It could provide a natural shelter in which to build a future lunar base, according to a NASA astronaut in a Reddit-based Q&A.

These lava tubes are long, tunnel-like structures formed after the surface of a lava flow hardens before hollowing out.  

The cave structures would provide a shield against both the moon's temperature fluctuations and harmful solar radiation — thereby cutting down on building costs. 

NASA geoscientist Daniel Moriarty and colleagues discussed the possibility of future moonbases during a Reddit 'ask me anything' session on May 16, 2019. 

The online Q&A session was focused on the upcoming 2024 moonshot — to be dubbed 'Artemis' — which the US space agency is working towards.

Questions turned, however, to the possibility of moonbases in the future and the steps that would be required to prepare the lunar surface for human inhabitants

'I don't think we're going to be able to change anything about the surface of the moon much,' Dr Moriarty wrote in response.

'Instead, I think it makes sense to work within some of the structures and resources that are already there.

'It could be interesting to set up shop within a pre-existing lava tube,' he added.

Setting up a base within an extinct lava tube, Dr Moriarty said, 'could provide astronauts with some shielding from temperature variations and incoming solar radiation.'