Moon's South Pole Mission Becomes Several Countries Target

India – India's Chandrayaan-3 mission is already revealing new insights about the Moon's South Pole. Future missions to this region are planned by the United States, China and Russia, so what makes it so interesting?

It's a place where no human-made object has trundled before. Last week, however, the diminutive Pragyaan rover slid down a ramp from its mothership, India's Vikram lander, and began exploring the region around the Moon's South Pole.

The uncrewed spacecraft is something of a pioneer – the first to make a soft-landing in the frigid, crater-strewn lunar polar landscape. 

Whereas the Apollo missions of the 1960s and 70s primarily set down near the Moon's equator, the lander from India's Chandrayaan-3 mission successfully touched down about 370 miles (600km) from the moon’s south pole, closer than any spacecraft has been to this location.

It arrived hot on the heels of a failed Russian attempt two days earlier, the Luna-25 spacecraft, which span out of control and crashed. 

India's mission is the start of a rush of activity at this enigmatic part of the lunar surface that will ultimately see humans set foot there later this decade.

"It's just incredible that this is happening," said Simeon Barber, a planetary scientist at The Open University in the United Kingdom. 

Alongside India and Russia, both the US and China have their sights set on the Moon's South Pole. There they hope to investigate some of the Moon's most intriguing mysteries and perhaps even exploit what they find.

But what is it about the Moon's South Pole that has made it so attractive to these visitors?

Already Chandrayaan-3 and its suitcase-sized rover have sent back a few tantalising hints of the strange environment they find themselves in. Travelling at around 1cm (0.4 inches) every second across the dusty surface, the Pragyaan rover has edged itself several metres away from its mothership.

Burrowing its sensors into the lunar soil along the way, the rover has revealed a curiously sharp drop in temperature beneath the surface. At the surface it measured a temperature of around 50C (120F), but just 80mm (3 inches) below this, it fell to -10C (14F) – a temperature difference that has "surprised" scientists.

Onboard chemical analysis equipment has also indicated the presence of sulphur, aluminium, calcium iron, titanium, manganese, chromium and oxygen in the lunar soil.

Both of these early findings hint at why scientists are eager to explore the south polar region of the Moon.

The Moon's shallow axis of rotation, 1.5 degrees compared to Earth's 23.5 degrees, means some craters at its poles never see sunlight. 

Coupled with low temperatures in these locations, scientists believe this has resulted in an abundance of ice, much of it made of water, that is either mixed into the soil or exposed on the surface. 

There are hopes that the ice could be used as both a resource for astronauts and a springboard for future scientific discoveries. 

"It is a unique location. The availability of water is very important,"  Saumitra Mukherjee, a professor of geology at Jawaharlal Nehru University in New Delhi, India stated. 

Our best evidence for water ice on the moon comes from a Nasa experiment in October 2009 when an empty rocket was purposefully slammed into a crater at the South Pole. 

"The plume of material had evidence of water. That's our one direct observation of water ice on the Moon," said Margaret Landis, a planetary scientist at the University of Colorado, Boulder, in the United States. 

Other data points to a higher reflectance at the poles, a likely result of ice, while a higher amount of hydrogen at the poles has been observed, perhaps a result of water ice. 

Last year scientist William Reach at Nasa's Ames Research Center in California flew Nasa's now-retired Sofia telescope in a plane to study the Moon, finding evidence of hydrogen just outside the landing site now occupied by Chandrayaan-3's Vikram and its rover since they touched down on 23 August.

These recent discoveries of water ice have spurred a renewed interest in exploring the Moon, and in particular, its South Pole.

Aanchal Sharma, a former engineer at the Indian Space Research Organisation (ISRO), now working at the University of Trento, Italy stated that India's lander and rover will now allow scientists to test theories that lunar researchers have been proposing about water ice presence in the lunar soil. 

While Chandrayaan-3's data will be useful, it is later missions that will land closer to the South Pole that scientists are particularly excited about. 

Here, there are craters known as permanently shadowed regions (PSRs). Sometimes dubbed "craters of eternal darkness", these are angled in such a way that the Sun's rays never reach their innards, meaning they have potentially stored ice for billions of years. 

The South Pole has more craters than the North Pole, likely a random outcome of how many meteorite impacts have hit the surface, making the South Pole a more attractive target.