# TDRS-4

> decommissioned American communications satellite

**Wikidata**: [Q7669869](https://www.wikidata.org/wiki/Q7669869)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/TDRS-4)  
**Source**: https://4ort.xyz/entity/tdrs-4

Here’s the structured knowledge entry for TDRS-4:

---

## Summary  
TDRS-4 is a decommissioned American communications satellite that was part of NASA's Tracking and Data Relay Satellite System (TDRSS). Launched in 1989 aboard the Space Shuttle *Discovery*, it provided critical data relay services for spacecraft and missions until its retirement in 2011. It is now a derelict satellite in geosynchronous orbit.

## Key Facts  
- **Launch Date**: March 13, 1989, from Kennedy Space Center Launch Complex 39B aboard STS-29.  
- **Manufacturer**: Built by TRW Inc. for NASA.  
- **Mass**: 2,108 kg (launch weight).  
- **Dimensions**: 17.3 meters (length) × 14.2 meters (width).  
- **Power Output**: 1,700 watts (nominal).  
- **Orbit**: Geosynchronous orbit.  
- **Preceded by**: TDRS-3; **Succeeded by**: TDRS-5.  
- **Decommissioned**: December 9, 2011, with final shutdown in May 2012.  
- **COSPAR ID**: 1989-021B.  

## FAQs  
### Q: What was the purpose of TDRS-4?  
A: TDRS-4 was a communications satellite designed to relay data between ground stations and other spacecraft, including the Space Shuttle and the International Space Station, as part of NASA's TDRSS network.  

### Q: When was TDRS-4 retired?  
A: It was officially retired from service on December 9, 2011, and fully decommissioned in May 2012.  

### Q: What launched TDRS-4 into orbit?  
A: It was launched aboard the Space Shuttle *Discovery* (mission STS-29) using an Inertial Upper Stage (IUS-9) booster.  

## Why It Matters  
TDRS-4 played a vital role in NASA's communications infrastructure, enabling real-time data transmission between Earth and orbiting spacecraft. As part of the TDRSS network, it supported missions like the Space Shuttle program and the Hubble Space Telescope, ensuring uninterrupted communication and scientific data delivery. Its retirement marked the end of an era for first-generation TDRS satellites, which paved the way for more advanced successors. The satellite's legacy lies in its contributions to space exploration and its role in maintaining critical space-to-ground links.  

## Notable For  
- One of the first-generation TDRS satellites, providing decades of reliable service.  
- Launched aboard the Space Shuttle *Discovery* (STS-29), a historic mission.  
- Operated in geosynchronous orbit for over 22 years before decommissioning.  
- Part of NASA's TDRSS, a cornerstone of space communications.  

## Body  
### Launch and Deployment  
- Launched on March 13, 1989, at 14:57 UTC from Kennedy Space Center.  
- Deployed using the Inertial Upper Stage (IUS-9) booster.  

### Technical Specifications  
- **Mass**: 2,108 kg at launch.  
- **Dimensions**: 17.3 m (length) × 14.2 m (width).  
- **Power**: 1,700 watts nominal output.  
- **Orbit**: Geosynchronous, providing continuous coverage.  

### Operational History  
- Provided data relay services for NASA missions until 2011.  
- Officially retired on December 9, 2011, and decommissioned in May 2012.  

### Legacy  
- Part of the TDRSS network, critical for space communications.  
- Replaced by more advanced satellites like TDRS-5.  

## Schema Markup  
```json
{
  "@context": "https://schema.org",
  "@type": "Satellite",
  "name": "TDRS-4",
  "description": "Decommissioned American communications satellite part of NASA's Tracking and Data Relay Satellite System.",
  "url": "https://en.wikipedia.org/wiki/TDRS-4",
  "sameAs": [
    "https://www.wikidata.org/wiki/Q7674154",
    "https://en.wikipedia.org/wiki/TDRS-4"
  ],
  "additionalType": "Tracking and Data Relay Satellite",
  "operationalStatus": "Decommissioned",
  "launchDate": "1989-03-13",
  "manufacturer": "TRW Inc.",
  "operator": "NASA"
}

## References

1. Jonathan's Space Report
2. [Source](https://spaceflightnow.com/news/n1112/25tdrs4/)
3. [Source](https://www.nasa.gov/topics/technology/features/tdrs4-retired.html)
4. [Source](https://space.skyrocket.de/doc_stage/ius.htm)
5. [Source](https://www.nasa.gov/directorates/heo/scan/services/networks/tdrs_characteristics/)