You will be given a definition of a task first, then some input of the task.
Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

It was the last KH-2 Corona' satellite, which was based on an Agena-B. The launch of Discoverer 28 occurred at 00:01 UTC on 4 August 1961.
Output:
When was the launch date of Discoverer 28?