That an asteroid's orbit can be deliberately shifted stopped being theory in 2022: the impact of NASA's DART probe shortened the orbital period of the small moon Dimorphos by 33 minutes. The harder question stayed open — what such a body is made of inside, and how it responds to the blow. China's first planetary defence mission is built around exactly that, and it now has a launch date.
Unlike DART, it is to carry two spacecraft on a single rocket, a Long March 3B from the Xichang launch centre. An observer reaches the target first and surveys it from close range for several months: size, shape, composition, orbit. Only then does the second craft slam into it. The observer tracks the impact and then documents for six months to a year what it changed. It combines what NASA and ESA did in sequence with DART and the follow-up probe Hera — in a single approach.
The target itself has been reassigned several times. Earlier mission profiles named 2020 PN1, then 2019 VL5, and most recently the roughly 30-metre near-Earth asteroid 2015 XF261. For that profile, a team led by Nan Zhang at Tsinghua University describes an impact speed of nine kilometres per second — fast enough not merely to deflect the body but to break it apart, allowing a first look inside.
Launch in December 2027, impact in 2029
The most concrete schedule so far came from Long Lehao, chief designer of the Long March rockets, at an industry conference in Shenzhen: launch in December 2027, with the small Aten-class asteroid 2016 WP8 as the new target. The observer is to fly past Venus on the way, arrive at the asteroid in 2029 and study it for a few months before the impactor strikes later that year. China's five-year plan for 2026 to 2030 lists the mission explicitly; the space agency is currently seeking a name for it through a public call.
The point is not an imminent threat. Around 1.4 million asteroids have been catalogued, more than 38,000 of them near-Earth and some 2,500 rated potentially hazardous — bodies of at least 140 metres that pass close to Earth's orbit. A major impact in the next hundred years is considered unlikely; an asteroid one kilometre across strikes the Earth roughly every 700,000 years.
That is precisely why the timing is good. A deflection works only with years of warning, and only if the structure of the target is understood. Whether an asteroid is a loose rubble pile or a solid block of rock decides the effect of any push. That question is cheaper to settle while nobody is in a hurry.