Ranger 9
Lunar impact probe that broadcast live television images to Earth.
Ranger 9 was a NASA lunar probe launched in 1965, designed to impact the Moon while transmitting high-resolution photographs during its final minutes of flight. It carried six television vidicon cameras and broadcast live images to millions of viewers across the United States. No other experiments were carried on the spacecraft.
Quick Facts
- Operator
- NASA
- Satcat
- 1294
- Manufacturer
- Jet Propulsion Laboratory
- Launch mass
- 366.87 kg / 809 lb
- Power
- 200 W
- Launched
- 21 March 1965, 21:37:02
- Launch rocket
- Atlas LV-3 Agena-B 204D/AA14
- Launch site
- Cape Canaveral LC-12
Facts from the source article.
Spacecraft design
The Ranger 9 spacecraft, like its Block 3 predecessors, was built around a hexagonal aluminum frame measuring 1.5 meters across. This base supported the propulsion and power systems, with a truncated conical tower above it housing the television cameras. Two solar panel wings, each 739 millimeters wide and 1537 millimeters long, extended from opposite sides of the base, giving a total wingspan of 4.6 meters. A steerable high-gain dish antenna was hinged at one corner of the base, away from the panels, while a cylindrical quasiomnidirectional antenna sat atop the conical tower. The entire spacecraft stood 3.6 meters tall. For mid-course trajectory adjustments, a 224-newton monopropellant hydrazine engine with four jet vanes for thrust vectoring was used. Three-axis orientation and attitude control relied on 12 nitrogen gas jets working with three gyroscopes, four primary and two secondary Sun sensors, and an Earth sensor. Power came from 9,792 silicon solar cells across the two panels, covering 2.3 square meters and generating 200 watts. Two 1,200 watt-hour batteries, rated at 26.5 volts with a 9-hour capacity, powered each separate communication and TV camera chain, while two additional 1,000 watt-hour batteries handled spacecraft operations. Communications were managed through the low-gain quasiomnidirectional antenna and the parabolic high-gain antenna. Onboard transmitters included a 60-watt TV channel F at 959.52 MHz, a 60-watt TV channel P at 960.05 MHz, and a 3-watt transponder channel 8 at 960.58 MHz. The telecommunications gear converted the composite video signal from the cameras into an RF signal for transmission via the high-gain antenna.
Mission profile
The Atlas 204D and Agena B 6007 boosters performed nominally, injecting the Agena and Ranger 9 into an Earth parking orbit at 185 km altitude. A 90-second Agena second burn put the spacecraft into lunar transfer trajectory, followed by separation of the Agena and Ranger. Seventy minutes after launch, commands deployed solar panels, activated attitude control, and switched from the omniantenna to the high-gain antenna. The initial trajectory's accuracy allowed delaying the planned mid-course correction from 22 to 23 March, when the maneuver began at 12:03 UT. After orientation, a 31-second rocket burn at 12:30 UT, and reorientation, the maneuver was completed at 13:30 UT. Ranger 9 reached the Moon on 24 March 1965. At 13:31 UTC, a terminal maneuver oriented the cameras more in line with the flight direction to improve picture resolution. Twenty minutes before impact, the one-minute camera system warm-up began. The first image was taken at 13:49:41 UTC at an altitude of 2363 km. Transmission of 5,814 good contrast photographs occurred during the final 19 minutes of flight. The final image had a resolution of 0.3 m. The spacecraft encountered the lunar surface with an incoming asymptotic direction at -5.6 degrees from the lunar equator, and the orbit plane was inclined 15.6 degrees to the lunar equator. After 64.5 hours of flight, impact occurred at 14:08:19.994 UTC at approximately 12.83 S latitude, 357.63 E longitude in the Alphonsus crater, with an impact velocity of 2670 m/s. Real-time television coverage with live network broadcasts of many F-channel images (primarily camera B but also some camera A pictures) were provided.
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