A massive solar eruption was felt on Earth, the Moon and Mars

A solar volcanic eruption detected simultaneously on Earth, the Moon and Mars in October 2021 underscores the importance of being prepared for the dangers of space radiation. The event allowed for rare simultaneous measurements, improving our understanding of solar eruptions and how planetary magnetic fields and atmospheres can mitigate their effects. This knowledge is essential for future human exploration of the Moon and Mars, where astronauts face significant radiation hazards.

A solar flare was detected simultaneously on the Earth and the Moon Mars Emphasizes the need to prepare human exploration missions for the dangers of space radiation.

A coronal mass ejection from the Sun erupted on October 28, 2021, and its impact was so widespread that both Mars and Earth, despite being on opposite sides of the Sun and about 250 million kilometers (160 million miles) apart, received an outpouring of energetic particles.

A rare and important event

This is the first time that a solar event has been measured simultaneously on the surfaces of Earth, the Moon and Mars, as reported on August 2 in Geosearch messages paper. The blast was detected by an international fleet of spacecraft including the ExoMars Trace Gas Orbiter (TGO), NASA’s Mars Curiosity, CNSA’s Chang’e-4 Moon Lander, Lunar Reconnaissance Orbiter (LRO), and DLR’s Eu:CROPIS Earth orbiter. .

These simultaneous measurements on different worlds help improve our knowledge of the impact of solar flares and how a planet’s magnetic field and atmosphere might help protect astronauts against them.

Coronal mass ejection as seen by the SOHO office on October 28, 2021. This event is a rare example of “ground level improvement”. During these events, particles from the Sun are energetic enough to pass through the magnetic bubble that surrounds Earth and protects us from less energetic solar flares. It was only the 73rd ground level improvement since records began in the 1940s, and none have been recorded since. Credit: SOHO (ESA and NASA), CC BY-SA 3.0 IGO

Compare different worlds

The event, which took place on October 28, 2021, is a rare example of “ground level improvement”. During these events, particles from the Sun are energetic enough to pass through the magnetic bubble that surrounds Earth and protects us from less energetic solar flares. It was only the 73rd ground level improvement since records began in the 1940s, and none have been recorded since.

Because the Moon and Mars do not generate their own magnetic fields, particles from the Sun can easily reach their surfaces and even interact with soil to generate secondary radiation. But Mars has a thin atmosphere that stops most of the low-energy solar particles and slows down the high-energy particles.

The importance of understanding solar events

With the Moon and Mars being the focus of future human exploration, it is extremely important to understand these solar events and their potential impact on the human body. Astronauts run the risk of radiation sickness. A radiation dose of more than 700 milligray — the radiation absorption unit — may cause radiation sickness by destroying the bone marrow, leading to symptoms such as infection and internal bleeding.

If an astronaut receives more than 10 grays, he is unlikely to survive more than 2 weeks. A single solar flare in August 1972 could have given such a high radiation dose to an astronaut on the surface of the Moon, but it, fortunately, fell between the manned Apollo 16 and 17 missions.

Feel the giant solar eruption on the Earth, Moon and Mars infographic. Credit: ESA

Recent findings and protection measures

By comparison, during the October 28, 2021 event, the dose in lunar orbit was measured at NASAThe Lunar Reconnaissance Orbiter was only 31 milligrams. “Our calculations of past Earth-level boosting events show that an average of one event every 5.5 years may have exceeded the safe dose level on the Moon if no radiation protection was provided. These events are critical to future manned missions to the lunar surface.”

When we compare the measurements made by the ExoMars TGO and the Curiosity rover, the protection provided by the Martian atmosphere becomes clear: the TGO measured 9 milligrams, 30 times more than the 0.3 milligram detected on the surface.

ESA’s inner solar system missions Solar Orbiter, SOHO and BepiColombo have also detected the outburst, providing more and better vantage points for studying this solar event.

Currently, we live in a golden age for solar system physics. Radiation detectors aboard interplanetary missions such as BepiColombo, en route to Mercury, and Juice, sailing to Jupiteradding much-needed coverage to the study of the acceleration and propagation of solar particles,” said Marco Pinto, a research fellow at the European Space Agency working on radiation detectors.

Protect our astronauts

Protecting astronauts during their adventures in space is an essential and important mission of the European Space Agency. Understanding and predicting extreme radiation events is a vital part of this. Dedicated instruments measure the radiation environment in space and are used to protect critical and terrestrial spaceborne infrastructure as well as to protect astronauts. If the astronauts are warned in time, they can request protection such as body clothing or shelter in caves. current policy on International Space Station It is a return to the sleeping quarters or the kitchen, where the walls protect from radiation.

The portal will enable sustainable exploration around and on the moon, while enabling research and demonstrating the technologies and processes needed to conduct a future mission to Mars. This computer rendering shows NASA’s Orion spacecraft docked at the Gateway (left) that will bring the astronauts to the lunar outpost. Credit: ESA

Moon Gate

The Artemis program that sends astronauts to the moon includes a space station in lunar orbit called the Gateway. On the Gateway, three groups of instruments will monitor the radiation environment around the Moon: the European Space Agency’s (ESA) European Radiation Sensor Array (ERSA), NASA’s Heliophysics Environmental Measurement and Radiation Experiment Suite (HERMES), and ESA/JAXA Internal dosimeter array (IDA).

Together, these experiments will measure the radiation environment outside the Gateway while monitoring specific radiation doses inside, between 3,000 km and 70,000 km (45,000 miles) from the lunar surface. These measurements will be necessary to better understand the environment astronauts will experience in interplanetary space.

Two radiation dummies carry groundbreaking flybys of the lunar surface to help protect space travelers from cosmic rays and energetic solar storms. These two female phantoms filled the passenger seats during Orion’s first mission around the Moon, going further than any human had flown before. Equipped with more than 5,600 sensors, the pair have measured the amount of radiation that astronauts would be exposed to on future missions with unprecedented accuracy. Credit: Lockheed Martin

Luna twins and future research

Space agencies are also looking into protective clothing to reduce the impact of space radiation on the body. Two identical mannequins, developed by the German Aerospace Center (DLR), were the passengers of the Artemis I test flight, which flew by the Moon during November-December 2022. Equipped with radiation sensors provided by DLR and NASA. Helga flew unprotected, but the Zohar wore a newly developed radiation protection vest covering her torso. The DLR researchers are currently comparing the two sets of data measured by Helga and Zohar.

Colin Wilson, ExoMars TGO project scientist, concludes: “Space radiation can create a very real risk to our exploration throughout the solar system. Measurements of high-level radiation events by robotic missions are critical to preparing for long-duration manned missions. Thanks to data from For missions like ExoMars TGO, we can prepare for the best way to protect our human explorers.”

Reference: “First Improvement of Earth’s Level Visible on Three Planetary Surfaces: Earth, Moon, and Mars” by Jingnan Gu, Xiaoli Li, Jian Zhang, and Michael I. . Wimmer-Schweingruber, Donald M. Hassler, Cary Zeitlin, Bent Ehresmann, Daniel Matthiä and Bin Zhuang, August 2, 2023, Available here. Geosearch messages.
doi: 10.1029/2023GL103069