Chandrayaan-4: What Are Sample-Return Missions And Why India Needs To Go Big On Them

The Narendra Modi government has approved Chandrayaan-4, a follow-up mission to the successful Chandrayaan-3, aimed at returning lunar samples to Earth for analysis. In this 2021 article, Dr Chaitanya Giri, Space Fellow at the Observer Research Foundation, explains what sample-return missions are and why India should invest heavily in them.

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26 April 2021 was the last day of the three-day-long China Space Conference held in Nanjing, a major city on the Yangtse River, west of Shanghai. 

The conference was substantial in pomp and show. In a glittering ceremony, the Chinese space agency, CNSA, ceremoniously named the rover accompanying the Tianwen-1 spacecraft, on its way to Mars, as Zhurong. 

The conference witnessed the Chang'e-6 lunar sample-return spacecraft announcement, China's eighth mission to the Moon. 

Scheduled for launch in 2024, the CNSA has pushed the space diplomacy throttle for this mission. It has secured payloads from the French, Swedish, Russian, and Italian space agencies.

However, the most interesting announcement is that of two independent space missions performed by a spacecraft. The first mission of this unnamed spacecraft will be to pick up extra-terrestrial geological samples from the asteroid 2016HO3 and drop the sample-containing space capsule on the Earth. 

After dropping this space capsule, the mother spacecraft will fly to the comet 311P/PANSTARRS, which exists between Mars and Jupiter. The dual-purpose asteroid-comet mission will last for 10 years. It will be the first-ever asteroid and comet-bound mission for China.

Major space agencies worldwide view the 2020s as a decade when the frequency of sample-return missions will grow. 

Until now, Japan and the United States have earned substantial success in such types of missions. During the Apollo-Luna contest in the 1960s and 1970s, the Americans were able to retrieve hundreds of kilograms of lunar geological samples. Russians, in turn, were able to procure a few grams of it through their Luna missions. 

After that, the first non-lunar extra-terrestrial samples came from the nebulous coma of the Comet Wild-2 by the NASA mission Stardust in 2006. In 2010, the Japanese demonstrated the prowess of the ion propulsion of their spacecraft Hayabusa which could touch the surface of asteroid Itokawa and brought back its samples.

More recently, in 2020, the Japanese space agency JAXA retrieved samples from the asteroid Ryugu through its Hayabusa-2 mission. Similarly, in October 2020, NASA has picked up pieces from the asteroid Ryugu.

On the comet front, the European Space Agency concluded its mission Rosetta, which I was part of as a payload investigating scientist, in 2016. Rosetta orbited around the comet 67P/Churyumov-Gerasimenko for over two years and had landed a probe, the first-ever on a comet, on it for in situ investigations.

On the scientific front, both asteroids and comets are considered precursors of the planets that never formed in this solar system. We only have eight of them, unfortunately discounting Pluto. 

Secondly, most of them carry exotic molecules and materials naturally synthesised through processes and physical forces distinct from those on the Earth. 

Such asteroids and comets also carry molecules that may have played a role in the origin of life on Earth. The water-ice on some of them has an isotopic composition similar to water delivered on early Earth, more than 3.8 billion years ago. Life on Earth perhaps arose using this comet-delivered water.

From an economic standpoint, both asteroids and comets and their inherent natural resources could significantly increase the human footprint in deep space. Humans may extract and utilise critical minerals, exotic materials, and clean fuel, which may help us survive in the arduous climes of outer space. 

The Chinese aspirations for asteroids and comets entail both these scientific and economic trajectories.

India, too must join the bandwagon without hesitation and aim for an asteroid or comet mission soon. The goal should not be to emulate the other countries, but our country’s scientific advancement and technological progress. 

An asteroid and comet mission can endow large swathes of the Indian scientific community. Such space missions will attract chemists, biologists, material scientists, physicists, mathematicians, mechanical engineers, and electronic engineers. 

Exploring these small solar system bodies is vital for missions bound for the Moon, Mars, and outer planetary system. 

The sample-return component adds tremendous value. For instance, the electronics, advanced materials, specialty chemicals industry might benefit tremendously from continuous analyses of samples returned from an asteroid or comet. These industries might stumble upon a lucrative molecule or material from an industry standpoint.

Indian space startups might find such missions particularly attractive. They could provide customised spacecraft designs, apt retro-firing engines with clean fuel, sample-acquisition mechanisms, and other technologies. They can benefit from their participation by spinning off such technologies to commercially viable space technology contracts.

Asteroids and comet missions, from my experience, are like Kamadhenu from our Bharatiya philosophy. They may appear mundane and tedious as compared to a space mission on a planet or the Moon. But they eventually generate tremendous return-on-investment. 

Had it not been the case, all these space agencies would not have successfully bid for such missions. The Chinese have taken a mature step ahead. It is time India follows suit without adjournment.