Pioneer 10
Pioneer 10, the most remote manmade object in the universe, began its unprecedented journey with a liftoff over 30 years ago on March 2, 1972, from Launch Complex 36 on the Cape (Florida, USA.)
Catapulted into space aboard an Atlas-Centaur with a Delta third stage attached to provide additional boost, the compact 570-pound (258-kg) spacecraft is now hurtling through the nether regions of the universe nearly seven billion miles from Earth. It takes nearly 18 hours for a signal to travel roundtrip from Earth to the spacecraft.
The journey of this interstellar energizer has been nothing short of harrowing, and stands as a testament to space engineering at its best.
The challenges began even before liftoff, recounted Launch Director John Neilon and Jim Johnson, NASA project engineer.
The launch marked the first time the Atlas-Centaur was used in the Pioneer program as well as the first time it was configured as a three-stage vehicle, with a Delta rocket third stage added to the stack. The combination was needed to accelerate the spacecraft to the highest velocity ever for a spacecraft leaving the Earth: 32,400 miles per hour (52,100 km/hr), fast enough to pass the Moon in just 11 hours and speed by Mars some 50 million miles away in just 12 weeks.
However, the biggest pre-launch challenge was Pioneer 10’s power source: Radioisotope Thermoelectric Generators (RTGs).
The basic mission called for Pioneer 10 to traverse the Asteroid Belt and then encounter Jupiter, the largest and most massive planet in the solar system. Because the Sun’s energy at Jupiter is only 4 percent of energy received at Earth and grows weaker beyond the planet, mission planners opted for a nuclear power source—RTGs—over solar cells. Pioneer 10 marked the first time nuclear power provided the sole energy source for a spacecraft, and was considered a test case for similar future missions.
“The RTGs were installed the day before launch,” said Johnson. There were four RTGs, two each located at the ends of two booms extending from the spacecraft. The heat from the plutonium-238 dioxide power source was converted into electricity. The internal temperature of the RTGs was several hundred degrees Fahrenheit, and they would start to melt if they heated up any further.
“There was no cooling system on the spacecraft itself to keep the RTGs cool enough,” Johnson said, so there were special cooling ducts in the payload fairing to perform this function.
Launch was originally set for Feb. 27, but was scrubbed a frustrating three times before liftoff on March 2.
Once on its way, Pioneer 10 faced still more perils. “The big unknown was whether the spacecraft would make it through the Asteroid Belt,” Johnson and Neilon recalled.
Looming like an impenetrable barrier between Pioneer 10 and Jupiter, the Asteroid Belt measures roughly 175 million miles (280 million kilometers) across. The Belt is too thick to fly over or under, and all outer planetary missions must fly through it. The material in the belt whizzes about at speeds averaging 12 miles a second (19 km/s.) Rock chunks can be as big as the state of Alaska.
Survive Pioneer did, blazing through the Asteroid Belt undeterred in July 1972. The next hurdle was Jupiter; second only to the Sun in size in our solar system and with a mass more than 300 times the mass of Earth. Its radiation belts—as much as one million times more intense than Earth’s Van Allen radiation belts—could cripple or destroy a spacecraft approaching too closely.
Pioneer 10 passed within 81,000 miles (130,000 km) of Jupiter’s cloud-tops on December 3, 1973 and escaped with no damage. The spacecraft obtained the first close images of Jupiter, charted the radiation belts, and discovered that the planet is predominantly liquid in composition.
By the time Pioneer 10’s 8-watt signal reached Earth from the environs of Jupiter, its strength was a piddly 1/100,000,000,000,000,000 (10-17) watt. Collected for 19 million years, this energy would light a 7.5-watt Christmas tree bulb for one-thousandth of a second.
On June 13, 1983, Pioneer 10 performed its most amazing feat yet, by becoming the first manmade artifact to leave the Solar System. It is now exploring the region where the solar wind meets the region of interstellar space.
Only 5 of its 11 scientific instruments were still operating (in 1999.) When a targeting maneuver was performed in January, the spacecraft’s transmitter had to be turned off to provide enough power for the procedure.
The RTGs have provided reliable power for 27 years but in a few more years, the RTG power will dwindle to a level that signals to Earth will be to low to receive, and Pioneer 10 will coast silently through interstellar space forever, gone but never forgotten.”
But … and announcement from Spain in 2001 – two years later -- said …
Pioneer 10 Lives!
Pioneer 10 is now over 11.74 billion kilometers (7.29 billion miles) from Earth. After months of anticipation contact has been reestablished with a distant pioneer over 10 light-hours from Earth. At GMT 17:27:30, Saturday, 4/28/01, the signal from Pioneer 10 was received at station 63 in Madrid, the first time since August 19 of last year.
As of April 30, 2001 Pioneer 10 was 77.693 AU from the Sun and traveling at a relative speed to the Sun of 12.292 km/sec (27,500 mph). The probes distance from Earth was 78.505 AUs, with a round-trip Light Time of 21 hours 45.
When Pioneer 10 reaches a distance of about 1.5 parsec (309,000 AUs) - about 126,000 years from now - it will cease to be dominated by the gravitational field of the Sun.
After that Pioneer 10 will be on an orbital path in the Milky Way galaxy influenced by the field of the stars that it passes. The probe is moving in a straight line away from the Sun at a constant velocity of about 12 km/sec.
Meanwhile, Project Phoenix has been trying to observe Pioneer 10 at Arecibo in Puerto Rico through the auspices of the SETI Institute. However, their most recent observation dates - from Feb 26 to March 5 and from March 8 through 18 for about an hour each night - did not pick up the Pioneer-10 signal.
Power for the Pioneer 10 is generated by the Radioisotope Thermoelectric Generators (RTG’s). Heat from the decay of the plutonium 238 isotope is converted by thermoelectric couples into electrical current. The electrical output depends on the hot junction temperature, the thermal path to the radiator fins, and the cold junction temperature.
It is the degradation of the thermoelectric junction that has the major effect in decreasing the power output of the RTG. In the 29-year time scale operation of Pioneer 10, the 92-year half-life of the isotope does not appreciably affect the RTG operation.
The nuclear decay heat will keep the hot junction temperature hot for many years but unfortunately will not be able to be converted into enough electricity to power the transmitter for much longer. How much longer contact with Pioneer 10 can be maintained remains unknown.
Back to Earlier Books
Pioneer 10, the most remote manmade object in the universe, began its unprecedented journey with a liftoff over 30 years ago on March 2, 1972, from Launch Complex 36 on the Cape (Florida, USA.)
Catapulted into space aboard an Atlas-Centaur with a Delta third stage attached to provide additional boost, the compact 570-pound (258-kg) spacecraft is now hurtling through the nether regions of the universe nearly seven billion miles from Earth. It takes nearly 18 hours for a signal to travel roundtrip from Earth to the spacecraft.
The journey of this interstellar energizer has been nothing short of harrowing, and stands as a testament to space engineering at its best.
The challenges began even before liftoff, recounted Launch Director John Neilon and Jim Johnson, NASA project engineer.
The launch marked the first time the Atlas-Centaur was used in the Pioneer program as well as the first time it was configured as a three-stage vehicle, with a Delta rocket third stage added to the stack. The combination was needed to accelerate the spacecraft to the highest velocity ever for a spacecraft leaving the Earth: 32,400 miles per hour (52,100 km/hr), fast enough to pass the Moon in just 11 hours and speed by Mars some 50 million miles away in just 12 weeks.
However, the biggest pre-launch challenge was Pioneer 10’s power source: Radioisotope Thermoelectric Generators (RTGs).
The basic mission called for Pioneer 10 to traverse the Asteroid Belt and then encounter Jupiter, the largest and most massive planet in the solar system. Because the Sun’s energy at Jupiter is only 4 percent of energy received at Earth and grows weaker beyond the planet, mission planners opted for a nuclear power source—RTGs—over solar cells. Pioneer 10 marked the first time nuclear power provided the sole energy source for a spacecraft, and was considered a test case for similar future missions.
“The RTGs were installed the day before launch,” said Johnson. There were four RTGs, two each located at the ends of two booms extending from the spacecraft. The heat from the plutonium-238 dioxide power source was converted into electricity. The internal temperature of the RTGs was several hundred degrees Fahrenheit, and they would start to melt if they heated up any further.
“There was no cooling system on the spacecraft itself to keep the RTGs cool enough,” Johnson said, so there were special cooling ducts in the payload fairing to perform this function.
Launch was originally set for Feb. 27, but was scrubbed a frustrating three times before liftoff on March 2.
Once on its way, Pioneer 10 faced still more perils. “The big unknown was whether the spacecraft would make it through the Asteroid Belt,” Johnson and Neilon recalled.
Looming like an impenetrable barrier between Pioneer 10 and Jupiter, the Asteroid Belt measures roughly 175 million miles (280 million kilometers) across. The Belt is too thick to fly over or under, and all outer planetary missions must fly through it. The material in the belt whizzes about at speeds averaging 12 miles a second (19 km/s.) Rock chunks can be as big as the state of Alaska.
Survive Pioneer did, blazing through the Asteroid Belt undeterred in July 1972. The next hurdle was Jupiter; second only to the Sun in size in our solar system and with a mass more than 300 times the mass of Earth. Its radiation belts—as much as one million times more intense than Earth’s Van Allen radiation belts—could cripple or destroy a spacecraft approaching too closely.
Pioneer 10 passed within 81,000 miles (130,000 km) of Jupiter’s cloud-tops on December 3, 1973 and escaped with no damage. The spacecraft obtained the first close images of Jupiter, charted the radiation belts, and discovered that the planet is predominantly liquid in composition.
By the time Pioneer 10’s 8-watt signal reached Earth from the environs of Jupiter, its strength was a piddly 1/100,000,000,000,000,000 (10-17) watt. Collected for 19 million years, this energy would light a 7.5-watt Christmas tree bulb for one-thousandth of a second.
On June 13, 1983, Pioneer 10 performed its most amazing feat yet, by becoming the first manmade artifact to leave the Solar System. It is now exploring the region where the solar wind meets the region of interstellar space.
Only 5 of its 11 scientific instruments were still operating (in 1999.) When a targeting maneuver was performed in January, the spacecraft’s transmitter had to be turned off to provide enough power for the procedure.
The RTGs have provided reliable power for 27 years but in a few more years, the RTG power will dwindle to a level that signals to Earth will be to low to receive, and Pioneer 10 will coast silently through interstellar space forever, gone but never forgotten.”
But … and announcement from Spain in 2001 – two years later -- said …
Pioneer 10 Lives!
Pioneer 10 is now over 11.74 billion kilometers (7.29 billion miles) from Earth. After months of anticipation contact has been reestablished with a distant pioneer over 10 light-hours from Earth. At GMT 17:27:30, Saturday, 4/28/01, the signal from Pioneer 10 was received at station 63 in Madrid, the first time since August 19 of last year.
As of April 30, 2001 Pioneer 10 was 77.693 AU from the Sun and traveling at a relative speed to the Sun of 12.292 km/sec (27,500 mph). The probes distance from Earth was 78.505 AUs, with a round-trip Light Time of 21 hours 45.
When Pioneer 10 reaches a distance of about 1.5 parsec (309,000 AUs) - about 126,000 years from now - it will cease to be dominated by the gravitational field of the Sun.
After that Pioneer 10 will be on an orbital path in the Milky Way galaxy influenced by the field of the stars that it passes. The probe is moving in a straight line away from the Sun at a constant velocity of about 12 km/sec.
Meanwhile, Project Phoenix has been trying to observe Pioneer 10 at Arecibo in Puerto Rico through the auspices of the SETI Institute. However, their most recent observation dates - from Feb 26 to March 5 and from March 8 through 18 for about an hour each night - did not pick up the Pioneer-10 signal.
Power for the Pioneer 10 is generated by the Radioisotope Thermoelectric Generators (RTG’s). Heat from the decay of the plutonium 238 isotope is converted by thermoelectric couples into electrical current. The electrical output depends on the hot junction temperature, the thermal path to the radiator fins, and the cold junction temperature.
It is the degradation of the thermoelectric junction that has the major effect in decreasing the power output of the RTG. In the 29-year time scale operation of Pioneer 10, the 92-year half-life of the isotope does not appreciably affect the RTG operation.
The nuclear decay heat will keep the hot junction temperature hot for many years but unfortunately will not be able to be converted into enough electricity to power the transmitter for much longer. How much longer contact with Pioneer 10 can be maintained remains unknown.
Back to Earlier Books