technical development activities (tda’s) strategy, status

BepiColombo TSR22/02/2005 J.M. Lautier – ESA/D/TEC-MMM - Mechanisms Section

HP EPPM’s

High Power Electric Propulsion Pointing Mechanisms (HP EPPM)

Technical Development Activities (TDA’s) strategy, status and planning


HP EPPM’s

Objectives of this presentation are:

To provide primes with:– ESA preliminary development strategy wrt High Power EPPM’s wrt

on-going TDA’s activities.– Status and planning of ESA TDA’s.– Preliminary main functional, operational and environmental

requirements that will be covered by ESA TDA’s.

To advertise the workshop meeting on EPPM’s in April 2005.


HP EPPM’s

On-going development activities baseline 1/2

Applications:– Baseline: HP GEO telecommunication platforms / @bus– Exploration, Science and manned missions scenarios will be

covered to the maximal extent.

Thrusters:– Baseline: T6 (QinetiQ)– Options: PPS5000 (Snecma) and RIT22 (EADS)

Mission scenario:– Baseline: NS Station Keeping + Wheel dumping + graveyard

manoeuvre + Orbit topping– Options: EW Station Keeping + Orbit Raising


HP EPPM’s

On-going development activities baseline 2/2

Configuration:– 2 thrusters per EPPM (1 nominal + 1 redundant).– Stowed parallel to the S/C interface mounting plane to increase the

EPPM robustness during launch.– Stowed configuration compatible with degraded mission scenarios.– Stowed and deployed envelop size compatible with telecom S/C’s.

Enabling technologies/concepts:– High passive damping EPPM/thrusters interface devices.– Fuel lines with high angular range capabilities.– Drive units providing high angular range and torque capabilities– Drive units capable of high number of cycle and accumulated

pointing angle.


HP EPPM’s

Pointing rangeAxis 1: +9° / -45°Axis 2: +9° / -9°

Pattern: Rectangular

Number of cycles> 25 000 cycles

> 40 000 cumulated angle

Lifetime > 15 years (Orbit)

HP EPPM preliminary main requirements:

Max. Operational T.TBC

Thruster I/F: + 250 °CDrive unit: + 100 °C

Min. Operational T.TBC

Drive unit: - 30 °C

Min./Max. thermal reflective and conductive heat flows at I/F’s

TBD

First resonance frequency > 80 Hz

Sine vibrations20 – 60Hz: 15 g60 – 100Hz: 10 g

Random vibrations 9 gRMS

Shock spectrum 3000 g

QS loads 25 g

Need for a specific platform interface structure and dedicated load carrying members.

GEO sun illumination

1 thruster firing at a time

Max. firing duration TBC


HP EPPM’s

Planning / Status of HP EPPM’s developments


HP EPPM’s

BepiColombo can benefit from parallel ESA TDA’s on HP EPPM’s but this can be achieved only if refined input requirements fromprimes are made available.

Specific BepiColombo requirements regarding HP EPPM’s are to be identified as soon as possible in order to: – Assess impacts on the ESA development baseline design for

possible/feasible implementation.– Identify BepiColombo specific EPPM related technologies to be

developed in parallel of ESA TDA’s.


HP EPPM’s

Conclusions– ESA on-going On-going development activities objectives is to

cover mainly HP GEO telecom platforms and to the maximal extend Exploration, Science and manned missions scenarios.

– To benefit from ESA TDA’s on HP EPPM’s, primes are invited to participate to the EPPM workshop at ESTEC in April 2005:

• Industry will be invited to present their needs regarding the new generation of EPPM for HP applications.

• Discussion will be based on a template summarising main HP EPPM’s requirements.

• The objective will be to compile European industries needs and vision of the market for HP platforms in order to derive the most promising EPPM design baseline and set of requirements for the performance of ESA TDA’s.

• A road map will be defined.


HP EPPM’sEPPM requirements template presentation 1/2

– Thrusters type– Number of thrusters per EPPM (nominal, redundant)– Max. firing duration– Angular range for axes 1 and 2– Pointing range pattern (cone or box)– Thruster stowed configuration angle versus interface mounting plane– Pointing accuracy/resolution/repeatability– Max. slew rate per axis– Need for angular position telemetry– Need for other type of telemetry– Number of cycle per operational modes/angular range– Total cumulated angle per axis– Lifetime (ground, orbit)– Power consumption (peak and average)– Fuel pipe pressure at S/C / EPPM interface


HP EPPM’s

EPPM requirements template presentation 2/2– Number of fuel and electrical lines to be conducted by the EPPM– First stowed resonance frequency– QS, Sine, random and shock load spectrum at S/C interface– Maximal shock spectrum generation (e.g. from EPPM hold down and

release mechanism).– Thermal environment:

• Extreme operating and non operating temperatures of the drive units• Extreme. temperatures at thruster and S/C I/Fs• EPPM conductive heat flow at I/Fs• EPPM radiative heat flow • Thermal reflective surface required

– Total appendages mass – EPPM overall mass – Overall available size envelope– S/C - mechanical interface definition (geometry + material)– Electrical - Drive electronics interfaces

technical development activities (tda’s) strategy, status

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