Space Events

Nuclear Explosions and Submarine Comms Distort Space Weather Near Earth

Space weather typically refers to charged particles ejected by the sun that can interact with Earth's atmosphere and magnetic field. However, a new study shows that humans also can change the near-Earth space environment.

According to the study, examples of human activity that can cause these changes include the use of very-low-frequency radio communications, and nuclear explosions detonated high in the atmosphere.

Most space weather comes from the influence of the sun, which sends out a steady stream of high-energy particles called the solar wind. The sun can also release bursts of highly energetic charged particles, called coronal mass ejections (CMEs). Near Earth, most of these particles are deflected by the magnetosphere, the protective magnetic field that surrounds the planet. These powerful particles, particularly those from CMEs, can cause satellites to short out or even create currents in the magnetic field that can reach the ground and damage power grids.

Similar effects were observed when both the United States and the Soviet Union denotated nuclear bombs at altitudes of between 16 miles and 250 miles (26 kilometers and 402 kilometers) between 1958 and 1962. Both countries ran high-altitude nuclear tests for military purposes, but the Comprehensive Nuclear-Test-Ban Treaty put an end to the tests in 1966.

Newly declassified information about these tests is included in the new study, in an effort to understand how the tests affected the space environment near Earth."Upon detonation, a first blast wave expelled an expanding fireball of plasma, a hot gas of electrically charged particles," NASA said in the statement. "This created a geomagnetic disturbance, which distorted Earth's magnetic-field lines and induced an electric field on the surface."

The Van Allen radiation belts are large, doughnut-shaped rings of highly energetic charged particles, trapped in their respective loops by magnetism, that loop outward from the Earth. NASA's Van Allen Probes are currently studying these belts. Surprisingly, they found that some of the nuclear tests created artificial belts that stayed in place for weeks and, in a single case, years.

The charged particles left from the explosions caused some satellites to fail, which is similar to what can happen during a space weather event.

While the effect of the nuclear explosions has passed, very-low-frequency (VLF) signals can still be observed by the Van Allen Probes. These VLF signals, emitted by ground stations, are transmitted "at huge powers," so they can reach submarines deep below the ocean's surface, according to a second statement from NASA. They also extend up beyond the planet's atmosphere, "shrouding Earth in a VLF bubble."

The Earth's Van Allen belts (shown in blue and purple) are massive loops of magnetically controlled, highly energetic charged particles.