CAPE CANAVERAL, Fla. (UPI) -- The United States Friday successfully launched into the longest and highest orbit yet achieved around the earth a 142-pound "Paddlewheel" satellite which may be the forerunner of spaceships to Mars or Venus.
The aluminum-coated Explorer VI satellite, roughly the size and shape of a medicine ball and packed with 15 major scientific experiments, was blasted into space atop a 100,000-pound Thor-Able III rocket at 10:23 a.m. EDT.
The Federal Space Agency in Washington announced that Explorer VI's orbit extends 25,000 statute miles from the earth at its farthest reach and curved back to 150 miles at its closest point.
The estimated period, the time it takes the satellite to complete one circuit, was placed at 12 1-2 hours. At 3:25 p.m. EDT it was roughly 25,000 miles over the tip of South Africa.
The agency said it would be at the lowest point of its orbit over Singapore between 10 and 11 p.m. EDT.
Scientists said all instruments aboard the satellite appeared to be working as planned and that data already was being received and processed. It will, however, take considerable time to analyze the information and establish results of the various experiments.
The satellite is not expected to be visible to the naked eye. It was not designed to reflect sunlight.
The space agency said the satellite should remain aloft "in excess of one year" before gradually falling back into the earth's atmosphere and being consumed by the heat of air friction.
Some scientists expressed concern that the satellite's swings back toward the earth would bring it too close to allow it to maintain its orbit as long as hoped. They had originally counted on Explorer VI coming no closer than 160 miles.
But the scientists said a lifetime of one year would be enough for the satellite to accomplish its several missions.
Explorer VI was nicknamed "The Paddlewheel" because it carried four projecting paddle-shaped vanes, each containing 2,000 tiny silicon-based cells for converting sunlight into electricity.
Explorer VI was by far the most scientifically advanced package the United States has yet put into orbit.
One highly important device aboard the satellite worked successfully within minutes after the long climb into space. This was a newly developed "space command" system which will be essential to future planetary probes.
Shortly after launching, Canaveral scientists used a ground signal which is part of this system to cut off one of Paddlewheel's three radio transmitters.
Fifteen minutes later this same transmitter was turned back on by a signal flashed from the Jodrell Bank Tracking Station at Manchester, England.
"Now we know the command system will work," Dr. Adolph K. Thiel, director of the Paddlewheel project, told reporters.
Explorer is 26 inches in diameter, 29 inches deep and its aluminum skin is 1-16 of an inch thick.
At launching, the Thor-Able III rocket, a three-stage vehicle of proven reliability, rose beautifully into the morning sky and through two cloud layers.