# Cassini

> space probe that went to Saturn, part of Cassini−Huygens mission

**Wikidata**: [Q2941291](https://www.wikidata.org/wiki/Q2941291)  
**Source**: https://4ort.xyz/entity/cassini

## Summary
Cassini was a sophisticated space probe and orbiter designed to investigate Saturn as the primary element of the Cassini-Huygens mission. Launched in 1997, the spacecraft spent 13 years orbiting the ringed planet from 2004 until its deliberate atmospheric entry in 2017. It was equipped with a suite of instruments and radioisotope power systems intended for long-term deep-space observation.

## Key Facts
- **Mission Identity:** Cassini was a planetary probe and orbiter, part of the joint Cassini-Huygens mission (COSPAR ID: 1997-061A).
- **Launch Date:** October 15, 1997, at 08:43:01 UTC from Cape Canaveral Space Launch Complex 40.
- **Launch Vehicle:** Titan IV (specifically Titan IV-B-33) rocket equipped with a Centaur upper stage (TC-21).
- **Mass:** 5,254 kilograms at launch (wet mass) and 2,113 kilograms dry.
- **Dimensions:** The spacecraft measured 6.7 meters in height and 4.0 meters in width.
- **Saturn Orbit:** Entered cronocentric orbit (Saturn orbit) on July 1, 2004, and remained active until September 15, 2017.
- **Power Source:** Powered by 3 GPHS-RTG units (Radioisotope Thermoelectric Generators) and 82 radioisotope heater units.
- **Operator:** Managed and operated by the Jet Propulsion Laboratory (JPL).
- **End of Mission:** Concluded via controlled atmospheric entry into Saturn on September 15, 2017.

## FAQs
### Q: When was the Cassini probe launched and by whom?
A: Cassini was launched on October 15, 1997, aboard a Titan IV rocket. While the Jet Propulsion Laboratory served as the general contractor and operator, major components were manufactured by Lockheed Martin Space, Aerojet Rocketdyne, and the Italian Space Agency.

### Q: How was the Cassini spacecraft powered?
A: The spacecraft utilized three GPHS-RTG nuclear batteries for electric power, generating 879 watts at launch and 601 watts by the end of the mission in 2017. It also employed 82 radioisotope heater units to maintain temperature.

### Q: How did the Cassini mission end?
A: The mission concluded on September 15, 2017, when the spacecraft performed a controlled dive into Saturn's atmosphere. This maneuver, known as the "Grand Finale," ensured the disposal of the probe while maximizing scientific data return.

## Why It Matters
Cassini represents one of the most ambitious and complex robotic expeditions ever undertaken in planetary science. As the first spacecraft to orbit Saturn, it provided a comprehensive, long-term study of the planet's atmosphere, magnetosphere, and ring system, fundamentally altering our understanding of the gas giant.

The mission is distinguished by its endurance and international collaboration. Engineered to survive the harsh radiation and thermal environment of deep space for nearly two decades, Cassini bridged the gap between initial reconnaissance and detailed, in-situ analysis. Its "Grand Finale" in 2017—diving between the planet and its rings before atmospheric destruction—demonstrated advanced risk-taking to gather unique data that would otherwise be impossible to obtain. The spacecraft's connection to the Huygens probe also made it a critical relay point for humanity's first landing in the outer solar system (on Titan).

## Notable For
- Being the first spacecraft to enter and maintain orbit around Saturn (July 1, 2004).
- Completing a complex seven-year cruise involving gravity assists from Venus (twice), Earth, and Jupiter.
- Executing a "Grand Finale" involving 22 dives between Saturn and its rings before atmospheric entry.
- Utilizing nuclear power (GPHS-RTG) for a deep-space mission lasting nearly 20 years.
- Acting as the communications relay for the Huygens lander.

## Body

### Technical Specifications and Manufacturing
The Cassini orbiter was a massive spacecraft with a launch mass of 5,254 kilograms. Standing 6.7 meters tall and 4.0 meters wide, it was built to withstand the extremes of the outer solar system.
*   **General Contractor:** Jet Propulsion Laboratory (JPL).
*   **Key Manufacturers:** Lockheed Martin Space (propulsion module), Aerojet Rocketdyne (propulsion), Italian Space Agency (high-gain antenna and other components), and the United States Department of Energy (power systems).
*   **Propulsion:** The craft used a bipropellant system featuring two R-4D-11 main engines and 16 MR-103H thrusters for reaction control.
*   **Power:** Electricity was generated by three GPHS-RTG units, which provided 879 watts of power at launch, declining to 601 watts by 2017 due to the decay of the plutonium fuel. It also carried 82 Radioisotope Heater Units (RHUs) for thermal management.

### Launch and Trajectory (1997–2004)
Cassini launched on October 15, 1997, utilizing a Titan IV-B rocket with a Centaur upper stage (TC-21). To build up enough speed to reach Saturn, it executed a "VEEGA" (Venus-Earth-Earth Gravity Assist) trajectory:
*   **Venus Flybys:** April 26, 1998 (284 km altitude) and June 24, 1999 (623 km altitude).
*   **Earth Flyby:** August 18, 1999 (1,171 km altitude).
*   **Asteroid Flyby:** January 23, 2000 (1.5 million km from 2685 Masursky).
*   **Jupiter Flyby:** December 30, 2000 (9.7 million km altitude), providing a final gravity assist toward Saturn.

### Saturn Operations (2004–2017)
Cassini entered a cronocentric orbit (Saturn orbit) on July 1, 2004. It served as the primary orbiter for the system, studying the planet, its rings, and its moons.
*   **Huygens Deployment:** The spacecraft carried and deployed the Huygens probe (constructed by ESA) to land on Saturn's moon Titan.
*   **Orbital Activity:** For over 13 years, Cassini mapped the surface of Titan, discovered new moons, and analyzed the icy plumes of Enceladus.
*   **Social Engagement:** The mission maintained an active public presence via the Twitter handle @CassiniSaturn, accumulating over 335,000 followers by May 2025.

### End of Mission
The mission concluded on September 15, 2017, with the spacecraft's scheduled atmospheric entry into Saturn. This destruction was planned to prevent biological contamination of Saturn's potentially habitable moons, such as Enceladus and Titan. The final signal was received by JPL on that date.

## References

1. [Source](https://science.nasa.gov/mission/cassini/faq/)
2. [Source](https://news.lockheedmartin.com/2004-07-01-The-Cassini-Spacecraft-Enters-Saturn-Orbit-With-Help-From-Lockheed-Martin-Built-Propulsion-Module)
3. [Source](https://spacenews.com/aerojet-rocketdyne-propulsion-guides-cassini-on-its-grand-finale-at-saturn/)
4. [Source](https://science.nasa.gov/resource/international-cooperation/)
5. [Source](https://www.energy.gov/articles/nuclear-heart-cassini)
6. Jonathan's Space Report
7. [Source](https://science.nasa.gov/mission/cassini/radioisotope-thermoelectric-generator/)
8. Final Cassini Propulsion System In-Flight Characterization
9. [Source](https://space.skyrocket.de/doc_sdat/cassini.htm)
10. [Source](https://science.nasa.gov/mission/cassini/spacecraft/cassini-orbiter/)
11. [Source](https://www.nasa.gov/press-release/nasa-s-cassini-spacecraft-ends-its-historic-exploration-of-saturn)
12. [Source](https://science.nasa.gov/mission/cassini-huygens/)
13. [Source](https://www.americanscientist.org/article/cassini-the-first-one-thousand-days)
14. [Source](https://www.planetary.org/articles/0915-cassini-the-dying-of-the-light)
15. [Source](https://science.nasa.gov/mission/cassini/quick-facts/)
16. [Source](https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/req/naif_ids.html)