  TianQin is a proposed mission for space-based gravitational-wave detection
that features a triangular constellation in circular high Earth orbits. The
mission entails three drag-free controlled satellites and long-range laser
interferometry with stringent beam pointing requirements at remote satellites.
For the payload architecture and pointing control strategies, having two test
masses per satellite, one for each laser arm, and rotating entire
opto-mechanical assemblies (each consisting of a telescope, an optical bench,
an inertial sensor, etc.) for constellation breathing angle compensation
represent an important option for TianQin. In this paper, we examine its
applicability from the perspectives of test mass and satellite control in the
science mode, taking into account of perturbed orbits and orbital gravity
gradients. First, based on the orbit-attitude coupling relationship, the
required electrostatic forces and torques for the test mass suspension control
are estimated and found to be sufficiently small for the acceleration noise
budget. Further optimization favors configuring the centers of masses of the
two test masses collinear and equidistant with the center of mass of the
satellite, and slightly offsetting the assembly pivots from the electrode
housing centers forward along the sensitive axes. Second, the required control
forces and torques on the satellites are calculated, and thrust allocation
solutions are found under the constraint of having a flat-top sunshield on the
satellite with varying solar angles. The findings give a green light to
adopting the two test masses and telescope pointing scheme for TianQin.
