July 29 is the 60th anniversary of the founding of NASA. What has been NASA's greatest achievement?

Landing humans on the moon and returning them to Earth
56% (20 votes)
Sending orbiters and rovers to Mars including Viking, Spirit, Opportunity and Curiosity
17% (6 votes)
The Voyager missions to the edge of the solar system
11% (4 votes)
The Cassini mission to Saturn, which landed the Huygens probe on Titan
0% (0 votes)
Hubble, Spitzer and other space telescopes, which have revealed the cosmos
17% (6 votes)
Total votes: 36