Straight from the source (3/9/23)

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The Start of Water

Scientists have long believed that water came to Earth via delivery by comet. Where the comets came from, though, is another question entirely.

New findings from the Atacama Large Millimeter/submillimeter Array (ALMA) telescope suggest that water may be far more prevalent than expected, floating loosely in the space between stars. This means that the water on Earth could have existed in our own solar system long before the formation of the Sun.

“We can think of the path of water through the Universe as a trail," John Tobin, an astronomer at the National Radio Astronomy Observatory (NRAO) and lead author on the new paper, said in a press release. "We know what the endpoints look like, which are water on planets and in comets, but we wanted to trace that trail back to the origins of water.”

Before a star is born…Matter from the interstellar medium, which is all the loose material floating around in space untethered to a particular solar system, coalesces first into a gaseous, dusty cloud, then into a flat, spinning formation referred to as a protoplanetary disc. At the center, a protostar forms by accreting material from the disc. Eventually, scientists believe that planets and other celestial bodies form from the loose material left around the young star.

The study, published yesterday in Nature, analyzed the protoplanetary disc V883 Orionis, which sits in the Orion constellation about 1,300 light years away from Earth. Looking at this disc, researchers identified the chemical signature for water vapor—about 1,200 times the amount of water that exists in all of Earth’s oceans.

Much of the water found in V883 Orionis is a heavier version of the form we’re used to seeing on Earth. In this form, one of the hydrogen atoms is swapped out for deuterium, a heavier isotope. The researchers compared the ratio of these heavier water molecules in the disc to the makeup of comets we’ve studied closer to home.

“The composition of the water in the disc is very similar to that of comets in our own Solar System,” Tobin said. “This is confirmation of the idea that the water in planetary systems formed billions of years ago, before the Sun, in interstellar space, and has been inherited by both comets and Earth, relatively unchanged.”

What now? This finding is the first time water has been found in a protoplanetary disc, and it begins to explain how water could have found its way to Earth in the first place. The path isn’t complete, though, and the research team plans to use the European Southern Observatory’s Very Large Telescope to continue examining the composition of the disc to uncover more clues.

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Other News from the Cosmos

• Hubble images are being slowly degraded by satellite trails, partly due to the telescope’s orbit decaying over time.

• ispace’s HAKUTO-R Mission 1 lunar lander has reached its farthest point from Earth in its trajectory to the Moon, and is expected to touch down in April.

• Real-life Vulcan—aka 40 Eri b, the proposed exoplanet orbiting Spock’s home star 40 Eridani—doesn’t exist after all, a new NASA survey found.

• The DoE and NASA are partnering to build the Lunar Surface Electromagnetics Experiment - Night, which will survey the radio environment on the dark side of the Moon.

• OCO-2 (Orbiting Carbon Observatory-2) collected data showing the carbon dioxide emissions of 100+ countries.

The View from Space