In February 2007, the fourth and last satellite of the BeiDou-1 system, <answer>BeiDou-1D</answer> (sometimes called BeiDou-2A, serving as a backup satellite), was sent up into space. It was reported that the satellite had suffered from a control system malfunction but was then fully restored.
What is the name of the fourth BeiDou-1 satellite?
BeiDou-1D