Space | 07. May 2011

Ecological Advanced Propulsion Systems (ECAPS) starts its final experiment campaign

From the 14th of April the ECAPS High Performance Green Propulsion System (HPGP) experiment started its final campaign HPGP-4, the one planned for the extended mission period.

After being subjected to the space environment for a substantial duration, the objectives of this HPGP-4 slot are to perform significant delta-V maneuvers with long firing durations of the thrusters. Further objectives are to verify performance and operational life thus contributing to establish the initial space flight heritage for the HPGP technology.

This fourth experiment slot is divided in two phases, respectively scheduled in the second half of April and May. During every phase a number of predefined thrusting sequences are executed where thrusters are operated individually.

The PRISMA mission provided a unique opportunity to demonstrate the novel HPGP technology in space, thus paving the way to its use in future space applications. The HPGP propulsion system has been used both for providing the required delta-v for the PRISMA Mango satellite maneuvers and as an experiment with the objective to demonstrate performance in space. Delta-v is nominally generated in an autonomous and combined operation of the HPGP and Hydrazine propulsion systems while the performance measurements are performed with one propulsion system at the time. The HPGP propulsion system uses the first “Green” monopropellant qualified for space flight, which is the ADN-based LMP-103S.

Operationally, during this HPGP-4 campaign, Mango follows Tango few kilometers back in flight direction. Its axes are aligned with respect to the orbital frame, with the Digital Video System (DVS) camera bore-sight pointing opposite to Tango. Slightly prior to any pulse train, Mango rotates in order to point the correct HPGP thruster in the aimed Delta-v direction. At the end of each test Mango rotates back and HPGP are temporary disabled. Delta-v direction, thruster, and test characteristics are jointly defined by Experimenter and GNC operator. The first one decides thruster to be used, on and off times of the thruster (duty cycle), number of pulses and thrust level. GNC operator has to take care that the thrusting activity will not bring the satellites into dangerous situations for the platforms.

During the first HPGP-4 phase all the thrusting sequences were performed in cross and anti-cross-track directions. As a result the shape of the relative orbit in the cross-track radial N-R plane was mainly affected. To provide an idea of the activities performed, figures 1-and 2 show how the projection of relative orbit on the N-R plane evolved.

Figure 1 HPGP-4, firings executed the 14th-15th of April


Figure 2 HPGP-4, firings executed the 26th-29th of April

At the end of the first phase of HPGP-4 ECAPS was satisfied of the data collected.