China’s Tianwen-2 spacecraft closed to within 20 kilometres of the near-Earth asteroid Kamo‘oalewa (2016 HO3) on Monday after a 400-day, one-billion-kilometre journey, the China National Space Administration confirmed. The probe has begun scientific observations ahead of a planned sample collection, a milestone that would make China the third nation—after Japan and the United States—to return asteroid material to Earth.

Early imagery, however, revealed that the asteroid is significantly smaller than previous estimates. Zhang Pengfei of the Chinese Academy of Sciences’ Institute of Geochemistry noted that the object appears to be only 20 to 30 metres across, compared with an earlier prediction of around 57 metres. The finding will influence the choice of sampling technique; Tianwen-2 carries both a touch-and-go mechanism and an untested anchoring system designed for uncertain terrain. A return capsule is scheduled to deliver samples to Earth in late 2027, after which the main spacecraft will continue toward a comet in the asteroid belt for a decade-long extended mission.

Japan’s Hayabusa2, meanwhile, executed a high-speed flyby of the asteroid Torifune on Sunday, passing within a few hundred metres at a relative velocity of five kilometres per second. An image captured one second before closest approach shows a snowman-shaped body with numerous surface rocks, suggesting it formed from the collision and merger of two smaller bodies. JAXA officials described the data—including infrared and spectrometer readings—as valuable for both planetary defence and understanding asteroid origins. The probe, which returned samples from Ryugu in 2020, is now en route to asteroid 1998 KY26, with arrival expected in July 2031.

The week’s terrestrial science brought its own revelations. An analysis of nearly one million Berlin Marathon finishers between 1999 and 2025 found that 17.6 per cent of men hit the “wall”—a sharp slowdown linked to glycogen depletion—compared with 9.7 per cent of women; among sub-three-hour finishers, men were six times more likely to experience it. Zoologists measuring 258 spider species across 64 families clocked the fastest, Australia’s Heteropoda genus, at 3.59 metres per second, while noting that the largest spiders, such as a 52-gram tarantula, are disproportionately slow. The World Meteorological Organization confirmed that El Niño has formed in the Pacific and is expected to be strong, raising global temperatures and the risk of extreme weather. And a study of a 1611 painting by Jan Brueghel the Elder suggests the artist may have depicted a giant noctule bat carrying a bird, predating zoological documentation of this hunting behaviour by nearly four centuries.

The next milestones for the asteroid missions are the detailed mapping and sampling attempt by Tianwen-2 in the coming months, and the continued cruise of Hayabusa2 toward its 2031 target. For climate observers, the evolution of El Niño through the boreal summer and autumn will determine the intensity of its global effects.