TanDEM-X. 1. Mission Overview. Science Meeting No SAR Imaging Modes & Performance 3. Satellite Design Overview 4. Launcher 5.

Transcription

1 TanDEM-X Science Meeting No. 1 Dresden Wolfgang Pitz EADS Astrium GmbH D Friedrichshafen 1. Mission Overview 2. SAR Imaging Modes & Performance 3. Satellite Design Overview 4. Launcher 5. Secondary Payload Page 1 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 1

2 1 TanDEM-X Mission Overview SAR Interferometry mission for generation of precise global Digital Elevation Model according to DTED-3 Standard (12 m posting, 2 m accuracy) Orbital constellation of two SAR satellites: TerraSAR-X TanDEM-X (Rebuild of TerraSAR-X with minor adaptations) Typical distance of 0,5-2 km between satellites during DEM acquisition phase Page 2 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 1 TanDEM-X Mission Overview Realisation in Public-Private Partnership Public Partner DLR Procurement of the TanDEM-X Satellite from EADS Astrium Development of the Satellite Operations System Development of the Processing & Archiving Facility Satellite operations Reception, processing, archiving and distribution of the data Scientific coordination System support, calibration and validation Private Partner EADS Astrium Development, manufacturing and launch of the TerraSAR-X Satellite (as contractor to DLR) Private Partner Infoterra Development of market for DEMs Development of commercial Service Segment Commercial exploitation of TanDEM-X DEM Total Mission Cost is equally shared by DLR / Industry Page 3 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 2

3 1 TanDEM-X Mission Overview S/C Characteristics S/C Lifetime: 5 years after in-orbit commissioning Reliability: 0,81 after 5 years Fully one failure tolerant S/C design Orbit: Orbit Parameter Orbit Height at Equator Inclination Argument of Perigee Eccentricity Right ascension of ascending node True Anomaly TSX Orbit 514 km RAAN 0 TA 0 TDX Orbit 514 km ±Libration ± RAAN 0 ± TA 0 ± 10.6 Page 4 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 1 TanDEM-X Mission Overview Schedule Page 5 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 3

4 1. Mission Overview 2. Imaging Modes & Performance 3. Satellite Design Overview 4. Launcher 5. Secondary Payload Page 6 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 2 TanDEM-X Imaging Modes & Performance StripMap Modus Satellite orbit ScanSAR Modus H satellite (514 km) Nadir track Θ 1 =20 o H satellite Satellite orbit Spotlight Modus Swath width: >30 km Nadir track Satellite orbit Θ 1 =20 o H satellite Resolution 3 m Swath width: 100 km Nadir track Θ 2 =45 o Resolution 16 m Θ 1 =20 o Full Performance Range Centre of rotation Θ 2 =55 o Resolution 1 m Page 7 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 4

5 2 TanDEM-X Imaging Modes & Performance Spotlight Mode StripMap Mode ScanSAR Mode Ground Resolution - Across Track -Along Track Product Coverage (Along* Across) Access Range (Full Perf) Access Range (Data Collection) Sensitivity (NESZ) -typical - worst case Data Rate, mean (8/4 BAQ) 1 m 1 m 5 km * 10 km x 463 km x 622 km -20 db -16 db 680 Mbps 3 m 3 m < 1500 km * 30 km x 287 km x 622 km -22 db -19 db 580 Mbps 16 m 16 m < 1500 km*100 km x 287 km x 577 km -21 db -19 db 580 Mbps Page 8 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 2 TanDEM-X Imaging Modes / Performance Interferometric Modes Bi-Static (Baseline for DEM Generation) Overlapping Footprint One S/C TX, both S/C RX Bi-Static Alternating Overlapping Footprint One S/C TX alternating from pulse to pulse, both S/C RX Mono-Static No Overlap of Footprint Both S/C RX & TX Page 9 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 5

6 2 TanDEM-X Special Modes 2 TanDEM-X Imaging Modes & Performance Special Modes Dual Receive Antenna Mode SAR Antenna can be split in half for TX and RX Both Radar chains (nominal and redundant) can be used simultaneously Repeat Pass Interferometry Satellite will be kept in repeat orbit within an orbit tube of 200 m down to 10 m diameter Page 10 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 2 TanDEM-X Imaging Modes & Performance SAR Imaging Capacity Stand-Alone operation: Average SAR Imaging Duration per Orbit: 170 s Maximum SAR Imaging Duration per Orbit: 600 s TanDEM operation: Average SAR Imaging Duration per Orbit: 300 s (50% RX/TX, 50% RX) Storage Capacity 256 Gbit EOL Command & Downlink Capacity Encrypted S-Band Command Uplink 4 kbit/s Encrypted X-Band SAR Data Downlink 300 Mbit/s S-Band HK Telemetry Downlink 1 Mbit/s Flexibility Left looking mode (roll of spacecraft) Simultaneous SAR Imaging and SAR Data Downlink Selectable On-line BAQ 8:4, 8:6, 8:3, 8:2 Page 11 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 6

7 1. Mission Overview 2. SAR Imaging Modes & Performance 3. Satellite Design Overview 4. Launcher 5. Secondary Payload Page 12 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 3 TanDEM-X S/C Design In preparation of the TanDEM-X Mission, the TerraSAR-X satellite was equipped with: Sync Horn Antennas for exchange of radar sync pulses between TerraSAR-X and TanDEM-X (incl. related change of Leaf Amplifier Assemblies and control S/W) Improved PRF timing accuracy by change of Radar Central Electronics Timing Generator Module TDX is a rebuild of TSX with the following additional features: Cold Gas System for Fine Constellation Control Inter-Satellite Link Receiver for oneway transmission of position, attitude and status information from TerraSAR-X to TanDEM-X Page 13 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 7

8 3 TanDEM-X S/C Design Sync Horn Antennas Six circular polarised horn antennas Omni-directional coverage Sync Horns are fed by the LAA TR-Modules - 2 TRMs feed 1 Sync Horn Built-in redundancy (only 3 db signal reduction if one TRM fails) One horn antenna is active at a time Page 14 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 3 TanDEM-X S/C Design Improved PRF Synchronisation Instrument timing is derived from GPS 1 pps, distributed by On-Board Computer Original TerraSAR-X data take start time uncertainty was ~ 1 PRI (500 μs / 2 khz, equivalent to ~ 3,6 m on ground) Bi-static operation needs data take start time uncertainty in the range of a small fraction of a PRI (typically <2% RMS) Radar Central Electronics H/W and S/W has been changed on TerraSAR-X to reduce uncertainty down to approx. ± 1 μs Page 15 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 8

9 3 TanDEM-X S/C Design Cold Gas System Cold Gas System design heritage and off-the-shelf units as on CHAMP, GRACE and Cryosat Cold Gas Delta-v needed for constellation maintenance: 16,7 m/s, equivalent to 32,8 kg gaseous N2. Tank capacity is 37,6 350 bar providing ~10 % margin Min. Impulse Bit: 0,05 mm/s Pressure Vessel Pressure to OBC HPT Pressure Regulator Relief Valve Status to OBC Latch Valve B Latch Valve A Cmd from OBC via PCDU Thrusters Branch B Thrusters Branch A Fill Valve Pressure to OBC LPT Status to OBC Cmd from OBC via PCDU Page 16 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 3 TanDEM-X S/C Design Inter-Satellite Link TSX HK S-Band Downlink System is used to transmit data to TDX TDX is equipped with S-band Receiver for TSX downlink signal Decoder Unit prepares data for TDX On-Board Computer ISL max. data rate: 32 kbps Planned Data Transmission: GPS position information plus attitude and status data once every 10 seconds32 kbps To OBC Main / From OBC Main / To OBC Main / Redundant Redundant Redundant RX RX TX TX Frame Converter Frame Converter FPGA RX Main Nom RX Red. Nom D A RFEA ISL-RX Patch RX Antenna Helix Antenna Patch TX Antenna Nadir LHC RX Antenna Turnstile Antennas Zenith RHC RX Antenna Page 17 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 9

10 1. Mission Overview 2. SAR Imaging Modes & Performance 3. Satellite Design Overview 4. Launcher 5. Secondary Payload Page 18 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 4 TanDEM-X Launcher Baseline Launcher: Dnepr-1 Same launch vehicle as for TerraSAR-X Civil version of military launcher SS-18 In operation in its basic configuration since mid-70s Mission reliability factor 0.97 Launch from silo Moderate mechanical launch loads Launch pads in Baikonur, Kasachstan and Yasni, Russia Launcher contract signed already Page 19 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 10

11 1. Mission Overview 2. SAR Imaging Modes & Performance 3. Satellite Design Overview 4. Launcher 5. Secondary Payload Page 20 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 5 TanDEM-X Secondary Payload Overview AO issued in frame of Phase A Study in October 2004, distributed to ~ 30 addressees 7 NOI s have been received containing different degree & quality of information: JPL 3 DLR 2 Astrium-UK 1 Astrium-France 1 Requests for full proposal submitted in January full proposal have been received, one from JPL (GSRT) and one from DLR (LCT) Final selection planned before October 2006 Page 21 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 11

12 5 TanDEM-X Secondary Payload JPL GSRT Proposal GNSS Science Receiver, (Global Navigation Satellite Systems, consisting of GPS and Galileo) Measurement of ocean and ice reflection Differential GPS using TASS (TDRSS Augmentation Service for Satellites) Receives and interprets L2-Civil, L5, Galileo Consisting of Reflection-, GPS- & TDRSS S-band antenna, GSRT electronics box Interfaces & accommodation compliant with available TanDEM-X resources Differential capability of the receiver is mature and carries a low risk NASA funding to be consolidated Page 22 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 5 TanDEM-X Secondary Payload DLR / TESAT Proposal Laser Communication Terminal (LCT) Based on TSX-LCT modified for space-to-space high rate data communications with coherent laser beams Requires geo-stationary relay satellite with receiving LCT terminal (e.g. Alphabus, SatComBW, NASA GOES-P) Routine transmission of SAR data to relay satellite (as alternative to X-Band Stations) Some changes wrt TSX-LCT implementation concerning Data I/F to mass memory, mechanical accommodation, and increased power consumption Funding still to be consolidated Page 23 TDX Science Meeting No. 1 Dresden EADS Astrium GmbH 12