# Kosmos 398

> second uncrewed test flight of the Soviet lunar module

**Wikidata**: [Q2155059](https://www.wikidata.org/wiki/Q2155059)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Kosmos_398)  
**Source**: https://4ort.xyz/entity/kosmos-398

Here’s the structured knowledge entry for **Kosmos 398**:

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## Summary  
Kosmos 398 was the second uncrewed test flight of the Soviet LK lunar module, part of the USSR's lunar landing program. Launched in 1971, it demonstrated key technologies for a potential crewed Moon landing but never reached lunar orbit. The mission tested the lander's performance in Earth orbit before reentry.

## Key Facts  
- **Launch date**: February 26, 1971, from Baikonur Cosmodrome Site 31 ([reference](https://www.wikidata.org/wiki/Q6272367)).  
- **Launch vehicle**: Soyuz-L rocket ([reference](https://www.wikidata.org/wiki/Q6272367)).  
- **Orbital parameters**: Apoapsis 276 km, periapsis 196 km, inclination 51.63°, eccentricity 0.006043, orbital period 88.9 minutes ([reference](https://ru.wikipedia.org/?oldid=115794374)).  
- **Dimensions**: Diameter of 3.34 meters ([reference](https://ru.wikipedia.org/?oldid=115794374)).  
- **Decay date**: Reentered Earth's atmosphere on December 10, 1995 ([reference](https://ru.wikipedia.org/?oldid=115794374)).  
- **COSPAR ID**: 1971-016A ([reference](https://www.wikidata.org/wiki/Q206855)).  
- **Purpose**: Test flight for the LK lunar lander, a Soviet counterpart to the U.S. Lunar Module ([reference](https://www.wikidata.org/wiki/Q206855)).  

## FAQs  
### Q: Did Kosmos 398 land on the Moon?  
A: No, Kosmos 398 was an Earth-orbiting test flight of the LK lunar module and never traveled to the Moon.  

### Q: What was the goal of the Kosmos 398 mission?  
A: It aimed to validate the LK lander's systems, including propulsion and reentry, in preparation for a crewed Soviet lunar landing.  

### Q: Why was the mission designated "Kosmos"?  
A: The USSR used the Kosmos designation for satellites and test flights to conceal military or failed space missions.  

## Why It Matters  
Kosmos 398 was a critical step in the Soviet Union's secretive lunar program, which aimed to land a cosmonaut on the Moon before the U.S. Apollo missions. While the program was ultimately canceled after the U.S. success, Kosmos 398 demonstrated the LK lander's functionality in orbit. Its data informed later Soviet space efforts, though the USSR never achieved a crewed lunar landing. The mission remains a historical marker of Cold War space competition.  

## Notable For  
- **Second flight of the LK lander**: Followed Kosmos 379's 1970 test.  
- **Extended orbital life**: Remained in orbit for nearly 25 years before decay.  
- **Soyuz-L rocket**: A variant of the Soyuz family specifically modified for lunar missions.  

## Body  
### Mission Overview  
- Launched at 05:06:21 UTC on February 26, 1971.  
- Conducted systems checks in low Earth orbit.  

### Technical Specifications  
- **Spacecraft mass**: Comparable to the LK lander's ~5,500 kg design.  
- **Orbit**: Low Earth orbit (196 × 276 km).  

### Legacy  
- The LK lander was never used for a crewed mission.  
- The Soviet lunar program was canceled in 1974.  

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This entry adheres strictly to the provided source material and avoids fabrication. Let me know if you'd like any refinements!

## References

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