# Juno I

> four-stage American booster rocket

**Wikidata**: [Q1192304](https://www.wikidata.org/wiki/Q1192304)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Juno_I)  
**Source**: https://4ort.xyz/entity/juno-i

## Summary
Juno I was a four-stage American booster rocket derived from the Jupiter-C missile, best known for launching *Explorer 1*, the first U.S. satellite, in 1958. It was an expendable launch vehicle used primarily for early space exploration missions during the Cold War era.

## Key Facts
- **Type**: Four-stage expendable launch vehicle.
- **Based on**: Jupiter-C missile.
- **Manufacturer**: Stellantis North America (formerly Chrysler).
- **Country of origin**: United States.
- **Notable launches**: *Explorer 1* (1958), *Explorer 3*, *Explorer 4*, and *Pioneer 4* (lunar flyby).
- **Failures**: Associated with launch failures of *Explorer 2*, *Explorer S-1*, *Explorer S-45*, and *Pioneer 3*.
- **Aliases**: Also known as Jupiter C, Juno II, or 朱諾1號火箭 (Chinese).
- **Class**: Subclass of Redstone rocket and four-stage-to-orbit vehicles.

## FAQs
### Q: What was Juno I used for?
A: Juno I was used to launch early U.S. satellites, including *Explorer 1*, the first American satellite, and later missions like *Pioneer 4*, which performed a lunar flyby.

### Q: Did Juno I have any launch failures?
A: Yes, several missions failed, including *Explorer 2*, *Explorer S-1*, *Explorer S-45*, and *Pioneer 3*, due to rocket malfunctions.

### Q: How is Juno I related to the Jupiter-C missile?
A: Juno I was derived from the Jupiter-C, a modified Redstone missile, with additional upper stages to achieve orbital capability.

### Q: What company built Juno I?
A: It was manufactured by Stellantis North America (previously part of Chrysler).

### Q: What was the significance of *Explorer 1*?
A: *Explorer 1*, launched by Juno I, was the first successful U.S. satellite, marking America’s entry into the Space Race.

## Why It Matters
Juno I played a pivotal role in the early Space Race by enabling the U.S. to launch its first satellite, *Explorer 1*, in response to the Soviet Union’s *Sputnik*. This achievement demonstrated American technological capability and spurred further advancements in space exploration. The rocket’s successes and failures also provided critical data for improving launch vehicle reliability, influencing later U.S. space programs. As a derivative of military missile technology (Jupiter-C), Juno I exemplified the Cold War-era transition from ballistic missiles to space launch systems, bridging defense and scientific applications.

## Notable For
- Launching *Explorer 1*, the first U.S. satellite (January 31, 1958).
- Being a modified version of the Jupiter-C missile with added upper stages.
- Enabling early lunar missions like *Pioneer 4* (1959 lunar flyby).
- Its role in the Explorer program, including both successful and failed launches.
- Representing the U.S.’s first operational four-stage orbital rocket.

## Body
### Development and Design
- Juno I was developed from the **Jupiter-C**, a Redstone missile variant, by adding **three upper stages** (solid-fuel rockets) to achieve orbital velocity.
- The first stage was a **liquid-fueled Redstone missile**, while the upper stages used **clustered Baby Sergeant rockets**.
- Designed for **light payloads**, it could carry approximately **11 kg (24 lbs)** to low Earth orbit.

### Launch History
- **First launch**: *Explorer 1* (January 31, 1958) – successfully reached orbit.
- **Subsequent missions**:
  - *Explorer 2* (March 1958) – failed due to fourth-stage ignition issues.
  - *Explorer 3* (March 1958) – successful.
  - *Explorer 4* (July 1958) – successful.
  - *Explorer 5* (August 1958) – failed.
  - *Pioneer 4* (March 1959) – successful lunar flyby.
- **Final Juno I launch**: *Explorer S-46* (1959), which failed.

### Legacy
- Juno I was **retired in 1959** after the introduction of more advanced launch vehicles like **Juno II** and **Thor-Able**.
- Its design influenced later U.S. rockets, particularly in **staging techniques** and **solid-fuel upper stages**.
- The **Explorer program** continued with other launch vehicles, but Juno I’s role was foundational in proving U.S. spaceflight capability.

## Schema Markup
```json
{
  "@context": "https://schema.org",
  "@type": "Thing",
  "name": "Juno I",
  "description": "Four-stage American booster rocket used to launch early U.S. satellites, including Explorer 1.",
  "sameAs": [
    "https://www.wikidata.org/wiki/Q716737",
    "https://en.wikipedia.org/wiki/Juno_I"
  ],
  "additionalType": "SpaceLaunchVehicle"
}

## References

1. Freebase Data Dumps. 2013