In this week's Science Saturday, we look at science news ranging from NASA space mission to China's oldest-known forest.

NASA space mission 
NASA says its astronauts will likely return to Earth in August. Americans, Bob Behnken and Doug Hurley, took SpaceX's Crew Dragon spacecraft on a test flight to the International Space Station last month. This is the first SpaceX mission to carry astronauts, and paves the way for NASA to purchase transport services from the commercial sector. 

Mayan remains 
A massive 3,000-year old Mayan monument has been found in Mexico. The giant, sprawling structure – made of clay and earth – was found at a site called Auada Fenix in the state of Tabasco. The monument is around 1,400 meters long, and about 10 to 15 meters high. Scientists believe it was built between 1,000 and 800 BC, and was probably used for mass rituals during the ancient Mayan civilization.

Ancient forest

China's oldest forest dates back to 371 million years ago. That is about 100 million years before dinosaurs lived on Earth. The ancient forest is located in northwest China's Xinjiang Uygur Autonomous Region. Researchers from China and the United States first found a fossil plant stem in the same place in 2015, and expanded their research to find the age of the forest.

Hollow man
Scientists can turn human cells partially transparent, thanks to squids. A species of squid uses proteins called reflectins to become "invisible" to predators. U.S. scientists harvested these color-changing proteins and injected them into human kidney cells. This turned the human cells partially transparent. Experts say this technique can help scientists better observe the processes inside living cells and tissues. 

"Science Saturday" is part of CGTN's science and technology series "Tech It Out." The segment brings you the latest news about innovations and technological breakthroughs in the past two weeks from across the world.