# International Cometary Explorer

> American magnetospheric research satellite

**Wikidata**: [Q1475301](https://www.wikidata.org/wiki/Q1475301)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/International_Cometary_Explorer)  
**Source**: https://4ort.xyz/entity/international-cometary-explorer

## Summary
The **International Cometary Explorer (ICE)** is an American space probe originally launched as **ISEE-3** (International Sun-Earth Explorer-3) to study Earth's magnetosphere before being repurposed to become the first spacecraft to fly through a comet's tail. Operated by NASA's Goddard Space Flight Center, it conducted groundbreaking research on solar wind, comets, and interplanetary space before its retirement in 1997.

## Key Facts
- Launched on **August 12, 1978**, from **Cape Canaveral Space Launch Complex 17B** aboard a **Delta 2000** rocket.
- Initially named **ISEE-3**, part of the **International Sun-Earth Explorer Program**, before being renamed **ICE** in 1983 for its comet mission.
- **First spacecraft to perform a comet flyby**, passing through the tail of **Comet Giacobini-Zinner (21P) on September 11, 1985**, at a distance of **7,862 km**.
- Also conducted a distant flyby of **Halley’s Comet** on **March 28, 1986**, at **40.2 million km**.
- **Mass**: 479 kg (launch weight), 390 kg (dry weight); **Dimensions**: 1.58 m height, 1.77 m diameter.
- Powered by a **173-watt solar array** and a **hydrazine reaction control system** with 12 thrusters.
- Operated by **NASA’s Goddard Space Flight Center** and manufactured by **Fairchild**.
- Retired from service on **May 5, 1997**, after nearly **19 years** of operation.

## FAQs
### Q: What was the original purpose of the International Cometary Explorer?
A: It was launched as **ISEE-3** to study Earth’s magnetosphere and solar wind from the **L1 Earth-Sun Lagrange point**, where it operated from **1978 to 1982**.

### Q: How did ISEE-3 become the International Cometary Explorer?
A: After completing its magnetospheric mission, NASA repurposed the spacecraft in **1983**, using **five lunar gravity assists** to redirect it toward **Comet Giacobini-Zinner**, making it the first comet flyby mission.

### Q: What comets did the International Cometary Explorer study?
A: It flew through the tail of **Comet Giacobini-Zinner (1985)** and conducted a distant observation of **Halley’s Comet (1986)**.

### Q: Who built and operated the International Cometary Explorer?
A: It was **manufactured by Fairchild**, launched by **Douglas (Delta 2000 rocket)**, and **operated by NASA’s Goddard Space Flight Center**.

### Q: When was the International Cometary Explorer retired?
A: The mission officially ended on **May 5, 1997**, after nearly two decades of service.

## Why It Matters
The International Cometary Explorer was a pioneering spacecraft that demonstrated the flexibility of robotic missions in space exploration. Originally designed to study Earth’s magnetosphere, it was **repurposed mid-mission** to achieve a historic first: the **first-ever comet flyby**. Its encounter with **Comet Giacobini-Zinner** provided critical data on comet composition, solar wind interactions, and plasma physics, advancing our understanding of the solar system. The mission also showcased innovative trajectory planning, using **lunar gravity assists** to redirect the spacecraft without excessive fuel. As part of NASA’s **Explorers Program**, ICE contributed to both **heliophysics** and **planetary science**, bridging two major fields of study. Its long operational life (1978–1997) and adaptability set a precedent for future missions, proving that spacecraft could be **reused for entirely new scientific objectives**.

## Notable For
- **First spacecraft to fly through a comet’s tail** (Giacobini-Zinner, 1985).
- **First use of lunar gravity assists** to redirect a spacecraft to a new target.
- **Longest-operating spacecraft of its time**, functioning for **nearly 19 years**.
- **Dual-mission design**: Initially a **geomagnetic satellite**, later a **comet explorer**.
- **Collaborative international effort**, part of the **International Sun-Earth Explorer Program** with ESA.

## Body
### Mission Overview
The **International Cometary Explorer (ICE)** began as **ISEE-3**, the third spacecraft in NASA’s **International Sun-Earth Explorer Program**, a joint effort with the **European Space Agency (ESA)**. Its primary goal was to study **Earth’s magnetosphere** and **solar wind** from the **L1 Lagrange point**, a stable orbit between Earth and the Sun.

- **Launch**: August 12, 1978, aboard a **Delta 2000 rocket** (D-144 variant) from **Cape Canaveral SLC-17B**.
- **Initial Orbit**: Placed into a **halo orbit around L1 Earth-Sun** (November 20, 1978 – June 10, 1982).
- **Mass & Dimensions**:
  - Launch weight: **479 kg**
  - Dry weight: **390 kg**
  - Height: **1.58 m**
  - Diameter: **1.77 m**

### Repurposing for Comet Exploration
After completing its magnetospheric mission, NASA **repurposed ISEE-3** in **1983** to study comets, renaming it the **International Cometary Explorer (ICE)**.

- **Trajectory Change**: Used **five lunar flybys** (March–December 1983) to eject the spacecraft from Earth’s orbit and send it toward **Comet Giacobini-Zinner**.
- **Comet Giacobini-Zinner Flyby (September 11, 1985)**:
  - Closest approach: **7,862 km** from the comet’s nucleus.
  - First direct measurement of a **comet’s plasma tail**.
- **Halley’s Comet Flyby (March 28, 1986)**:
  - Distance: **40.2 million km** (distant observation due to fuel constraints).

### Scientific Instruments & Power
ICE carried **13 scientific instruments** to study:
- **Solar wind plasma**
- **Cosmic rays**
- **Magnetic fields**
- **Cometary particles**

- **Power Source**:
  - **173-watt solar array**
  - **Hydrazine reaction control system** (12 thrusters, 12 kg of propellant)

### End of Mission
- **Last contact**: May 5, 1997 (officially retired).
- **Legacy**: Paved the way for future comet missions like **Stardust** and **Rosetta**.

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## References

1. [Source](https://solarsystem.nasa.gov/missions/isee-3-ice/in-depth/)
2. [Source](https://space.skyrocket.de/doc_sdat/explorer_isee-3.htm)
3. Jonathan's Space Report
4. [Source](https://directory.eoportal.org/web/eoportal/satellite-missions/i/isee-3)
5. Freebase Data Dumps. 2013
6. [Source](http://solarsystem.nasa.gov/missions/profile.cfm?MCode=ISEEICE&Display=ReadMore)
7. [Source](https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1978-079A)
8. [Source](https://www.spaceflightinsider.com/space-flight-history/our-spaceflight-heritage-ice-the-first-comet-flyby/)
9. [Source](https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/req/naif_ids.html)