The Venus Express propulsion system is the same as the bi-propellant system employed on Mars Express, but with a higher propellant mass (~530 kg for Venus express as compared to ~430 kg for Mars Express).

The propulsion system is divided into three areas:

• High pressure gas side, comprising a 35.5 litre pressurant tank, normally open and normally closed pyrovalves, a high range pressure transducer, a fill & drain valve and a test port
• Low pressure gas side, comprising a pressure regulator, non-return valves, a pair of low flow latch valves, a low range pressure transducer, normally closed pyrovalves, test ports, and fill & vent valves
• Liquid side, which supplies propellant to the main engine and thrusters. Made up of two 267 litre propellant tanks, normally open and normally closed pyrovalves, propellant filters, low-range pressure transducers, the main engine, four pairs of reaction control thrusters, test ports and fill & drain valves

The pressurisation agent is gaseous helium, stored under high pressure. The high-pressure gas passes from the storage tank, via pyrotechnically actuated valves to start and stop the pressurisation process, and a filter, to the pressure regulator. From the regulator, the low-pressure gas passes through non-return valves and low flow level valves to normally closed, pyrotechnically actuated valves, which are opened to admit the pressurant to the fuel tanks.

The propellant tanks, one containing nitrogen tetroxide and the other mono-methyl hydrazine, supply their contents, via latch valves and flow control valves, to the thrusters. The thrusters are arranged in four pairs, located at the lower corners of the spacecraft.

The propellants are also supplied, via pyrotechnically actuated valves, filters and flow control valves, to the main engine. The main engine is located on the lower floor of the spacecraft.

The main engine generates a thrust of 415 N, while the thrusters are each capable of producing thrusts of 10 N.
 

	Electric Power
	Attitude and Orbit Control