Tianwen-2 has sent back its first image of Kamo'oalewa, the Earth quasi-moon it is tracking on a sample-return mission. Claire Cameron reported the late June image after the spacecraft had spent 400 days traveling about 621 million miles to the target.
The spacecraft reached a distance of 12 miles from Kamo'oalewa in late June, according to the China National Space Administration. China is aiming to collect material from the object and return it to Earth in 2027, with the samples expected to drop through Earth's atmosphere during a flyby.
Tianwen-2 and Claire Cameron
Claire Cameron, the breaking news chief at Scientific American, reported the new image as Tianwen-2 moved from transit into close study of the asteroid. Kamo'oalewa is only about 66 feet in diameter and spins once every 28 minutes, so operations near it depend on precise positioning rather than prolonged contact.
The China National Space Administration said, "The probe will progressively conduct more detailed scientific exploration to acquire data on the asteroid’s morphology, material composition and internal structure, laying the groundwork for subsequent sample collection operations". That sequence puts imaging first, then closer analysis, then the sampling attempt.
Kamo'oalewa and Earth
Kamo'oalewa loops by Earth and comes as close as 9 million miles and as far as 25 million miles from Earth. Astronomers have discovered eight space rocks that seem to follow Earth's path, and some scientists call them Earth's mini moons or quasi moons.
Research suggests Kamo'oalewa may be a stray piece of the Moon thrown into space by an ancient impact, but other evidence, including James Webb Space Telescope observations, disputes that theory. That debate is part of why Tianwen-2's first close image matters: it adds a new data point to a target that is already unusual in both orbit and origin.
Three sampling methods
Tianwen-2 may use a touch-and-go sampling method similar to the methods used by OSIRIS-REx and Hayabusa2. It may also attempt an anchor-and-attach method that physically attaches the spacecraft to the space rock, or a hovering method in which a robotic arm scoops surface material while the spacecraft hovers above the asteroid.
How the 3 sampling methods will be chosen is not explained, but the mission's next phase will have to settle that before collection starts. After the samples are dropped into Earth's atmosphere in 2027, Tianwen-2 is set to continue to comet 311P/PanSTARRS.
