# Lunar Orbiter 1-5 Series
**Wikidata**: [Q113044400](https://www.wikidata.org/wiki/Q113044400)  
**Source**: https://4ort.xyz/entity/lunar-orbiter-1-5-series

## Summary
The Lunar Orbiter 1-5 Series was a group of unmanned robotic spacecraft launched by NASA between 1966 and 1967 to photograph the Moon's surface. These missions mapped potential landing sites for the Apollo program, ensuring safe crewed missions. The five orbiters operated in lunar orbit, returning critical data to Earth.

## Key Facts
- **COSPAR ID**: 1966-073Z (shared across the series)
- **NSSDCA ID**: 1966-073Z (shared across the series)
- **Class**: Space probe (unmanned robotic spacecraft)
- **Missions**: 5 successful launches (Lunar Orbiter 1–5)
- **Launch Years**: 1966–1967
- **Primary Purpose**: High-resolution photographic mapping of the Moon
- **Operator**: NASA
- **Outcome**: 100% mission success rate, enabling Apollo landing site selection

## FAQs
### Q: What was the main goal of the Lunar Orbiter 1-5 Series?
A: The primary objective was to photograph the Moon’s surface to identify safe landing sites for NASA’s Apollo missions.

### Q: Were all Lunar Orbiter missions successful?
A: Yes, all five missions (Lunar Orbiter 1–5) achieved their imaging goals, with no failures.

### Q: How did the Lunar Orbiter Series contribute to the Apollo program?
A: The probes captured detailed images of the Moon’s terrain, allowing scientists to map craters, mountains, and other features critical for planning crewed landings.

## Why It Matters
The Lunar Orbiter 1-5 Series was pivotal in advancing NASA’s Apollo program by eliminating the unknowns of lunar geography. Before these missions, much of the Moon’s surface was unmapped, posing significant risks to astronauts. By returning over 1,800 high-resolution images, the orbiters enabled precise selection of landing sites, ensured safer trajectories, and validated the feasibility of human exploration. Their success demonstrated the reliability of unmanned robotic spacecraft for deep-space reconnaissance, setting a precedent for future planetary missions.

## Notable For
- **First Comprehensive Lunar Mapping**: Produced the first detailed photographic atlas of the Moon’s surface.
- **100% Mission Success**: All five orbiters completed their objectives without failure.
- **Direct Apollo Support**: Directly influenced the choice of the Sea of Tranquility for Apollo 11’s historic landing.
- **Technological Achievement**: Used onboard film development and scanning systems to transmit images to Earth.

## Body
### Mission Overview
The Lunar Orbiter 1-5 Series consisted of five identical spacecraft launched between August 1966 and August 1967. Each orbiter carried two cameras: a medium-resolution lens for broad surveys and a high-resolution lens for detailed images. After completing their photographic missions, the probes were intentionally crashed into the Moon to avoid interference with future operations.

### Technical Specifications
- **Payload**: Dual-camera system (Hasselblad lenses)
- **Orbit**: Elliptical lunar orbit (perilune ~50 km, apolune ~6,000 km)
- **Image Resolution**: Up to 1 meter per pixel in high-resolution mode
- **Data Transmission**: Film strips developed onboard and scanned for transmission

### Legacy
The Lunar Orbiter Series concluded in 1967, having captured 99% of the Moon’s nearside surface. The images were later digitized and remain a foundational dataset for lunar science. The program’s success underscored the critical role of robotic precursors in human spaceflight, a model still used today for Mars exploration and Artemis program planning.