A Regional Microsatellite Constellation with Electric Propulsion In Support of Tuscan Agriculture

Transcription

1 Berlin, 20 th - 24 th 2015 University of Pisa 10 th IAA Symposium on Small Satellites for Earth Observation Student Conference A Regional Microsatellite Constellation with Electric Propulsion In Support of Tuscan Agriculture A. Papa, A. Bechi, S. Gregucci, P. Pergola, S. Marcuccio Aerospace division, Dept. Of Civil and Industrial Engineering, University of Pisa

2 Objectives Realization of a versatile constellation aimed at supporting Tuscan region agriculture. Design of a small satellite platform with electric propulsion while retaining low cost, high performance and large compatibility with existing small remote sensing instruments.

3 Electric Propulsion: advantages Drag compensation High Performance Electric Propulsion VERSATILITY Orbital transfer Low cost

4 Alta HT100 Performance Value Thrust, [mn] 6-18 Power, [W] Specific Impulse, [s] Thrust Efficiency, [%] Up to 40 (HT100 firing in IV4 vacuum facility, Alta)

5 Alta SATSLab

6 Mission analysis: users objectives Weekly planning capability during the whole year: Production efficiency increase and environmental impact reduction Crops description land, vegetation and soil parameters measurements: Temporal Thermal state Small units management Fine spectral details Optical system specifications: High Revisit Time (1-7 days) Appropriate combination of multispectral, hyperspectral and thermal infrared sensors Introduction Objectives Mission Analysis Design Simulations Conclusions A versatile constellation of microsatellites with electric propulsion for Earth Observation: mission analysis and platform design

7 Mission analysis: constellation design Conceptual division of the entire constellation in specificoptical task sub-constellations. One sensor type for each sub-constellation each subconstellation is ad hoc designed to independently fulfill individual requirements. Realization of a versatile service easy access to space data for many users.

8 Mission analysis: sub-constellations According to actual small optical sensors state-of-art: Sub-constellation Optical Task Main Applications Large swath multispectral Thermal Infrared Hyperspectral Add-value multispectral RED and NIR m GSD m GSD. VIS, NIR and SWIR m GSD. RGB and NIR. < 5 m GSD. Land and vegetation monitoring. Floods monitoring. Irrigation practices. Wild fire detection. Crop health monitoring and classification. Soil moisture. In-field variability: precision agriculture.

9 Orbit design: general assumptions Circular shape: more stable respect to elliptic orbits for Earth Observation. LEO altitude range comprised between 250 and 1000 km. Sun-synchronus, polar or tropical inclination Repeating Ground Track orbits (1-15 days of nominal Repeat Cycles)

10 Orbit design: scenarios (1) Sub-constellation configurations s/c equally phased s/c appropriately phased Single plane: Common altitude Different altitudes Multiple plane: Common altitude Different altitudes Single plane: Common altitude Different altitudes Multiple plane: Common altitude Different altitudes Differentiation of: Spatial resolution levels. Illumination conditions. Target angles of view and revisit frequencies. Coverage. Orbit conditions also during the mission.

11 Orbit design: scenarios (2) Sun-Synchronus Very appropriate illumination conditions Satellites equally phased within a single plane Repeating Ground Track (1-5 days of RC) Frequent observations at regional level with few satellites

12 Tuscany constellation architectures (1) Instrument type h, [km] i, [deg] RC, [days] GSD, [m] Ns RT, [days] Large swath multispectral Thermal Infrared Hyperspectral Add-value multispectral ~ Total spacecraft number = 14 Instrument type h, [km] i, [deg] RC, [days] GSD, [m] Ns RT, [days] Large swath multispectral Thermal Infrared Hyperspectral Add-value multispectral ~ Total spacecraft number = 11

13 Tuscany constellation architectures (2) Instrument type h, [km] i, [deg] RC, [days] GSD, [m] Ns RT, [days] Large swath multispectral Thermal Infrared Hyperspectral Add-value multispectral Total spacecraft number = 5 Instrument type h, [km] i, [deg] RC, [days] GSD, [m] Ns RT, [days] Large swath multispectral Thermal Infrared Hyperspectral Add-value multispectral Total spacecraft number = 4

14 Tuscany agriculture constellation Constellation of four satellites launchable by a single Vega-class launcher Instrument h, [km] i, [deg] GSD, [m] Large swath multispectral Thermal Infrared High GSD multispectral Hyperspectral

15 Platform design: criteria Performance Target value Total launch mass, [kg] 60 Available payload mass, [kg] 12 Available payload power, [W] 30 Pointing accuracy, [deg] < 0.1 (Earth pointing 3-axis stabilization) Data rate, [Mbit/s] 8 Operational altitude, [km] 350 Lifetime, [years] Up to 5

16 Platform design: logic architecture

17 Star Sensors (x2) X-band Antennas Platform design: performance Payload vane HT100 S-band Antennas (x2) Performance Value Total mass, [kg] < 60 Dimensions, [m] 0.5 x 0.4 x 0.5 Power, [W] Up to 250 Data rate, [Mbit/s] Up to 100 Pointing accuracy, [deg] Payload vane Available volume, [lit] 20 Available mass, [kg] 12 Available power, [W] 30-90

18 Platform design: thrusting module (1)

19 Platform design: thrusting module (2) Redundant HT100 Performance Value Reference thrust, [mn] 9 Total specific Impulse, [s] 1100 Power, [W] 175 Propellant capability, [kg] Up to 6.5 Plume Shields (Dual HT100 in IV4 vacuum facility, Alta)

20 SATSLab simulations: input Parameter Value Altitude, [km] 358 Eccentricity ~ 0 Inclination, [deg] 96.9 Local Time of Ascending Node 10:30 am Drag area, [mm 22 ] 0.2 Ballistic Coefficient ~ 135 Semimajor Axis max drift, [km] Solar Radiation Pressure area, [mm 22 ] 1.25 Maximum atmospheric drag, JJ 22 effects, Sun & Moon third body interactions are also simulated

21 SATSLab simulations: results (1) Eclipse Eclipse firing About 16 minutes per thruster firing

22 SATSLab simulations: results (2) HT100 firing Payload (30 W), Transmitter (35 W) & ADCS (28.8 W) Base consumption (20 W) HT100 eclipse firing

23 SATSLab simulations: results (3) Large margin during maximum atmospheric drag also at the EOL DOD limit

24 SATSLab simulations: results (4) Parameter Value X-band Rx antenna diameter, [m] 1.2 X-band Tx antenna gain, [dbi] 5 RF output power, [dbw] 8 Good margin respect to 8 Mbit/s

25 Conclusions Small satellites Electric propulsion FEASIBLE Versatile constellations Low cost Easy access to space data High performance

26 Thanks for the attention!