In his 1995 history of NASA Langley, Space Revolution, Dr. James Hansen wrote:
The Echo balloon was perhaps the most beautiful object ever to be put into space. The big and brilliant sphere had a 31,416-square foot surface of Mylar plastic covered smoothly with a mere 4 pounds of vapor-deposited aluminum. All told, counting 30 pounds of inflating chemicals and two 11-ounce, 3/8-inch-thick radio tracking beacons (packed with 70 solar cells and 5 storage batteries), the sphere weighed only 132 pounds.
For those enamored with its aesthetics, folding the beautiful balloon into its small container for packing into the nose cone of a Thor-Delta rocket was somewhat like folding a large Rembrandt canvas into a tiny square and taking it home from an art sale in one's wallet.