# Kosmos 275

> satellite

**Wikidata**: [Q53029](https://www.wikidata.org/wiki/Q53029)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Kosmos_275)  
**Source**: https://4ort.xyz/entity/kosmos-275

## Summary  
Kosmos 275 was a Soviet DS‑P1‑I radar‑calibration satellite launched on 28 March 1969 from the Plesetsk Cosmodrome aboard a Kosmos‑2I carrier rocket. Built by the Pivdenne Design Office, it served to test and calibrate ground‑based radar systems used for tracking spacecraft and missiles.

## Key Facts  
- **Launch date:** 28 March 1969 (16:00:08 UTC) from Plesetsk Cosmodrome Site 133【source】.  
- **Satellite type:** DS‑P1‑I radar‑calibration satellite, also known as DS‑P1‑I No.5【source】.  
- **COSPAR ID:** 1969‑031A【source】.  
- **Spacecraft catalog number (SCN):** 03846【source】.  
- **Manufacturer:** Pivdenne Design Office (Ukrainian design bureau)【source】.  
- **Launch vehicle:** Kosmos‑2I carrier rocket, a Soviet launch system that superseded earlier models【source】.  
- **Mission purpose:** Provide radar calibration and testing for Soviet tracking and missile‑defence radars【source】.  
- **Related class:** Part of the DS‑P1‑I series of calibration satellites【source】.  
- **Wikipedia language editions:** English, Spanish, Galician, Hungarian, Macedonian, Serbo‑Croatian, Serbian【source】.

## FAQs  
### Q: What was the primary purpose of Kosmos 275?  
**A:** Kosmos 275 was launched to serve as a radar‑calibration target, allowing Soviet ground‑based radar stations to verify and fine‑tune their tracking accuracy for both spacecraft and missile trajectories.  

### Q: When and where was Kosmos 275 launched?  
**A:** It was launched on 28 March 1969 at 16:00:08 UTC from Plesetsk Cosmodrome’s Site 133, using a Kosmos‑2I launch vehicle.  

### Q: Which organization built Kosmos 275?  
**A:** The satellite was manufactured by the Pivdenne Design Office, a Soviet (now Ukrainian) aerospace design bureau.  

### Q: How does Kosmos 275 fit into the DS‑P1‑I series?  
**A:** It is the fifth satellite in the DS‑P1‑I series (also catalogued as DS‑P1‑I No.5), a family of radar‑calibration satellites used throughout the 1960s and 1970s.  

### Q: What is the COSPAR identifier for Kosmos 275?  
**A:** Its COSPAR ID is 1969‑031A, which uniquely identifies the launch and payload in international space catalogs.  

## Why It Matters  
Kosmos 275 represents a critical component of the Soviet Union’s early space‑surveillance infrastructure. By providing reliable radar‑calibration targets, the satellite helped ensure that ground‑based tracking radars could accurately monitor both orbital objects and ballistic missiles—a capability essential for national security and for the safe operation of the burgeoning Soviet space program. The data gathered from DS‑P1‑I missions like Kosmos 275 fed directly into improvements in radar technology, contributing to more precise orbit determination, better collision avoidance, and enhanced missile‑defence readiness. Moreover, the satellite illustrates the broader strategy of using low‑cost, purpose‑built spacecraft to support larger scientific and military objectives, a practice that continues in modern satellite constellations.

## Notable For  
- **First‑generation radar‑calibration satellite** in the DS‑P1‑I series, enabling systematic testing of Soviet radar networks.  
- **Launch from Plesetsk Cosmodrome**, highlighting the strategic use of the northern launch site for military‑oriented missions.  
- **Utilization of the Kosmos‑2I launch vehicle**, a workhorse rocket that superseded earlier carriers and demonstrated reliable low‑orbit insertion capability.  
- **Manufactured by Pivdenne Design Office**, showcasing the bureau’s role in producing specialized military satellites.  
- **Catalogued under SCN 03846 and COSPAR 1969‑031A**, ensuring its traceability in international space object databases.

## Body  

### Overview  
Kosmos 275 (DS‑P1‑I No.5) was part of the Soviet Union’s DS‑P1‑I series, a line of small, purpose‑built satellites designed to act as radar calibration targets. These satellites were not intended for scientific research but for technical support of ground‑based tracking systems.

### Mission Profile  
- **Objective:** Provide a known radar cross‑section for calibration of Soviet early‑warning and space‑tracking radars.  
- **Orbit:** Low Earth orbit typical of DS‑P1‑I satellites (exact parameters not listed in the source).  
- **Operational lifetime:** Sufficient to complete multiple radar passes during its mission window; exact decay date not recorded in the provided data.

### Technical Specifications  
- **Spacecraft class:** DS‑P1‑I (radar‑calibration).  
- **Manufacturer:** Pivdenne Design Office.  
- **Identifiers:** COSPAR 1969‑031A; SCN 03846; Freebase /m/064n2dn.  
- **Aliases:** DS‑P1‑I No.5, Kosmos 275.  

### Launch Details  
- **Date & Time:** 28 March 1969, 16:00:08 UTC.  
- **Site:** Plesetsk Cosmodrome, Site 133 (northern Russian launch complex).  
- **Vehicle:** Kosmos‑2I, a two‑stage launch rocket derived from the R‑12 missile, widely used for small payloads.  

### Legacy and Impact  
Kosmos 275 contributed to the refinement of Soviet radar capabilities during a period of rapid space activity and heightened Cold‑War tensions. The successful deployment of DS‑P1‑I satellites demonstrated the feasibility of using dedicated calibration targets, a concept that persists in modern space situational awareness programs. The satellite’s data helped improve tracking accuracy, which was essential for both civilian space operations and military missile‑defence strategies.  

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*All information above is drawn exclusively from the supplied source material.*

## References

1. Jonathan's Space Report
2. Freebase Data Dumps. 2013