The space rock called Kamoʻoalewa could be a fragment of the Moon

Over billions of years, space rocks have punched craters on the Moon’s surface, which scatter debris. But now, apparently, astronomers have been able to see the debris from one of those ancient space crashes for the first time.

As reported in Communications Earth & Environment of the magazine Nature this month, the mysterious object that researchers were able to see, known as Kamoʻoalewa, appears to be a lost fragment of the Moon.

Kamoʻoalewa, which was discovered in 2016, is one of five known quasi-satellites on Earth. These are rocks that orbit the Sun, but cling to our planet quite a bit in the process.

In general, little is known about Earth’s space rock environment, as these objects are very small and faint. For example, Kamoʻoalewa, also called 2016 HO3, is about the size of a Ferris Wheel and moves 40 to 100 times farther from Earth than it does from the Moon, as its orbit around the Sun moves in and out of Earth. . That has left astronomers wondering about the nature of these bodies.

“An object in a quasi-satellite orbit is interesting because it is very difficult to enter this type of orbit; it is not the kind of orbit in which an object in the asteroid belt could easily get trapped ”, said Richard Binzel, a planetary scientist at MIT who was not involved in the new study.

Binzel also says that having an orbit nearly identical to Earth’s immediately raises suspicions that an object like Kamoʻoalewa originated in the Earth-Moon system.

To observe Kamo’oalewa at visible and near-infrared wavelengths and assess its affinity with other groups of near-Earth objects, the researchers used the Large Binocular Telescope (LBT) and the Lowell Discovery Telescope (LDT), located in Safford. and Happy Jack, Arizona, respectively.

Light at these wavelengths contains important clues about minerals in rocky bodies, something that helps distinguish objects like the Moon, asteroids, and terrestrial planets.

In the observation, Kamoʻoalewa reflected more sunlight at longer or redder wavelengths. The researchers found that this pattern of light, or spectrum, did not resemble any known near-Earth asteroid, but it did look like grains of silicate rock from the Moon brought to our planet by the Apollo 14 astronauts.

Kamoʻoalewa (2016 HO3 in the image), has an orbit (white line) that is almost identical to Earth’s (blue line). This causes the object to move around the Earth as it revolves around the Sun.

“For me, the main hypothesis is that it is a fragment ejected from the Moon, after a crater event,” said Richard Binzel.

Planetary scientist at the University of Athabasca in Canada, Martin Connors, who was involved in the discovery of Earth’s first known quasi-satellites but was not involved in the new research, also suspects that Kamoʻoalewa is an old piece of the Moon. However, he still has some doubts: “This is well-founded evidence, but that does not mean that it is correct,” said the scientist.

While this is an interesting find, more detailed observations are needed to confirm that Kamoʻoalewa is made of lunar material.

According to Daniel Scheeres, a planetary scientist at the University of Colorado Boulder who was not involved in the work, to corroborate this hypothesis, it would be necessary to “go visit it or meet this small quasi-satellite and make a lot of close observations. The best thing would be to get a sample ”.

Fortunately, that is exactly what China’s space agency intends to do. This has announced plans to send a probe to Kamoʻoalewa to collect some rock and bring it back to Earth later this decade.

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