority for ESA,” says Jennifer Ngo-Anh, ESA’s team leader human research, biology and physical sciences.
While astronauts are not considered radiation workers in all countries, they are exposed to 200 times more radiation on the ISS (International Space Station) than an airline pilot or a radiology nurse.
Radiation is in the Space Station’s spotlight every day. A console at NASA’s mission control in Houston, Texas, is constantly showing space weather information.
If a burst of space radiation is detected, teams on Earth can abort a spacewalk, instruct astronauts to move to more shielded areas and even change the altitude of the Station to minimize impact.
One of the main recommendations of the topical team is to develop a risk model with the radiation dose limits for crews travelling beyond the International Space Station.
ESA’s flight surgeon and radiologist Ulrich Straube believes that the model should “provide information on the risks that could cause cancer and non-cancer health issues for astronauts going to the Moon and Mars in agreement with all space agencies.”
Recent data from ExoMars TGO (Trace Gas Orbiter) showed that on a six-month journey to the Red Planet an astronaut could be exposed to at least 60% of the total radiation dose limit recommended for their entire career.
“As it stands today, we can’t go to Mars due to radiation. It would be impossible to meet acceptable dose limits,” reminds Marco.
Figure 3: Space risks – fighting radiation (image credit: ESA)
Measure to protect
ESA has teamed up with five particle accelerators in Europe that can recreate cosmic radiation by ‘shooting’ atomic particles to speeds approaching the speed of light. Researchers have been bombarding biological cells and materials with radiation to understand how to best protect astronauts.
Figure 4: A particle accelerator to help make spaceflight safer (image credit: GSI Helmholtzzentrum für Schwerionenforschung GmbH/Jan Michael Hosan 2018)
The constant ‘rain’ of radiation in space includes cosmic rays, which, despite the name ‘ray’, comprises highly energetic particles arriving from beyond the Solar System. These rays are considered the main health hazard for astronauts conducting future exploration missions to the Moon, Mars and beyond. This bad stuff can also play havoc with sensitive spacecraft electronics, corrupting data, damaging circuits and degrading microchips.
There are many different kinds of cosmic rays, and they can have very different effects on spacecraft and their occupants, depending on the types of particles, the particles’ energies and the duration of the exposure.
A new international accelerator, the Facility for Antiproton and Ion Research (FAIR) near Darmstadt, Germany, at the existing GSI Helmholtz Center for Heavy Ion Research (GSI), will provide particle beams like the ones that exist in space and make them available to scientists for studies that will be used to make spacecraft more robust and help humans survive the rigors of spaceflight. — On 14 February 2018, ESA and FAIR inked a cooperation agreement that will build on an existing framework of cooperation between the Agency and GSI, and see the two cooperate in the fields of radiation biology, electronic components, materials research, shielding materials and instrument calibration.
For example, researchers will be able to investigate how cells and human DNA are altered or damaged by exposure to cosmic radiation and how well microchips stand up to the extreme conditions in space.
ESA is opening the doors to research into the biological effects of space radiation. Experiments should investigate radiation doses that astronauts could cope with while staying safe from cancer or other degenerative diseases during and after a mission.
Scientists are encouraged to investigate radiation risks and how to stop them with the right countermeasures.
ESA is offering access to a high-energy accelerator to recreate cosmic radiation by ‘shooting’ atomic particles to speeds approaching the speed of light. 2)
Experiments will take place at the GSI accelerator facility in Darmstadt, Germany, also known for the discovery of six chemical elements and the development of a new type of tumor therapy using ion beams.
This facility has seen 36 experiments bombarding cells and materials with radiation to address the effects of space radiation. The accelerator will host a workshop in September for researchers interested in its potential.
The results from these studies are not solely space bound. “This research could contribute to better assess ionizing radiation risks on Earth and improve charged particle therapy for oncology patients,” says Jennifer.
Figure 5: Heavy but fast. To understand the full biological effects of cosmic rays and accurately calculate how much exposure humans can safely withstand is where GSI, the Helmholtz Center for Heavy Ion Research, comes in. ESA is inviting researchers to investigate the biological effects of space radiation using GSI’s large particle accelerator in Darmstadt, Germany. Researchers from all over the world use this facility to gain new insights into the building blocks of matter and the evolution of the Universe, as well as developing new applications in medicine and technology (image credit: Gabi Otto/GSI Helmholtzzentrum für Schwerionenforschung GmbH)
1) ”The radiation showstopper for Mars exploration,” ESA, 31 May 2019, URL: http://www.esa.int/Our_Activities
2) ”Radiation sensitive,” ESA, 1 July 2019, URL: http://www.esa.int/Our_Activities
The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (firstname.lastname@example.org).