# Thor-Agena B

> American orbital launch vehicle

**Wikidata**: [Q9358556](https://www.wikidata.org/wiki/Q9358556)  
**Source**: https://4ort.xyz/entity/thor-agena-b

## Summary  
Thor‑Agena B is an American two‑stage orbital launch vehicle developed by Douglas in the early 1960s. It combines a Thor DM‑21 first stage with an Agena B upper stage and was used to place a series of military and scientific satellites—most notably the Discoverer and Corona reconnaissance missions—into low‑Earth orbit.

## Key Facts  
- **Manufacturer:** Douglas (United States).  
- **Vehicle type:** Rocket model; subclass of the Thor‑Agena launch‑vehicle family.  
- **Configuration:** First stage = Thor DM‑21; second stage = Agena B (ordered as part 1 and part 2).  
- **Primary use:** Launching U.S. military reconnaissance satellites (e.g., Discoverer 16‑36, Corona series) and early meteorological satellites (Nimbus 1‑2).  
- **Operational period:** Early 1960s; an example launch pad photo shows a Thor‑Agena B with Discoverer 37 on 13 January 1962.  
- **Aliases:** Thor‑DM21 Agena‑B, Thor‑SLV2 Agena‑B, ソー・アジェナB.  
- **Related payloads:** Discoverer 16‑36, Corona 40‑56, Nimbus 1‑2, OSCAR 1, Echo 2, among others.  
- **Country of origin:** United States.  
- **Image reference:** ![Thor‑Agena B on launch pad (Jan 13 1962)](https://commons.wikimedia.org/wiki/Special:FilePath/Thor_Agena_B_with_Discoverer_37_on_launch_pad_(Jan._13_1962).jpg)

## FAQs  
### Q: What was the purpose of the Thor‑Agena B launch vehicle?  
A: It was built to deliver a variety of U.S. military and scientific payloads—especially early optical reconnaissance satellites—into low‑Earth orbit during the Cold‑War era.  

### Q: Who manufactured the Thor‑Agena B?  
A: The vehicle was manufactured by the Douglas Aircraft Company in the United States.  

### Q: Which satellites were commonly launched on Thor‑Agena B?  
A: The vehicle launched many Discoverer and Corona reconnaissance satellites, as well as early meteorological satellites such as Nimbus 1 and Nimbus 2, and the amateur radio satellite OSCAR 1.  

### Q: How is Thor‑Agena B different from earlier Thor‑Agena versions?  
A: Thor‑Agena B uses the upgraded Agena B upper stage, providing improved performance and reliability over the original Agena A configuration.  

### Q: Is Thor‑Agena B still in use today?  
A: No. The vehicle was retired after the early 1960s as newer launch systems replaced it.

## Why It Matters  
Thor‑Agena B played a pivotal role in establishing the United States’ early space‑based reconnaissance capability. By reliably delivering the Discoverer and Corona series of optical spy satellites, it gave the U.S. intelligence community unprecedented access to photographic imagery of the Soviet Union and other strategic regions, fundamentally shaping Cold‑War geopolitics. The vehicle also supported the first U.S. meteorological satellites (Nimbus 1‑2) and pioneering amateur radio missions (OSCAR 1), demonstrating the versatility of a two‑stage launch architecture. Its successful integration of the Thor first stage with the Agena B upper stage set a technical precedent for modular launch‑vehicle design, influencing later American rockets and contributing to the rapid expansion of satellite technology in the 1960s.

## Notable For  
- **First use of the Agena B upper stage** in the Thor‑Agena family, offering higher payload capacity.  
- **Key platform for the Corona reconnaissance program**, the United States’ first successful photo‑reconnaissance satellite series.  
- **Versatile payload capability**, handling both military (Discoverer, Corona) and civilian (Nimbus, OSCAR) missions.  
- **Manufactured by Douglas**, showcasing private‑industry leadership in early U.S. launch‑vehicle development.  
- **Historical launch imagery** captured on 13 January 1962, illustrating its operational era.

## Body  

### Overview  
Thor‑Agena B is a two‑stage launch vehicle belonging to the broader Thor‑Agena class. It was designed in the late 1950s and entered service in the early 1960s to meet the United States’ growing demand for reliable orbital launch capability.

### Design  

- **First stage – Thor DM‑21**  
  - Derived from the Thor intermediate‑range ballistic missile.  
  - Provides the initial thrust to lift the vehicle out of the lower atmosphere.  

- **Second stage – Agena B**  
  - An upgraded version of the Agena upper stage, featuring improved propulsion and guidance.  
  - Serves as both the orbital insertion stage and, after payload deployment, as a maneuverable platform for some missions.  

- **Integration**  
  - The two stages are stacked in a “part 1 / part 2” configuration, formally recorded as Thor DM‑21 (P1545 = 1) and Agena B (P1545 = 2).  

### Operational History  

- **First documented launch** (photo evidence): 13 January 1962, carrying Discoverer 37.  
- **Primary mission set**: Launch of the Discoverer series (numbers 16‑36) and Corona satellites (e.g., Corona 40‑56).  
- **Secondary missions**: Deployment of early meteorological satellites (Nimbus 1, Nimbus 2) and the amateur radio satellite OSCAR 1.  

### Payloads  

| Payload Type | Example | Mission Goal |
|--------------|---------|--------------|
| Reconnaissance | Discoverer 16‑36, Corona 40‑56 | Optical imaging of strategic targets |
| Meteorology | Nimbus 1, Nimbus 2 | Atmospheric and weather data collection |
| Communications | OSCAR 1 | Amateur radio communications |
| Experimental | Echo 2 | Passive communications reflector |

### Legacy  

Thor‑Agena B’s success demonstrated the feasibility of a modular launch system that could be adapted for diverse payloads. Its contributions to the Corona program laid the groundwork for modern satellite reconnaissance, while its meteorological missions helped inaugurate routine Earth‑observation from space.

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