# SSTL-S1 4

> Earth observation satellite

**Wikidata**: [Q60982412](https://www.wikidata.org/wiki/Q60982412)  
**Source**: https://4ort.xyz/entity/sstl-s1-4

## Summary
SSTL-S1 4 is a UK-built Earth observation satellite operated by DMC International Imaging, designed to observe Earth from a sun-synchronous orbit as part of the Disaster Monitoring Constellation (DMC).

## Key Facts
- **Launch Date**: 16 September 2018 at 16:38 UTC from Satish Dhawan Space Centre First Launch Pad.
- **Operator**: DMC International Imaging.
- **Manufacturer**: Surrey Satellite Technology (SSTL).
- **Mass**: 447 kilograms (launch weight).
- **Orbit**: Sun-synchronous orbit.
- **Launch Vehicle**: Polar Satellite Launch Vehicle (PSLV-C42).
- **Cospar ID**: 2018-071A.
- **Aliases**: S1-4, Beijing 2-4, SSTL S1-4.
- **Spacecraft Bus**: SSTL-300.

## FAQs
### Q: What is SSTL-S1 4?
A: SSTL-S1 4 is an Earth observation satellite built by Surrey Satellite Technology (SSTL) for the UK, operated by DMC International Imaging as part of the Disaster Monitoring Constellation.

### Q: Who operates SSTL-S1 4?
A: DMC International Imaging operates SSTL-S1 4. It provides Earth observation imagery, notably used by 21AT.

### Q: When and where was SSTL-S1 4 launched?
A: SSTL-S1 4 was launched on 16 September 2018 at 16:38 UTC from the Satish Dhawan Space Centre First Launch Pad in India using a PSLV-C42 rocket.

### Q: What is SSTL-S1 4 used for?
A: SSTL-S1 4 is used for Earth observation, providing imagery primarily for disaster monitoring applications through the DMC constellation and commercial services via 21AT.

### Q: What distinguishes SSTL-S1 4's design?
A: It is built on the SSTL-300 spacecraft bus and specifically designed for Earth observation from a sun-synchronous orbit.

## Why It Matters
SSTL-S1 4 is significant as part of the Disaster Monitoring Constellation (DMC), a satellite network specifically designed to provide rapid imaging of the Earth's surface. This capability is crucial for timely disaster response, environmental monitoring, and resource management. As a UK-manufactured satellite launched by India, it also exemplifies international collaboration in space technology. Its data, commercially utilized by 21AT, contributes to diverse applications including agriculture, urban planning, and emergency preparedness, enhancing global Earth observation capabilities and supporting decision-making on the ground.

## Notable For
- **DMC Constellation Member**: One of the satellites in the Disaster Monitoring Constellation, focused on rapid Earth imaging.
- **UK Space Engineering**: Manufactured in the United Kingdom by Surrey Satellite Technology (SSTL), showcasing British space manufacturing capabilities.
- **International Launch**: Successfully launched by the Indian Space Research Organisation (ISRO) using a PSLV-C42 rocket from India.
- **Sun-Synchronous Orbit**: Operates in a sun-synchronous orbit, enabling consistent lighting conditions for Earth imagery.
- **Commercial Utilization**: Earth observation data from SSTL-S1 4 is commercially exploited by 21AT.

## Body
### Technical Specifications
- **Spacecraft Bus**: SSTL-300
- **Mass**: 447 kilograms (Launch Weight)
- **Orbit**: Sun-synchronous orbit
- **Country of Origin**: United Kingdom

### Operational Details
- **Operator**: DMC International Imaging
- **Primary User**: 21AT (utilizes its Earth observation data)
- **Launch Vehicle**: Polar Satellite Launch Vehicle (PSLV-C42)
- **Launch Site**: Satish Dhawan Space Centre First Launch Pad
- **Launch Date**: 16 September 2018 at 16:38 UTC
- **Cospar ID / NSSDCA ID**: 2018-071A

### Historical Context
- **Manufacturer**: Surrey Satellite Technology
- **Project Role**: Part of the Disaster Monitoring Constellation (DMC), specifically designated S1-4.
- **Aliases**: Also known as S1-4, Beijing 2-4, and SSTL S1-4.
- **Key Reference Data**: Details sourced from space.skyrocket.de (uk-dmc-3.htm, sstl_300.htm) and the Catalog of Space Objects (Q6272367, Q48183).

## References

1. [Source](https://space.skyrocket.de/doc_sdat/uk-dmc-3.htm)
2. Jonathan's Space Report
3. [Source](https://space.skyrocket.de/doc_sat/sstl_300.htm)