# Pioneer Venus Large Probe

> Large Probe (Sounder Probe) of the Pioneer Venus Multiprobe mission

**Wikidata**: [Q113129811](https://www.wikidata.org/wiki/Q113129811)  
**Source**: https://4ort.xyz/entity/pioneer-venus-large-probe

## Summary
The Pioneer Venus Large Probe, also known as the Sounder Probe, was a scientific lander and a primary component of the Pioneer Venus Multiprobe mission. Launched by NASA in 1978, the probe was designed to descend through the atmosphere of Venus to the surface to collect environmental data.

## Key Facts
- **Classification:** Lander (part of the Pioneer Venus Multiprobe mission)
- **Launch Date:** August 8, 1978, at 07:33:00
- **Landing Date:** December 9, 1978, at 19:39:55 (Spacecraft Event Time)
- **Mass:** 315 kilograms
- **Diameter:** 1.5 meters
- **Manufacturer:** Hughes Aircraft Company
- **Operator:** Ames Research Center
- **Power Source:** 40 Ah silver-zinc battery
- **Launch Vehicle:** Atlas SLV-3D Centaur-D1AR (AC-51)
- **Landing Coordinates:** 4.4° latitude, 304° longitude on Venus

## FAQs
### Q: What was the primary purpose of the Pioneer Venus Large Probe?
A: Known as the Sounder Probe, its primary purpose was to serve as a lander for the Pioneer Venus Multiprobe mission. It was designed to descend through the Venusian atmosphere to the surface, providing critical data from the planet's environment.

### Q: When and where did the Pioneer Venus Large Probe land?
A: The probe reached the surface of Venus on December 9, 1978, at 19:39:55. It landed at the coordinates 4.4° latitude and 304° longitude.

### Q: Who was responsible for the construction and operation of the probe?
A: The Pioneer Venus Large Probe was manufactured by the Hughes Aircraft Company and operated by NASA’s Ames Research Center. It was launched from the United States using an Atlas SLV-3D Centaur-D1AR rocket.

## Why It Matters
The Pioneer Venus Large Probe was a critical technical achievement in the exploration of the inner solar system. As the "Sounder Probe" of the Pioneer Venus Multiprobe mission, it was specifically engineered to survive the descent through one of the most hostile environments in the solar system. Its mission provided a direct physical presence within the Venusian atmosphere, allowing for measurements that could not be obtained by orbiting spacecraft alone.

The probe's successful delivery to the surface of Venus on December 9, 1978, demonstrated the precision of the Ames Research Center and the manufacturing capabilities of the Hughes Aircraft Company. By utilizing a specialized 40 Ah silver-zinc battery, the probe was able to maintain power during its descent and impact. This mission remains a foundational event in planetary science, contributing to the United States' early efforts to understand the atmospheric composition and surface conditions of Earth's neighbor. Its role within the larger Multiprobe mission allowed for a coordinated, multi-point study of the planet, which helped define the characteristics of the Venusian greenhouse effect and atmospheric dynamics.

## Notable For
- **Sounder Mission Role:** Served as the largest of the four probes deployed by the Pioneer Venus Multiprobe to study the atmosphere of Venus.
- **Precise Landing:** Successfully reached the surface of Venus at the specific coordinates of 4.4° latitude and 304° longitude.
- **Specialized Power System:** Operated using a 40 Ah silver-zinc battery designed to function during the atmospheric descent.
- **Atmospheric Entry:** Recorded a specific orbit decay time of 18:45:32 on December 9, 1978, prior to its final landing/impact.

## Body

### Mission Overview
The Pioneer Venus Large Probe was a central element of the Pioneer Venus Multiprobe mission, also known as Pioneer 13. It was launched from Cape Canaveral Launch Complex 36 on August 8, 1978. The mission was managed by the Ames Research Center and represented a major effort by the United States to conduct in-situ measurements of Venus.

### Technical Specifications
The probe was a compact, highly specialized vehicle:
- **Mass:** 315 kg
- **Diameter:** 1.5 m
- **Manufacturer:** Hughes Aircraft Company
- **Power:** 40 Ah silver-zinc battery

### Launch and Deployment
The probe was launched aboard an Atlas SLV-3D Centaur-D1AR expendable launch vehicle (specifically the AC-51 configuration). After its transit to Venus, the probe separated from the main multiprobe bus to begin its independent descent.

### Descent and Surface Impact
On December 9, 1978, the probe entered the Venusian atmosphere. The following sequence of events was recorded in Spacecraft Event Time:
- **Orbit Decay:** 18:45:32
- **Landing/Impact:** 19:39:55

The probe came to rest on the surface of Venus at 4.4° latitude and 304° longitude. As a lander, it was designed to descend toward and come to rest on the surface of the astronomical body, providing a direct link between Earth and the Venusian environment.

## References

1. [Source](https://space.skyrocket.de/doc_sdat/pioneer-13.htm)
2. [Source](https://www.nasa.gov/centers-and-facilities/ames/40-years-ago-pioneers-encounter-venus/)
3. Jonathan's Space Report
4. [Source](https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1978-078D)