# Explorer 20

> NASA satellite of the Explorer program

**Wikidata**: [Q3736073](https://www.wikidata.org/wiki/Q3736073)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Explorer_20)  
**Source**: https://4ort.xyz/entity/explorer-20

## Summary
Explorer 20, also known as Ionosphere 2 or Science S-48, was a NASA Earth observation satellite launched on August 25, 1964. As part of the Explorer program, it was designed to observe Earth from orbit and was launched aboard a Scout X-4 rocket from Vandenberg Space Launch Complex 5.

## Key Facts
- **Official Names:** Explorer 20; aliases include Ionosphere 2 and Science S-48.
- **Launch Date:** August 25, 1964.
- **Mission Type:** Earth observation satellite (specifically categorized under NASA's Explorer program).
- **Launch Vehicle:** Scout X-4.
- **Launch Site:** Vandenberg Space Launch Complex 5.
- **COSPAR ID:** 1964-051A.
- **Satellite Catalog Number (SCN):** 00870.
- **NSSDC ID:** 1964-051A.
- **Management:** Operated by NASA.

## FAQs
### Q: What was Explorer 20?
A: Explorer 20 was a NASA satellite and part of the Explorer program. Classified as an Earth observation satellite, it was also identified by the aliases Ionosphere 2 and Science S-48.

### Q: When and how was Explorer 20 launched?
A: Explorer 20 was launched on August 25, 1964. It was deployed using a Scout X-4 rocket from Vandenberg Space Launch Complex 5.

### Q: What are the specific identifiers for Explorer 20?
A: The satellite is identified by the Satellite Catalog Number (SCN) 00870 and the COSPAR ID 1964-051A. It is also listed in the Google Knowledge Graph with the ID `/g/120vz0r5`.

## Why It Matters
Explorer 20 serves as a representative example of NASA's sustained efforts in the mid-20th century to gather data about the Earth's atmosphere and near-space environment. As a unit within the broader Explorer program—which was the United States' first successful series of scientific satellites—Explorer 20 contributed to the systematic observation of the planet from orbit.

The mission is notable for its use of the Scout X-4 launch vehicle, highlighting the reliance on solid-fuel rockets during that era for placing smaller scientific payloads into orbit. Its launch from Vandenberg Space Launch Complex 5 also underscores the strategic use of the West Coast facilities for achieving specific orbital trajectories suitable for Earth observation. By carrying the designation "Ionosphere 2," the satellite implies a specific focus on ionospheric studies, a critical field for understanding radio communication and space weather. The mission's data and classification (COSPAR ID 1964-051A) remain recorded in international space registries, maintaining its historical footprint in the annals of astronautics.

## Notable For
- **Program Inclusion:** Being a distinct component of the historic NASA Explorer program.
- **Nomenclature:** Holding the specific aliases "Ionosphere 2" and "Science S-48."
- **Launch Configuration:** Utilizing the Scout X-4, an American launch vehicle of the Scout family.
- **Orbital Designation:** Receiving the sequential Satellite Catalog Number 00870.

## Body

### Mission Profile and Launch
Explorer 20 was successfully launched into orbit on **August 25, 1964**. The mission utilized a **Scout X-4** rocket, a four-stage orbital launch vehicle. The launch originated from **Vandenberg Space Launch Complex 5** (SLC-5), a facility historically used for Scout rocket launches.

### Technical Specifications and Classification
The entity is formally classified as an **Earth observation satellite**, defined as an artificial satellite specifically designed to observe Earth from orbit. The satellite's technical records align with this definition, tracking it under the **Wikidata** description as a "NASA satellite of the Explorer program."

**Identifiers and Cataloging:**
*   **Satellite Catalog Number (SCN):** 00870
*   **COSPAR ID:** 1964-051A
*   **NSSDC ID:** 1964-051A
*   **Google Knowledge Graph ID:** `/g/120vz0r5`
*   **Wolfram Language Entity Code:** `Entity["Satellite", "00870"]`

### Nomenclature
While officially designated **Explorer 20**, the satellite is referred to in various records by its alternate names:
*   **Ionosphere 2**
*   **Science S-48**

## References

1. Jonathan's Space Report