TanDEM-X BLOG – On 12 July, the first deceleration manoeuvres began, to prevent TanDEM-X from overtaking TerraSAR-X. On 16 July, the distance between the satellites had shrunk to 370 kilometres. This distance corresponds to a time gap of 48 seconds, during which Earth continues to turn, so that the trailing satellite does not cover the same territory. Although the orbits are nearly identical for both satellites, Earth’s rotation causes the ground tracks at the equator to be separated from one another by more than 20 kilometres. Read More