CGG for satellite mono-propellant pressurisation

The development of a CGG advanced CGG for satellite propulsion system pressuirsation has started. This 18 month development will lead to a CGG with a nitrogen production of 500 liters and a mass performance of 250 nl/kg. The expected volumetric performance will be 290 nl/l. Prtners in this development are Aerospace propulsion products (APP), TNO and OHB-Sweden.

In most constellations of LEO communication satellites mono propellant propulsion systems are used for constellation and orbit maintenance. For all satellites decreasing the mass and volume is very important to lower the cost. In mono propellant propulsion systems, about 25 to 30% of the tank volume is occupied by pressurisation gas and using the tank more optimally would mean an increase of performance at the same mass and volume or, in a new design, a smaller propulsion system offering the same performance.

From satellite primes viewpoint there is a need for a pressurisation system that is simple, compact, modular and which has a very long life time under harsh conditions.

System studies, as reported in the CGG Safety & Systems’ paper presented at Propulsion 2014, have shown that the Cool Gas Generator technology fulfils these demands and it is in advanced state of development. Two satellites are already successfully flying with this technology (the Proba 2 and Delfi-n3Xt satellites) and for a third one (InflateSail) the flight hardware has been delivered.

In such a system, the propellant tank would be filled up to 95% with propellants and only 5% is filled with pressurized nitrogen at 25 bars. When this gas is expanded to 25%, the pressure has decreased to 5 bars. At that moment, the CGG is activated, which produces the gas needed to bring the tank pressure up to 25 bars again. After that, a blow down sequence like in an existing tank can start. By adding a CGG, the amount of propellant in a tank increases from 75% to 95% only by adding a relatively small CGG.

Such a CGG Repressurisation System will have a number of advantages for the satellites in a constellation:

CGG propulsion system pressurisation.

  • The propellant tanks can be made smaller for the same amount of propellant. This leads to smaller and therefore more cost efficient satellites, or a longer, revenue generating life for existing platforms due to the more efficient propellant storage.
  • Existing LEO platforms can be re-used for a broader range of missions, due to the more flexible loading of the propellant tanks (“as is”, “super loaded” with CGG Repressurisation System, “off loaded”). This leads to a strong reduction in development costs for new constellations.
  • The use of CGG allows a reduction in size which might allow a larger number of satellites to be launched in multi launch configuration.

These advantages can be achieved by a moderate technology development in terms of cost and risk and will yield significant advantages for the satellite operators in terms of lower satellite procurement cost and / or longer revenue generating life time. In a constellation this effect is multiplied over a large number of satellites and becomes even more pronounced.