Mars Express Reuse: Call for Ideas CALL FOR IDEAS FOR THE RE-USE OF THE MARS EXPRESS PLATFORM PLATFORM CAPABILITIES D. McCoy PARIS 23 MARCH 2001 page 1
Mars Express Reuse: Call for Ideas PRESENTATION CONTENTS MARS EXPRESS PLATFORM CHARACTERISTICS OPTIMAL DESIGN OF MISSION AND INSTRUMENTS PLANNING STUDY PRIORITIES page 2
MARS EXPRESS PLATFORM CHARACTERISTICS PRINCIPLE PHYSICAL CHARACTERISTICS Three Axis stabilised: gyros, star trackers, reaction wheels Bi-propellant Propulsion System: main engine (400 N) and attitude thrusters (10 N) Fixed Communications Antennae: X/S band transmit and receive Single Axis Solar Array Articulation two deployable arrays with rotation motors Fixed orientations for experiment viewing, earth communications and cold face for cryogenic radiators page 3
MARS EXPRESS PLATFORM CHARACTERISTICS Experiment Panel Dimensions ~ 1.5 x 1.5 m 25/10/2000 15:39:21 High Gain Antenna = 1.6 m diameter page 4 Solar Array Length = 11 m Cruise Phase Configuration Orbit Phase Configuration
MARS EXPRESS PLATFORM CHARACTERISTICS PERFORMANCE CHARACTERISTICS Attitude Control: During NADIR ~ 0.05 deg. With stability 0.005 deg (30 sec) Slew rate up to 0.15 deg/second with reaction wheels Fuel Load: Tanks capable of ~480 kg (equivalent to ~1500 m/s velocity increment on Mars Express) Data Handling: Maximum data transmission of 228 kbps (without coding) On board mass memory with 12 Gbits capacity page 5
MARS EXPRESS PLATFORM CHARACTERISTICS PERFORMANCE CHARACTERISTICS cont d Power System Capable of distributing up to 1500 watts Mars Express maximum power generation is on the order of 750 watts (currently consuming ~600 watts maximum) Three batteries (Lithium Ion) to support eclipse and smooth out power generation fluctuations over mission life. Thermal System Power dissipation is relatively smooth over typical operations cycle allowing passive controls. Radiator (for low temperature at experiment IR sensor) provides 180 deg Kelvin with heat load of 7 watts. page 6
MARS EXPRESS PLATFORM CHARACTERISTICS Experiment Panel (interior side) Equipment Panel (interior side) 27/11/2000 17:30:48 Main Engine and Attitude Thrusters Radiator Panel (interior side) Equipment Panel (exterior side with stowed solar array) Propulsion Tank page 7
MARS EXPRESS PLATFORM CHARACTERISTICS Experiment Panel (exterior side) Equipment Panel (interior side) 27/11/2000 17:30:12 Star Trackers Radiator Panel (exterior side) Large Experiment Mounting Propulsion Tank Equipment Panel (exterior side with stowed solar array and stowed radar ant.) page 8
OPTIMAL DESIGN OF MISSION AND INSTRUMENTS CONSTRAINTS RESULTING FROM THE REUSE OBJECTIVE Structure/propulsion maintain the basic platform/shear wall construction and propulsion layout Spacecraft electrical architecture maintain the existing cold redundant system with reallocation of resources such as power, pyros, data, and commanding Software maintain the core functions and operational modes Launch environment maintain the Soyuz/Fregat launch environment; other launchers might require re-qualifications in Sine/Acoustic. page 9
LAUNCH CONFIGURATION ON FREGAT Soyuz Fairing 07/12/2000 18:09:15 Adaptor Insert view of spacecraft in fairing with notes on fairing dimensions, and interface to Fregat. Fregat Upper Stage page 10
OPTIMAL DESIGN OF MISSION AND INSTRUMENTS MISSION CONSIDERATIONS Mission operations must be oriented to a store and forward type of approach divide into observation period and a communications period to optimise use of existing operations modes. The thermal environment of the chosen mission can alter the design significantly. Try to work within existing thermal limits (typical operational unit temperatures from -10 to +40 C). Maintain overall spacecraft inertias to minimise changes to the attitude and orbit control system Limited by pointing requirements and reaction wheel capacities as well as dynamics. page 11
OPTIMAL DESIGN OF MISSION AND INSTRUMENTS INSTRUMENT CONSIDERATIONS Accommodate experiments within existing envelopes Departures from this will require a new structure design. Use the existing data and power interfaces. Three high rate data carriers (IEEE 1355 ~500 kbps - 10 Mbps. Remaining four are OBDH links (10-80 kbps) Total power to experiments ~ 250 watts. No special EMC or Magnetic requirements for experiments (platform for normal EMC standards). Moderate pointing performance requirements page 12
EXAMPLE OF LARGE MARS EXPRESS INSTRUMENT Optical and electronic units of OMEGA during integration at Paris Observatory (http://www.ias.fr/cdp/omega/omega.html) Mass = 29 kg Dimensions ~ 900 x 260 x 380 mm (2 units) page 13
PLANNING MINIMUM SCHEDULE Assumes no major developmental undertakings. Refurbishing and use of Mars Express spare units is baselined. Assumes the re-use of MGSE and EGSE as well as test benches and other supporting test items such as software test environments. Based on actual Mars Express planning experience. page 14
PLANNING Activity Description Origem % Early Dur u Start Return from Baikonur 0 30JUN03* Early Finish 2001 2002 2003 2004 2005 JAFEMAAPMAJUJUAUSEOCNODEJAFEMAAPMAJUJUAUSEOCNODEJAFEMAAPMAJUJUAUSEOCNODEJAFEMAAPMAJUJUAUSEOCNODEJAFEMAAPMAJUJUAUSEOCNODEA Mars Express Refurbishment period 66 30JUN03 29SEP03 3 1 01JAN01 01JAN01 Initiate Units Procurement 0 01NOV01* Start manufacture Structure & Propulsion 0 03JUN02* Structure/Propulsion mating start 0 01JUL03* FM Experiment Delivery 0 03NOV03* Procurement of S/C FM Units 261 01NOV01 31OCT02 EM Experiment Development 218 01MAR02* 31DEC02 FM Experiment Development 173 01NOV02* 01JUL03 Test Bench S/W Validation 261 01NOV02* 31OCT03 Design/Manufacture Structure/Propulsion 522 01NOV01* 31OCT03 Start FM Integration 0 03NOV03* FM System Integration 174 03NOV03 01JUL04 FM Environmental Testing 172 02JUL04 28FEB05 FM Delivery to ESA 0 01MAR05* ESA Launch Campaign/margin 109 01MAR05 29JUL05 Launch 0 01AUG05* Start Date 01JAN01 Early Bar Finish Date 29JUL05 Data Date 01JAN01 Progress Bar Run Date 02MAR01 13:39 Critical Activity Primavera Systems, Inc. Schedule Overview 2005 Science Mission ESA/ESTEC (tentative) 12 10 8 12 24 8 8 5 page 15
STUDY PRIORITIES Accommodation Study The restrictions imposed by the platform re-use require study to ensure scientific objectives can be met. Particular items to clarify with respect to proposed missions are Experiment mounting arrangements and stability needs Platform operations Thermal environments; operational and non-operational Power requirements page 16