Samples from Comet WILD 2 reveal surprising past

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 becoming clearer.

Stardust collected material from Wild 2, a comet thought to have formed beyond Neptune and is currently orbiting the sun between Mars and Jupiter. Recently, careful analysis of microscopic samples has been carried out. explained in diary geochemistrya surprising truth about the origin and history of comets has been revealed, said Ryan Oriole, an associate professor of physics at Washington University Arts and Sciences in St. Louis, who has been studying Stardust samples for several years.

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” that gave the mission its name. Ta.

However, 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 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.

The comet was kept in a cold storage in space for most of its life, avoiding 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. ” Oriole said. “And all of these objects are beautifully preserved within Wild 2.”

Nearly 20 years later, scientists appear to have had enough time to analyze the tiny amounts of material returned by the Stardust mission, less than a milligram (think grains of sand). maybe. 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,” Ogliore says. “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, the samples will be able to be studied using new techniques that did not exist at the start of the mission.

“Stardust samples, microscopic particles taken from objects less than two miles wide, contain a deep record of the past that spans billions of miles,” Oriole said. “After studying this comet for 18 years, we now have a better understanding of the solar system’s dynamic formation.”