# Pioneer Venus Orbiter

> NASA space probe to Venus

**Wikidata**: [Q1611468](https://www.wikidata.org/wiki/Q1611468)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Pioneer_Venus_Orbiter)  
**Source**: https://4ort.xyz/entity/pioneer-venus-orbiter

## Summary
The Pioneer Venus Orbiter (also known as Pioneer Venus 1 or Pioneer 12) was a NASA space probe designed to investigate Venus from orbit. Launched in May 1978, it was the first component of the Pioneer Venus project to arrive at the planet, entering an elliptical orbit in December 1978. The spacecraft operated for 14 years until it ceased transmitting in October 1992 and subsequently entered the Venusian atmosphere.

## Key Facts
*   **Names & IDs:** Also known as Pioneer Venus 1, Pioneer 12, and PVO; COSPAR ID 1978-051A.
*   **Launch Date:** May 20, 1978, at 13:13:00 UTC.
*   **Launch Site:** Cape Canaveral Launch Complex 36.
*   **Launch Vehicle:** Atlas SLV-3D Centaur-D1AR (AC-50).
*   **Operator:** NASA Ames Research Center.
*   **Manufacturer:** Hughes Aircraft Company.
*   **Mass:** 582 kg (launch weight); 517 kg (dry weight).
*   **Orbital Period:** 24 hours.
*   **Mission End:** Loss of signal on October 8, 1992; atmospheric entry on October 22, 1992.
*   **Dimensions:** 1.2 meters in length and 2.5 meters in diameter.

## FAQs
### Q: When did the Pioneer Venus Orbiter reach Venus?
A: The spacecraft began orbital activity around Venus on December 4, 1978, approximately six months after its launch in May.

### Q: How long did the Pioneer Venus Orbiter mission last?
A: The mission lasted over 14 years. It launched in May 1978 and continued operating until it lost signal in October 1992, far exceeding its planned lifespan.

### Q: What was the fate of the Pioneer Venus Orbiter?
A: Following the loss of signal on October 8, 1992, the spacecraft underwent uncontrolled reentry and atmospheric entry into Venus on October 22, 1992.

## Why It Matters
The Pioneer Venus Orbiter represents a significant chapter in the United States' exploration of the inner solar system. As the orbital component of the two-part Pioneer Venus mission (followed by the Pioneer Venus Multiprobe), it provided a sustained platform for observing the planet Venus.

Its mission architecture was notable for its durability; designed as a planetary probe to investigate a celestial body, it maintained a 24-hour orbital period that allowed for consistent data collection over a decade and a half. The spacecraft's highly elliptical orbit (with a periapsis of 181.6 km and apoapsis of 66,630 km) enabled it to sample both the upper atmosphere and the space environment around Venus. By the time of its uncontrolled reentry in 1992, it had served as one of the longest-running planetary missions of its era, bridging the gap between early Mariner flybys and later missions like Magellan.

## Notable For
*   **Longevity:** Operated for nearly 14 years in the harsh environment near Venus before burning up in the atmosphere.
*   **Mission Design:** Featured a highly eccentric orbit (eccentricity 0.842) allowing it to act as both an atmospheric probe at low altitudes and a space physics observatory at high altitudes.
*   **Orbital Period:** Possessed a precise 24-hour orbital period, synchronous with Earth-based operations.
*   **Series Succession:** It followed **Pioneer 11** in the broader Pioneer program chronology and preceded the **Pioneer Venus Multiprobe** in the specific Venus project sequence.
*   **Power System:** Generated a nominal power output of 312 watts.

## Body
### Development and Launch
Designated as a **planetary probe** and **orbiter**, the Pioneer Venus Orbiter was manufactured by **Hughes Aircraft Company** and operated by NASA's **Ames Research Center**. It was launched atop an **Atlas SLV-3D Centaur-D1AR** rocket from **Cape Canaveral Launch Complex 36** on **May 20, 1978**. At launch, the spacecraft weighed **582 kilograms**, consisting of a dry mass of 517 kg and propellant.

### Orbital Specifications
Upon arrival at Venus on **December 4, 1978**, the probe entered a distinct elliptical orbit designed for comprehensive study.
*   **Periapsis:** 181.6 km (closest approach)
*   **Apoapsis:** 66,630 km (farthest point)
*   **Inclination:** 105 degrees
*   **Semi-major axis:** 33,405.8 km
*   **Eccentricity:** 0.842

This orbit facilitated a **24-hour orbital period**, allowing for regular communication windows and systematic mapping of the planet.

### End of Mission
The mission concluded in October 1992. Significant events included:
*   **October 8, 1992:** Loss of signal occurred as the spacecraft's power system degraded.
*   **October 22, 1992:** The probe officially ended its mission via **atmospheric entry** into Venus, where it was destroyed.

## References

1. Jonathan's Space Report
2. [Source](https://space.skyrocket.de/doc_sdat/pioneer-12.htm)
3. [Source](https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/req/naif_ids.html)