# Delta Cryogenic Second Stage

> rocket stage used in Delta rockets

**Wikidata**: [Q967349](https://www.wikidata.org/wiki/Q967349)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Delta_Cryogenic_Second_Stage)  
**Source**: https://4ort.xyz/entity/delta-cryogenic-second-stage

## Summary
The Delta Cryogenic Second Stage (DCSS) is a rocket stage manufactured by United Launch Alliance and used in the Delta III and Delta IV launch vehicle families. Classified as a type of space tug, it is designed to move payloads from a reference orbit to a target orbit or direct them toward an interplanetary trajectory. The stage is powered by a single RL-10B-2 engine and serves as a critical upper-stage component for deploying satellites and other spacecraft.

## Key Facts
- **Also Known As:** DCSS
- **Classification:** It is an instance of a rocket series and a subclass of space tug.
- **Manufacturer:** United Launch Alliance.
- **Country of Origin:** United States.
- **Used By:** Delta III, Delta IV, and Delta IV Heavy rockets.
- **Propulsion:** Powered by 1 RL-10B-2 engine.
- **Function:** Acts as a spacecraft vehicle to move payloads from a reference orbit to a target orbit or interplanetary trajectory.
- **Wikidata Description:** Rocket stage used in Delta rockets.
- **Wikipedia Presence:** Documented in 10 language editions (bg, commons, en, fi, fr, id, it, lv, pl, pt).
- **Commons Category:** Delta Cryogenic Second Stage.

## FAQs

### What is the primary function of the Delta Cryogenic Second Stage?
The DCSS functions as a space tug, designed to provide the necessary propulsion to move payloads from a reference orbit to a specific target orbit or to direct them onto an interplanetary trajectory after the initial launch phase.

### Which rockets utilize the Delta Cryogenic Second Stage?
This stage is utilized by the Delta III, Delta IV, and Delta IV Heavy launch vehicles.

### What engine powers the Delta Cryogenic Second Stage?
The stage is powered by a single RL-10B-2 engine.

### Who manufactures the Delta Cryogenic Second Stage?
The DCSS is manufactured by United Launch Alliance in the United States.

## Why It Matters
The Delta Cryogenic Second Stage plays a pivotal role in modern space deployment by solving the "last mile" problem of spaceflight. As a subclass of the space tug, it enables launch vehicles to deliver payloads to precise orbits that the core rocket stages cannot reach alone. By providing the thrust needed for orbital insertion and transfer, the DCSS extends the mission capabilities of the Delta rocket family, allowing for the deployment of critical satellites into geostationary orbits and facilitating complex interplanetary missions. This capability reduces the need for payloads to carry their own heavy propulsion systems, optimizing launch mass and cost efficiency.

## Notable For
- Serving as the upper stage for the Delta III and Delta IV families of rockets.
- Being a specific implementation of a "space tug," a class of vehicles essential for orbital transfer.
- Utilizing the RL-10B-2 engine, a specialized cryogenic engine.
- Being manufactured by United Launch Alliance, a major entity in the aerospace sector.
- Enabling high-precision orbital maneuvers for high-value payloads.

## Body

### Definition and Classification
The Delta Cryogenic Second Stage (DCSS) is a rocket stage utilized in the Delta family of rockets. In the broader taxonomy of spacecraft, it is classified as an instance of a "rocket series" and is a distinct subclass of "space tug." As a space tug, its fundamental design purpose is to act as a spacecraft vehicle capable of moving payloads from a reference orbit to a target orbit or directing them toward an interplanetary trajectory.

### Technical Specifications and Propulsion
The DCSS is an expendable orbital transfer vehicle. Its primary technical specification is its propulsion system. The stage is powered by a single RL-10B-2 engine. This engine allows the stage to perform the precise orbital maneuvers required to settle payloads into their final operational orbits, whether that is a geostationary orbit or a trajectory leaving Earth's influence.

### Operational Context and Usage
The DCSS is a critical component for the United States' space infrastructure, originating in the United States and manufactured by United Launch Alliance. It is operationally integrated into three specific rocket configurations:
- **Delta III:** An earlier evolution of the Delta family.
- **Delta IV:** A common launch vehicle used for medium to heavy payloads.
- **Delta IV Heavy:** A heavy-lift variant capable of launching large satellites and probes.

In these configurations, the DCSS fires after the lower stages have exhausted their fuel, taking over the mission to finalize the payload's position in space.

### Documentation and Global Presence
The entity is documented across various international knowledge bases. It maintains a presence on Wikipedia in 10 distinct language editions, including English, French, Italian, Polish, and Portuguese. It is categorized under "Delta Cryogenic Second Stage" on Wikimedia Commons and is indexed in Wikidata with a Freebase ID (/m/0j26hfj). The technical and functional aspects of the stage align with the general definitions of space tugs found in academic and technical sources like BabelNet.

## References

1. [Source](https://space.skyrocket.de/doc_lau/delta-4.htm)
2. Freebase Data Dumps. 2013