Ranger 5
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Ranger 5 was a spacecraft of the Ranger program
Ranger program
The Ranger program was a series of unmanned space missions by the United States in the 1960s whose objective was to obtain the first close-up images of the surface of the Moon. The Ranger spacecraft were designed to take images of the lunar surface, returning those images until they were destroyed...
designed to transmit pictures of the lunar surface to Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
stations during a period of 10 minutes of flight prior to impacting on the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
, to rough-land a seismometer
Seismometer
Seismometers are instruments that measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources...
capsule on the Moon, to collect gamma-ray data in flight, to study radar reflectivity of the lunar surface, and to continue testing of the Ranger program for development of lunar and interplanetary spacecraft. Due to an unknown malfunction, the spacecraft ran out of power and ceased operation. It passed within 725 km of the Moon.
Spacecraft design
Ranger 5 was a Block II Ranger spacecraft similar to Ranger 3Ranger 3
Ranger 3 is a spacecraft of the Ranger program that was launched to study the Moon on January 26, 1962. The space probe was designed to transmit pictures of the lunar surface to Earth stations during a period of 10 minutes of flight prior to impacting on the Moon, to rough-land a seismometer...
and Ranger 4
Ranger 4
Ranger 4 was a spacecraft of the Ranger program designed to transmit pictures of the lunar surface to Earth stations during a period of 10 minutes of flight prior to crashing upon the Moon, to rough-land a seismometer capsule on the Moon, to collect gamma-ray data in flight, to study radar...
. The basic vehicle was 3.1 m high and consisted of a lunar capsule covered with a balsawood impact-limiter, 65 cm in diameter, a mono-propellant mid-course motor, a retrorocket with a thrust of 5080 lbf (23 kN), and a gold and chrome plated hexagonal base 1.5 m in diameter. A large high-gain dish antenna was attached to the base. Two wing-like solar panels (5.2 m across) were attached to the base and deployed early in the flight. Power was generated by 8680 solar cells contained in the solar panels which charged an 11.5 kg 1 kWh capacity AgZn launching and backup battery. Spacecraft control was provided by a solid-state digital computer and sequencer and an earth-controlled command system. Attitude control was provided by six Sun and one Earth sensor, gyroscope
Gyroscope
A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...
s, and pitch and roll cold nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
gas jets. The telemetry system aboard the spacecraft consisted of two 960 MHz transmitters, one at 3 W power output and the other at 50 mW power output, the high-gain antenna, and an omnidirectional antenna. White paint, gold and chrome plating, and a silvered plastic sheet encasing the retrorocket furnished thermal control.
The experimental apparatus included: (1) a vidicon television camera, which employed a scan mechanism that yielded one complete frame in 10 s; (2) a gamma-ray spectrometer in a 300 mm sphere mounted on a 1.8 m 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 mW transmitter, voltage control, a turnstile antenna
Turnstile antenna
A turnstile antenna is a set of two dipole antennas aligned at right angles to each other and fed 90 degrees out-of-phase. The name reflects that the antenna looks like a turnstile when mounted horizontally. When mounted horizontally the antenna is nearly omnidirectional on the horizontal plane...
, and 6 silver-cadmium batteries capable of operating the lunar capsule transmitter for 30 days, all designed to land on the Moon at 130 to 160 km/h (80 to 100 mph). The instrument package floated in a layer of freon within the balsawood sphere. The radar altimeter would be used for reflectivity studies, but was also designed to initiate capsule separation and ignite the retro-rocket.
Mission
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. Due to an unknown malfunction after injection into lunar trajectory from Earth parking orbitParking orbit
A parking orbit is a temporary orbit used during the launch of a satellite or other space probe. A launch vehicle boosts into the parking orbit, then coasts for a while, then fires again to enter the final desired trajectory...
, the spacecraft failed to receive power. The batteries ran down after 8 hours, 44 minutes, rendering the spacecraft inoperable. Ranger 5 missed the Moon by 725 km. It is now in a heliocentric orbit
Heliocentric orbit
A heliocentric orbit is an orbit around the Sun. All planets, comets, and asteroids in our Solar System are in such orbits, as are many artificial probes and pieces of debris. The moons of planets in the Solar System, by contrast, are not in heliocentric orbits as they orbit their respective planet...
. Gamma-ray data were collected for four hours prior to the loss of power. Mission controllers tracked it to a distance of 1.3 million km (808,000) miles.
This was the third attempt to impact the lunar surface with a Block II Ranger
spacecraft. On this mission, just 15 minutes after normal operation, a malfunction led to the transfer of power from solar to battery power. Normal operation never resumed; battery power was depleted after 8 hours, and all spacecraft systems died. The first midcourse correction was never implemented, and Ranger 5 passed the Moon at a range of 724 kilometers on 21 October and entered heliocentric orbit. It was tracked to a distance of 1,271,381 kilometers. Before loss of signal, the spacecraft sent back about 4 hours of data from the gamma-ray experiment.
Following the failure of this launch (missing the moon), the electronic assembly for the next versions were completely rebuilt by RCA Astro Electronics Division in East Windsor, New Jersey. The satellites rebuilt by RCA Astro worked up to expectations. All photos were returned and helped NASA determine good landing sites for the lunar landers.