Final answer:
The Mercury 7 astronauts were Americans who had already been to space, trained in the US, and trained on US military aircraft.
Step-by-step explanation:
The information that can be gathered from the photo and caption is that the Mercury 7 astronauts were Americans who had already been to space. They were not from all over the world, but trained in the US. Additionally, they were not soldiers who had fought for the US in a war. Instead, they were trained on US military aircraft.