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S.1 Spacecraft Propulsion Systems Chapter 1: Introduction to ...

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Under Development:<br />

- 47-<br />

A new family of environmentally friendly monopropellants has been identified as an<br />

alternative <strong>to</strong> hydrazine. These new propellants are based on blends of e.g. hydroxyl<br />

ammonium nitrate (HAN), ammonium dinitramide (AND), hydrazinium nitroformate (HNF),<br />

nitrous oxide (N2O), and hydrogen peroxide (H2O2)<br />

When compared <strong>to</strong> hydrazine, e.g. HAN blends have a range of specific impulse (Isp) which<br />

can exceed that of hydrazine. Testing of HAN based propellants has begun <strong>to</strong> show<br />

promise and could soon be adopted for on-board propulsion systems of LEO satellites<br />

and constellations.<br />

Advantages:<br />

Safer propellants (also called ‘green’ or ‘reduced hazard propellants’) reduce costs by:<br />

• Eliminating the need for self-contained atmospheric protective ensemble (SCAPE)<br />

suits needed for <strong>to</strong>xic propellants.<br />

• No extensive and prohibitive propellant safety precautions and isolation of the<br />

space vehicle from parallel activities during propellant loading operations.

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