  High-precision inertial sensors or accelerometers can provide us references
of free-falling motions in gravitational field in space. They serve as the key
payloads for gravity recovery missions such as the CHAMP, the GRACE-type
missions, and the planned Next Generation Gravity Missions. In this work, a
systematic method of electrostatic inertial sensor calibrations for gravity
recovery satellites is suggested, which is applied to and verified with the
Taiji-1 mission. With this method, the complete operating parameters including
the scale factors, the center of mass offset vector and the intrinsic biased
acceleration can be precisely calibrated with only two sets of short-term
in-orbit experiments. Taiji-1 is the first technology demonstration satellite
of the "Taiji Program in Space", which, in its final extended phase in 2022,
could be viewed as operating in the mode of a high-low satellite-to-satellite
tracking gravity mission. Based on the calibration principles, swing maneuvers
with time span about 200 s and rolling maneuvers for 19 days were conducted by
Taiji-1 in 2022. The inertial sensor's operating parameters are precisely
re-calibrated with Kalman filters and are updated to the Taiji-1 science team.
Data from one of the sensitive axis is re-processed with the updated operating
parameters, and the performance is found to be slightly improved compared with
former results. This approach could be of high reference value for the
accelerometer or inertial sensor calibrations of the GFO, the Chinese
GRACE-type mission, and the Next Generation Gravity Missions. This could also
shed some light on the in-orbit calibrations of the ultra-precision inertial
sensors for future GW space antennas because of the technological inheritance
between these two generations of inertial sensors.
