The Vietnam War may have been one of the most unpopular wars in U.S. history, but the massive solar event that took place in August 1972, towards the end of the war may have caused a greater impact than the government let on.
According to a new study published in the journal Space Weather, the enormous solar storm may have actually caused old sea mines to detonate unintentionally.
"These effects, long buried in the Vietnam War archives, add credence to the severity of the storm: a nearly instantaneous, unintended detonation of dozens of sea mines south of Hai Phong, North Vietnam on 4 August 1972," the plain language summary of the study reads. "This event occurred near the end of the Vietnam War. The U.S. Navy attributed the dramatic event to magnetic perturbations of solar storms."
It continues: "In researching these events we determined that the widespread electric‐ and communication‐grid disturbances that plagued North America and the disturbances in southeast Asia late on 4 August likely resulted from propagation of major eruptive activity from the Sun to the Earth."
News of the study was first reported by LiveScience.
The solar flares caused significant disruptions to Earth's communications equipment, with X-ray emissions remaining high for more than 16 hours, the researchers wrote.
They also noted that a defense communications satellite "suffered a mission-ending on orbit power failure;" and Air Force sensors turned on, giving a false reading that a nuclear weapon had detonated on Earth.
NASA describes the 1972 event as "legendary" because it happened between two Apollo missions: "the crew of Apollo 16 had returned to Earth in April and the crew of Apollo 17 was preparing for a moon landing in December," NASA writes on its website. Former radiation health officer Francis Cucinotta estimates that had astronauts been in space, they could have absorbed 400 rem from the solar flare. Perhaps not enough to cause death, although they would have needed "a quick trip back to Earth for medical care" to save their lives.
According to LiveScience, pilots flying near that part of Vietnam noticed approximately two dozen explosions in just a 30-second period. Eventually, the U.S. Navy investigated the situation and determined the solar storm caused the magnetic sensors in the mines to trip as if ships were passing them, causing them to detonate.
The events were felt all over the Earth. A 3,080 kilometer/second shock was felt near the Guam observatory. Magnetometer traces went "off scale" in Boulder, CO and a "bright aurora appeared in the northern United States," the researchers wrote.
Effects were also felt in Honolulu, HI, along the southern coast of the U.K. and "within 2 hours, "commercial airline pilots reported aurora as far south as Bilbao, Spain."
Ultimately, the solar event caused the U.S. Navy to look for alternatives to magnetic sensor mines that would be not be affected by solar events, such as this.
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