Ranger 3
Mission type | Lunar impactor | ||||||||||
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Operator | NASA | ||||||||||
Harvard designation | 1962 Alpha 1 | ||||||||||
COSPAR ID | 1962-001A | ||||||||||
SATCAT no. | 221 | ||||||||||
Mission duration | Launch to last scientific data transmitted 1.405 days; launch day to official mission end day 5 days | ||||||||||
Spacecraft properties | |||||||||||
Manufacturer | Jet Propulsion Laboratory | ||||||||||
Launch mass | 330 kg [1] | ||||||||||
Power | 150 W | ||||||||||
Start of mission | |||||||||||
Launch date | January 26, 1962, 20:30:00 LC-12 | UTC ||||||||||
End of mission | |||||||||||
Last contact | Last scientific data transmitted between 12:52 and 1:33 a.m. EST, January 28, 1962[2] | ||||||||||
Orbital parameters | |||||||||||
Reference system | Heliocentric | ||||||||||
Eccentricity | 0.083 | ||||||||||
Perihelion altitude | 0.9839 astronomical units (147,190,000 km) | ||||||||||
Aphelion altitude | 1.163 astronomical units (174,000,000 km) | ||||||||||
Inclination | 0.398° | ||||||||||
Period | 406.4 days | ||||||||||
Lunar flyby (failed impact) | |||||||||||
Closest approach | January 28, 1962 | ||||||||||
Distance | 36,874 kilometers (22,912 mi) | ||||||||||
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Ranger 3 was a
The Ranger 3
Spacecraft design
Ranger 3 was the first of the Block II Ranger designs. The basic vehicle was 3.1 m high and consisted of a lunar capsule covered with a
During prelaunch preparations for
The experimental apparatus included: (1) a
Mission
This was the first American attempt to achieve impact on the lunar surface. The Block II Ranger spacecraft carried a TV camera that used an optical telescope that would allow imaging down to about 24 kilometers above the lunar surface during the descent. The main bus also carried a 42.6 kilogram instrument capsule that would separate from the bus at 21.4 kilometers altitude and then independently impact on the Moon. Protected by a balsa-wood outer casing, the capsule was designed to bounce several times on the lunar surface before coming to rest. The primary onboard instrument was a seismometer.
The mission was designed to boost towards the Moon by an Atlas/Agena, undergo one mid-course correction, and impact the lunar surface. At the appropriate altitude, the capsule was to separate and the retrorockets ignite to cushion the landing. A malfunction in the booster guidance system resulted in excessive spacecraft speed.[6]
Reversed command signals caused the spacecraft to pitch in the wrong direction and the TM antenna to lose earth acquisition, and mid-course correction was not possible. Finally, a spurious signal during the terminal maneuver prevented transmission of useful images. Ranger 3 missed the Moon by approximately 36,800 km on January 28 and was now in a heliocentric orbit. Some useful engineering data were obtained from the flight.[4]
Preparation for launch
Preparation for Ranger 3 was complicated by developmental issues with the Agena B stage, which had failed to operate correctly on Rangers 1-2. Agena was primarily the domain of the
While the Thor-Agena B had begun flying in October 1960, the Atlas-Agena B did not make its maiden voyage until July 1961, meaning that Ranger 1 was only the second time this launch vehicle combination been flown. This delay was explained by the fact that Air Force programs such as MIDAS were taking much longer to develop than Ranger. In addition, as 1961 ended, Agena Bs had malfunctioned no less than seven times (the two Ranger launches and five Thor-Agena launches).
Major General
In mid-December 1961, Atlas 121D and Agena 6003 arrived at
Equipment malfunctions and trajectory errors
Liftoff took place at 3:30 PM EST on January 26, an hour and 15 minutes before the launch window closed, after which Ranger 3 could not have been launched for another month.
At T+49 seconds into launch, the pulse beacon on the Atlas guidance system ceased operating, which prevented the transmission of any steering or cutoff directions for the remainder of the launch. Backup commands from the missile programmer were used to perform booster jettison and Agena separation, but without the guidance program, it was impossible to perform the necessary fine-tuning maneuvers to put the Atlas on the correct flight path. Second engine cut-off occurred due to fuel running out, rather than a programmed cut-off command, causing the Agena and probe to be accelerated higher and faster than planned.
Even worse, equipment at a Florida tracking station malfunctioned and picked up Ranger 3's orbital parameters 5 minutes late. Meanwhile, the Agena restarted and sent the probe out of Earth orbit, but another error in its guidance program resulted in yet another trajectory error. As a consequence, the spacecraft reached the Moon 14 hours early and on January 28 missed striking the Moon by 36,793 kilometers (22,862 miles).
The trajectory errors made impact with the Moon impossible, but Ranger 3 could still have been used for deep-space studies. So the flight controllers issued commands to unfurl the camera boom, and on January 28 an amended computer program was uploaded. However, midway through the upload, the probe's signal strength began to weaken and the onboard computer system failed completely. Without a functioning computer, the spacecraft was not able keep its high-gain antenna aimed at the Earth, which impeded communication with controllers on the ground.
Mission failure, propellant exhaustion, and cancellation
The TV camera did transmit images, but since the antenna was now pointed away from Earth, the received images were extremely weak and noisy. It was possible to see the reference crosses on the camera lens, illuminated by reflected sunlight from the probe's chassis, but the Moon was not visible.
With the computer dead, Ranger 3 became completely unresponsive to any ground commands and the Earth and Sun sensors were rendered useless. The gyroscopes continued to maneuver the probe and ground controllers momentarily reacquired a lock on the antenna, but without stable attitude control, they could not hold it steady. As they were unaware of the computer failure, they continued sending commands to Ranger 3 in vain. Sporadic tracking of the probe continued until January 31 when the attitude control thrusters exhausted their propellant supply, at which point the mission was officially terminated.[4]
See also
References
- ^ a b "Ranger 3". NASA's Solar System Exploration website. Retrieved December 1, 2022.
- ^ E. Clark, Ranger 3 flight stirs reliability question, Aviation Week and Space Technology, February 5, 1962, p. 30-32
- ^ NASA, Goddard Space Flight Center. "Experiments on Ranger 3". NSSDC Master Catalog. Retrieved December 3, 2022.
- ^ a b c d e "National Space Science Data Center - Ranger 3". National Air and Space Administration. Retrieved June 19, 2012.
- ^ "In Depth | Ranger 3". NASA Solar System Exploration. Retrieved August 25, 2023.
- ^ "US racing with the Moon; but Ranger goes too fast". Montreal, Quebec: The Gazette. Associated Press. January 27, 1962. p. 1. Retrieved December 30, 2015.
External links