Solid-fueled rocket motors derived from the MGM-29 Sergeant were used as upper stages,eleven for the second stage,three for the third stage,and one for the fourth stage,the same configuration as used for the upper stages of the smaller Juno I launch vehicle.[1][2][3][5] On some launches to low Earth orbit the fourth stage was not flown,allowing the launch vehicle to carry an additional nine kilograms of payload. Development of the Juno II was extremely fast due to being completely built from existing hardware. The project began in early 1958 and the first vehicle flew at the end of the year. Chrysler was responsible for the overall contract,while Rocketdyne handled the first stage propulsion and Jet Propulsion Laboratory handled the upper stage propulsion. The first three Juno IIs were converted Jupiter missiles,however all remaining boosters were built as Juno IIs from the beginning.[1][2][3]
The main differences between the Juno II and Jupiter were stretched propellant tanks for increased burn time (the first stage burn time was approximately 20 seconds longer than on the Jupiter),a reinforced structure to support the added weight of upper stages,and the inertial guidance system replaced with a radio ground guidance package,which was moved to the upper stages.
The first launch of a Juno II,Pioneer 3 on 6 December 1958,suffered a premature first-stage cutoff,preventing the upper stages from achieving sufficient velocity.[1][2] Pioneer 3 could not escape Earth orbit,but transmitted data for some 40 hours before reentering the atmosphere.[1][2] A malfunction in a propellant depletion circuit was found to be the cause of the failure,although the exact nature of it could not be determined. The circuit was redesigned afterwards.
Pioneer 4 launched successfully on 3 March 1959,making for the only first-generation U.S. lunar probe to accomplish all of its mission goals,as well as the sole successful U.S. lunar probe until 1964.[1][2] After Pioneer 4,NASA shifted their lunar efforts to the bigger Atlas-Able booster and decided instead to utilize the Juno II for Earth orbital launches. By removing the fourth stage,the payload capacity was nearly doubled.
The attempted launch of an Explorer satellite on 16 July 1959 failed dramatically when the Juno II lost control almost immediately at liftoff,performing a cartwheel before the range safety officer sent the destruct command.[1][2][9] The almost fully fueled booster crashed a few hundred feet from the pad,blockhouse crews watching in stunned surprise at the upper stage motors burning on the ground. Cause of the mishap was quickly traced to a short between two diodes in a power inverter,which cut off power to the guidance system at liftoff and caused the Juno's engine to gimbal to full stop,flipping the vehicle onto its side before Range Safety action was taken. To prevent a recurrence of this failure mode,improved coatings were used on the circuit boards in the booster.
On 15 August 1959,the next Juno II was flown,carrying the Beacon satellite. While first-stage performance was nominal,the upper stages malfunctioned.[1][2][10] One intended experiment on this mission was the ejection of four flares stowed in the interstage section which would be tracked and photographed during the launch. However,things went awry when the flare ejection failed to take place on schedule. The control system also malfunctioned and drove the upper stages into the Atlantic Ocean instead of orbit. It was concluded that one of the flares deployed inside the interstage section instead of outside like it was intended to,causing the guidance compartment to depressurize and cause loss of vehicle control.
Explorer 7 was scheduled for launch in the last week of September 1959,but a Jupiter missile test on an adjacent pad failed just after liftoff on 15 September 1959 and the Juno II suffered minor damage from flying debris. This was quickly repaired and the launch performed successfully on 13 October 1959.[1][2] Explorer 7 would be the last Juno II launch from LC-5 as the pad was then permanently reassigned to Project Mercury.
On 23 March 1960,another Explorer satellite failed to reach orbit when one second-stage motor failed to ignite,causing imbalanced thrust that sent the payload into the Atlantic Ocean.[1][2]
In mid-1960,with only two successful launches in six attempts,a NASA board conducted a thorough reevaluation of the Juno II as a launch vehicle. The failures were mostly traced to isolated component failures that occurred as a result of inadequate testing and checkouts. This was blamed on the program being close-ended,with no further plans for development of the booster,leading to low interest and apathy among those in the program. The JPL team who developed the Juno II had originally only intended it for the Pioneer lunar probes and their interest started waning as soon as NASA began Earth orbital launches with the vehicle. Even worse,most of the design team had been disbanded and its members reassigned to other projects,making it difficult to obtain technical information for the Juno II. The conversion of the booster for LEO launches also threw off the calibration of the spinning tub third stage which was designed for the tiny Pioneer probes and not the larger Explorer satellites.
At this time,NASA had four Juno IIs remaining in their inventory. The review board predicted that two of them would launch successfully,but recommended that there was no reason not to fly the boosters since they had already been bought and paid for. Their assumptions proved correct.
Explorer 8 was launched successfully on 3 November 1960,with the next attempt on 24 February 1961 a failure.[1][2] A control cable came loose during ascent and wrapped itself around the spinning third-stage tub,damaging the upper stages and payload. Second-stage ignition occurred on time,but the third stage did not ignite and the satellite failed to reach orbit. Explorer 11 launched successfully on 27 April 1961,[1][2] an event that raised NASA's morale during a mostly disastrous month characterized by Project Mercury failures and the Soviet launch of a man into space. On 24 May 1961,the final Juno II lifted from LC-26A carrying another ionospheric beacon satellite.[1][2] The instrument unit lost power following first-stage separation,resulting in no second-stage ignition and the payload falling into the ocean instead of reaching orbit. By this time however,the fast-rising Thor-Delta and Agena vehicles were on their way to take over as mainstays of the U.S. light and medium-lift launch vehicle arsenal.
Launch history
Juno II was launched ten times by NASA,with the first launch being joint with ABMA.[1][2][10][6]
Explorer 1 was the first satellite launched by the United States in 1958 and was part of the U.S. participation in the International Geophysical Year (IGY). The mission followed the first two satellites, both launched by the Soviet Union during the previous year, Sputnik 1 and Sputnik 2. This began a Space Race during the Cold War between the two nations.
The Juno I was a four-stage American space launch vehicle, used to launch lightweight payloads into low Earth orbit. The launch vehicle was used between January 1958 to December 1959. The launch vehicle is a member of the Redstone launch vehicle family, and was derived from the Jupiter-C sounding rocket. It is commonly confused with the Juno II launch vehicle, which was derived from the PGM-19 Jupiter medium-range ballistic missile. In 1958, a Juno I launch vehicle was used to launch America's first satellite, Explorer 1.
Pioneer 4 was an American spin-stabilized uncrewed spacecraft launched as part of the Pioneer program on a lunar flyby trajectory and into a heliocentric orbit making it the first probe of the United States to escape from the Earth's gravity. Launched on March 3, 1959, it carried a payload similar to Pioneer 3: a lunar radiation environment experiment using a Geiger–Müller tube detector and a lunar photography experiment. It passed within 58,983 km (36,650 mi) of the Moon's surface. However, Pioneer 4 did not come close enough to trigger its photoelectric sensor. The spacecraft was still in solar orbit as of 1969. It was the only successful lunar probe launched by the U.S. in 12 attempts between 1958 and 1963; only in 1964 would Ranger 7 surpass its success by accomplishing all of its mission objectives.
Soyuz is a family of expendable Russian and Soviet carrier rockets developed by OKB-1 and manufactured by Progress Rocket Space Centre in Samara, Russia. The Soyuz is the rocket with the most launches in the history of spaceflight.
The Saturn family of American rockets was developed by a team of former German rocket engineers and scientists led by Wernher von Braun to launch heavy payloads to Earth orbit and beyond. The Saturn family used liquid hydrogen as fuel in the upper stages. Originally proposed as a military satellite launcher, they were adopted as the launch vehicles for the Apollo Moon program. Three versions were built and flown: the medium-lift Saturn I, the heavy-lift Saturn IB, and the super heavy-lift Saturn V.
The Delta rocket family was a versatile range of American rocket-powered expendable launch systems that provided space launch capability in the United States from 1960 to 2024. Japan also launched license-built derivatives from 1975 to 1992. More than 300 Delta rockets were launched with a 95% success rate. The series was phased out in favor of the Vulcan Centaur, with the Delta IV Heavy rocket's last launch occurring on April 9, 2024.
The Saturn I was a rocket designed as the United States' first medium lift launch vehicle for up to 20,000-pound (9,100 kg) low Earth orbit payloads. The rocket's first stage was built as a cluster of propellant tanks engineered from older rocket tank designs, leading critics to jokingly refer to it as "Cluster's Last Stand". Its development was taken over from the Advanced Research Projects Agency (ARPA) in 1958 by the newly formed civilian NASA. Its design proved sound and flexible. It was successful in initiating the development of liquid hydrogen-fueled rocket propulsion, launching the Pegasus satellites, and flight verification of the Apollo command and service module launch phase aerodynamics. Ten Saturn I rockets were flown before it was replaced by the heavy lift derivative Saturn IB, which used a larger, higher total impulse second stage and an improved guidance and control system. It also led the way to development of the super-heavy lift Saturn V which carried the first men to landings on the Moon in the Apollo program.
The Thor-Able was an American expendable launch system and sounding rocket used for a series of re-entry vehicle tests and satellite launches between 1958 and 1960.
The Atlas-Centaur was a United States expendable launch vehicle derived from the SM-65 Atlas D missile. The vehicle featured a Centaur upper stage, the first such stage to use high-performance liquid hydrogen as fuel. Launches were conducted from Launch Complex 36 at the Cape Canaveral Air Force Station (CCAFS) in Florida. After a strenuous flight test program, Atlas-Centaur went on to launch several crucial spaceflight missions for the United States, including Surveyor 1, Mariner 4, and Pioneer 10/11. The vehicle would be continuously developed and improved into the 1990s, with the last direct descendant being the highly successful Atlas II.
A Moon landing or lunar landing is the arrival of a spacecraft on the surface of the Moon, including both crewed and robotic missions. The first human-made object to touch the Moon was Luna 2 in 1959.
In aerospace engineering, spin stabilization is a method of stabilizing a satellite or launch vehicle by means of spin, i.e. rotation along the longitudinal axis. The concept originates from conservation of angular momentum as applied to ballistics, where the spin is commonly obtained by means of rifling. For most satellite applications this approach has been superseded by three-axis stabilization.
A payload fairing is a nose cone used to protect a spacecraft payload against the impact of dynamic pressure and aerodynamic heating during launch through an atmosphere. An additional function on some flights is to maintain the cleanroom environment for precision instruments. Once outside the atmosphere the fairing is jettisoned, exposing the payload to outer space.
The Atlas-Agena was an American expendable launch system derived from the SM-65 Atlas missile. It was a member of the Atlas family of rockets, and was launched 109 times between 1960 and 1978. It was used to launch the first five Mariner uncrewed probes to the planets Venus and Mars, and the Ranger and Lunar Orbiter uncrewed probes to the Moon. The upper stage was also used as an uncrewed orbital target vehicle for the Gemini crewed spacecraft to practice rendezvous and docking. However, the launch vehicle family was originally developed for the Air Force and most of its launches were classified DoD payloads.
Thor was a US space launch vehicle derived from the PGM-17 Thor intermediate-range ballistic missile. The Thor rocket was the first member of the Delta rocket family of space launch vehicles. The last launch of a direct derivative of the Thor missile occurred in 2018 as the first stage of the final Delta II.
Milton William Rosen was a United States Navy engineer and project manager in the US space program between the end of World War II and the early days of the Apollo Program. He led development of the Viking and Vanguard rockets, and was influential in the critical decisions early in NASA's history that led to the definition of the Saturn rockets, which were central to the eventual success of the American Moon landing program. He died of prostate cancer in 2014.
The Luna 8K72 vehicles were carrier rockets used by the Soviet Union for nine space probe launch attempts in the Luna programme between 23 September 1958 and 16 April 1960. Like many other Soviet launchers of that era, the Luna 8K72 vehicles were derived from the R-7 Semyorka design, part of the R-7, which was also the basis for the Vostok and modern Soyuz rocket.
The year 2023 saw rapid growth and significant technical achievements in spaceflight. For the third year in a row, new world records were set for both orbital launch attempts (223) and successful orbital launches (211). The growth in orbital launch cadence can in large part be attributed to SpaceX, as they increased their number of launches from 61 in 2022 to 98 in 2023. The deployment of the Starlink satellite megaconstellation was a major contributing factor to this increase over previous years. This year also featured numerous maiden launches of new launch vehicles. In particular, SSLV, Qaem 100, Tianlong-2, Chollima-1,and Zhuque-2 performed their first successful orbital launch, while SpaceX's Starship – the world's largest rocket – launched two times during its development stage: IFT-1 and IFT-2.
Explorer S-1, also known as NASA S-1 or Explorer 7X, was a NASA Earth science satellite equipped with a suite of scientific instruments to study the environment around the Earth. The spacecraft and its Juno II launch vehicle were destroyed five seconds after launch on 16 July 1959, in a spectacular launch failure caused by complications with the launch vehicle's power supply. A relaunch of the mission in October 1959, Explorer 7 (S-1A), was successful.
Beacon was one of America's first satellite programs. A balloon satellite, its objective was to study atmospheric density at its orbital altitude and to be the first United States satellite visible to the naked eye. Booster problems caused both orbital attempts to end in failure.
Zond program was a Soviet robotic spacecraft program launched between 1964 and 1970, using two spacecraft series, one for interplanetary exploration, and the other for lunar exploration.
This Template lists historical, current, and future space rockets that at least once attempted (but not necessarily succeeded in) an orbital launch or that are planned to attempt such a launch in the future
Symbol † indicates past or current rockets that attempted orbital launches but never succeeded (never did or has yet to perform a successful orbital launch)
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