Comet Wild 2: A window into the birth of the solar system?

Three larger rocks, each containing several crystals, from comet Wild 2 are shown on the left of this image in cross-section, as imaged by an electron microscope. Fine-grained dust from the comet, still embedded in the aerogel it was captured in, shown at right. All images are at the same scale; 5 micrometer scale bar is shown. Credit: R. Ogliore (Univ. of Hawaii) and Z. Gainsforth (Univ. of California, Berkeley).

When a team of scientists from SOEST and the University of California-Berkeley investigated the oxygen isotope and mineral composition of the dust and rock from comet Wild 2 they found an unexpected combination of material — deepening the mystery of Wild 2’s past.

Our solar system, and other planetary systems, started as a disk of microscopic dust, gas and ice around the young Sun. The amazing diversity of objects in the solar system today—the planets, moons, asteroids and comets—was made from this primitive dust.

NASA’s Stardust mission returned to Earth with samples of comet Wild 2, a comet that originated outside the orbit of Neptune and was subsequently kicked closer to Earth’s orbit in 1974, when Jupiter’s gravity altered Wild 2’s orbit.

Lead author, Hawaiʻi Institute of Geophysics and Planetology Assistant Researcher Ryan Ogliore, reported, “The comet’s nucleus today is made up of small rocks and ice, separated by fractions of an inch, that originally formed billions of miles apart. Some rocks have seen temperatures above 2,500 degrees Fahrenheit, but adjacent ice has been kept close to absolute zero for billions of years. Every tiny grain we look at has its own fascinating story to tell.”

“So, now we ask the question: Does the fine-grained dust from comet Wild 2 represent a diverse sampling of many inner-solar-system objects that were transported to the outer solar system, or in fact, the raw starting materials of the solar system?” said Ogliore.

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