Ranger 4
Mission type | Lunar impactor | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Operator | NASA | ||||||||||
Harvard designation | 1962 Mu 1 | ||||||||||
COSPAR ID | 1962-012A | ||||||||||
SATCAT no. | 280 | ||||||||||
Mission duration | 10 hours (operational) 64 hours (to impact) | ||||||||||
Spacecraft properties | |||||||||||
Manufacturer | Jet Propulsion Laboratory | ||||||||||
Launch mass | 331.1 kg (730 lb) | ||||||||||
Dimensions | 1.52 m × 2.51 m (5.0 ft × 8.2 ft) | ||||||||||
Power | 135 W | ||||||||||
Start of mission | |||||||||||
Launch date | April 23, 1962, 20:50:00 | UTC||||||||||
Rocket | LC-12 | ||||||||||
Lunar impactor | |||||||||||
Impact date | April 26, 1962, 12:49:53 Failed before impact | UTC||||||||||
Impact site | 15°30′S 130°42′W / 15.5°S 130.7°W | ||||||||||
| |||||||||||
→ |
Ranger 4 was a spacecraft of the
An onboard computer failure caused failure of the deployment of the
and the first of any nation to reach the surface of the far side of the Moon.Spacecraft design
Ranger 4 was a Block II Ranger spacecraft virtually identical to Ranger 3. The basic vehicle was 331 kg (730 lb), 3.1 m (10 ft) high and consisted of a lunar capsule covered with a balsawood impact-limiter, 0.65 m (26 in) in diameter, a mono-propellant mid-course motor, a 22.6 kN (5,080 lbf) thrust retrorocket, and a gold- and chrome-plated hexagonal base 1.5 m (4 ft 11 in) in diameter. A large high-gain dish antenna was attached to the base. Two wing-like solar panels (5.2 m (17 ft) across) were attached to the base and deployed early in the flight.
Power was generated by 8,680 solar cells contained in the solar panels which charged an 11.5 kg (25 lb) 1 kWh capacity
Because heat sterilization was suspected to have caused the malfunction of Ranger 3's computer, this procedure was dropped on Ranger 4. The seismometer capsule was also painted with a sawtooth pattern for better thermal protection.[2]
The experimental apparatus included: (1) a vidicon television camera, which employed a scan mechanism that yielded one complete frame in ten seconds; 2) a gamma-ray spectrometer mounted on a 1.8 m (5 ft 11 in) boom; (3) a radar altimeter; and (4) a seismometer to be rough-landed on the lunar surface. The seismometer was encased in the lunar capsule along with an amplifier, a 50-milliwatt transmitter, voltage control, a
Mission
Atlas 133D and Agena 6004 arrived at
After separation from the Agena, it was apparent that something was seriously amiss when tracking stations picked up Ranger 4's radio transmitter, but there was no telemetry data being returned or any response when commands were sent to the computer. Without telemetry, it could not be confirmed that the probe's solar panels had unfolded, but the fluctuating radio transponder indicated that Ranger 4 was tumbling and that the solar panels and high-gain antenna were not deployed either.
The Atlas and Agena had both performed perfectly, in fact so well that Ranger 4 would not even need a midcourse correction burn to impact the Moon. However, this was all futile if the spacecraft was inoperative. Ground controllers sent commands to the probe to unfurl the solar panels and high-gain antenna and manually use the attitude control system to stop the rolling motion it was in, but the probe was unresponsive. The Spacecraft Data Analysis Team at JPL concluded that the main timer in Ranger 4's computer had stopped, which disabled the telemetry system, preprogrammed events such as solar panel deployment, and also made the probe completely unresponsive to manual commands. Even though lunar impact would occur as planned, the mission was for all intents and purposes a failure. Making it a more bitter pill to swallow was the nearly-flawless launch vehicle performance. The booster problems that affected Rangers 1-3 had been resolved, only for the probe itself to completely fail, as unlike the previous missions, Ranger 4 did not return any useful data. Finding the cause of the timer malfunction could also be difficult since it had occurred during the coasting phase prior to trans-lunar injection when Ranger 4 was passing between tracking stations in the Caribbean and South Africa.
Without solar power, Ranger 4's batteries ran down on the morning of April 26 and the radio transponder ceased operating. The tiny transmitter in the seismometer capsule continued sending out a 50-milliwatt signal. According to the NASA, Ranger 4 impacted the far side of the Moon (229.3 degrees E, 15.5 degrees S) at 9,600 km/h (5,970 mph) at 12:49:53 UT on April 26, 1962, after 64 hours of flight.[2][3][4] However, the coordinates were ″guesstimated" and the crater of the impact could not be identified by high-resolution images of the Lunar Reconnaissance Orbiter.[7]
NASA officials tried to put a positive spin on the mission,[4] noting that it was the first time an American spacecraft had reached the surface of the Moon and that the probe was "far more sophisticated" than the Soviet Luna 2 space probe in 1959, which had been little more than a pressurized sphere designed to deposit pennants on the surface at impact. The excellent performance of the Atlas-Agena booster had also raised morale.
This spacecraft, similar in design to Ranger 3, was the first American spacecraft to reach another celestial body. It was also the first spacecraft to impact the far side of the Moon. Although the spacecraft did not achieve its primary objective, the Atlas-Agena-Ranger combination performed without fault for the first time.[8]
See also
References
- ^ NASA, Goddard Space Flight Center. "Experiments on Ranger 4". NSSDC Master Catalog. Retrieved December 3, 2022.
- ^ a b c d e "National Space Science Data Center - Ranger 4". National Air and Space Administration. Retrieved 19 June 2012.
- ^ a b "Ranger 4 crashes on Moon". Lewiston Morning Tribune. (Idaho). Associated Press. April 27, 1962. p. 1.
- ^ a b c "Ranger-4 hits moon in new space triumph". Bend Bulletin. (Oregon). UPI. April 26, 1962. p. 1.
- ^ "'Brainless' Ranger tumbles into space". Lawrence Daily Journal-World. (Kansas). Associated Press. April 24, 1962. p. 1.
- ^ "Ranger 4 shot starts 60-hr trip". Bend Bulletin. (Oregon). UPI. April 23, 1962. p. 1.
- ^ Leonard, David (2018-12-30). "Farside Science: The Sage of Ranger 4's Moon Journey". Retrieved 2023-01-02.
- .
External links
- Lunar impact: A history of Project Ranger (PDF) 1977
- Reuters.com, Planned lunar missions
- Reuters.com, Chronology – Five key dates in the race to the Moon