Submitted URL: : http://www.nasa.gov/multimedia/imagegallery/image_feature_2124.html Echo II is shown here undergoing a tensile stress test in a dirigible hanger at Weekesville, North Carolina. A dirigible is a type of aerostat or “lighter-than-air” aircraft. The 135-foot rigidized balloon satellite was sent into orbit as a passive communications experiment by NASA on January 25, 1964. When folded, the [...]