# THEMIS-A

> satellite in the THEMIS constellation

**Wikidata**: [Q111497132](https://www.wikidata.org/wiki/Q111497132)  
**Source**: https://4ort.xyz/entity/themis-a

## Summary
THEMIS-A is a geomagnetic satellite launched as part of NASA's THEMIS constellation, designed to study Earth's magnetosphere and related regions. It was launched on February 17, 2007, aboard a Delta II rocket and operated by the National Aeronautics and Space Administration (NASA).

## Key Facts
- **Class**: Geomagnetic satellite (designed to monitor Earth's magnetosphere and related regions)
- **Launch Date**: February 17, 2007, at 23:01:00 UTC
- **Launch Vehicle**: Delta II (model D-323)
- **Launch Site**: Cape Canaveral Space Launch Complex 17B
- **Operator**: National Aeronautics and Space Administration (NASA)
- **Manufacturer**: Swales Aerospace (general contractor), University of California, Berkeley (subcontractor for space instrument and system integration)
- **Mass**:
  - Dry weight: 77 kg
  - Launch weight: 126 kg
- **Dimensions**:
  - Height: 51 cm
  - Diameter: 84 cm
- **Power System**: Spacecraft solar array (37 W) and reaction control system (hydrazine, 4 thrusters)
- **Part of**: THEMIS constellation
- **Aliases**: Explorer 85, THEMIS-P5, MIDEX-5A, Эксплорер-85
- **Country of Origin**: United States

## FAQs
### Q: What was the purpose of THEMIS-A?
A: THEMIS-A was part of NASA's THEMIS mission to study Earth's magnetosphere and related regions, particularly focusing on the causes of geomagnetic substorms.

### Q: Who built THEMIS-A?
A: THEMIS-A was built by Swales Aerospace as the general contractor, with the University of California, Berkeley handling the space instrument and system integration.

### Q: What launch vehicle was used for THEMIS-A?
A: THEMIS-A was launched aboard a Delta II rocket (model D-323) on February 17, 2007, from Cape Canaveral Space Launch Complex 17B.

### Q: How much did THEMIS-A weigh?
A: THEMIS-A had a dry weight of 77 kg and a launch weight of 126 kg.

### Q: What was the significance of THEMIS-A's launch?
A: THEMIS-A was part of a constellation of five satellites launched to study the dynamics of Earth's magnetosphere, particularly the causes of geomagnetic substorms.

## Why It Matters
THEMIS-A played a crucial role in NASA's THEMIS mission, which aimed to understand the causes of geomagnetic substorms—sudden disturbances in Earth's magnetosphere. By studying these phenomena, the mission contributed to a better understanding of space weather and its potential impacts on satellites, power grids, and communication systems. The data collected by THEMIS-A and its sister satellites helped scientists develop models to predict and mitigate the effects of geomagnetic storms, enhancing our ability to protect critical infrastructure from space weather events.

## Notable For
- **First in Constellation**: THEMIS-A was the first of five satellites launched as part of NASA's THEMIS mission to study geomagnetic substorms.
- **Geomagnetic Focus**: Designed specifically to monitor Earth's magnetosphere and related regions, providing critical data on space weather.
- **Collaborative Effort**: Built in collaboration between Swales Aerospace and the University of California, Berkeley, showcasing interdisciplinary research.
- **Delta II Launch**: Launched aboard a Delta II rocket, demonstrating the reliability of the Delta rocket family for scientific missions.
- **International Collaboration**: Involved contributions from the United States, reflecting NASA's commitment to global space exploration.

## Body
### Mission Overview
THEMIS-A was part of NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission, launched to investigate the causes of geomagnetic substorms. These substorms are sudden disturbances in Earth's magnetosphere, which can disrupt satellites, power grids, and communication systems.

### Technical Specifications
- **Mass**: THEMIS-A had a dry weight of 77 kg and a launch weight of 126 kg.
- **Dimensions**: The satellite measured 51 cm in height and 84 cm in diameter.
- **Power System**: It was powered by a spacecraft solar array generating 37 W, supplemented by a reaction control system using hydrazine fuel with four thrusters.

### Launch Details
- **Launch Date**: February 17, 2007, at 23:01:00 UTC.
- **Launch Vehicle**: Delta II (model D-323), operated by United Launch Alliance.
- **Launch Site**: Cape Canaveral Space Launch Complex 17B.

### Construction and Operation
- **Manufacturer**: Swales Aerospace served as the general contractor, while the University of California, Berkeley handled the space instrument and system integration.
- **Operator**: NASA managed the mission, ensuring the satellite's operation and data collection.

### Significance
THEMIS-A's data contributed to a deeper understanding of geomagnetic substorms, helping scientists develop models to predict and mitigate the effects of space weather. The mission's findings have implications for protecting critical infrastructure from the impacts of geomagnetic storms.

## Schema Markup
```json
{
  "@context": "https://schema.org",
  "@type": "Thing",
  "name": "THEMIS-A",
  "description": "A geomagnetic satellite launched as part of NASA's THEMIS constellation to study Earth's magnetosphere.",
  "additionalType": "Spacecraft",
  "manufacturer": {
    "@type": "Organization",
    "name": "Swales Aerospace"
  },
  "operator": {
    "@type": "Organization",
    "name": "National Aeronautics and Space Administration"
  },
  "launchDate": "2007-02-17",
  "launchVehicle": "Delta II",
  "countryOfOrigin": "United States"
}

## References

1. [Source](http://www.swales.com/spacecraft/themis.html)
2. [Source](https://www.nasaspaceflight.com/2007/02/ulas-delta-ii-launches-with-themis/)
3. Jonathan's Space Report
4. [Source](https://directory.eoportal.org/web/eoportal/satellite-missions/t/themis#spacecraft)
5. [Source](https://directory.eoportal.org/web/eoportal/satellite-missions/t/themis)