What was the name of the first satellite launched into orbit, sent up in 1958 and operating until 1970, and what space programme followed it?

• A Vanguard 1
• B Explorer 1 ✓
• C Pioneer 1
• D Discoverer 1

Explorer 1, launched by the Army Ballistic Missile Agency and JPL, discovered the Van Allen radiation belts and marked the country's entry into the Space Age after Sputnik.