From Chandrayaan 1 (image credit: Isro) to Artemis 2 (Image credit: Nasa)

For much of the late 20th century, the Moon was treated as a closed chapter. After Apollo, samples brought back to Earth seemed to settle the argument. The Moon was dry, ancient and geologically inactive. There was no water to sustain life, no resources to exploit, and no compelling reason to return. Human spaceflight moved inward, towards low-Earth orbit, while the Moon slipped into the background.That consensus began to fracture in 2008, when Isro’s Chandrayaan-1 entered lunar orbit. What followed overturned assumptions that had shaped global space strategy for decades and quietly reset humanity’s relationship with its nearest celestial neighbour.“After man landings on the Moon, people took a view that there was nothing much interesting there, and that it was an uninhabitable place,” says G Madhavan Nair, former Isro chairman, who oversaw Chandrayaan-1. Across the world, lunar exploration slowed because the Moon was considered scientifically exhausted and strategically irrelevant.Apollo’s legacy played a role in that retreat. Analysis of lunar rocks returned by US astronauts led scientists to conclude that the Moon lacked water and geological activity. Without water, there could be no sustained human presence. Every kilogram needed for life support or propulsion would have to be launched from Earth, making missions impractical.

Chandrayaan-1 challenged that verdict. Designed as a remote-sensing mission, it carried a mix of Indian and international instruments, including Nasa’s Moon Mineralogy Mapper and Isro’s own spectrometer. The mission was not built around certainty that water would be found.“With Chandrayaan-1, there was no certainty that we would detect water, though the theory existed. That is why a Nasa payload with the ability to detect water lines was flown on Chandrayaan-1, along with Isro’s own spectrometer,” says S Somanath, former Isro chairman, who oversaw Chandrayaan-3 in 2023.The data that came back was subtle, and the response cautious. Spectral signatures indicated the presence of hydroxyl and water molecules embedded in lunar minerals across large regions of the surface. Concentrations appeared higher towards the poles. Initially, Isro scientists hesitated to make a definitive claim. Only after the Nasa team published its results did Isro reanalyse its own datasets.“Once the American side published the presence of water on the Moon, we published our data which had also found that it was true,” Somanath says. Nair stresses the collaborative nature of the finding. “It was actually a combined experiment between Nasa and ourselves. Both datasets together confirmed this aspect.”The discovery went beyond surface chemistry. Further analysis suggested that in permanently shadowed craters near the lunar south pole, where sunlight never reaches and temperatures remain extremely low, water could exist as ice beneath the surface. “In the southern polar region, in the deep craters, there are billions of tonnes of ice,” Nair says.That possibility transformed lunar thinking. “That was a huge finding as far as future missions are concerned, because for anything and everything, you need water,” Nair says. Water enables life support, oxygen production and construction. It can also be split into hydrogen and oxygen. “If water is there, you can even make hydrogen out of it and use it as fuel for a rocket.”In one stroke, the Moon shifted from dead end to staging ground. “When hydroxyl molecules were identified, especially at higher concentrations near the poles, the possibility of finding trapped water ice became real,” Somanath says. In the absence of an atmosphere, water cannot remain liquid on the surface, but buried in polar regolith, it becomes a viable resource.Chandrayaan-1 also pointed to another asset. Its data indicated significant helium deposits, including helium-3, an isotope often cited as future fuel for nuclear fusion. “We were able to confirm large quantities of helium deposits, which can become a potential fuel for atomic fusion,” Nair says.M Annadurai, project director, Chandrayaan-1, says the impact is broadly acknowledged. “Things revived because of Chandrayaan-1. There is no doubt about that. Our mission is frequently cited in international forums,” he said. The post-Chandrayaan vision goes beyond brief visits. It includes longer stays, international cooperation, a possible lunar space station, and the Moon as an outpost for deeper space missions. “The Moon becomes an outpost, a launch pad to Mars,” Annadurai says.Isro followed discovery with validation. Chandrayaan-1 identified targets from orbit. Chandrayaan-2 attempted a soft landing near the south pole but failed during descent. Chandrayaan-3 succeeded, delivering surface-level data on regolith behaviour, thermal properties and seismic activity.“Chandrayaan-3 gave us direct surface-level information that earlier missions could only infer remotely. Together, the missions demonstrated that the Moon is not geologically inert. The measurements showed that the Moon is not a dead body,” Somanath says.

The timing mattered. Chandrayaan coincided with the maturation of lower-cost robotic technologies, making lunar missions accessible to more actors. After its findings, missions were commissioned by the US, Russia, China, Japan, and several European, Arab and African nations. The US adopted a commercial model, funding multiple private landers and orbiters that fed into Artemis planning.By the time Nasa formally committed to Artemis, the scientific justification was in place. Orbiter missions and renewed funding discussions had begun earlier. In that sense, Artemis is not the start of the lunar revival, but its political and operational expression.

The four Artemis II astronauts awaiting their launch will carry more than the legacy of Apollo.