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

摘要度位二阶导数，可以通过星载度仪进行观测。

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

由于高温超导究成功，使得超导磁度仪实际应用成现实。