Where Are the Propellant Tanks on the International Space Station Located?

The International Space Station (ISS) does not have a dedicated propellant tank like a spacecraft would. Instead, it relies on various propulsion systems for attitude control and orbital adjustments. These systems primarily use thrusters from visiting spacecraft, like the Russian Progress resupply ships or the station's own thrusters.

Propulsion Systems on the ISS

The ISS is equipped with a Russian Zvezda Service Module, which contains thrusters that use a propellant called hydrazine. Hydrazine is a hypergolic propellant, which means it ignites spontaneously upon contact with an oxidizer. This type of propellant is ideal for quick maneuvering in space.

These thrusters are located within the unpressurized Assembly Compartment, which is part of the Transfer Chamber at the aft of the Zvezda module.

Each thruster is designed to handle specific tasks, and the hydrazine propellant allows for quick and precise adjustments. This modular approach allows the ISS to have a robust and versatile propulsion system.

Other Propulsion Systems

In addition to the hydrazine used by the Zvezda thrusters, the ISS can also utilize the thrusters of visiting spacecraft, which may contain different types of propellants depending on the spacecraft's design.

For example, the European Automated Transfer Vehicle (ATV) and the Northrop Grumman Cygnus spacecraft both use hydrazine for their propulsion systems. This versatility ensures that the ISS can adapt to different mission requirements and emergency situations.

The Role of the Zarya Module

The Zarya module, the first module launched for the ISS, also stores fuel tanks and maneuvering thrusters. The thrusters on Zarya were disabled when the Zvezda module was installed, but the fuel tanks are still usable and can provide additional fuel to the thrusters on Zvezda. This added flexibility in fuel storage ensures that the ISS has a robust backup system in case of emergencies.

Key Components of the Zvezda Module:

16 small reaction control system (RCS) thrusters 2 main propulsion thrusters Fuel and oxidizer tanks for these thrusters (specifically UDMH and Nitrogen Tetroxide)

The Zvezda module is a crucial component of the ISS, providing essential propellant and control for the entire station. Its dual-purpose design, with both active and standby systems, ensures reliable and efficient operation.