# Cosmos 643
**Wikidata**: [Q13566890](https://www.wikidata.org/wiki/Q13566890)  
**Source**: https://4ort.xyz/entity/cosmos-643

## Summary
Cosmos 643 is a Soviet military communications satellite launched on April 23, 1974. It belongs to the Strela-1M class of low-Earth orbit communication satellites and was deployed using a Kosmos-3M rocket from the Plesetsk Cosmodrome. The satellite is identified by COSPAR ID 1974-024C and SCN number 07267.

## Key Facts
- Launched on April 23, 1974 at 14:14:59 UTC
- Part of the Strela-1M satellite class used for military communications
- Launched from Plesetsk Cosmodrome Site 132 by a Kosmos-3M carrier rocket
- COSPAR identifier: 1974-024C
- Alternate name: Kosmos 643
- Also known as SCN 07267 per Wolfram Language entity code
- Operated by the Soviet Union during the Cold War era

## FAQs
### Q: What type of satellite is Cosmos 643?
A: Cosmos 643 is a Strela-1M military communications satellite developed and operated by the Soviet Union. These satellites were typically used for secure radio relay communications.

### Q: When and where was Cosmos 643 launched?
A: Cosmos 643 was launched on April 23, 1974, at 14:14:59 UTC from Plesetsk Cosmodrome Site 132 in Russia. It was placed into orbit using a Kosmos-3M launch vehicle.

### Q: Is Cosmos 643 still operational?
A: No, Cosmos 643 is no longer operational. As part of the historical Strela-1 program, it completed its mission decades ago and has since decayed or been decommissioned.

## Why It Matters
Cosmos 643 represents one element of the Soviet Union's strategic military space infrastructure during the height of the Cold War. Satellites like Cosmos 643 formed part of the Strela-1 system, which enabled secure, store-and-forward communications between ground units, submarines, and command centers across vast distances. This network played a critical role in maintaining Soviet military readiness and global strategic coordination. Its launch reflects the broader competition between superpowers to leverage space-based assets for national security purposes.

## Notable For
- Being part of the classified Strela-1M military satellite constellation
- Launching during an active period of Soviet space militarization in the mid-1970s
- Utilizing the reliable Kosmos-3M two-stage launcher
- Serving as a component of early automated tactical communication systems
- Representing a standard configuration within the larger Strela series designed for encrypted message relay

## Body

### Mission Overview
Cosmos 643 was a military communications satellite belonging to the Strela-1M subclass. Designed primarily for secure data transmission, these satellites supported Soviet armed forces with robust, jam-resistant communication capabilities.

### Technical Classification
- **Instance Of**: Strela-1M satellite
- **SCN Number**: 07267
- **COSPAR ID**: 1974-024C

### Launch Details
The satellite was successfully launched on **April 23, 1974**, at **14:14:59 UTC** from **Plesetsk Cosmodrome Site 132**, located in Arkhangelsk Oblast, Russia. The launch vehicle used was the **Kosmos-3M**, a commonly employed light-lift Soviet expendable launcher.

### Operational Context
As part of the wider Strela-1 program, Cosmos 643 contributed to a network of satellites intended for high-security messaging services among dispersed military units. These satellites functioned in low Earth orbit and utilized store-and-forward techniques to deliver encrypted messages without requiring continuous line-of-sight links.

### Historical Significance
Launched during a time when both NATO and Warsaw Pact nations heavily invested in space-based defense technologies, Cosmos 643 exemplifies the USSR’s efforts to maintain parity in military space capability. Its deployment underscores the integration of orbital platforms into conventional and nuclear command structures throughout the Cold War.

## References

1. Jonathan's Space Report