Vanguard 1 was the fourth satellite launched into space and the first that was solar powered. It was also, perhaps, the most successful of the early satellites. Though Vanguard 1 weighed in at a paltry 3.2 pounds, it remained operational for 2,200 days, and took readings from space which showed that the Earth is slightly pear-shaped. Soviet Premier Nikita Khrushchev derided Vanguard as "the grapefruit satellite" (probably out of jealousy). Vanguard 1 remains in orbit to this day, making it the oldest manmade satellite in space.