Concepts and status of Chinese space gravitational wave detection projects

Gravitational wave (GW) detection in space probes the GW spectrum that is inaccessible from the Earth. In addition to the LISA project led by the European Space Agency, and the DECIGO detector proposed by the Japan Aerospace Exploration Agency, two Chinese space-based GW observatories—TianQin and Taiji—are planned to be launched in the 2030s. TianQin has a unique concept in its design with a geocentric orbit. Taiji’s design is similar to LISA, but is more ambitious with a longer arm distance. Both facilities are complementary to LISA, considering that TianQin is sensitive to higher frequencies and Taiji probes similar frequencies but with a higher sensitivity. In this Perspective we explain the concepts of both facilities and introduce the development milestones of the TianQin and Taiji projects in testing key technologies to pave the way for future space-based GW detections. Considering that LISA, TianQin and Taiji have similar scientific goals, are all scheduled to be launched around the 2030s and will operate concurrently, we discuss possible collaborations among them to improve GW source localization and characterization. The concepts and development milestones of the two Chinese space-based gravitational wave observatories, TianQin and Taiji, are introduced. Considering their similar goals and operation window with LISA, possible collaborations among them are discussed.