Description

Ranger 6 was designed to achieve a lunar impact trajectory and to transmit high-resolution photographs of the lunar surface during the final minutes of flight up to impact. The spacecraft carried six television vidicon cameras, 2 full-scan cameras (channel F, one wide-angle, one narrow-angle) and 4 partial scan cameras (channel P, two wide-angle, two narrow-angle) to accomplish these objectives. The cameras were arranged in two separate chains, or channels, each self-contained with separate power supplies, timers, and transmitters so as to afford the greatest reliability and probability of obtaining high-quality video pictures. No other experiments were carried on the spacecraft. Due to a failure of the camera system no images were returned.

Spacecraft and Subsytems
Spacecraft and Subsystems

Rangers 6, 7, 8, and 9 were the so-called Block 3 versions of the Ranger spacecraft. The spacecraft consisted of a hexagonal aluminum frame base 1.5 m across on which was mounted the propulsion and power units, topped by a truncated conical tower which held the TV cameras. Two solar panel wings, each 73.9 cm wide by 153.7 cm long, extended from opposite edges of the base with a full span of 4.6 m, and a pointable high gain dish antenna was hinge mounted at one of the corners of the base away from the solar panels. A cylindrical quasiomnidirectional antenna was seated on top of the conical tower. The overall height of the spacecraft was 3.6 m.

Propulsion for the mid-course trajectory correction was provided by a 224-N thrust monopropellant hydrazine engine with 4 jet-vane vector control. Orientation and attitude control about 3 axes was enabled by 12 nitrogen gas jets coupled to a system of 3 gyros, 4 primary Sun sensors, 2 secondary Sun sensors, and an Earth sensor. Power was supplied by 9792 Si solar cells contained in the two solar panels, giving a total array area of 2.3 square meters and producing 200 W. Two 1200 Watt-hr AgZnO batteries rated at 26.5 V with a capacity for 9 hours of operation provided power to each of the separate communication/TV camera chains. Two 1000 Watt-hr AgZnO batteries stored power for spacecraft operations.

Communications were through the quasiomnidirectional low-gain antenna and the parabolic high-gain antenna. Transmitters aboard the spacecraft included a 60 W TV channel F at 959.52 MHz, a 60 W TV channel P at 960.05 MHz, and a 3 W transponder channel 8 at 960.58 MHz. The telecommunications equipment converted the composite video signal from the camera transmitters into an RF signal for subsequent transmission through the spacecraft high-gain antenna. Sufficient video bandwidth was provided to allow for rapid framing sequences of both narrow- and wide-angle television pictures.

Instruments

Television

Six vidicon TV cameras arranged in two separate channels were designed to transmit high-resolution, closeup television pictures of the lunar surface during a period of 10 min of flight before spacecraft impact on the moon. The two channels had independent power distribution networks and signal links such that the greatest reliability and probability of obtaining highest video pictures would be afforded. Vidicons 1 in. in diameter with an antimony-sulfide oxy-sulfide (ASOS) photoconductor target were used for image sensing in all six cameras. The first channel had two full-scan cameras, on wide-angle and on narrow-angle. These cameras utilized an active image area of 11 sq mm which was scanned with 1152 lines in 2.5 sec. The other channel had four partial-scan cameras, two narrow-angle scan and two wide-angle scan. The image area of these four cameras was 2.8 sq mm and was scanned with 300 lines in 0.2 sec. The camera shutter on all six cameras was an electromagnetically-driven, linearly activated slit, located in front of the vidicon focal plane. The scan and erase cycles were designed to act alternately in the full scan cameras and subsequently in the partial-scan cameras. The instrument allowed for camera field views to overlap and produce a 'nesting' sequence of pictures. No camera data were obtained, probably because of failure due to arc-over in the television power system when it inadvertently turned on during the period of booster-engine separation.

Launch-Orbit Information

Launch Information

Launch Date:1964-01-30 at 15:49:00 UTC
Launch Vehicle: Atlas-Agena B
Launch Site: Cape Canaveral, United States
Decay Date: 1964-02-02
Mass: 381.0 kg kg Nominal Power: 200.0 W

Type: Lander

Central Body: Moon

Epoch start: 1964-02-02 09:24:33 UTC
Lander Coordinates
Latitude: 9.33°
Longitude: 21.52°
Regions Traversed
Lithosphere
Planet
The Moon

Mission Profile

Ranger 6 was launched into an Earth parking orbit and injected on a lunar trajectory by a second Agena burn. The midcourse trajectory correction was accomplished early in the flight by ground control. On February 2, 1964, 65.5 hours after launch, Ranger 6 impacted the Moon on the eastern edge of Mare Tranquillitatis (Sea of Tranquility) at 9.358 N, 21.480 E (impact site identified from Lunar Reconnaissance Orbiter images). The orientation of the spacecraft to the surface during descent was correct, but no video signal was received and no camera data obtained. A review board determined the most likely cause of failure was due to an arc-over in the TV power system when it inadvertently turned on for 67 seconds approximately 2 minutes after launch during the period of booster-engine separation.

Total research, development, launch, and support costs for the Ranger series of spacecraft (Rangers 1 through 9) was approximately $170 million.

Summary