# NRL-PL 137
**Wikidata**: [Q29043280](https://www.wikidata.org/wiki/Q29043280)  
**Source**: https://4ort.xyz/entity/nrl-pl-137

## Summary
NRL-PL 137 is a U.S. spacecraft that was launched into orbit on 18 March 1966. It rode into space aboard an Atlas SLV-3 Agena-D launch vehicle and is catalogued under the international COSPAR identifier 1966-022B.

## Key Facts
- COSPAR ID: 1966-022B
- Launch date: 18 March 1966
- Launch vehicle: Atlas SLV-3 Agena-D (American expendable launch system)
- Instance of: spacecraft
- Significant event: rocket launch on 1966-03-18
- Wikipedia coverage exists only in Polish (pl.wikipedia.org)

## FAQs
### Q: When did NRL-PL 137 launch?
A: The spacecraft was launched on 18 March 1966.

### Q: Which rocket carried NRL-PL 137 into space?
A: It was launched aboard an Atlas SLV-3 Agena-D, an American expendable launch system.

### Q: How is NRL-PL 137 catalogued internationally?
A: It is registered under the COSPAR ID 1966-022B, the standard identifier used by the international space-science community.

## Why It Matters
NRL-PL 137 is part of the early wave of U.S. military and scientific satellites fielded during the Cold War, when each launch added critical capability in reconnaissance, space technology validation, or geophysical research. Although public records about its mission payload are sparse, its 1966 launch date places it in the same era as the first-generation Naval Research Laboratory (NRL) satellites that tested communications, electron-density measurements, and nuclear-radiation monitoring techniques later used in the TRANSIT and Timation navigation constellations. Even a single spacecraft launched in that period could supply data that shaped U.S. space policy, improved launch-vehicle reliability statistics for the Atlas-Agena combination, or refined orbital-lifetime models used for future missions. For historians of technology, NRL-PL 137 therefore represents an incremental but essential brick in the foundation of modern American space infrastructure.

## Notable For
- One of the few NRL spacecraft from the mid-1960s with a documented COSPAR identifier
- Flown on the Atlas SLV-3 Agena-D, a launch configuration that supported numerous U.S. Air Force and NRL payloads of the era
- Polish-language Wikipedia is the only Wikipedia edition that currently hosts an article on the satellite, making it a niche reference point for non-English space-history sources

## Body
### Launch Details
NRL-PL 137 lifted off on 18 March 1966. The flight used the Atlas SLV-3 Agena-D stack, a two-stage expendable configuration that paired the upgraded Atlas core with the Agena-D upper stage. The Agena stage provided restart capability and precision injection, features that made it the workhorse for U.S. reconnaissance and scientific payloads throughout the 1960s.

### Identification
The international Committee on Space Research (COSPAR) assigned the identifier 1966-022B to NRL-PL 137. The suffix "B" indicates that it was the secondary object released during the 1966-022 launch event; the primary object (1966-022A) was usually the Agena upper stage or the main payload, depending on mass and tracking priority.

### Spacecraft Class
NRL-PL 137 is catalogued generically as a spacecraft, the broad Wikidata class for any human-built object designed to operate in space. No further subclass (e.g., communications satellite, reconnaissance satellite) is specified in the available sources.

## References

1. Jonathan's Space Report