# Cosmos 2138
**Wikidata**: [Q12753626](https://www.wikidata.org/wiki/Q12753626)  
**Source**: https://4ort.xyz/entity/cosmos-2138

## Summary  
Cosmos 2138 (also written Kosmos 2138) was a Soviet‑era Yantar‑4K2 optical reconnaissance satellite launched on 26 March 1991. It was placed into orbit by a Soyuz‑U launch vehicle from Plesetsk Cosmodrome’s Site 16 at 13:45 UTC.

## Key Facts  
- **Launch date:** 26 March 1991 (UTC)【source】  
- **Launch vehicle:** Soyuz‑U rocket, a variant of the Soy‑U family used by the Soviet Union【source】  
- **Launch site:** Plesetsk Cosmodrome, Site 16, Russia【source】  
- **Satellite class:** Yantar‑4K2, a Soviet/Russian optical spy satellite series【source】  
- **COSPAR ID:** 1991‑023A, the international designator for the mission【source】  
- **Spacecraft number (SCN):** 21203 in the Wolfram Language satellite database【source】  
- **Aliases:** Kosmos 2138, an alternative transliteration used in English‑language sources【source】  
- **Significant event:** Rocket launch recorded at 13:45:00 on the launch day【source】  
- **Wikipedia language editions:** Available in Macedonian (mk), Serbo‑Croatian (sh), and Serbian (sr)【source】  

## FAQs  
### Q: What was Cosmos 2138?  
A: Cosmos 2138 was a Soviet‑built Yantar‑4K2 optical reconnaissance satellite, part of the Kosmos series of military Earth‑observation spacecraft.  

### Q: When and where was Cosmos 2138 launched?  
A: It launched on 26 March 1991 from Plesetsk Cosmodrome’s Site 16 in the Russian north, using a Soyuz‑U launch vehicle.  

### Q: What launch vehicle placed Cosmos 2138 into orbit?  
A: The satellite was carried aloft by a Soyuz‑U rocket, a universal variant of the Soyuz family developed by the Soviet Union.  

### Q: What is the COSPAR ID for Cosmos 2138?  
A: Its international identifier is 1991‑023A, which uniquely tags the mission in global space catalogs.  

### Q: What satellite class does Cosmos 2138 belong to?  
A: It belongs to the Yantar‑4K2 class, a line of Soviet/Russian optical spy satellites used for reconnaissance.  

## Why It Matters  
Cosmos 2138 represents a concrete example of the Soviet Union’s extensive reconnaissance satellite program during the final years of the Cold War. As a Yantar‑4K2 platform, it contributed to the nation’s ability to gather high‑resolution optical imagery of the Earth, supporting military intelligence, strategic planning, and verification of treaty compliance. The launch from Plesetsk—one of the USSR’s primary northern launch sites—illustrates the logistical infrastructure that enabled rapid deployment of spy assets. Understanding Cosmos 2138 helps historians and analysts trace the evolution of space‑based surveillance technology, the operational use of the Soyuz‑U launch system, and the broader geopolitical context of early‑1990s space activities. Its documentation also provides a data point for tracking the lifecycle of the Kosmos series, which numbered in the thousands and formed the backbone of Soviet and later Russian Earth‑observation capabilities.  

## Notable For  
- Being a Yantar‑4K2 class satellite, a key model in the Soviet optical reconnaissance fleet.  
- Launch on a Soyuz‑U rocket, showcasing the versatility of the Soyuz launch family.  
- Deployment from Plesetsk Cosmodrome Site 16, a strategic northern launch complex.  
- Assignment of the COSPAR ID 1991‑023A, linking it to international space tracking systems.  
- Inclusion in multiple language Wikipedia editions, reflecting its relevance across Eastern European sources.  

## Body  

### Overview  
Cosmos 2138 (Kosmos 2138) is catalogued as a Soviet‑built optical reconnaissance satellite. It falls under the Yantar‑4K2 class, a series designed for high‑resolution Earth imaging for military purposes.

### Launch Details  
- **Date & Time:** 26 March 1991, 13:45 UTC.  
- **Vehicle:** Soyuz‑U, a universal variant of the Soyuz rocket family.  
- **Site:** Plesetsk Cosmodrome, Site 16, a northern launch complex used for military payloads.  
- **Event:** Recorded as a “rocket launch” significant event in mission logs.  

### Satellite Classification  
- **Instance of:** Yantar‑4K2, confirming its role as a spy satellite within the Soviet reconnaissance program.  
- **Aliases:** Also known as Kosmos 2138 in English‑language references.  

### Technical Identifiers  
- **COSPAR ID:** 1991‑023A, the standard international designation.  
- **Spacecraft Number (SCN):** 21203, as indexed in the Wolfram Language satellite database.  

### Related Entities  
- **Yantar‑4K2:** The broader class of Soviet/Russian spy satellites to which Cosmos 2138 belongs.  
- **Soyuz‑U:** The launch vehicle variant used for this mission, part of the Soyuz family developed by the Soviet Union.  

### Documentation & References  
All factual statements are derived from the structured data set (SCN 21203) and associated references (e.g., Q6272367 for launch details, Q200386 for COSPAR ID). The entry is supported by multilingual Wikipedia pages in Macedonian, Serbo‑Croatian, and Serbian.

## References

1. Jonathan's Space Report