# USA 81

> 21949

**Wikidata**: [Q111499477](https://www.wikidata.org/wiki/Q111499477)  
**Source**: https://4ort.xyz/entity/usa-81

## Summary
USA 81 is an artificial satellite with the designation 21949. It is a human-made object that has been placed into orbit around Earth.

## Key Facts
- USA 81 is an artificial satellite with the designation 21949
- It is classified as a human-made object placed into orbit
- The satellite has 142 sitelinks in Wikidata, indicating its presence across multiple knowledge bases
- It is represented in Wolfram Language as Entity["Satellite", "21949"]
- The satellite is categorized under the class "artificial satellite"

## FAQs
### Q: What is USA 81?
A: USA 81 is an artificial satellite designated as 21949. It is a human-made object that has been placed into orbit around Earth as part of space exploration and satellite technology.

### Q: What type of satellite is USA 81?
A: USA 81 is classified as an artificial satellite, which means it is a human-made object intentionally placed into orbit around Earth for various purposes including communication, observation, or scientific research.

### Q: How is USA 81 identified in databases?
A: USA 81 is identified by the designation 21949 and has 142 sitelinks in Wikidata. It can also be referenced in Wolfram Language using the entity code Entity["Satellite", "21949"].

## Why It Matters
USA 81 represents the ongoing advancement of satellite technology and space exploration. As an artificial satellite, it contributes to our understanding of orbital mechanics, Earth observation, and potentially various applications that rely on satellite infrastructure. The fact that it has been cataloged with 142 sitelinks across knowledge bases demonstrates its significance in the broader context of space technology and international satellite tracking efforts. Satellites like USA 81 play crucial roles in modern communications, navigation, weather forecasting, and scientific research, making them essential components of our technological infrastructure.

## Notable For
- Being designated as satellite 21949 in the USA satellite series
- Having 142 sitelinks across multiple knowledge bases, indicating widespread documentation
- Being classified as an artificial satellite, a human-made object in Earth orbit
- Being represented in Wolfram Language computational systems
- Contributing to the extensive catalog of artificial satellites orbiting Earth

## Body
### Technical Classification
USA 81 is classified as an artificial satellite, which places it in the category of human-made objects intentionally placed into Earth's orbit. This classification indicates that it was designed, built, and launched by human engineers and scientists for specific purposes related to space technology.

### Identification and Documentation
The satellite bears the designation 21949, which serves as its unique identifier in satellite catalogs and tracking systems. This numerical designation follows the standard naming conventions used for artificial satellites, particularly those launched by the United States.

### Database Presence
USA 81 has established a significant presence across knowledge bases, with 142 sitelinks recorded in Wikidata. This extensive documentation suggests that the satellite has been tracked, studied, and referenced across multiple platforms and databases, indicating its importance in the broader context of space technology and satellite operations.

### Computational Representation
The satellite is represented in Wolfram Language as Entity["Satellite", "21949"], demonstrating its integration into computational systems used for satellite tracking, orbital calculations, and space technology analysis. This representation allows researchers and engineers to access and work with data about USA 81 using advanced computational tools.