Telescopes on the Moon

A small telescope on the Moon is already delivering unusually sharp views of the universe—because the lunar environment removes the two biggest limits on Earth-based astronomy: atmospheric turbulence and atmospheric absorption. The Chang’E 3 lander, which soft-landed in December 2013, has been operating ever since, including its Lunar Ultraviolet Telescope (LUT). Despite a modest ~15-centimeter aperture, LUT can observe near-ultraviolet wavelengths and visible light that Earth’s atmosphere blocks or blurs, producing clear images such as a near-UV view of the pinwheel galaxy. The Moon’s near-vacuum atmosphere means there’s no weather-like “seeing” from turbulence, no scattering that creates a bright blue sky, and stars remain visible even during lunar daytime.

The episode then pivots from what’s been achieved to what could be built next: much larger lunar telescopes. Aperture size still matters—both for collecting more light and for improving resolution via the diffraction limit, which scales inversely with diameter. LUT’s small size limits its sharpness, but it functions as a proof of concept for scaling up. The usual bottleneck for space telescopes is logistics: large mirrors must fit inside rockets and survive launch acceleration. Even advanced designs such as folding mirrors have practical limits, and mirrors are fragile enough that launch vibrations can ruin them.

On the Moon, engineers may be able to sidestep those constraints by constructing mirrors directly on the surface, where the platform is far more stable than a rocket. That opens the door to mirrors far larger than what can be launched. Two major technical challenges stand in the way: surviving the Moon’s harsh environment and solving the mirror-material problem.

The rover Yutu (Jade Rabbit) illustrates the environment’s brutality. With almost no atmospheric buffering, lunar temperatures swing from about 125°C in sunlight to −150°C or lower in shade, quickly halting mobility. Even after that, moondust becomes the killer: electrically charged regolith particles repel each other and form dust fountains in low gravity, sticking to electronics, clogging solar panels, and grinding moving parts.

Yet moondust may also be repurposed. NASA Goddard’s Pete Ching proposes mixing epoxy and carbon nanotubes with lunar dust to form a concrete-like material, then grinding it into shape and coating it with aluminum—an approach aimed at a ~50-meter mirror. Another path uses liquid mirror telescopes. On Earth, the Large Zenith Telescope spins a six-meter dish of mercury to create a parabolic mirror, but it can only point straight up and mercury is costly and evaporates. Researchers including Pete Worden (NASA Ames) and Ermanno Borra (University of Quebec) are instead exploring nonevaporating ionic liquids (molten-salt-like fluids) with a thin silver coating, potentially enabling liquid mirrors up to ~100 meters. Lower gravity could help the mirror form at large scales, and the resulting telescopes might not need complex pointing—making them attractive for cosmology.

Momentum is building beyond government missions. More Chang’E landings are planned, and private efforts such as the International Lunar Observatory Association and Moon Express have received approval for lunar landing, with plans for a small ~7-centimeter optical telescope. A manned base is also being discussed, which could support future giant lunar observatories. The core message is clear: the Moon’s stable surface and atmospheric advantages could turn it into a long-duration “lookout tower” for the clearest views of space—if engineers can tame dust, temperature extremes, and mirror construction at scale.