NASA’s Stardust mission returned rocky material from the coma of comet 81P/Wild 2 (pronounced “Wild-2”) to Earth on January 15, 2006. Comet Wild 2 contains volatile ice, which may have accreted beyond Neptune’s orbit. The Wild 2 sample was expected to be rich in primordial molecular cloud material, i.e., interstellar and circumstellar particles. Instead, it turns out that Wild 2’s interstellar component is very small, and nearly all of the returned particles formed in a wide and diverse region of the solar nebula. Although some features of the Wild 2 material resemble primitive chondrite meteorites, the diversity of its composition attests to a very different origin and evolutionary history from asteroids. Wild 2 has very little impact debris from asteroids, and may have accreted dust from the outer and inner Solar System before the solar nebula dispersed.

wild 2 is a small comet in the shape of a flat sphere, approximately 1.65 x 2 x 2.75 km (1.03 x 1.24 x 1.71 miles).

Discovered by Paul Wilde on January 6, 1978, this comet has an orbital period of 6.2 years.

Wild 2 is known as a fresh periodic comet. It orbits the Sun between Mars and Jupiter, but it did not always follow this orbit.

Originally, this comet’s orbit was between the orbits of Uranus and Jupiter. On September 9, 1974, a gravitational interaction between Wild 2 and Jupiter changed its orbital period from her 43 years to her 6.2 years.

“Eighteen years after NASA’s Stardust mission returned the first known sample from a comet to Earth, the true nature of the icy object is coming into focus,” says the new study. said author Ryan Oriol, a researcher at Washington University in St. Louis.

“When Stardust launched in 1999, many scientists predicted that the comet’s rocky material would be dominated by the primordial dust that built our solar system, the ‘stardust’ from which the mission takes its name. I was there.”

“But the actual samples told a different story: Wild 2 contained a potpourri of dust formed from various early events in the solar system’s history.”

For Dr. Oriole, the discovery that Wild 2 contained records of “local” events was exciting.

“This comet was a witness to the events that shaped the solar system into what we see today,” he said.

“Because the comet was kept in a cold storage in space for almost its entire life, it avoided the heat and water alterations seen in asteroid samples.”

“Comet Wild 2 contains things never seen before in a meteorite, including rare carbon and iron assemblages and precursors to the igneous globules that make up the most common type of meteorite. . And all of these objects are beautifully preserved within Wild 2.”

“Almost 20 years later, scientists have had enough time to analyze the tiny amounts of material returned from the Stardust mission, less than a milligram (think a grain of sand). You might see it.”

“But this material is dispersed into thousands of tiny particles on a collector the size of a pizza.”

“Almost every Wild 2 particle is unique and has a different story to tell. Extracting and analyzing these grains is a time-consuming process. But the scientific benefits are huge. .”

“Most of the Wild 2 particles have not yet been studied and certainly hold many more surprises. Over time, we will be able to study the samples using new techniques that did not exist at the start of the mission.” Masu.”

“Stardust samples, microscopic particles taken from celestial bodies less than two miles wide, contain a deep record of the past that spans billions of miles. After 18 years of studying this comet, we have We now have a better understanding of the dynamic formative period.”

study Published in Journal November 2023 issue geochemistry.

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Ryan C. Oriol. 2023. Comet 81P/Wild 2: A record of the solar system’s wild youth. geochemistry 83 (4): 126046; doi: 10.1016/j.chemer.2023.126046