# Apollo 15 Subsatellite

> The Apollo Saturn V SIVB was the third stage of the Saturn V booster.

**Wikidata**: [Q111912938](https://www.wikidata.org/wiki/Q111912938)  
**Source**: https://4ort.xyz/entity/apollo-15-subsatellite

## Summary
The Apollo 15 Subsatellite was a small scientific satellite deployed from the Apollo 15 Command/Service Module during the mission. It was launched on July 26, 1971, aboard a Saturn V rocket and operated in lunar orbit to conduct scientific experiments. The subsatellite was part of NASA's Apollo program and carried instruments to study the Moon's magnetic field, solar wind, and other phenomena.

## Key Facts
- Launched on July 26, 1971, aboard a Saturn V rocket
- Deployed from the Apollo 15 Command/Service Module
- Operated in lunar orbit for scientific research
- Carried instruments to study the Moon's magnetic field and solar wind
- Part of NASA's Apollo program
- Weighed approximately 35.6 kg (78.5 lbs)
- Powered by solar cells and chemical batteries
- Designed for a one-year mission but operated for 18 months
- Data helped scientists understand lunar environment and space weather
- Contributed to knowledge of the Moon's composition and structure

## FAQs
### Q: What was the purpose of the Apollo 15 Subsatellite?
A: The Apollo 15 Subsatellite was designed to conduct scientific experiments in lunar orbit, studying the Moon's magnetic field, solar wind, and other phenomena to enhance our understanding of the lunar environment and space weather.

### Q: How long did the Apollo 15 Subsatellite operate?
A: The Apollo 15 Subsatellite was designed for a one-year mission but exceeded expectations by operating for 18 months in lunar orbit before its mission ended.

### Q: What kind of data did the Apollo 15 Subsatellite collect?
A: The Apollo 15 Subsatellite collected data on the Moon's magnetic field, solar wind, and other lunar phenomena, contributing to our knowledge of the Moon's composition, structure, and interaction with space weather.

## Why It Matters
The Apollo 15 Subsatellite was a crucial component of NASA's Apollo program, extending scientific exploration beyond the lunar surface. By operating in lunar orbit for an extended period, it provided continuous data collection that would have been impossible during brief surface missions. This satellite helped scientists understand the Moon's magnetic field, solar wind interactions, and other phenomena that are essential for planning future lunar missions and understanding the Moon's role in the Earth-Moon system. The data collected by the Apollo 15 Subsatellite contributed to our knowledge of space weather and its effects on spacecraft, which is vital for the safety and success of future space exploration missions. Additionally, the success of this small satellite demonstrated the feasibility of using lunar orbit for long-term scientific studies, paving the way for more advanced lunar satellites and potential future lunar bases.

## Notable For
- First scientific satellite deployed from a crewed Apollo mission
- Longest-operating lunar satellite at the time (18 months)
- Provided continuous data on lunar magnetic field and solar wind
- Demonstrated the feasibility of extended lunar orbit missions
- Contributed to understanding of space weather effects on spacecraft

## Body
### Design and Construction
The Apollo 15 Subsatellite was a small, drum-shaped spacecraft measuring approximately 48 cm (19 inches) in diameter and 56 cm (22 inches) in height. It was constructed primarily of aluminum and weighed 35.6 kg (78.5 lbs) at launch. The satellite's exterior was covered with solar cells to provide power, supplemented by chemical batteries for energy storage.

### Scientific Instruments
The subsatellite carried three main scientific instruments:
1. A magnetometer to measure the Moon's magnetic field
2. A plasma detector to study the solar wind
3. A lunar dust detector to measure the accumulation of interplanetary dust particles

### Deployment and Operation
The Apollo 15 Subsatellite was deployed from the Apollo 15 Command/Service Module on August 4, 1971, during the mission's return journey to Earth. It was placed into a lunar orbit with an inclination of 28 degrees, a perilune of 100 km (62 miles), and an apolune of 170 km (106 miles). The satellite's orbit was designed to provide comprehensive coverage of the Moon's near and far sides.

### Mission Results
During its 18-month operational period, the Apollo 15 Subsatellite transmitted valuable data back to Earth, including:
- Detailed measurements of the Moon's weak magnetic field
- Information on the interaction between the solar wind and the lunar surface
- Data on the distribution of lunar mass concentrations (mascons)
- Observations of meteoroid impacts on the lunar surface

The mission's success led to the deployment of similar subsatellites on subsequent Apollo missions, further expanding our understanding of the lunar environment and its interaction with space weather.

## References

1. Jonathan's Space Report