With the invention of high-temperature-superconductor, the superconductive magnetic gradiometer be-comes available in application.

由于高温超导体的研究成功，使得超导磁仪的实际应用成现实。

Gravity gradient is the second order derivative of gravitational potential, which can be observed by satellite gradiometer.

位的二阶导数，可以通过星载仪进行观测。