Three Chinese astronauts aboard the country's under construction space station Tiangong, successfully entered the Wentian lab module in orbit for the first time on Monday, according to the China Manned Space Agency. <br />''<br />''China launched its space laboratory called Wentian on Sunday, sending the country's largest-ever spacecraft into Earth's orbit to become part of the under-construction space station. The Wentian module consists of a work cabin, an airlock cabin, and a resource cabin. <br />''<br />''The construction of China's Tiangong space station is expected to be completed this year. State media reported it is the first time in Chinese space history that Wentian, a 20-tonne-level spacecraft conducted space rendezvous and docking during the astronauts' in-orbit stay in the space station. It was the first time the Chinese astronauts had entered the lab module in orbit.<br />''<br />''The new lab module will function both as a backup of the core module and as a powerful scientific experiment platform, state media reported. <br />''<br />''It will then evolve from a single-module structure into a national space laboratory with three modules – the core module called Tianhe, and lab modules named Wentian and Mengtian. The Tianhe module was launched in April 2021, and the Mengtian module is set to be launched in October this year. The three astronauts who were sent into orbit on June 5 will help assemble the modules in their six-month space mission. During their stay in orbit, they will also witness the Tianzhou-5 cargo craft and Shenzhou-15 crewed spaceship dock with the core module. Then, they will live and work with the next batch of astronauts before returning to Earth.<br />''<br />''<span style="color: #222222;">Once ready, China will be the only country to own a space station. The International Space Station (ISS) of Russia is a collaborative project of several countries. Experts say Chinese Space station (CSS) may become the sole space station to remain in orbit once the ISS retires in the coming years. <br />''<br />''The significant feature of China's under-construction space station is its two robotic arms, especially the long one over which the US has previously expressed concern over its ability to grab objects including satellites from space. The 10-meter-long arm earlier successfully grabbed and moved a 20-tonne Tianzhou-2 cargo ship in a test, according to China Manned Space Engineering Office (CMSEO).</span><br />