# CALIPSO

> decommissioned joint NASA and CNES Earth observation satellite

**Wikidata**: [Q35494](https://www.wikidata.org/wiki/Q35494)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/CALIPSO)  
**Source**: https://4ort.xyz/entity/calipso

## Summary
CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) was a joint Earth observation satellite mission operated by NASA in the United States and CNES in France. Launched in 2006 and decommissioned in 2023, the spacecraft was designed to observe the Earth from orbit to study the role of clouds and aerosols in the climate system.

## Key Facts
*   **Official Name:** Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO).
*   **Operators:** Joint mission between the National Aeronautics and Space Administration (NASA) and the Centre National d'Études Spatiales (CNES).
*   **Launch Date:** April 28, 2006, at 10:02:16 UTC.
*   **Launch Vehicle:** Delta II (variant D-314).
*   **Launch Site:** Vandenberg Space Launch Complex 2 West.
*   **Decommissioning:** The mission ended service retirement on August 1, 2023, followed by spacecraft decommissioning on December 15, 2023.
*   **Orbit:** Sun-synchronous orbit.
*   **Satellite Bus:** PROTEUS.
*   **Physical Specifications:** The spacecraft had a launch mass of 635 kilograms, a width of 1.84 meters, a height of 2.31 meters, and a length of 1.49 meters.

## FAQs
### Q: What was the primary purpose of the CALIPSO satellite?
A: CALIPSO was an Earth observation satellite designed to study the impact of clouds and aerosols on Earth's climate. It provided data to help scientists understand how these atmospheric elements affect the Earth's radiation budget.

### Q: Who built and operated CALIPSO?
A: The spacecraft bus was manufactured by Alcatel Space. It was jointly operated by NASA (National Aeronautics and Space Administration) and CNES (the French space agency).

### Q: How long was the CALIPSO mission active?
A: CALIPSO launched on April 28, 2006, and provided data until its service retirement on August 1, 2023, operating for over 17 years.

## Why It Matters
CALIPSO served a critical role in Earth science by providing a vertical view of the atmosphere that passive sensors could not achieve. As a joint endeavor between the United States and France, it exemplified international cooperation in space-based climate research. The satellite was a key component of the "A-Train" (Afternoon Train) constellation—a formation of satellites flying in close proximity to study the Earth's water cycle and atmospheric composition—before moving to the "C-Train" later in its mission life.

By utilizing its primary instrument, the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), the mission revolutionized the understanding of the vertical structure of clouds and aerosols. This data was essential for improving climate models, predicting weather patterns, and assessing air quality. The mission's longevity, spanning nearly two decades, provided a long-term dataset that is invaluable for tracking climate change and atmospheric trends, distinguishing it as one of the most successful Earth-observing partnerships.

## Notable For
*   **Joint International Mission:** A collaborative effort between NASA (USA) and CNES (France).
*   **Constellation Formation Flying:** A long-term member of the A-Train satellite constellation (until 2018) and later the C-Train.
*   **Longevity:** Operational for over 17 years (2006–2023).
*   **Specific Atmospheric Focus:** Designed to measure the vertical distribution of clouds and aerosols, including volcanic ash and dust.
*   **Principal Investigator:** The scientific mission was led by Principal Investigator David M. Winker.

## Body

### Mission History
The CALIPSO mission began with a significant event on **April 28, 2006**, when it was launched aboard a **Delta II** rocket (variant D-314) from **Vandenberg Space Launch Complex 2 West**. It shared this launch event with the **CloudSat** satellite.

Upon reaching orbit, CALIPSO entered a **Sun-synchronous orbit**, allowing it to pass over the same point on Earth at roughly the same local time every day. This orbit is optimal for consistent lighting conditions in observation data.

### Constellation Membership
CALIPSO was an integral part of a coordinated satellite formation:
*   **A-Train:** It was part of the A-Train constellation. According to provided data, its membership in this formation is noted around early 2018, prior to its transition.
*   **C-Train:** Following its time in the A-Train, CALIPSO moved to the C-Train, operating there from **September 20, 2018**, until **August 1, 2023**.

### End of Mission
The mission concluded in two stages:
1.  **Service Retirement:** Occurred on **August 1, 2023**.
2.  **Spacecraft Decommissioning:** Officially finalized on **December 15, 2023**.

### Technical Specifications
The spacecraft was built on the **PROTEUS** bus, a versatile satellite platform often used for low-Earth orbit missions.
*   **Mass:** 635 kg (Launch weight).
*   **Dimensions:**
    *   Width: 1.84 meters
    *   Height: 2.31 meters
    *   Length: 1.49 meters
*   **Power:** The spacecraft was powered by a **spacecraft solar array** consisting of two panels.
*   **Identifiers:**
    *   COSPAR ID: 2006-016B
    *   NSSDCA ID: 2006-016B
    *   SCN (Satellite Catalog Number): 29108

### Alternate Names and Aliases
The mission has been referred to by several names and acronyms throughout its development and history, including:
*   ESSP 3 / ESSP3
*   PICASSO-CENA
*   Pathfinder Instrument for Cloud and Aerosol Spaceborne Obeservation - Climatologie Etendue des Nuages et des Aerosols

## References

1. [Source](https://space.skyrocket.de/doc_sdat/calipso.htm)
2. [Source](https://atrain.nasa.gov/)
3. [Source](https://calipso.cnes.fr/en/calipso-bows-out)
4. Jonathan's Space Report
5. [Source](https://atrain.nasa.gov/publications/CALIPSO.pdf)
6. Freebase Data Dumps. 2013
7. [Source](https://gizmodo.com/nasa-calipso-cloud-observing-satellite-mission-ends-1850879472)
8. [Source](https://cnes.fr/en/projects/calipso)