So in recent times, we have discovered the interstellar craft also, the spacecraft Voyager 1 that was found sailing through space. What about the lesser-known manhole cover from Operation Plumbbob Pascal-B test? I am sure with the right calculations, someone could see where it would be in the system.
Not know what I am talking about?
"Every kid who has put a firecracker under a tin can understands the principle of using high explosives to loft an object into space. What was novel to scientists at Los Alamos [the atomic laboratory in New Mexico] was the idea of using an atomic bomb as a propellant. That strategy was the serendipitous result of an experiment that had gone somewhat awry.
"Project Thunderwell was the inspiration of astrophysicist Bob Brownlee, who in the summer of 1957 was faced with the problem of containing underground an explosion, expected to be equivalent to a few hundred tons of dynamite. Brownlee put the bomb at the bottom of a 500-foot vertical tunnel in the Nevada desert, sealing the opening with a four-inch-thick steel plate weighing several hundred pounds. He knew the lid would be blown off; he didn't know exactly how fast. High-speed cameras caught the giant manhole cover as it began its unscheduled flight into history. Based upon his calculations and the evidence from the cameras, Brownlee estimated that the steel plate was travelling at a velocity six times that needed to escape Earth's gravity when it soared into the flawless blue Nevada sky. 'We never found it. It was gone,' Brownlee says, a touch of awe in his voice almost 35 years later.
"The following October the Soviet Union launched Sputnik, billed as the first man-made object in Earth orbit. Brownlee has never publicly challenged the Soviet's claim. But he has his doubts."
Just a thought.
Not know what I am talking about?
"Every kid who has put a firecracker under a tin can understands the principle of using high explosives to loft an object into space. What was novel to scientists at Los Alamos [the atomic laboratory in New Mexico] was the idea of using an atomic bomb as a propellant. That strategy was the serendipitous result of an experiment that had gone somewhat awry.
"Project Thunderwell was the inspiration of astrophysicist Bob Brownlee, who in the summer of 1957 was faced with the problem of containing underground an explosion, expected to be equivalent to a few hundred tons of dynamite. Brownlee put the bomb at the bottom of a 500-foot vertical tunnel in the Nevada desert, sealing the opening with a four-inch-thick steel plate weighing several hundred pounds. He knew the lid would be blown off; he didn't know exactly how fast. High-speed cameras caught the giant manhole cover as it began its unscheduled flight into history. Based upon his calculations and the evidence from the cameras, Brownlee estimated that the steel plate was travelling at a velocity six times that needed to escape Earth's gravity when it soared into the flawless blue Nevada sky. 'We never found it. It was gone,' Brownlee says, a touch of awe in his voice almost 35 years later.
"The following October the Soviet Union launched Sputnik, billed as the first man-made object in Earth orbit. Brownlee has never publicly challenged the Soviet's claim. But he has his doubts."
Just a thought.
I suspect it was either vaporized or fragmented due to aerodynamic resistance. If it did somehow survive into space, it wouldn't be able to enter earth orbit on its own, as it would have an intersecting trajectory with the Earth, but interaction from the moon could compensate, though unlikely. If it didn't retain escape velocity after leaving the atmosphere, it would come back down after several days, or less. Assuming it still had escape velocity after exiting the atmosphere, the more likely scenario is that it would be on an Earth-crossing Solar orbit. If it were going fast enough, it would be a long period, highly eccentric orbit, and it could take a very long time to come back. 
