The TianQin Project

TianQin is a space-based gravitational wave detector expected in the 2030s. TianQin will be a constellation of three satellites equally spaced on a geocentric orbit with a radius of about 105 km. The satellites will be carefully controlled to provide a nearly disturbance-free environment for a set of test masses floating inside them, allowing the gravitational field to take full governance of the motion of the test masses. In this way, the minute variation in the distance between the test masses (partially caused by gravitational waves) can be measured with high-precision inter-satellite laser interferometry. The TianQin project was proposed by Jun Luo in 2014 and a systematic development of the TianQin project started at Sun Yat-sen University in 2015.

TianQin aims to detect gravitational waves in the frequency band 10-4 Hz ~ 1 Hz, which can come from a variety of important astrophysical and cosmological sources, and can thus provide key information to discover new types of astrophysical objects, help reveal the origin,  growth and environment of black holes, test the nature of gravity in the strong field regime, measure the expansion history of the Universe, probe the dynamics of certain epochs of the early Universe, and so on.

 

Some key mission parameters of TianQin

Sensitive Frequency Band

10-4 Hz ~ 1 Hz

Orbit and Constellation

Geocentric, Regular Triangle

Arm Length

1.7×105 km

Residual Acceleration

1×10-15 m/s2/Hz1/2

Displacement Measurement noise

1×10-12 m/Hz1/2

 

The TianQin project has adopted the “0123” technology roadmap to guide its development:

  • Step 0: Acquiring the capability to obtain high-precision orbit information for the TianQin satellites through lunar laser ranging experiments.
  • Step 1: Implement TianQin-1, a single satellite mission, where the main goal is to test and demonstrate the maturity of the inertial reference technology.
  • Step 2: Implement TianQin-2, a mission with a pair of satellites, where the main goal is to test and demonstrate the maturity of the inter-satellite laser interferometry technology.
  • Step 3: Implement TianQin-3, a mission with a constellation of three satellites to form the final detector, TianQin, to detect gravitational waves in space.

The number at each step indicates the number of satellites that need to be built.

A set of research facility has been constructed for the TianQin project: the TianQin Center Building, the TianQin Ranging Station, the TianQin Geodetic Station, and the TianQin Simulation Station.