# Inertial Upper Stage

> two-stage solid-fueled booster rocket developed by the U.S. Air Force

**Wikidata**: [Q1662192](https://www.wikidata.org/wiki/Q1662192)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Inertial_Upper_Stage)  
**Source**: https://4ort.xyz/entity/inertial-upper-stage

## Summary
The Inertial Upper Stage (IUS) is a two-stage solid-fueled booster rocket developed by the U.S. Air Force. It functions as a space tug, designed to move payloads from a reference orbit to a target orbit or direct them to an interplanetary trajectory.

## Key Facts
*   The Inertial Upper Stage is a two-stage solid-fueled booster rocket developed by the U.S. Air Force.
*   It is classified as a rocket model, a space tug, and a solid-propellant rocket.
*   Boeing served as the general contractor for its manufacture.
*   The IUS entered service in 1982 and was retired in 2004.
*   It has a height of 5.17 metres and a diameter of 2.9 metres.
*   The first stage of the IUS uses an Orbus-21 motor, and the second stage uses an Orbus-6 motor.
*   Its country of origin is the United States.
*   Aliases for the IUS include Interim Upper Stage, SSB-7, and IUS.

## FAQs
### Q: What is the Inertial Upper Stage (IUS)?
A: The Inertial Upper Stage (IUS) is a two-stage solid-fueled booster rocket developed by the U.S. Air Force. It is designed to function as a space tug, moving payloads between orbits or directing them onto interplanetary trajectories.

### Q: Who developed and manufactured the Inertial Upper Stage?
A: The Inertial Upper Stage was developed by the U.S. Air Force. Boeing served as the general contractor for its manufacture, with United Technologies Corporation as a subcontractor for the rocket engine and Marquardt Corporation for the reaction control system.

### Q: When was the Inertial Upper Stage in service?
A: The Inertial Upper Stage entered service in 1982 and was retired in 2004, providing over two decades of operational use.

### Q: What are the physical dimensions of the Inertial Upper Stage?
A: The Inertial Upper Stage has a height of 5.17 metres and a diameter of 2.9 metres.

## Why It Matters
The Inertial Upper Stage (IUS) played a crucial role in expanding the capabilities of space launches for the United States from 1982 to 2004. As a dedicated space tug, it provided the necessary propulsion to precisely maneuver payloads, such as satellites and probes, into their final operational orbits or onto distant interplanetary trajectories. Its development by the U.S. Air Force underscored its strategic importance for national security and scientific exploration, enabling missions that required more power and precision than the primary launch vehicle could provide alone. By bridging the gap between initial launch and final destination, the IUS facilitated the deployment of critical space assets, contributing significantly to advancements in telecommunications, navigation, and space science during its operational lifespan. Its solid-fueled, two-stage design offered a reliable and powerful solution for complex orbital transfers, making it an indispensable component for various space missions.

## Notable For
*   Being a two-stage solid-fueled booster rocket specifically developed by the U.S. Air Force.
*   Its primary function as a "space tug," enabling the precise transfer of payloads to target orbits or interplanetary trajectories.
*   Its operational service life spanning over two decades, from 1982 to 2004.
*   Utilizing distinct Orbus-21 and Orbus-6 solid rocket motors for its first and second stages, respectively.

## Body

### Overview
The Inertial Upper Stage (IUS) is defined as a two-stage solid-fueled booster rocket. It was developed by the U.S. Air Force and is classified as a rocket model, a solid-propellant rocket, and a space tug. The IUS is also known by aliases such as Interim Upper Stage, SSB-7, and IUS. Its country of origin is the United States.

### Specifications
The IUS has a height of 5.17 metres and a diameter of 2.9 metres. It is composed of two distinct stages:
*   **First Stage:** Utilizes an Orbus-21 motor.
*   **Second Stage:** Utilizes an Orbus-6 motor.

### Development and Service
Boeing served as the general contractor for the manufacture of the Inertial Upper Stage. Key subcontractors included:
*   **United Technologies Corporation:** Responsible for the rocket engine.
*   **Marquardt Corporation:** Responsible for the reaction control system.

The Inertial Upper Stage entered service in 1982. It remained operational for over two decades, with its service retirement occurring in 2004.

### Classification and Relationships
The Inertial Upper Stage is an instance of a rocket model. It is a subclass of both space tugs and solid-propellant rockets. As a space tug, it belongs to a class of spacecraft vehicles designed to move payloads from a reference orbit to a target orbit, or direct them to an interplanetary trajectory.

## References

1. [Source](https://www.globalsecurity.org/space/systems/t4-config-2b.htm)
2. [Source](https://science.ksc.nasa.gov/shuttle/technology/sts-newsref/carriers.html)
3. [Source](http://www.braeunig.us/space/specs/ius.htm)
4. [Source](https://www.spacelaunchreport.com/sts.html)
5. Freebase Data Dumps. 2013
6. [Source](https://www.webcitation.org/69KZgqasj?url=http://www.boeing.com/history/boeing/ius.html)