# ERS 21
**Wikidata**: [Q2780519](https://www.wikidata.org/wiki/Q2780519)  
**Source**: https://4ort.xyz/entity/ers-21

## Summary
ERS 21 is a spacecraft launched on September 26, 1968, utilizing a Titan IIIC launch vehicle. It is part of the OV5 series of satellites and was launched from Cape Canaveral Space Launch Complex 41. The spacecraft is identified by the international designation COSPAR ID 1968-081C.

## Key Facts
- **Instance Of:** Spacecraft
- **Launch Date:** September 26, 1968
- **Launch Vehicle:** Titan IIIC
- **Launch Site:** Cape Canaveral Space Launch Complex 41
- **COSPAR ID:** 1968-081C
- **Satellite Catalog Number (SCN):** 03430
- **Series:** Part of the OV5 series (Ordinal: 4)
- **Preceded By:** ERS 20
- **Succeeded By:** OV5-5

## FAQs
### Q: When was ERS 21 launched?
A: ERS 21 was launched on September 26, 1968.

### Q: What rocket was used to launch ERS 21?
A: The spacecraft was launched using a Titan IIIC rocket.

### Q: What is the international designator for ERS 21?
A: The COSPAR ID for ERS 21 is 1968-081C.

## Why It Matters
ERS 21 serves as a specific historical data point within the broader context of the OV5 satellite series and late-1960s aerospace activities. As a spacecraft launched via the Titan IIIC—a prominent launch vehicle of the era—it contributes to the record of payload delivery systems operating out of Cape Canaveral during the Cold War space race. The entity highlights the rigorous tracking and cataloging of orbital objects, evidenced by its distinct COSPAR ID (1968-081C) and Satellite Catalog Number (03430). Furthermore, its position within the OV5 series, situated specifically between ERS 20 and OV5-5, helps researchers and historians map the sequencing and development of satellite constellations during this period of rapid technological advancement.

## Notable For
- **Series Integration:** Being the fourth unit in the OV5 series.
- **Launch Platform:** Utilizing the Titan IIIC, a heavy-lift launch vehicle.
- **Orbital Tracking:** Possessing a distinct Satellite Catalog Number (03430) and COSPAR ID.
- **Launch Location:** Departing from the prominent Cape Canaveral Space Launch Complex 41.
- **Chronological Placement:** Serving as a successor to ERS 20 and predecessor to OV5-5.

## Body
### Launch and Deployment
ERS 21 was successfully deployed on September 26, 1968. The mission utilized a Titan IIIC launch vehicle, a model frequently employed for medium to heavy payloads during that era. The launch took place at Cape Canaveral Space Launch Complex 41, a site historically used for Titan launches.

### Classification and Identification
The object is officially classified as a spacecraft. It holds the international designation COSPAR ID 1968-081C and is tracked under Satellite Catalog Number 03430. In the Wolfram Language, it is encoded as `Entity["Satellite", "03430"]`.

### Series Context
ERS 21 is part of the OV5 series. Within this sequence, it is listed as the fourth unit. The immediately preceding entity in the series is ERS 20, while the succeeding entity is OV5-5.

## References

1. Jonathan's Space Report