The TianQin project: current progress on science and technology

TL;DR

TianQin is a space-based gravitational wave observatory project aiming to detect a broad range of astrophysical sources, with significant technological advancements and milestones achieved towards its 2035 science operation goal.

Contribution

This paper reports on the current progress of TianQin's technological development and key milestones, including satellite launches and ground station capabilities, advancing the project towards operational readiness.

Findings

Successful launch of the TianQin-1 satellite exceeding mission requirements

Development of a new generation hollow corner-cube retro-reflector

Construction and successful testing of a 1.2 m laser ranging station

Abstract

TianQin is a planned space-based gravitational wave (GW) observatory consisting of three earth orbiting satellites with an orbital radius of about $10^5~{\rm km}$. The satellites will form a equilateral triangle constellation the plane of which is nearly perpendicular to the ecliptic plane. TianQin aims to detect GWs between $10^{-4}~{\rm Hz}$ and $1~{\rm Hz}$ that can be generated by a wide variety of important astrophysical and cosmological sources, including the inspiral of Galactic ultra-compact binaries, the inspiral of stellar-mass black hole binaries, extreme mass ratio inspirals, the merger of massive black hole binaries, and possibly the energetic processes in the very early universe or exotic sources such as cosmic strings. In order to start science operations around 2035, a roadmap called the 0123 plan is being used to bring the key technologies of TianQin to maturity, supported by the construction of a series of research facilities on the ground. Two major projects of the 0123 plan are being carried out. In this process, the team has created a new generation $17~{\rm cm}$ single-body hollow corner-cube retro-reflector which has been launched with the QueQiao satellite on 21 May 2018; a new laser ranging station equipped with a $1.2~{\rm m}$ telescope has been constructed and the station has successfully ranged to all the five retro-reflectors on the Moon; and the TianQin-1 experimental satellite has been launched on 20 December 2019 and the first round result shows that the satellite has exceeded all of its mission requirements.