LONG DURATION STRATOSPHERIC BALLOONS SCIENTIFIC INSTRUMENTS ABOARD ISBA OR PLM, ROC INSTRUMENT SPECIFICATION DOCUMENT

LONG DURATION STRATOSPHERIC BALLOONS SCIENTIFIC INSTRUMENTS ABOARD ISBA OR PLM, ROC INSTRUMENT SPECIFICATION DOCUMENT Instrument: ROC - dual frequency GPS receivers for occultation Institute: Purdue University Project: Funded by NSF Polar Programs and Climate /Large Scale Dynamics – GPS radio occultation sounding of the Antarctic atmosphere from stratospheric balloons Instrument location: Payload Module / Nacelle Charge Utile (PM/NCU) Version 2008.09 Version Version 2008.06.26 2008.06.24 Version 2.1-2 Version 2.0 2007.06.27 2007.06.27 Version 1.0 2007.05.17 acronym CNES CNRS CST DS msp1666090107.doc Definition Centre National d’Etudes Spatiales Centre National de la Recherche Scientifique CNES Toulouse Space Center Driftsondes Reised as instrument specification Includes software specifications Revised communication parameters Changed location of ROC from ISP to Payload Module Minor changes – ROC-MB acronym Changed from cylindrical antenna to second avionics antenna First Draft IPEV LMD LMDOz GTS ICAO ISBA MCU MSD NCAR NSF NSO NSO-ISBA-RE Institut Polaire Franỗais Paul Emile Victor Laboratoire de Météorologie Dynamique Ozone meter (UV photometer / nitrogen) (CNRS-LMD), Global Telecommunications System (WMO) TSEN UC UCOz UV WPC Thermodynamic sensors: air pressure and temperature (CNRS LMD), University of Colorado Ozone meter (UV photometer / scrubber) (University of Colorado) Ultraviolet In situ measurement of aerosols (U Wyoming) Iridium System for Balloons Module Charge Utile – superceded by NCU = Payload Module Meteorology and Stratospheric Dynamics flights National Center for Atmospheric Research National Science Foundation Nacelle Servitude Operationelle = Flight Control Gondola Flight Control Gondola with Renewable Energy ( Science package in payload module) NSO-ISBA-RE Flight Control Gondola with Renewable Energy with Science ( TSEN Science package is in flight control gondola for driftsonde flights) NTS Nacelle Technique et Scientifique - Obsolete PM / NCU Payload Module / Nacelle Charge Utile ROC “ROC” : GPS radio occultation system for meteorological sounding and for fine measurements of vertical motion of the balloon (U Purdue) SPB / PSB Super-pressure Balloons PSB Payload Supervisor Board PSC Physics, Chemistry and Stratospheric Dynamics flights TBC To Be Confirmed TBC Order of launches in the Mission Specification has one launch of each type of PSC payload first I suggest the first launch of the ROC instrument AFTER the firsd MSD launch has succeeded and directly after one of the MSD launches designated as a validation flight TBC Number of driftsondes dedicated to validation of ROC data, from a MSD flight launched just prior to the ROC launch TBC Confirm approximate altitude corresponding to flight density TBC Verification of continuity of data by flight control center and delay for data availability to scientists TBC Evaluate the multipath environment of the antennas on the PM to assure no interference from elements located above, ie ISBA and ballast tank TBC Target size of enclosure is 18cm x 22 cm x 12 cm Actual volume available in WPC space inside PM is 22 cm x 60 cm x 21.5 cm Reduce this size further if possible TBC Target weight of enclosure is 300g msp1666090107.doc TBC Target weight of processor board is 128 g TBC Weight of cables and connectors is TBD TBC 10 Angle of antennas with respect to horizon is 20 degrees TBC 11 Power to GPS receivers is provided at 5V Is that optimal given the voltage supplied to the PM of 8.5 to 16V TBC 12 Duration of time to wait after sending signal to turn off before power is cut (ie minutes) has not been determined TBC 13 Power requirement for processor board is based on specs for TS7260 but final choice on processor has not yet been made TBC 14 Power requirements as a function of operating mode have not been determined TBC 15 Waveform of power demand (peak power when turned on) has not yet been characterized TBC 16 Temperature specs provided for TS7260 processor board, but final decision for board has not been made TBC 17 Verification that there is no interference between GPS receiver boards or between receiver boards and iridium add this: 1 We provide the power on a single line, one relay per instrument 2 The voltage is as follows: Nominal situation: voltage may vary in the range [10, 16] V, depending on the state of charge of the accumulator, (most frequently 12 volt) The associated requirement is that the WPC should work properly in this range,  Extreme : the range may extend to [9, 18] V . The associated requirement is that the WPC should withstand without damage voltage in this range, SCOPE OF THE DOCUMENT: The scope of this document is to identify the main technical requirements induced by the flight of your instrument aboard the Long Duration Balloons, and define the instrument hardware and software systems In a later stage an Interface Control Document will be jointly defined between the instrument Manager and CNES msp1666090107.doc MISSION OVERVIEW The Concordiasi mission is described in the Concordiasi Mission Specification Document Summarized here is an overview of the mission that will contain the Purdue University ROC The Concordiasi mission science objectives are to further the understanding of the south polar atmosphere The three science objectives are: 1) Vertical soundings of temperature, pressure, winds, and humidity for improving assimilation and validation of numerical weather prediction models in the Antarctic These observations will be made by NCAR driftsondes, and a new radio occultation system (ROC) will be tested 2) Measurements of ozone, temperature, and aerosol concentration during the annual cycle of the Antartctic Ozone Hole will be made using the LMD Ozone meter (UV photometer / nitrogen) and the UCOz Ozone meter (UV photometer / scrubber) and the University of Wyoming WPC in-situ aerosol measurement system 3) Stratospheric dynamics and gravity waves will be studied from vertical motions of balloons using the LMD TSEN thermodynamic sensors of air pressure and temperature The driftsonde gondola is equipped with at least 50 dropsondes Because of power requirements, the ROC will fly with the LMDOz instrument The platforms for the mission are 12 meter diameter superpressure balloons (SPB) filled with lighter than air gas, helium, that keep a constant volume all along the flight This makes them float at constant air density, provided that the suspended mass is constant The duration of the flight extends to several months Constant volume is obtained by maintaining a quantity of helium inside the envelope sufficient to maintain an internal pressure higher than the air pressure This requires the design of the envelope to meet stiffness, strength and helium-tightness criteria The balloons carry a maximum suspended weight of 50 kg Up and down telemetry links through the Iridium global coverage communication system monitor the flight and provide data transmission in compliance with the ICAO rules The balloon flights, and the scientific instruments controlled through the balloon flight systems, will be monitored and controlled from McMurdo and Toulouse The Concordiasi campaign will take place from McMurdo Station, during the “Winfly” period, from late August to late October 2009 The mission will start as soon as possible during the Austral winter in order to observe the return of the sun illumination for the ozone chemistry, and when the winter polar vortex still constrains the trajectory of the balloons to the polar region for all of the other objectives There will be 12 flights dedicated to Meteorolgogy and Stratospheric Dynamics (MSD) and up to flights concerned with Physics Chemistry and Stratospheric Dynamics (PSC ) MSD flights will carry the Thermodynamic sensors (TSEN) in the ISBA and the driftsonde gondola (DS) PSC flights in configuration (PSC-1) will contain the TSEN, WPC, and LMDOz in the payload module (PM) PSC flights in configuration (PSC-2) will contain the TSEN, ROC and LMDOz in the PM PSC flights in configuration (PSC-3) will contain the TSEN, WPC and UCOz in the PM The operations are to be planned for flights of duration months Two of the PSC flights will carry the ROC These flights will be planned for launch within one hour of a driftsonde payload (MSD) flight This will provide independent soundings from the MSD driftsonde within a close distance (100 km) of the PSC-ROC flight for postflight validation of the soundings retrieved from ROC The MSD dropsonde flights are planned for mid- September through late October, 2009, with the capability of driftsondes released per day by one balloon Release of several (TBC 2) driftsondes on these validation flights should be planned to coincide with the times of occultations The flights will be adjusted over the first 24 hours using ballast to be at an altitude with density within 110 to 105 g/m2, or an altitude of approximately 20 km (TBC 3) The rest of the flight should be left with characteristics that are quasi-Lagrangian msp1666090107.doc The ROC instrument will be operated continuously, though data recording may be reduced or the instrument shut down in special circumstances when power resources become too limited, for instance in case of a trajectory producing long night times for the vehicle The flight control centers at McMurdo will download and monitor the data in real time The flight control center will automatically verify the continuity of the data and rerequest any missing packets (TBC 4), as the quality of the scientific results depends highly on the continuity of the time series The flight control center will make the data available to scientists via the internet within hours of collection under normal operating conditions ROC data will be quality controlled by Purdue U A final quality controlled data set will be made available by Purdue U within one year of the experiment SYSTEM CONFIGURATION: CNES offers two types of vehicle for long duration flights:) Superpressure balloons “BPS”: flight duration of up to months, at constant air density level, in the range 70 - 120 g/m3, depending on balloon size and payload mass Infrared Montgolfière “MIR”: flights of up to months, at variable altitude, ~24000m / 18000m during resp the day / night flight phases The CNES flight systems for these two types of vehicle are very similar; they provide the scientific instrument with power, telemetry and commands, mass memory, structural link and thermal insulation The standard overall configuration of the flight system is illustrated in appendix This scheme represents a BPS; the configuration for a MIR is very similar, the main difference being the length of the flight train, extending in that case to 30/40 m The scientific instruments are normally located in the Payload Module (“PM” or “NCU”) The ROC instrument will be deployed in the payload module of the superpressure balloon (BPS) as shown in Figure The multipath environment of the PM location will be evaluated to assure that ISBA and the ballast tank not interfere with the quality of the data msp1666090107.doc Figure Flight configuration for PSC1 flights containing ROC msp1666090107.doc INFORMATION REQUESTED 3.1 MEASUREMENT OBJECTIVES AND MISSION DESCRIPTION:  Describe briefly the measurements that will be performed by the instrument, and the main associated constraints (e.g.: specific periods for observations, frequency of observations…) Each of the two GPS receivers will make continuous measurements of phase to calculate (on the ground) the precise position of each antenna The main constraint for the placement of the antennas is the unobstructed line of sight to the GPS satellites The GPS receivers will make continuous measurements for approximately 20 minutes during setting occultations of individual satellites with higher sample rate  Describe briefly the main components of the instrument, and give a block diagram Aero Antenna L1/L2 GPS antennas AT2775-41F with internal 40dB LNA Trimble BD950 GPS receiver boards and one processor board in an aluminum enclosure cables to antennas with SMA connectors  Identify the consumables, if any, and the expected lifetime of the instrument years - no consumables 3.2 OPERATING MODES:  Describe all the operating configurations/modes of the instruments, related commands and transitions between these modes Modes (Functional description, when, duration, criteria for msp1666090107.doc D1) Off (never off during flight if possible), D2) On – Default mode, automatic on power on, recording the following: transition to another mode…) phase measurements for position on GPS1 phase measurements for occultation on GPS1 phase measurements for position on GPS2 phase measurements for position on GPS2 D3) On – GPS1 only occultation: phase measurements for position on GPS1 phase measurements for occultation on GPS1 D4) On – GPS2 only occultation: phase measurements for position on GPS1 phase measurements for occultation on GPS1 D5) On – GPS1 only higher rate position: phase measurements for position on GPS1 D6) On – GPS2 only higher rate position: phase measurements for position on GPS2 Stand-by D7) On – GPS1 and GPS2 higher rate position, orientation: phase measurements for position on GPS1 phase measurements for position on GPS2 D8) On – no recording (allows continuous tracking of GPS phase even though it is not recorded) Transient D9) Turn off – send signal for instrument to shut down This will be followed by a TC to remove power from bus for instrument after a to be determined delay (TBC 12) Reset yes: requirement to reset receiver if monitoring housekeeping data shows there is a problem Others Application Files on BD950 Reciever: D1) Off (never off during flight if possible), D2) On – Nominal default mode, automatic on power on, GPS1 and GPS2 occultation: GPS1 pos,vel,occ = 60s, 15s, 2s GPS2 pos,vel, occ= 60s, 15s, 2s D3) On – GPS1 only occultation: GPS1 pos,vel,occ = 60s, 15s, 2s GPS2 off D4) On – GPS2 only occultation: GPS1 off GPS2 pos,vel,occ = 60s, 15s, 2s msp1666090107.doc D5) On – GPS1 only higher rate position continuous (for gravity wave study only): GPS1 pos,vel,occ = 10s, 0, GPS2 off D6) On – GPS2 only higher rate position: phase measurements for position on GPS2 D7) On – GPS1 only very high rate position, limited time (for ballon dynamics, or GW in special locations): GPS1 pos,vel,occ = 1s, 0, GPS2 off D8) On – GPS1 and GPS2 higher rate position, orientation: phase measurements for position on GPS1, RTK heading GPS2-GPS1 D8) D8) On – no recording (allows continuous tracking of GPS phase even though it is not recorded) 3.3 EXTERNAL SHAPE AND MECHANICAL INTERFACES The location for the ROC instrument is inside the PM The physical description of the components of the instrument and of the main physical integration constraints are the following:  External shape, mass and material, Aluminum enclosure 18 cm W x 22 cm H x 12 cm D (TBC 6) (actual volume inside PM is 22 cm x 60 cm x 21.5 cm) Target weight (TBC 7) Two BD950 GPS receiver cards processor board Target weight (TBC 8) Two avionics antennas Aluminum with polyurethane enamel coating 7.6 cm W x 1.9 cm H x 12 cm D Cables and connectors (approximate) TBC Total Requirements 300g 65g x 130g 130g 237g x 474g 200g 1234 g < 1600 g  Required sights of view or other accesses Avionics antennas: Line of sight from vertical to degrees below horizontal for visibility to all overhead satellites Antennas mounted rigidly to Payload Module to assure rigid connection between them Antennas mounted at a tilt of 20 degrees to the horizon (TBC 10) msp1666090107.doc 10 Antenna cable on inside or protected so it is not a heat sink for receiver  Mechanical interface – GPS receiver enclosure secured with screws to two horizontal brackets on interior frame of PM Avionics antennas attached with screws Rigid connection between antennas is required  Location of the connectors msp1666090107.doc 11     SMA connectors at base of avionics antennas SMA female connectors on exterior of GPS receiver enclosure SubDB9 power connector on exterior of GPS receiver enclosure SubDB9 serial connector on exterior of GPS receiver enclosure  Needs for late access to the instrument (“late” means after complete integration of the PM while the balloon is on the ground before launch), Turn on instrument on ground before launch Instrument must receive synchronization message from PSB to set flight identification number in data stream  Special needs/concern about cleanliness, No special needs/concerns about cleanliness Verify enclosure is watertight Note: in order to simplify the development testing and integration, it is preferred to arrange all components of an instrument in a single housing, provided this is not too detrimental to the overall mass 3.4 POWER: Power is provided for the PM with voltage between 8.5 and 16 V Power is delivered on a single bus for an instrument, up to three connections to this bus through relays driven by the PM are offered This is only intended to give flexibility in the long term flight management of the instrument (eg redundancy management, connection dedicated to heaters…) POWER  describe the instrument power needs Number of connections required one for processor board Power required on each of these +4.5V to +32V DC; typical 2.3 W at 5V DC (includes power msp1666090107.doc 12 connections, maximum value and mean value wrt operating mode This figure should include a first estimate of the power needs for heaters, if any through GPS receiver to antenna) for each receiver +4.5 to +20 VDC; W for processor board (1/4 W minimum) (TBC 13) Total required 5.6 W No estimate made for heaters provided by CNES Power will be provided on a single line, one relay per instrument Nominal situation: voltage may vary in the range [10, 16] V, depending on the state of charge of the accumulator, (most frequently 12 volt) The associated requirement is that the ROC should work properly in this range, Extreme : the range may extend to [9, 18] V The associated requirement is that the ROC should withstand without damage voltage in this range DUTY CYCLE AND ENERGY  Give an estimate of the duty cycle (time on/off in the various modes) of the instrument over typical periods of time (routine, intense observation periods …) and derive the energy need over these periods of time GPS receivers: continuously on, x 2.3 Watts Processor board: Watt Estimate of the energy need is 5.6 Watts for default mode D2 and for mode D7 Energy need is 3.3 Watts when operating only one receiver in modes D3, D4, D5, D6 Any variation of energy needs of the instrument as a function of sampling rate and positioning operating mode versus positioning and occultation operating modes has not yet been determined (TBC 14) Waveform describing peak power when turned on, background power requirements and noise have not yet been described (TBC 15) 3.5 ENVIRONMENT: THERMAL: PM provides for thermal insulation of the instrument The definition of the optimal layout of the instrument inside the PM, in particular for minimizing the power needed for active thermal control, will be carried out through a close collaboration between the instrument designer and CNES As a starting point, the instrument designer is expected to well identify the instrument’s constraints (e.g temperature limitations versus operating mode, as close as possible to the real needs)  Give the temperature specification at the level of each component versus the operating mode, msp1666090107.doc 13 o o GPS BD950 receiver – operating -40 to 75 C, storage -55 to 80 C (note: manufacturer states that it can be stored at -80 oC, then brought to -40 oC before turning on, then turned on and operated at -40oC Manufacturer will replace one unit if it fails during temperature testing) AT2775-41F avionics antenna – operating temperature -55 to 80oC (note: manufacturer states that it will operate at -80 oC as there are no internal components that would be affected by temperature, and it has been operated at -60 oC in previous tests) TS-7260 processor board – operating temperature -40 oC to 70 oC (TBC 16) Cables -70 oC to 200 oC operating temperature  Provide if possible a basic thermal model of the instrument N/A ELECTRICAL ENVIRONMENT:  Specific needs w.r.t electromagnetic compatibility Verify there is no interference between iridium antennas and GPS (test on ground) Verify there is no interference between receiver boards in one enclosure (test on ground) (TBC 17) 3.6 DATA FORMAT DESCRIPTION: Note that on ground, CNES will make available to the scientists informations such as GPS position of the vehicle, flight level pressure and air temperature (the accuracy depends on the flight configuration, recurrence is min) Measurement Measurement Data transmission msp1666090107.doc Parameters: Header record: time, receiver number 1, number of satellites Data record: L1+P1+P2+D1+D2+SNR1+SNR2 Time may be irregularly spaced Number of satellites, thus number of data records for each time sample, will vary between and 12 Parameters: Header record: time, receiver number 2, number of satellites Data record: L1+P1+P2+D1+D2+SNR1+SNR2 Time may be irregularly spaced Number of satellites, thus number of data records for each time sample, will vary between and 12 approximately 1.2 Mbytes of data per day, which can be transmitted in 1.5 hours once per day or smaller amounts several times per day, no real time requirement 14 3.6 DATA INTERFACE: The instruments are linked to the CNES flight systems through a digital bus (RS 485) This link is bidirectional:  Up link includes the possibility to send some digital commands from ground to the instrument,  Time and position data of the vehicle (GPS) are available in the PM, and simple parameters such as solar zenithal angle (SZA) can be derived from these data in the PM  Down link includes the possibility to collect scientific and housekeeping data The data are stored onboard in the CNES system, and then unloaded through the iridium link This “store and forward” approach is necessary because the communication can be interrupted; however thanks to a handshaking process all the data can be retrieved UPLINK  Give the following information related to data exchange from PM to the instrument: Do you need time, position NO, except as required to put in the header of the data packet such as information transferred from the the flight identification number, and the packet counter PM to the instrument ? Do you need information from NO the PM to the instrument that some threshold has been reached (eg SZA < tbd) ? Size of the frame for digital command to be sent from ground to the instrument ? 10 bytes = flags to determining mode, and sample rates messages must be sent to completely configure instrument Message 1: 1-2 bytes record mode: through depending on operating mode described in section 3.2 3-4 bytes GPS id: or 2, indicates whether following sampling parameters are for GPS receiver or GPS receiver 5-6 bytes intpos1: interval for recording positioning data for GPS receiver 1, in seconds Default 30 seconds 7-8 bytes intvel1: interval for recording positioning data during occultation for GPS receiver 1, in seconds Default 10 seconds 9-10 bytes intocc1: interval for recording phase data for occultation for GPS receiver 1, in seconds Default seconds Message 2: 1-2 bytes record mode: through depending on operating mode msp1666090107.doc 15 described in section 3.2 3-4 bytes GPS id: or 2, indicates whether following sampling parameters are for GPS receiver or GPS receiver 5-6 bytes intpos2: interval for recording positioning data for GPS receiver 1, in seconds Default 30 seconds 7-8 bytes intvel2: interval for recording positioning data during occultation for GPS receiver 2, in seconds Default 10 seconds 9-10 bytes intocc2: interval for recording phase data for occultation for GPS receiver 2, in seconds Default seconds Negative integers indicate frequency in Hz for sampling rates higher than Hz Zero values indicate the data stream is not sampled DOWN LINK In order to download your data we need to format, complement and store them in the PM:  Give the following information related to data exchange from instrument to the PM: After each command sent from PSB to the instrument, the instrument will send an acknowledgement message After each data frame sent from the instrument to the PSB, the PSB will send an acknowledgement This is described in more detail in the PSB and Science Data Packet Definition Document Data rate 1.2 Mbytes per day, on average 14 bytes/sec Size of telemetry frame 1017 bytes with bytes of packet header and CRC Continuous stream of GPS data will be broken into packets of this size Quantity of data versus operating mode on (same as above) Quantity of data versus mission phase (typical 24 hours period, intense observation period…) on – same as above off - none off – none (though several different measurement modes are proposed, all measurements benefit from the maximum sample rate possible, while remaining within the 1.2 Mbytes/day data rate) Data packet constructed by instrument will contain in the packet counter and a CRC The PSB will put in the correct packet count and recalculate the CRC before sending to the ground After 18 days the packet counter will reset to msp1666090107.doc 16 The PSB sends a command to the ROC to request a data packet one time each minute The PSB stores the data packets then sends them to the ground each hour Storage capacity of PSB (or is it ISBA?) is Mb, of which 900 kb is available for ROC data This assures that 14 hours of data is stored on board in case some data needs to be resent Packets are sent again if not acknowledged following the procedure described in the PSB and Science data packet definition document Commands and Synchronization messages are sent from the PSB to the instrument with the address of the instrument indicated Instrument must distinguish between messages addressed to it and those not addressed to it  Give the following information related to data exchange between PM and the ground: The PSB stores the data packets then sends them to the ground each hour Packets are sent again if not acknowledged following the procedure described in the PSB and Science data packet definition document Continuity of data is critical for the ROC science mission Therefore quality checking in the ground processing is necessary to assure all packets are transmitted correctly, and retransmitted if necessary, both between the ROC and PSB and also between the PSB and the ground 3.7 ON/OFF (DISCRETE) COMMANDS: In addition to the digital commands, PM provides discrete command to each instrument The discrete command turns on the power to the instrument All further commands are digital commands sent via the TC messages 3.8 INTERFACE BETWEEN ON BOARD AND GROUND STATION: Define the requested periodicity for:  Sending commands to the instrument,  Retrieving the scientific and housekeeping data, And describe your needs concerning the availability of CNES data (position, pressure …) Propose an operational scheme Periodicity for sending commands Commands will be sent infrequently, maximum times per day, to switch between modes Periodicity for retrieving the data 24 times per day (once per hour), for minutes, in order to transmit 1017*60 bytes for a total of 1.2 Mbytes per day Requirements concerning CNES data availability (on ground) Necessary to have data available on internet immediately to quality check for data continuity msp1666090107.doc 17 This requires reconstructing the individual data packets to get the continuous data stream This processing will be carried out by Purdue with sufficient speed to request data be downloaded again within 12 hours of initial download VALIDATION TESTS REQUIRED Verify the following: -no interference between two receiver boards -functional test of L2 signal recording -offsets of antennas -no multipath from ballast and ISBA -effect of polystyrene enclosure for PM on SNR - no interference between iridium and GPS receivers msp1666090107.doc ... DOCUMENT: The scope of this document is to identify the main technical requirements induced by the flight of your instrument aboard the Long Duration Balloons, and define the instrument hardware and... data recording may be reduced or the instrument shut down in special circumstances when power resources become too limited, for instance in case of a trajectory producing long night times for the... female connectors on exterior of GPS receiver enclosure SubDB9 power connector on exterior of GPS receiver enclosure SubDB9 serial connector on exterior of GPS receiver enclosure  Needs for late access