Voyager 2/Titan IIIE-Centaur launch, LC-41, Kennedy Space Center, Florida, 20 August 1977. (NASA)
20 August 1977: Voyager 2 was launched from Launch Complex 41 at the Kennedy Space Center, Cape Canaveral, Florida, aboard a Titan IIIE-Centaur launch vehicle. It was placed on an orbital trajectory that would take it on a journey throughout the Solar System and beyond.
Nearly two years later, 9 July 1979, Voyager 2 made its closest approach to Jupiter, passing within 350,000 miles (570,000 kilometers) of the planet. Many dramatic images as well as scientific data were transmitted back to Earth.
Artist’s concept of Voyager. (NASA/JPL)
The probe continued outward to Saturn, Neptune and Uranus, continuously transmitting images and data. In 1990, the space probe passed beyond the limits of the Solar System.
Voyager 2 is now in interstellar space. It crossed the heliopause, where “solar wind” is slowed by the pressure of interstellar gas, 5 November 2018. It is still operating, 46 years after it was launched.
Voyager 2 captured this image of the moon Io transiting Jupiter, 9 July 1979. (NASA)Uranus, imaged by Voyager 2, 24 January 1986. (NASA/JPL–Caltech)This image of Neptune was captured by Voyager 2 on 20 August 1989, 28 years ago. (NASA)
On 21 July 2023, an erroneous instruction caused Voyager 2 to turn its antenna away from Earth, but on 5 August 2023, contact was reestablished. A power reduction strategy is hoped to allow the space probe to continue operating until 2026.
As of 15 August 2024, Voyager 2 was 136 Astronomical Units from Earth (20,345,310,413 kilometers/12,641,989,788 statute miles/10,985,588,776 nautical miles). Radio signals, traveling at the Speed of Light, take 18 hours, 56 minutes to cross that distance. It continues outbound at a rate of 3.3 AU/year. (With respect to the Sun, Voyager 2 is traveling outbound at 15.35 kilometers per second (33,330.48 miles per hour/29,832.37 knots).
Viking 1/Titan IIIE-Centaur launches from Kennedy Space Centaur, enroute to Mars, 20 August 1975. (NASA)
20 August 1975: The Viking 1 space probe was launched from Kennedy Space Center, Cape Canaveral, Florida, aboard a Titan IIIE/Centaur rocket. For the next ten months it traveled to Mars, the fourth planet of the Solar System. Once there, it was placed in orbit and began sending telemetry data back to Earth. A Viking Lander descended to the planet’s surface, landing at Chryse Planitia.
This was the first time that a spacecraft had landed on another planet. The orbiter continued to operate over the course of 1,485 orbits. As it ran low on fuel, mission controllers boosted it into a higher orbit to prevent it falling to the planet. Orbiter operations were terminated 17 August 1980. The lander operated for 6 years, 116 days, before the mission was terminated by a faulty transmission which resulted in a loss of contact, 11 November 1982.
The surface of Chryse Planitia, Mars, photographed by the Viking 1 Lander. (NASA)
Thor-Able 127 being prepared for launch at the Cape Canaveral Air Force Station. (U.S. Air Force)
17 August 1958: In what was the first attempt to launch a spacecraft beyond Earth orbit, Thor-Able 1 (Missile Number 127) was to place a small instrumented satellite in orbit around the Moon. Called Pioneer,¹ the satellite carried a television camera, a micrometeorite detector and a magnetometer.
The mission was carried out by the U.S. Air Force Ballistic Missile Division and the Advanced Research Projects Agency (ARPA).
The Thor-Able lifted off from Launch Complex 17A at the Cape Canaveral Air Force Station, Florida, at 12:28:00 UTC, 4 minutes behind schedule.
73.6 seconds into the flight, at an altitude of 9.9 miles (16 kilometers), the first stage of the rocket exploded. Telemetry from the upper stages continued and was tracked until impact in the Atlantic Ocean.
An investigation found the cause of the explosion to be a turbopump failure. It was determined that a bearing in the pump’s gearbox seized, halting the flow of liquid oxygen.
The Thor Able was a two-stage orbital launch vehicle which was developed from the Douglas Aircraft Company’s SM-75 Thor intermediate-range ballistic missile.
Designated Thor DM-19, the first stage was 60.43 feet (18.42 meters) long and 8 feet (2.44 meters) in diameter. Fully fueled, the first stage had a gross weight of 108,770 pounds (49,337 kilograms). It was powered by a Rocketdyne LR-79-7 engine which burned liquid oxygen and RP-1 (a highly-refined kerosene rocket fuel) and produced 170,565 pounds of thrust (758.711 kilonewtons). This stage had a burn time of 2 minutes, 45 seconds.
The second stage was an Aerojet General Corporation-built Able, a second stage for the U.S. Navy’s Vanguard rocket. It was 21 feet, 6.6 inches (6.57 meters) long with a maximum diameter of 2 feet, 9 inches (0.84 meters), and had a gross weight of 5,000 pounds (2,268 kilograms). It used an Aerojet AJ10-101 rocket engine which burned a hypergolic mixture of nitric acid and UDMH. The second stage produced 7,711 pounds of thrust (34.300 kilonewtons) and burned for 1 minutes, 55 seconds.
Thor-Able second stage being prepared to mount to the Thor 127 first stage. (Drew ex Machina)
The Altair X248 third stage was developed by the Alleghany Ballistics Laboratory for the U.S. Navy’s Vanguard rocket. It was 4 feet, 11 inches (1.499 meters) long, 2 feet, 7 inches (0.787 meters) in diameter, and weighed 505 pounds (229 kilograms). It was powered by a solid fuel rocket engine producing 2,300 pounds (10.231 kilonewtons) of thrust. Its burn time was 38 seconds.
Thor-Able 127 lifts off from Launch Complex 17A, 17 August 1958. (NASA)
The first Pioneer space probe is today designated Pioneer 0. It was built by the Ramo-Wooldridge Corporation’s Space Technologies Laboratory (STL) in Redondo Beach, California.
The lunar probe was the fourth stage of the Thor-Able launch vehicle. It was 74 centimeters (2 feet, 5.13 inches) in diameter, 76 centimeters (2 feet, 5.9 inches) long, and weighed 38.1 kilograms (83.996 pounds). The probe’s external shell was constructed of metal and fiberglass. It carried 11.3 kilograms (24.9 pounds) of instruments designed to measure magnetic fields, radiation and micrometeorites. It also carried an infrared camera system intended to obtain close-up images of The Moon’s surface. Pioneer 0 was spin-stabilized, turning 108 r.p.m.
The probe was equipped with a Thiokol TX-8-6 solid rocket engine to decelerate it for entry into lunar orbit. The rocket engine was the main structural component of the probe. There were 8 vernier rockets to correct its trajectory.
Space Technologies Laboratory Pioneer lunar orbiter. (STL/Drew ex Machina)
The Thiokol TX-8 was produced at the U.S. Army’s Longhorn Army Ammunition Plant near Karnack, Texas. It was designed to power the GAR-1 Falcon radar-homing air-to-air guided missile (later designated AIM-4 Falcon). The rocket motor weighed 11 kilograms (24.3 pounds).
Arrangement of equipment within the Pioneer lunar orbiter. (Drew ex Machina)
