# Cosmos 551
**Wikidata**: [Q12753895](https://www.wikidata.org/wiki/Q12753895)  
**Source**: https://4ort.xyz/entity/cosmos-551

## Summary
Cosmos 551 was a Soviet satellite launched on March 6, 1973, as part of the Zenit-4M program. It was deployed from the Baikonur Cosmodrome using a Voskhod launch vehicle. The mission contributed to the Soviet Union's reconnaissance and space surveillance capabilities during the Cold War era.

## Key Facts
- Official designation: Cosmos 551
- Alternate name: Kosmos 551
- COSPAR ID: 1973-012A
- Launch date: March 6, 1973
- Launch time: 09:20:00 UTC
- Launch site: Baikonur Cosmodrome Site 31
- Launch vehicle: Voskhod
- Spacecraft class: Zenit-4M
- SCN (Spacecraft Number): 06378
- Wikipedia languages: Macedonian (mk), Serbo-Croatian (sh), Serbian (sr)

## FAQs
### Q: What was the purpose of Cosmos 551?
A: Cosmos 551 was part of the Zenit-4M series, which were Soviet military reconnaissance satellites used for optical intelligence gathering. These missions supported national defense and strategic monitoring during the Cold War.

### Q: When and where was Cosmos 551 launched?
A: Cosmos 551 was launched on March 6, 1973, at 09:20:00 UTC from Baikonur Cosmodrome Site 31 in Kazakhstan, then part of the Soviet Union.

### Q: What kind of spacecraft was Cosmos 551?
A: Cosmos 551 was a Zenit-4M satellite, a variant of the Zenit program designed for Earth observation and reconnaissance. It was launched using the Voskhod family of rockets.

## Why It Matters
Cosmos 551 represents one component of the Soviet Union’s extensive use of space-based reconnaissance during the Cold War. As part of the Zenit-4M program, it played a role in advancing Soviet intelligence-gathering capabilities through orbital surveillance. Missions like Cosmos 551 enabled the USSR to monitor geopolitical developments, military movements, and other strategic activities globally. Its launch also reflects the broader competition between superpowers in space technology and application, contributing to the historical record of dual-use space programs that combined scientific advancement with national security objectives.

## Notable For
- Part of the classified Zenit-4M reconnaissance satellite program
- Launched using the historically significant Voskhod rocket family
- One of many Cosmos-designated missions indicating Soviet military or experimental spacecraft
- Represents Soviet advancements in photo-reconnaissance satellite technology
- Included in international satellite tracking databases under COSPAR ID 1973-012A

## Body
### Mission Overview
Cosmos 551 was a Soviet reconnaissance satellite launched into low Earth orbit as part of the Zenit-4M program. The Zenit series was developed primarily for photographic intelligence collection, supporting Soviet military and strategic operations throughout the Cold War period.

### Technical Details
The spacecraft was identified by the Spacecraft Number (SCN) 06378 and registered internationally under the COSPAR identifier 1973-012A. It belonged to the Zenit-4M subclass, an evolution within the broader Zenit program optimized for improved resolution and operational flexibility.

### Launch Event
- **Date**: March 6, 1973  
- **Time**: 09:20:00 UTC  
- **Location**: Baikonur Cosmodrome, Site 31  
- **Vehicle**: Voskhod  

This launch marked another successful deployment in the Soviet Union's robust space infrastructure, leveraging proven technologies from earlier Voskhod missions.

### Operational Context
As with other Zenit-class satellites, Cosmos 551 likely conducted Earth observation tasks over predetermined ground tracks, returning film canisters or transmitting imagery back to Soviet ground stations. These missions were instrumental in maintaining situational awareness across global theaters of interest to Soviet leadership.

### Legacy and Documentation
Information about Cosmos 551 remains limited due to the classified nature of its mission. However, it is documented in several academic and archival sources including reference works such as Q6272367. Online coverage exists in multiple Slavic-language Wikipedias, reflecting ongoing scholarly and public interest in Soviet-era space history.

## References

1. Jonathan's Space Report