# GSAT0101

> European navigation validation satellite in the Galileo constellation

**Wikidata**: [Q14083892](https://www.wikidata.org/wiki/Q14083892)  
**Source**: https://4ort.xyz/entity/gsat0101

## Summary
GSAT0101, also known as Galileo-IOV PFM or Thijs, is a European navigation validation satellite and the ProtoFlight Model for the Galileo constellation. Launched on October 21, 2011, it was the first satellite deployed to validate the Galileo navigation system in orbit. It operates in medium Earth orbit under the management of the European Union Agency for the Space Programme.

## Key Facts
- **Launch Date:** October 21, 2011, at 10:30:26 UTC.
- **Identifiers:** COSPAR ID 2011-060A; NSSDCA ID 2011-060A; SCCN 37846.
- **Classification:** Instance of "Galileo In-Orbit Validation" satellite.
- **Mass:** 640 kilograms (launch weight).
- **Orbit:** Medium Earth Orbit with a semi-major axis of 29,599.8 km, inclination of 56 degrees, and eccentricity of 0.0.
- **Launch Vehicle:** Soyuz-2.1b rocket assisted by a Fregat-MT space tug.
- **Launch Site:** Ensemble de Lancement Soyouz.
- **Operator:** European Union Agency for the Space Programme.
- **Manufacturers:** Astrium (prime) and Thales Alenia Space (responsible for assembly, integration, and testing).
- **Power:** Powered by two spacecraft solar arrays.

## FAQs
### Q: What is the primary purpose of GSAT0101?
A: GSAT0101 serves as an In-Orbit Validation (IOV) satellite designed to test and validate the technologies for the European Galileo navigation constellation.

### Q: When and how was GSAT0101 launched?
A: It was launched on October 21, 2011, using a Soyuz-2.1b rocket from the Ensemble de Lancement Soyouz, supported by a Fregat-MT upper stage.

### Q: What are the aliases for GSAT0101?
A: The satellite is also known as Thijs, Galileo-IOV PFM, Galileo In-Orbit Validation ProtoFlight Model, Galileo 1, Galileo-PFM, and GalileoSat-1.

## Why It Matters
GSAT0101 represents a critical milestone in the development of Europe's independent global navigation satellite system, Galileo. As the ProtoFlight Model (PFM) for the In-Orbit Validation phase, this satellite was tasked with validating the critical technologies and signal characteristics that would be used by the full operational constellation. Its successful deployment and operation in 2011 provided the European Union Agency for the Space Programme and its partners (Astrium and Thales Alenia Space) with essential data to verify system performance in a realistic space environment. By securing a European alternative to GPS and GLONASS, GSAT0101 played a foundational role in establishing the continent's strategic autonomy in satellite navigation and timing services.

## Notable For
- Being the **ProtoFlight Model (PFM)** for the Galileo constellation.
- Serving as the **first** operational flight unit for the Galileo program (Galileo 1).
- Validating the European navigation system infrastructure in **Medium Earth Orbit**.
- Launching on the inaugural Galileo mission via a **Soyuz-2.1b** rocket.

## Body
### Specifications and Design
GSAT0101 is a navigation satellite with a launch mass of 640 kilograms. It was manufactured by a consortium led by **Astrium**, with **Thales Alenia Space** handling assembly, integration, and testing. The satellite is powered by two dedicated solar arrays and is designed to operate in a circular Medium Earth Orbit (MEO).

### Launch and Deployment
The satellite was successfully launched on **October 21, 2011**, at 10:30:26 UTC. The launch vehicle was a **Soyuz-2.1b** (rocket version B 15000-001) launched from the **Ensemble de Lancement Soyouz**. To reach its final orbital position, the satellite was deployed using a **Fregat-MT** space tug.

### Orbital Parameters
GSAT0101 occupies a precise orbital slot characterized by the following technical parameters:
- **Semi-major Axis:** 29,599.8 kilometers
- **Inclination:** 56 degrees
- **Eccentricity:** 0.0 (circular orbit)
- **Orbital Regime:** Medium Earth Orbit (satellite of Earth)

### Cataloging and Identifiers
The satellite is officially tracked and cataloged by multiple agencies under the following designations:
- **SCN:** 37846
- **COSPAR ID:** 2011-060A
- **NSSDCA ID:** 2011-060A
- **Wolfram Language Entity:** `Entity["Satellite", "37846"]`

## References

1. [Source](https://www.gsc-europa.eu/system-status/orbital-and-technical-parameters)
2. [Source](https://www.esa.int/Applications/Satellite_navigation/Galileo/Galileo_partners)
3. [Source](https://www.esa.int/Newsroom/Press_Releases/Deployment_of_Europe_s_Galileo_constellation_continues)
4. [Source](http://space.skyrocket.de/doc_sdat/galileo-iov.htm)
5. Jonathan's Space Report
6. [Source](https://www.celestrak.com/satcat/2011/2011-060.asp)
7. [Source](https://space.skyrocket.de/doc_sdat/galileo-iov.htm)
8. [Source](https://www.gsc-europa.eu/system-service-status/orbital-and-technical-parameters)