# CloudSat

> decommissioned NASA Earth observation satellite

**Wikidata**: [Q49397](https://www.wikidata.org/wiki/Q49397)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/CloudSat)  
**Source**: https://4ort.xyz/entity/cloudsat

## Summary
CloudSat was a decommissioned NASA Earth observation satellite designed to study the vertical structure of clouds and precipitation from orbit. Launched on April 28, 2006, the satellite utilized a Cloud Profiling Radar to provide critical data on cloud properties for 17 years. It was decommissioned on March 20, 2024, after concluding its operational mission in December 2023.

## Key Facts
- **Classification:** Earth observation satellite (instance_of).
- **Launch Date:** April 28, 2006, at 10:02:16 UTC.
- **Launch Vehicle:** Delta II (specifically D-314).
- **Launch Site:** Vandenberg Space Launch Complex 2 West.
- **Operator:** National Aeronautics and Space Administration (NASA).
- **Manufacturer:** Ball Aerospace & Technologies.
- **Mass:** 999 kilograms (launch weight).
- **Dimensions:** 2.3 meters (width) x 2.8 meters (height) x 2.3 meters (length).
- **Orbit:** Sun-synchronous orbit.
- **Constellation Membership:** Part of the "A-Train" (2006–2018) and later the "C-Train" (2018–2023).
- **Mission End:** Service retirement on December 20, 2023; spacecraft decommissioning on March 20, 2024.

## FAQs
### Q: What was the primary instrument on CloudSat?
A: CloudSat carried the Cloud Profiling Radar (CPR), a scientific instrument designed to observe the vertical structure of clouds. It was the first satellite-borne radar to provide such detailed global cloud profiles.

### Q: How long did the CloudSat mission last?
A: CloudSat launched on April 28, 2006, and entered service in June 2006. It remained operational for 17 years until its service retirement on December 20, 2023.

### Q: What was the "A-Train" in relation to CloudSat?
A: The "A-Train" (Afternoon Train) was a satellite constellation formation. CloudSat flew in this formation from April 28, 2006, until February 22, 2018, allowing it to coordinate observations with other Earth science satellites.

## Why It Matters
CloudSat represented a significant advancement in Earth science by allowing researchers to look inside clouds rather than just observing their tops. By carrying the first space-based Cloud Profiling Radar, it provided the first global, vertical profiles of cloud structure. This data was essential for improving weather forecasting, understanding the Earth's hydrological cycle, and refining climate models regarding how clouds reflect and absorb solar energy.

The satellite's longevity allowed for a 17-year record of cloud data, bridging the gap between earlier experimental missions and modern operational systems. Its transition from the A-Train to the C-Train constellation demonstrated flexible operational capabilities, ensuring data continuity even after its orbit was lowered in 2018.

## Notable For
- **First Cloud Profiling Radar:** CloudSat was the first satellite to carry a millimeter-wavelength radar (Cloud Profiling Radar) capable of probing the vertical internal structure of clouds.
- **A-Train Constellation Member:** It was a core component of NASA's "A-Train" formation, flying in tight coordination with other satellites like CALIPSO to provide a comprehensive view of the atmosphere.
- **Long Operational Life:** The mission successfully operated for 17 years, far exceeding its original planned mission duration, providing a long-term climate data record.
- **Scientific Leadership:** The mission was led by Principal Investigator Graeme Stephens and involved significant contributions from Colorado State University and Ball Aerospace.

## Body

### Mission History
CloudSat was launched on April 28, 2006, aboard a Delta II rocket (vehicle code D-314) from Vandenberg Space Launch Complex 2 West. It entered service in June 2006. Initially, CloudSat was placed in a Sun-synchronous orbit as part of the "A-Train" constellation, a group of satellites flying in close proximity to synchronize their observations. CloudSat remained in the A-Train until February 22, 2018.

Following a battery anomaly, the satellite was moved to a lower orbit, known as the "C-Train," on May 7, 2018. It continued operations in this formation until its service retirement on December 20, 2023. The spacecraft was officially decommissioned on March 20, 2024.

### Technical Specifications
The CloudSat spacecraft was built by Ball Aerospace & Technologies using the BCP-2000 bus. It had a launch mass of 999 kilograms. The satellite's physical dimensions were 2.3 meters in width, 2.8 meters in height, and 2.3 meters in length. It was powered by two solar arrays capable of generating 700 watts of power.

### Scientific Instrumentation
The primary payload was the Cloud Profiling Radar (CPR). This instrument was specifically designed to measure the vertical profile of cloud liquid water and ice content. The data collected by the CPR helped scientists understand the crucial role clouds play in the Earth's radiation budget and climate system. The mission was managed by NASA, with Graeme Stephens serving as the Principal Investigator.

## References

1. [Source](https://space.skyrocket.de/doc_sdat/cloudsat.htm)
2. [Source](https://atrain.nasa.gov/)
3. Jonathan's Space Report
4. [Source](https://atrain.nasa.gov/publications/CloudSat.pdf)
5. Freebase Data Dumps. 2013
6. [Source](https://engr.source.colostate.edu/cloudsat-first-cloud-profiling-radar-developed-by-csu-ends-its-17-year-mission/)
7. [Source](https://www.ssc.spaceforce.mil/Portals/3/Documents/PRESS%20RELEASES/US%20Space%20Forces%20Space%20Systems%20Command%20Completes%20CloudSat%20Operational%20Mission.pdf?ver=sgYx3Xci6WlEauYVYgw-RQ%3D%3D)