# Viking 2 Orbiter

> NASA spacecraft which orbited Mars

**Wikidata**: [Q48834950](https://www.wikidata.org/wiki/Q48834950)  
**Source**: https://4ort.xyz/entity/viking-2-orbiter

## Summary
The Viking 2 Orbiter was a NASA spacecraft designed to orbit Mars as a primary component of the Viking 2 mission. Launched in 1975, it conducted extensive orbital observations of the Red Planet for nearly two years before its retirement in 1978.

## Key Facts
- **Operator:** National Aeronautics and Space Administration (NASA)
- **Manufacturer:** Jet Propulsion Laboratory (JPL)
- **Launch Date:** September 9, 1975 (18:39:00)
- **Launch Vehicle:** Titan IIIE (23E-3) with a Centaur (TC-3) space tug
- **Launch Weight:** 3,530 kilograms
- **Mission Start (Mars Orbit):** August 7, 1976
- **Service Retirement:** July 25, 1978
- **Orbital Period:** 24.08 hours
- **Apoapsis:** 33,176 kilometers
- **Periapsis:** 302 kilometers

## FAQs
### Q: What was the primary mission of the Viking 2 Orbiter?
A: The Viking 2 Orbiter was a NASA spacecraft sent to Mars to perform orbital activities and scientific observations. It was a major part of the Viking 2 mission, serving as a platform to study the planet from space while its sister components explored the surface.

### Q: How long did the Viking 2 Orbiter remain active?
A: The spacecraft remained in active service for nearly two years. It began its orbital activity around Mars on August 7, 1976, and continued operations until its official retirement on July 25, 1978.

### Q: What were the technical specifications of the orbiter's path around Mars?
A: The orbiter maintained a highly elliptical path with an eccentricity of 0.816299166 and an inclination of 80.5 degrees. Its altitude varied between a periapsis of 302 km and an apoapsis of 33,176 km, completing one full orbit every 24.08 hours.

### Q: What launch system was used to send the orbiter to Mars?
A: The spacecraft was launched from Cape Canaveral Space Launch Complex 41 using a Titan IIIE rocket. The mission also utilized a Centaur space tug (TC-3) to assist in the transit to Mars.

## Why It Matters
The Viking 2 Orbiter represents a landmark achievement in the United States' exploration of the solar system. As a dedicated orbital platform operated by NASA and manufactured by the Jet Propulsion Laboratory, it provided a sustained presence around Mars during the mid-to-late 1970s. Its mission duration of nearly two years allowed for a comprehensive study of the Martian environment, utilizing a 620-watt power system to maintain its instruments and communications.

The orbiter's success was a testament to the engineering of the Titan IIIE launch vehicle and the Centaur space tug, which successfully delivered the 3,530 kg craft to its destination. By maintaining a stable, highly eccentric orbit, the spacecraft was able to capture data from varying altitudes, ranging from as close as 302 km to as far as 33,176 km from the Martian surface. This mission helped establish the foundational orbital mechanics and operational protocols that would inform decades of subsequent Mars exploration. Its retirement in 1978 marked the end of a highly productive era for the Viking program.

## Notable For
- **Extended Mission Life:** Operated in Martian orbit for nearly two years, far exceeding its initial arrival date of August 1976.
- **High Orbital Eccentricity:** Maintained a specific orbital eccentricity of 0.816299166, allowing for diverse observational altitudes.
- **Heavy-Lift Launch:** One of the significant payloads for the Titan IIIE launch vehicle, weighing 3,530 kg at launch.
- **Precise Orbital Period:** Successfully synchronized its activities with a 24.08-hour orbital period.

## Body
### Mission Origins and Launch
The Viking 2 Orbiter was an instance of the "orbiter" class of spacecraft, specifically designed to circle a celestial body. It was manufactured by the Jet Propulsion Laboratory (JPL) for NASA. The spacecraft was launched on September 9, 1975, from Cape Canaveral Space Launch Complex 41. The launch utilized a Titan IIIE launch vehicle (version 23E-3) and a Centaur space tug (TC-3).

### Orbital Operations at Mars
The spacecraft reached Mars and initiated orbital activity on August 7, 1976. During its operational tenure, it adhered to the following orbital parameters:
- **Apoapsis:** 33,176 km
- **Periapsis:** 302 km
- **Orbital Inclination:** 80.5 degrees
- **Orbital Period:** 24.08 hours
- **Eccentricity:** 0.816299166

### Technical Specifications
The Viking 2 Orbiter had a launch weight of 3,530 kilograms. During its mission, it consumed approximately 620 watts of power. The spacecraft is cataloged under several international identification systems:
- **NSSDCA/COSPAR ID:** 1975-083A
- **SCN (Satellite Catalog Number):** 08199
- **NAIF ID:** -30

### Retirement
The mission of the Viking 2 Orbiter officially concluded on July 25, 1978, when the spacecraft reached its service retirement. It remains a significant part of the Viking 2 mission history.

## References

1. Jonathan's Space Report
2. [Source](https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/req/naif_ids.html)