Did you feel it? As Artemis II nears reentry, scientists want to know how far the sonic boom travels

Southern Californians may hear a distinct “boom” around 5 p.m. Friday as NASA’s Artemis II moon flyby mission makes its energetic reentry off the coast of San Diego, the U.S. Geological Survey said.

USGS does not know how far up and down the coast — or how far inland — Californians will be able to hear this sonic boom, produced as the capsule breaks the sound barrier as it slows down, said John Bellini, a geophysicist with the agency.

For this reason, USGS is asking for the public’s help: Californians can report whether or not they heard the boom to the agency’s “Did You Feel It” survey.

This information, Bellini said, will help scientists better predict sonic booms in the future, which are dependent on a variety of atmospheric conditions.

“Since this is a known source with a relatively known location and time of occurrence, people reporting this can help us in the future to better characterize unknown sources of a similar type,” he said.

For example, meteorites and space debris piercing the atmosphere can produce sonic booms — as can supersonic tests from the military and private aerospace companies.

While Southern Californians might hear the intense reentry, NASA isn’t so confident they’ll be able to see it.

However, Aaron Rosengren, assistant professor of space systems at UC San Diego, is more optimistic.

“The weather is quite nice today,” he said. “If you have any view along the Southern Coast and you’re looking westward along the horizon, you should be able to see a faint light in the sky as it reenters.”

Rosengren expects that streak in the sky to last less than a minute.

The Artemis II crew, the first to reach the moon in a half-century, will slam into the atmosphere at 30 times the speed of sound, generating a fireball of nearly 5,000 degrees Fahrenheit around the capsule.

When Artemis II pilot and SoCal native Victor Glover was asked Wednesday evening about the moments from this mission he’ll carry with him for the rest of his life, he joked: “We’ve still got two more days, and riding a fireball through the atmosphere is profound as well.”