Three major experiments on Tiangong II

1. Growing plants in space, directed by Institute of Plant Physiology and Ecology at the Shanghai Institutes for Biological Sciences

In the movie The Martian, astronaut Mark Watney survives on the Red Planet by growing potatoes. In reality, growing plants in space is much harder. On Tiangong II, scientists have built a mini "greenhouse", with controlled temperature and light. Rice and mouse-ear cress will be grown.

"China will conduct its first seed-to-seed experiment in space through Tiangong II," Zheng Huiqiong, sciences professor at the Shanghai institutes, said in an interview with China Central Television.

She said that before the launch of the Tiangong space lab, most biological experiments in space were limited to 20 days, and it was impossible for higher forms of plants to finish a life cycle. China has never conducted a full seed-to-seed growth cycle experiment in space.

2. Cold atomic clock experiment in space, directed by the Shanghai Institute of Optics and Fine Mechanics at the Chinese Academy of Sciences

Tiangong II will be equipped with a cutting-edge cold atomic clock, which can measure time more accurately and increase the precision of navigation systems.

The clock, which uses atomic transitions to measure time, took more than 10 years for Chinese scientists to develop. It will be the world's first "cold" atomic clock used to conduct experiments in space, according to an announcement from CAS earlier this year. The clock's first spaceflight can raise the spacecraft's autonomous precision by two orders of magnitude, a substantial increase in navigation and positioning accuracy.

3. Gamma ray detector POLAR, directed by the Chinese Academy of Sciences

Tiangong II also can observe gamma rays using the detector named POLAR, a project developed through collaboration among China, Switzerland and Poland. It's the only experiment involving international cooperation.

Completed in 2015, POLAR can measure the polarization of hard X-ray photons, in particular the polarization of prompt photons from gamma ray bursts.

Tools of high energy physics, such as POLAR, are used to detect and characterize gamma ray photons and allow scientists to observe the cosmos.