Chengdu
Artificial Moon
In October 2018, a Chinese aerospace institute announced plans to replace Chengdu's street lights with an orbital mirror satellite — 8× brighter than the real moon. The plan attracted global headlines, withering scrutiny from physicists, and has never been launched.
Anything in low orbit is falling around the Earth at roughly 27,000 km/h. It crosses the sky in minutes — watch the dot above.
Only geostationary orbit stays fixed above one city, and it is 72× further away. No mirror of buildable size delivers useful light from there.
Log scale — on a linear one the 500 km bar would be invisible. That gap is the whole story: the altitude where a mirror is bright enough is the altitude where it cannot stop moving, and the altitude where it could hold still is far too high to be bright. Chengdu’s proposal was announced, covered worldwide, and quietly shelved without hardware ever being built.
Chengdu’s “artificial moon” could never have worked as described. At the proposed 500 km altitude a satellite travels at about 7.6 km/s — it cannot hover over a city. The only orbit that holds station above one point is geostationary, at 36,000 km, and no mirror of any buildable size delivers useful light from that range. The concept was announced, covered worldwide, and quietly shelved without hardware ever being built.
The Announcement
On 10 October 2018, Wu Chunfeng — chairman of the Chengdu Aerospace Science and Technology Microelectronics System Research Institute and head of the Tianfu New Area Science Society — announced the plan at a national innovation and entrepreneurship conference in Chengdu. He stated that China planned to launch an "illumination satellite" from the Xichang Satellite Launch Centre by 2020, with three more to follow in 2022 if the first succeeded.
The satellite would carry a large reflective coating to redirect sunlight toward Chengdu at night, producing a "dusk-like glow" Wu described as 8× brighter than the real moon but equivalent to roughly one-fifth the brightness of street lighting. The beam could illuminate an area 10 to 80km in diameter, with precision control down to a few dozen metres. If the 50 sq km around central Chengdu were illuminated, Wu estimated the city would save 1.2 billion yuan ($174 million) annually in electricity costs. Together, three moons could rotate to cover 3,600–6,400 sq km continuously for 24 hours.
The concept, Wu noted, was directly inspired by a French artist who had imagined hanging a necklace of mirrors above the Earth to reflect sunlight through the streets of Paris year-round. It was also — though Wu framed it as novel — a direct continuation of the Znamya concept Russia had attempted in 1993 and 1999.
Why Experts Were Sceptical
The announcement was met with immediate and pointed criticism from aerospace engineers. Ryan Russell, an associate professor of aerospace engineering at the University of Texas at Austin, identified the central flaw: a satellite at 500km cannot stay above one city. At that altitude, orbital velocity is approximately 7.6 km/s. The satellite would pass overhead and disappear in minutes — exactly the same problem that made Znamya-2's beam a one-second flash rather than a sustained light source.
To actually hover above Chengdu, the satellite would need to be in geostationary orbit at 35,786km altitude — nearly 72 times higher than proposed. But at that distance, a reflective satellite can produce no meaningful illumination at the surface. The physics of reflection over that distance, given the Sun's angular size, would spread the beam across an area so vast as to be invisible against the sky background. As Russell told Discover magazine: "It's a very complicated solution that affects everyone to a simple problem that affects a few. It's light pollution on steroids."
Wu's proposal claimed a satellite at 500km could illuminate a specific city. But at 500km, no satellite can be geostationary — it circles Earth in roughly 95 minutes. To provide steady light over one city requires geostationary orbit at 36,000km. At that range, no mirror of practical size can deliver meaningful brightness. The proposal as stated violated basic orbital mechanics. No technical detail was ever published that resolved this contradiction, and no response from Wu to the specific criticism was recorded.
The Quiet Disappearance
After the initial burst of international coverage in October 2018, the project went dark. No launch occurred in 2020. No technical specifications were ever published. No hardware was publicly displayed. No follow-up announcement came in 2022. The Chengdu artificial moon joined a long list of aspirational space proposals that generated headlines and then quietly dissolved without ever becoming hardware.
Whether the project was formally cancelled, indefinitely delayed, or simply abandoned is unknown — no official statement was ever made. Wu Chunfeng's institution, the Tianfu New Area Science Society, has made no further public statements about the programme. The Chinese national space agency (CNSA) was never publicly confirmed as a supporter, and no government funding was announced. The proposal may have been primarily a private initiative that never secured the institutional backing required to progress beyond the announcement stage.