There may be far more water on the Moon than previously thought, according to two studies published Monday raising the tantalising prospect that astronauts on future space missions could find refreshment -- and maybe even fuel -- on the lunar surface.

The Moon was believed to be bone dry until around a decade ago when a series of findings suggested that our nearest celestial neighbour has traces of water trapped in the surface.

Two new studies published in Nature Astronomy on Monday suggest there could be much more water than previously thought, including ice stored in permanently shadowed "cold traps" at lunar polar regions.

Asymptomatic coronavirus sufferers appear to lose detectable antibodies sooner than people who have exhibited Covid-19 symptoms, according to one of the biggest studies of its kind in Britain published on Tuesday.

The findings by Imperial College London and market research firm Ipsos Mori also suggest the loss of antibodies was slower in 18–24 year-olds compared to those aged 75 and over.

Overall, samples from hundreds of thousands of people across England between mid-June and late September showed the prevalence of virus antibodies fell by more than a quarter.

The research, commissioned by the British government and published Tuesday by Imperial, indicates people's immune response to Covid-19 reduces over time following infection.