# Payload Assist Module

> single-stage solid-fueled booster stage

**Wikidata**: [Q1424161](https://www.wikidata.org/wiki/Q1424161)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Payload_Assist_Module)  
**Source**: https://4ort.xyz/entity/payload-assist-module

## Summary
The Payload Assist Module (PAM) is a single-stage solid-fueled booster stage used to propel satellites into higher orbits or interplanetary trajectories. It was developed as part of the space tug class of spacecraft, functioning as an upper stage to augment launch vehicles like the Delta rocket and Space Shuttle. The PAM series includes variants like PAM-D, PAM-D2, and PAM-S, each tailored for specific missions.

## Key Facts
- **Type**: Single-stage solid-fueled booster stage
- **Class**: Space tug, apogee kick motor
- **Manufacturer**: McDonnell Douglas (United States)
- **Powered by**: STAR (Solid Apogee Rocket)
- **Variants**: PAM-D, PAM-D2, PAM-S
- **Primary Use**: Boosting satellites into higher orbits or interplanetary trajectories
- **Launched by**: Delta rockets, Space Shuttle, Titan 3 rockets
- **Notable Mission**: Used for the Ulysses spacecraft (PAM-S variant)
- **Instance of**: Rocket series
- **Aliases**: PAM, Spinning Solid Upper Stage (SSUS)

## FAQs
### Q: What was the Payload Assist Module (PAM) used for?
A: The PAM was a single-stage solid-fueled booster stage designed to propel satellites into higher orbits or interplanetary trajectories. It served as an upper stage for launch vehicles like the Delta rocket and Space Shuttle.

### Q: What are the main variants of the PAM?
A: The PAM series includes PAM-D, PAM-D2, and PAM-S. PAM-D was used with Delta rockets and the Space Shuttle, PAM-D2 with the Space Shuttle and Titan 3 rockets, and PAM-S specifically for the Ulysses mission.

### Q: Who manufactured the PAM?
A: The PAM was manufactured by McDonnell Douglas, a United States aerospace company.

### Q: What propulsion system did the PAM use?
A: The PAM was powered by the STAR (Solid Apogee Rocket), a solid-fueled rocket motor.

### Q: What was the significance of the PAM-S variant?
A: The PAM-S was a specialized booster stage used exclusively for the Ulysses spacecraft, enabling its journey to study the Sun’s polar regions.

## Why It Matters
The Payload Assist Module played a crucial role in expanding the capabilities of satellite launches during the late 20th century. As a single-stage solid-fueled booster, it provided the additional thrust needed to place satellites into higher orbits or interplanetary trajectories, overcoming the limitations of primary launch vehicles. The PAM series, particularly PAM-D and PAM-D2, became integral to missions involving the Space Shuttle and Delta rockets, demonstrating the flexibility of solid-fueled upper stages. Its most notable mission was the PAM-S, which propelled the Ulysses spacecraft on its groundbreaking journey to study the Sun’s poles. By acting as a space tug, the PAM enabled missions that would have otherwise been impossible, contributing significantly to advancements in space exploration and satellite deployment.

## Notable For
- **Versatility**: Served as an upper stage for multiple launch vehicles, including Delta rockets and the Space Shuttle.
- **Specialized Missions**: The PAM-S variant was specifically designed for the Ulysses mission, a pioneering solar exploration.
- **Solid-Fueled Innovation**: Demonstrated the effectiveness of solid-fueled booster stages in space missions.
- **Interplanetary Capabilities**: Enabled satellites to reach higher orbits or interplanetary trajectories.
- **Collaboration**: Developed in partnership with McDonnell Douglas, a key player in aerospace technology.

## Body
### Overview
The Payload Assist Module (PAM) was a single-stage solid-fueled booster stage designed to augment the capabilities of primary launch vehicles. It functioned as a space tug, providing the necessary thrust to place satellites into higher orbits or interplanetary trajectories. The PAM series included variants tailored for specific missions, each powered by the STAR (Solid Apogee Rocket) motor.

### Variants and Applications
#### PAM-D
- **Primary Use**: Boosted satellites launched by Delta rockets and the Space Shuttle.
- **Sitelink Count**: 1

#### PAM-D2
- **Primary Use**: Used with the Space Shuttle and Titan 3 rockets.
- **Sitelink Count**: 1

#### PAM-S
- **Primary Use**: Specialized booster for the Ulysses spacecraft.
- **Sitelink Count**: 1

### Technical Specifications
- **Power Source**: STAR solid-fueled rocket motor.
- **Manufacturer**: McDonnell Douglas (United States).
- **Country of Origin**: United States.

### Notable Missions
- **Ulysses Spacecraft**: The PAM-S variant was crucial for this mission, which studied the Sun’s polar regions.
- **Space Shuttle Integration**: PAM-D and PAM-D2 were frequently used in conjunction with the Space Shuttle, demonstrating their reliability and adaptability.

### Classification and Relationships
- **Class**: Space tug, apogee kick motor.
- **Instance of**: Rocket series.
- **Subclass of**: Apogee kick motor, space tug.

### Media and Documentation
- **Image**: Available on Wikimedia Commons ([PAM-D rocket stage](https://commons.wikimedia.org/wiki/Special:FilePath/PAM-D_rocket_stage.jpg)).
- **Wikipedia**: Available in multiple languages (en, de, fr, etc.).
- **Commons Category**: "Payload Assist Module" on Wikimedia Commons.

### Historical Context
The PAM was developed during a period of significant advancements in space technology, particularly in the late 20th century. Its introduction allowed for more ambitious missions, including interplanetary exploration. The PAM’s success paved the way for future solid-fueled upper stages and contributed to the broader field of space propulsion.

## References

1. [Source](https://www.globalsecurity.org/space/systems/pam.htm)
2. Freebase Data Dumps. 2013