China’s Tianwen-2 Spacecraft Reaches Quasi-Moon Asteroid Kamo’oalewa

Tianwen-2 Reaches Kamo’oalewa After 400-Day Voyage

The China National Space Administration’s asteroid probe Tianwen-2 successfully reached the asteroid Kamo’oalewa, which orbits the sun in a path nearly identical to Earth’s. After undergoing multiple orbital adjustments in deep space, it first detected Kamo’oalewa on June 6, 2026. On July 2, it successfully captured the first-ever images of Kamo’oalewa from a distance of about 20 kilometers. This achievement comes at the end of a 400-day journey covering a distance of roughly 1 billion kilometers (620 million miles).

Kamo’oalewa, formally identified as 2016 HO3, is classified as a “quasi-moon”—a small body that circles the sun on orbits that keep it close to our planet. Earth has at least seven known quasi-satellites, and our planet’s gravity will occasionally capture others temporarily. Unlike true moons, these objects are gravitationally tied to the sun. Kamo’oalewa is considered the most stable of Earth’s known quasi-satellites, and because it orbits the sun in near-synchronous motion with Earth, it is considered a relatively accessible celestial body. The spacecraft will spend nearly a year studying the asteroid with a suite of 11 different scientific instruments before attempting to collect a sample.

Scientific Challenges of the “Anchor-and-Attach” Mission

The mission faces significant technical hurdles due to the asteroid’s physical characteristics. Kamo’oalewa has an average diameter of only about 41 meters (roughly 50–65 feet) and rotates at high speed. This means the spacecraft must achieve stable contact and collect samples within a limited time frame. The probe is equipped with multiple cameras with different focal lengths, including a detachable camera that will be used during sample collection. Since the probe’s orientation must be finely adjusted when capturing images, seizing these limited windows of opportunity is an extremely difficult task.

Pointy, asymmetric and just 60 feet in length, Kamoʻoalewa looks very different from the far more rubbly and rotund asteroids that various uncrewed spacecraft have visited in recent years. “Kamo‘oalewa looks amazing, like nothing we’ve seen floating in space before,” said Sabina Raducan, a researcher at the International Space Science Institute in Bern, Switzerland.

To secure a sample, the probe plans to utilize an “anchor-and-attach” method. This involves the spacecraft physically securing itself to the quasi-moon before using an ultrasonic drill to bore into it. If the operation is successful, China will become the third country to successfully pull a sample from an asteroid, and could be the first to do so using the anchor-and-attach method. The gathered samples are planned to be released in a capsule during an Earth flyby in November 2027.

Debating the Origins of Kamo’oalewa

Its craggy, diminutive nature suggests a dramatic origin story. “It could be a remnant of a catastrophic event,” said Cristina Thomas, a planetary scientist and planetary defense researcher at Northern Arizona University. Some scientists believe this quasi-moon could have been created when a massive impact knocked a chunk of our own moon into space between 1 million and 10 million years ago. A 2024 study published in Nature Astronomy proposes Kamo’oalewa could be material ejected from the Moon.

Unlike most near-Earth asteroids that are thought to originate from the main asteroid belt between Mars and Jupiter, Kamo’oalewa could have come from much closer to home. Quasi-moons offer clues as to how asteroids that started life between Mars and Jupiter ended up at Earth’s doorstep. By conducting more detailed scientific observations, Tianwen-2 aims to unlock these secrets.

Comparative Context

The Chinese space age is currently cementing the nation as a power player in Earth’s orbit and beyond, with developments like reusable rocket boosters and its own orbital space station. The Tianwen-2 mission represents a significant expansion of these capabilities. While the mission to Kamo’oalewa is underway, astronomers are also looking at other nearby candidates for life, such as the exoplanet GJ 3378b. Located 25 light-years away, researchers from the University of California, Irvine, recently found that the planet is twice the mass of Earth, making it a “tantalizing” candidate for study, according to lead author Paul Robertson, a UC Irvine associate professor of astronomy. Much like the study of Kamo’oalewa, the examination of GJ 3378b requires precise detective work to understand the composition and potential of these distant and nearby cosmic bodies.

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