The final module of China's Tiangong space station successfully docked with the core structure on Tuesday, state media said—a key step in its completion by year's end and a landmark moment in the country's space ambitions.

Tiangong is one of the crown jewels in Beijing's well-funded programme—which has landed robotic rovers on Mars and the Moon, and made the country only the third to put humans in orbit—as it looks to catch up with major spacefaring powers like the United States and Russia.

China has been excluded from the International Space Station (ISS) since 2011, when Washington banned NASA from engaging with Beijing.

Tiangong's completion would signal "China is now an equal player in space with the United States, Russia and Europe", analyst Chen Lan told AFP.

"In terms of scientific and commercial aspects, it is always good to see new players coming.... Competition will always speed up innovation," he added.

From his unique viewpoint hundreds of kilometres above Earth, French astronaut Thomas Pesquet told AFP he felt helpless watching fires rage across the planet below, calling for more to be done to protect this fragile "island of life".

Pesquet said his two tours onboard the International Space Station convinced him more than ever that the world is failing to address the threat posed by climate change.

He also witnessed moments of astonishing beauty while in space, some of which are captured in 300 photos published in his new book "La Terre entre nos mains" (Earth is in our Hands), released this week in France, the profits of which will go to charity.

Pesquet wrote that he initially "caught the photo bug" during his first tour on the ISS in 2016-2017.

NASA and several other national space agencies have recently revived their lunar colonization programs. One of the key factors that needs to be solved is how to power such a colony. Can uninterrupted solar power feasibly be realized without energy storage? On Earth, providing 100% of electricity demand 100% of the time solely from renewables, but without energy storage, is unfeasible.

This Earth-bound mindset has been challenged recently by a paradigm shift developed by Ben-Gurion University's Prof. Jeffrey Gordon, which he was invited to present to NASA in late August. His idea was published earlier this year in Renewable Energy.

On the moon, solar is the sole available renewable resource. The overriding challenge is to completely supply the main energy consumer: factories that need to continuously (24/7, 365 days a year) produce thousands of tons of oxygen (O₂) per year from the lunar soil, for rocket propellant, orbiting satellite refueling and human sustenance. A large part of the challenge derives from any location on the moon on average spending half of the lunar rotational period of 29.5 days in the dark.