# ROSAT

> German space observatory

**Wikidata**: [Q54284](https://www.wikidata.org/wiki/Q54284)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/ROSAT)  
**Source**: https://4ort.xyz/entity/rosat

## Summary
ROSAT (ROentgen SATellite) was a German space observatory and X-ray telescope launched in 1990 to observe distant space objects. Weighing 2,426 kilograms, this artificial satellite was operated by the German Space Operations Center and spent nearly a decade in orbit before retiring in 1999 and eventually re-entering Earth's atmosphere over the Bay of Bengal in 2011.

## Key Facts
- **Classification:** ROSAT is classified as an artificial satellite, a space telescope, and an X-ray telescope.
- **Launch Date:** June 1, 1990, at 21:48:00.
- **Launch Site:** Cape Canaveral Space Launch Complex 17A.
- **Launch Vehicle:** Delta II (specifically variant D195).
- **Operator:** German Space Operations Center.
- **Mass:** 2,426 kilograms.
- **Dimensions:** 2.2 meters in height, 4.7 meters in width, and 8.9 meters in length.
- **Retirement Date:** February 12, 1999.
- **Atmospheric Re-entry:** October 23, 2011, at 01:50, over the Bay of Bengal.
- **Identifiers:** COSPAR ID 1990-049A; NSSDCA ID 1990-049A.

## FAQs
### Q: What does ROSAT stand for?
A: ROSAT is an acronym for "ROentgen SATellite." It was named for the German physicist Wilhelm Röntgen.

### Q: When did ROSAT fall back to Earth?
A: ROSAT re-entered Earth's atmosphere on October 23, 2011, at approximately 01:50 UTC. The decay occurred over the Bay of Bengal.

### Q: Who operated the ROSAT satellite?
A: The satellite was operated by the German Space Operations Center.

## Why It Matters
ROSAT represents a significant milestone in space astronomy as a major German-led scientific mission. As an X-ray telescope, it played a crucial role in observing distant space objects, contributing valuable data to the scientific community during its operational lifespan. Launched in 1990, it bridged the gap between earlier X-ray astronomy missions and modern observatories, demonstrating the capability of the Delta II launch system to deploy complex scientific hardware. Its mission life, extending nearly nine years until its retirement in 1999, provided a long-term platform for deep space observation. The satellite's eventual uncontrolled re-entry in 2011 also highlighted the ongoing challenges and discussions surrounding space debris and the lifecycle of artificial satellites in low Earth orbit.

## Notable For
- Being a dedicated **X-ray telescope** designed for observing distant space objects.
- Its longevity, operating from **1990 to 1999**.
- Its specific re-entry event on **October 23, 2011**, which occurred over the Bay of Bengal.
- Launch aboard the **Delta II** rocket, a retired expendable launch system.
- Its substantial mass of **2,426 kg**, making it a significant payload for its time.

## Body

### Mission Profile and Launch
ROSAT was launched on June 1, 1990, at 21:48:00 UTC from the Cape Canaveral Space Launch Complex 17A. The launch vehicle used was a Delta II rocket, specifically the D195 variant. Designated with the COSPAR ID 1990-049A, the satellite successfully achieved orbit to begin its mission as a space observatory.

### Physical Specifications
The satellite had a total mass of 2,426 kilograms. Its physical structure measured 2.2 meters in height, 4.7 meters in width, and 8.9 meters in length. ROSAT was powered by a spacecraft solar array.

### Operational History
Managed by the German Space Operations Center, ROSAT functioned as an artificial satellite and space telescope for nearly a decade. The mission officially concluded with its service retirement on February 12, 1999.

### End of Mission
Following its retirement, ROSAT remained in orbit until its orbital decay led to atmospheric entry. This significant event occurred on October 23, 2011, at 01:50 UTC. The satellite re-entered the atmosphere over the Bay of Bengal.

## References

1. [Source](https://www.dlr.de/content/en/articles/missions-projects/past-missions/rosat/rosat-mission.html)
2. Jonathan's Space Report
3. [Source](https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1990-049A)
4. [Source](http://www.collectspace.com/news/news-102211a.html)
5. [Source](https://www.dlr.de/content/en/downloads/news-archive/2011/20111025_rosat-re-entered-atmosphere-over-bay-of-bengal_1779.pdf)
6. Freebase Data Dumps. 2013
7. [OpenAlex](https://docs.openalex.org/download-snapshot/snapshot-data-format)