With Tianwen-2, China Enters the Asteroid Race

I missed some interesting news a couple months ago, and I’m guessing you did, too. The launch of China’s Tianwen-2 on May 28 took place without much fanfare. Just one space probe among many. Except, it isn’t—China is flexing its muscles with an ambitious two-in-one mission, which will not only expand the nation’s scientific knowledge and technical know-how, but lay the groundwork for a vast new industry in asteroid mining. Today, we will explore how.

The Chinese word tianwen translates to “Questions to Heaven.” The Chinese program Tianwen, also known as the Planetary Exploration of China, is the branch of the China National Space Administration (CNSA) concerned with missions to other worlds in the Solar System. Back in 2021, Tianwen-1 put an orbiter around Mars and a rover on its surface; Tianwen-3 will return samples from Mars around 2031; Tianwen-4 is intended to explore Jupiter in the mid-2030s, entering orbit around its moon Callisto, and perhaps launching a sub-probe to fly by the planet Uranus. Ambitious stuff! Here we see a space program at full throttle, rapidly catching up to NASA.

Tianwen-2 marks China’s first attempt at returning samples from an asteroid. This is a feat that has only been achieved three times before—twice by Japan, with Hayabusa and Hayabusa2, and once by NASA, with OSIRIS-REx. While Earth already collects plenty of space rocks, sample return is much better than hunting for meteorites; by going out into space we can access pristine material, unchanged since the dawn of the Solar System, and unaltered by a fiery passage through Earth’s atmosphere. For the planetary scientist, few things are better than having a fresh piece of an asteroid in your laboratory.

At the time of writing, Tianwen-2 is on a trajectory away from Earth, due to rendezvous with the asteroid 469219 Kamo’oalewa in June 2026. Kamo’oalewa is quite small, somewhere between 40 and 100 meters across. It has some unusual characteristics: it spins on its axis exceptionally fast, rotating once every half-hour; its composition is similar to lunar silicate rockets, suggesting it might be a piece of debris blasted off the Moon; and it is a “quasi-satellite” of Earth, hovering around Earth as it orbits the Sun, while never being fully bound by its gravity. No space probe has ever visited an object quite like this one.

Tianwen-2 will spend nearly a year circling Kamo’oalewa, poking around its craters and seeing what it can see. This won’t be easy; the asteroid’s gravity is impossibly light, so any orbit will require the very gentlest of touches to maintain. For the key task—capturing material from the surface—the probe will use two different methods, to make sure that at least one works. The first is the “touch-and-go” approach, successfully used by the Hayabusa missions and by OSIRIS-REx. This entails bumping into the asteroid, snatching a sample at the moment of contact, then bouncing off again. The other method, “anchor-and-attach,” is harder to pull off, but offers more control—it involves physically latching onto the asteroid with a grappling hook, then holding the ship in place while it collects samples. Tianwen-2 would be the first spacecraft in history to achieve this.

Once it has its samples, Tianwen-2 will make its way back to Earth, dropping off its return capsule in November of 2027. The capsule is expected to land in the Inner Mongolian desert with carefully preserved pieces of Kamo’oalewa, destined for test labs around the globe. The main spacecraft, meanwhile, will use Earth’s gravity for a slingshot maneuver, propelling it to the Asteroid Belt to visit its second target: the comet 311P/PanSTARRS¹.

311P/PanSTARRS is an unusual specimen. You see, it’s a comet—“comet” defined as an object that outgasses material into space—but it orbits between Mars and Jupiter, like a normal main-belt asteroid. Such objects are called “main-belt comets,” or “active asteroids.” Some active asteroids are believed to have icy compositions, like normal comets. When ice is uncovered, such as by impacts, it sublimates into jets of vapor, producing a cometary appearance. Other active asteroids lack ice, but generate tails of dust from impacts with other asteroids. 311P/PanSTARRS falls into this second category. Something seems to have set it into a rapid spin, so rapid that pieces are breaking off. 311P/PanSTARRS appears to be literally pulling itself apart.

Only a close approach will uncover what’s happening there. Tianwen-2 is slated to arrive in January of 2035, seven years after its flyby of Earth, and it will use its onboard thrusters to brake into orbit, positioning itself for a months-long survey of the asteroid. We can expect it to beam back photographs of a disintegrating rubble pile, tumbling chaotically as it ejects pieces of itself into space. A specialized radar aboard Tianwen-2 will peer into the internal structure of 311P/PanSTARRS, determining its porosity as well as the presence or absence of water ice.

Without a doubt, Tianwen-2 will expand the frontiers of planetary science, closely investigating two objects that are unlike anything else we have yet explored. But it plays into a bigger picture, too. China, just like the United States, has ambitions of one day mining the Solar System’s asteroids for precious metals. It’s hard to imagine the scale of the mineral wealth that’s up for grabs. A typical S-type asteroid, just one kilometer wide, would host 200 million tons of iron, 30 million tons of nickel, 1.5 million tons of cobalt, and 7,500 tons of platinum-group metals (platinum, iridium, osmium, etc)². There may be millions of such asteroids in the Solar System.

As access to space gets cheaper, it will become economical to extract material from asteroids and return it to Earth. Platinum and lithium—essential to modern electronics and clean energy technology—will be especially coveted off-world imports. The exploitation of space resources will be the 21st century’s version of the Gold Rush; those people and countries who are first to capitalize on it could become very, very rich.

China is already positioning itself to succeed in this new arena, with Tianwen-2 as the opening move in a much more ambitious program. Scientists at the China University of Mining and Technology have prototyped a six-legged mining robot for use on the low-gravity surfaces of asteroids; meanwhile, the firm Origin Space, based in Shenzen, has already launched a test vehicle to research methods for space mining, albeit at a very small scale. Origin Space also operates a commercial space telescope, dedicated to identifying near-Earth asteroids for future exploitation.

Wang Wei, of the state-owned China Aerospace Science and Technology Corporation, presented a policy paper in 2023 that placed asteroid mining at the center of China’s expansion into deep space. In his words: “Just like the miracles created in the great age of navigation, a ‘great space age’ featuring the use of space resources will … create the next miracles in human history and bring new prosperity to our civilisation.” He went on to state that of the 1.3 million asteroids in the Solar System, 700 are reasonably near Earth; 122 of those would be economical to mine, with an average value of $100 trillion each. That’s “trillion,” not “billion.” There’s a lot of money to be made out there.

How does the humble space probe Tianwen-2 factor into all this? Well, it’s the Chinese space program’s first venture into the world of the asteroids, pioneering countless techniques—interplanetary navigation, asteroid rendezvous, landing and sample collection—that will prove indispensable for a commercial operation, decades out. It’s extremely audacious for a country that doesn’t yet have the deep-space experience of Western countries. China is catching up, though. It is a nation on the march, determined to seize its place as the foremost power in space. NASA’s going to have to watch its back…

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Thanks for reading this one! To my regular readers, I’ll catch y’all again in a few days, probably with a continuation of my fiction snapshot “Last Flight from Tazab Station”; for those who wandered in here off Google, why not subscribe? I post all kinds of space and sci-fi content, but with the artistic flare of a creative writing major—you won’t want to miss it.

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1. Yes, it’s a funny name. “311P” denotes that this is the 311th periodic (P) comet to be discovered; periodic comets are those with low, fast orbits, less than 200 years, which can be observed through multiple passages near the Sun. “PanSTARRS” refers to the Pan-STARRS telescope in Hawaii, where this comet was discovered. ↩︎
2. These figures are taken from Robert Zubrin’s superb book The Case for Space, which has a chapter on asteroid mining. I reviewed it here. ↩︎