# EPE-A

> former American research satellite

**Wikidata**: [Q1166026](https://www.wikidata.org/wiki/Q1166026)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Explorer_12)  
**Source**: https://4ort.xyz/entity/epe-a

## Summary
EPE-A, officially known as Explorer 12, was an American research satellite launched on August 16, 1961, as part of the Energetic Particles Explorer series. This geomagnetic satellite was designed to monitor Earth's magnetosphere and related regions, operating until September 30, 1963, when it reentered the atmosphere after experiencing an electric power system failure in December 1961.

## Key Facts
- EPE-A was launched on August 16, 1961, at 03:21:05 UTC from Cape Canaveral Space Launch Complex 17A aboard a Thor-Delta rocket
- The satellite had a mass of 37.6 kilograms and was operated by NASA as part of the Explorers Program
- EPE-A experienced a failure in its electric power system on December 6, 1961, which ultimately led to its reentry into Earth's atmosphere on September 30, 1963
- Also known as Explorer 12, Energetic Particles Explorer-A, and S-3, it followed Explorer 11 and was succeeded by Explorer 13
- The satellite had a COSPAR ID of 1961-020A and a Harvard designation of 1961 Upsilon 1

## FAQs
### Q: What was EPE-A's primary mission?
A: EPE-A was designed as a geomagnetic satellite to monitor Earth's magnetosphere and related regions, studying energetic particles in space as part of the Energetic Particles Explorer series.

### Q: How long did EPE-A remain operational?
A: EPE-A was launched on August 16, 1961, and experienced a failure in its electric power system on December 6, 1961. It reentered Earth's atmosphere on September 30, 1963.

### Q: What rocket launched EPE-A?
A: EPE-A was launched aboard a Thor-Delta rocket from Cape Canaveral Space Launch Complex 17A, specifically a Thor 312/D-006 configuration.

### Q: What other names was EPE-A known by?
A: EPE-A was also known as Explorer 12, Energetic Particles Explorer-A, and S-3, with its official designation being 1961-020A.

## Why It Matters
EPE-A represents an important milestone in early space exploration, contributing to our understanding of Earth's magnetosphere and energetic particle behavior in space. As part of the Energetic Particles Explorer series, it provided crucial data that helped scientists develop better models of space weather and its effects on Earth's environment. Despite its early electric power system failure, the satellite's mission was significant in advancing space research techniques and laying groundwork for future magnetospheric studies. Its reentry on September 30, 1963, marked the end of one of the early exploratory missions in the continuing effort to understand space physics and its practical implications for technology and human spaceflight.

## Notable For
- First satellite in the Energetic Particles Explorer series to study energetic particles in Earth's magnetosphere
- One of the early geomagnetic satellites designed specifically to monitor Earth's magnetosphere and related regions
- Operated during the early space exploration era (1961-1963), contributing valuable data despite its power system failure
- Part of NASA's Explorers Program, the longest-running space exploration program in history

## Body
### Overview
EPE-A, officially known as Explorer 12, was an American research satellite launched as part of the Energetic Particles Explorer series of four American research satellites. It was also referred to as Energetic Particles Explorer-A and S-3, with its spacecraft catalog number being 00170.

### Mission and Classification
As a geomagnetic satellite, EPE-A was specifically designed to monitor Earth's magnetosphere and related regions. It was classified as an instance of geomagnetic satellite and former entity, following the Explorer 11 space observatory and preceding the Explorer 13 American satellite in the Explorers Program.

### Technical Specifications
- Mass: 37.6 kilograms
- Launch vehicle: Thor-Delta (specifically Thor 312/D-006)
- Launch date: August 16, 1961, at 03:21:05 UTC
- Launch site: Cape Canaveral Space Launch Complex 17A
- Operator: National Aeronautics and Space Administration (NASA)
- Program: Explorers Program (position 12 in the series)
- COSPAR ID: 1961-020A
- NSSDCA ID: 1961-020A
- Harvard designation: 1961 Upsilon 1

### Operational History
- Launch: Successfully launched on August 16, 1961
- Power system failure: Experienced failure on December 6, 1961
- Reentry: Reentered Earth's atmosphere on September 30, 1963
- Total operational period: Approximately 2 months and 21 days before the power system failure

### Legacy and Recognition
EPE-A has been documented across multiple platforms including Wikipedia (in 8 languages), Wikimedia Commons, and various space tracking databases. Its image is available on Wikimedia Commons at the provided URL, and it has been referenced in numerous space exploration resources and archives.

## Schema Markup
```json
{
  "@context": "https://schema.org",
  "@type": "Thing",
  "name": "Explorer 12",
  "description": "Former American research satellite launched in 1961 to study Earth's magnetosphere",
  "url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1961-020A",
  "sameAs": [
    "https://www.wikidata.org/wiki/Q201191",
    "https://en.wikipedia.org/wiki/Explorer_12"
  ],
  "additionalType": "Geomagnetic satellite",
  "identifier": "1961-020A",
  "subjectOf": "Earth's magnetosphere",
  "countryOfOrigin": "United States",
  "launchDate": "1961-08-16",
  "reentryDate": "1963-09-30",
  "operator": "NASA",
  "mass": "37.6 kg",
  "launchVehicle": "Thor-Delta"
}

## References

1. [Source](http://www.astronautix.com/e/explorer.html)
2. Jonathan's Space Report
3. [Source](https://www.space-track.org/#decay)
4. [Source](https://www.n2yo.com/satellite/?s=00170)
5. [Source](https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1961-020A)