Elon Musk says he has "great respect" for the "amazing progress" China has made on space exploration.

He was responding to an article about China's space station Tiangong-2, which is due to fall to Earth on Friday.

Tiangong-2 has been orbiting Earth since 2016 and has housed astronauts.

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Elon Musk applauded China's national space program in a tweet Thursday.

The SpaceX CEO was responding to a New Scientist article about China's Tiangong-2 space station, which is due to fall out of orbit Friday after circling the Earth for almost three years.

Tiangong-2 — which means "heavenly palace" — was never meant to be a permanent fixture but rather a test run for various technologies ahead of the launch of a bigger space station, which China hopes to send into orbit in 2020.

According to the New Scientist, it has housed astronauts researching (among other things) the effects that being in space has on human physiology.

Read more: A huge fireball briefly swallowed SpaceX's Mars rocket prototype, but Elon Musk says there is 'no major damage'

Once Tiangong-2 starts its controlled fall, most of it is expected to burn up on reentry, with any surviving parts falling into the Pacific Ocean. China lost control of its predecessor, Tiangong-1, resulting in an uncontrolled fall from orbit in April 2016.

Musk is CEO of the space-exploration company SpaceX, which faces growing competition from China as the country pumps money into its own space-travel companies.

Musk went on a charm-offensive trip to China earlier this year, when his electric-car company, Tesla, kicked off construction on its new $2 billion Gigafactory in Shanghai.