strofio science plan & operations
DESCRIPTION
Strofio Science Plan & Operations. Mihir Desai Southwest Research Institute [email protected] (210) 522-6754. Strofio - part of SERENA suite. What is Strofio?. - PowerPoint PPT PresentationTRANSCRIPT
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 1
Strofio: Analysis of Mercury’s Exosphere
Strofio Science Plan & Operations
Mihir DesaiSouthwest Research Institute
[email protected](210) 522-6754
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 2
Strofio: Analysis of Mercury’s Exosphere
Strofio - part of SERENA suite
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Strofio: Analysis of Mercury’s Exosphere
3
What is Strofio?
• Strofio is a scientific investigation of the Hermean exosphere based on a novel mass spectrograph that determines the mass-per-charge (m/q) of low-energy (~1 eV) neutral atoms by a time-of-flight (TOF) technique.
• The name comes from the Greek word Strofi, which means “to rotate”: the phase of a rotating electric field “stamps” a start time on the particles’ trajectory. The detector records the hit position (hence the start time) and the stop time.
• Strofio achieves high-sensitivity (0.14 counts/s when the density is 1 particle/cm3) within limited resources (~2 kg).
• The mass resolution (m/m ≥ 60) is achieved by fast electronics and does not require tight mechanical tolerances.
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 4
Strofio: Analysis of Mercury’s ExospherePresentation Topics
Science Objectives MPO timeline Strofio Pointing and Observing Strategy Science & Engineering Modes Data Collection and Telemetry
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 5
Strofio: Analysis of Mercury’s Exosphere
Science Objectives & Measurements
Science ObjectivesDetermine Exospheric CompositionStudy Exosphere-Magnetosphere InteractionsStudy Exosphere-Surface InteractionsDerive Surface Composition
Measurement Strategy Identify major (He, O, Na etc) and rare (e.g., Mg,
Ar, Ne isotopes) exospheric neutralsMeasure their temporal and spatial variations
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 6
Strofio: Analysis of Mercury’s ExosphereStrofio Flight Operations - Overview
Cruise Phase – ~6.5 years Activation and Check out Calibration and Voltage Optimization Background Rejection Tests & Characterization
Commissioning Phase – ~90 days Power off (orbit insertion) ~72 days Same as Cruise Phase ~6 days Normal Science Mode ~11 days
Science Operations Phase – 2 years Timeline-based Power off +/-3 days at Eclipse Engineering Modes during safing, thruster firing etc.,
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 7
Strofio: Analysis of Mercury’s Exosphere
Timeline of Flight Operations
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Strofio: Analysis of Mercury’s Exosphere
Strofio pointing & Ops Planning Primary source points into +X direction Strofio
collects Mercury gas when the spacecraft velocity is pointing in +X direction
Going with Mercury, away from the Sun (from Perihelion to aphelion), RAM is from the –X direction, hence the secondary source is active
From Aphelion to Perihelion, RAM is in the +X direction and so the Primary Source is active
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 9
Strofio: Analysis of Mercury’s Exosphere
Exospheric Asymmetries day/night
Aphelion Perihelion
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 10
Strofio: Analysis of Mercury’s Exosphere
Strofio Measurements Aphelionthe pericenter is on the dayside, close to
local noon, where the PSD has its maximum Measurement Strategy
Perihelion the pericenter is at midnight; Strofio has best observing chances for meteorite impact vaporization (MIV)
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 11
Strofio: Analysis of Mercury’s Exosphere
Overview of Mode Transitions Engineering Modes
Stand-by ModeDiagnostic ModeSafe ModePre-Science Mode
Science Survey ModeNormal mode
interleaved with 4 Sub-modes
Calibration Mode
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 12
Strofio: Analysis of Mercury’s Exosphere
Stand-By Mode After Power-onAfter Power On Reset
Diagnostic Mode After Stand-ByCheck Strofio health,
checksums, S/W & H/WHV, Filaments, RF off FSW Enabled
Safe ModeAutomatic in case of
instrument or system failureGround Intervention
required to de-activate
Pre-Science Mode Used for filament changeSource Voltages onMCP bias below operationalFilament Heaters ~10-20%
of operational levels
Engineering Modes
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 13
Strofio: Analysis of Mercury’s Exosphere
Normal Science Mode Measure ~50 meV/AMU exospheric neutrals Default data collection mode Ionizing Electron Energy range: -90 – -110 V Interleaved with one of the following four sub-modes
Sub-Mode 1: Ion Mode Measure ions between 0.5-10 eV Switch filament off Heater at <5% of operational levels
Science Survey Mode
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 14
Strofio: Analysis of Mercury’s Exosphere
Sub-Mode 2: Molecular Mode Measure molecular species, H2O, CO2, O2, N2 etc. Vary ionizing electron energy between -40 – -60 V
Sub-Mode 3: High Energy Mode Measure higher energy exospheric neutrals Scan above ~5-10 eV energy range
Sub-Mode 4: Background Mode Measure instrument background Switch Filament from Ram to anti-Ram direction
Science Modes...cont’d
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Strofio: Analysis of Mercury’s Exosphere
Independent Calibration Mode Parameters are updated to perform calibration
functions such as: Check Instrument performance Adjust MCP gain Tune and Optimize Voltages Optimize ionizing source performance
Strofio collects raw, double coincidence paired-event data (TOF: position & sync.)
Calibration Mode
14-17 May 2013 SERENA-HEWG Workshop, Key Largo, Fl,, USA Desai - 16
Strofio: Analysis of Mercury’s Exosphere
Instrument Commanding Implementation
Simple Mode/State Transitions implemented through Flight Software macros
Macros based on Engineering, Science (sub-modes) and calibration modes
Extensive Tests and Verification of all commands and macros on ground
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Strofio: Analysis of Mercury’s Exosphere
Instrument Commanding Strategy
Nominal commanding – timeline basedNo real-time commands
Timeline & Command Strategy based onBepiColombo mission phase Orbit orientationPeriodic Feedback Types of science investigations Science coordination with other instrumentsPower ManagementDuty cycling
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Strofio: Analysis of Mercury’s ExosphereScience Operations Plan
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Strofio: Analysis of Mercury’s Exosphere
Data Acquisition 1 particle creates 1 event ==> 25-bit word
11 + 1 bits for ToF and its validity 11 + 1 bits for position and its validity 1 bit = Identify hit location hemisphere of the annulus
FPGA creates 24-bit word for 1 VALID event 11 bits for ToF 11 bits for position 1 bit = Identify hit location hemisphere of the annulus 1 bit for high or low position resolution
Use lookup tables to fill 2048 or 64 bins The 64 bins or counters correspond to major masses of
interest (He, Na, O, Mg…), and background and guard channels.
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Strofio: Analysis of Mercury’s Exosphere
Data Description & Telemetry AllocationData
ProductDescription
Bins or Bytes
Bits/bin
Integration Time (s)
Bitrate (bits/s)
Percent (%)
ADetailed Mass Histogram (Ultra-High Mass Resolution events)
2048 10 120 170.6 28.4
BMass Histogram (High Position Resolution)
64 10 10 64.0 10.7
CMass Histogram (Low Position Resolution)
64 10 10 64.0 10.7
D Single Events 106000 24 9000 282.7 47.1
Telemetry Before Compression (not including Housekeeping data)
581.3
Compression Factor 3.0
Telemetry After Compression (not including Housekeeping data)
193.8
E1Uncompressed Housekeeping (Temperature fields)
6 8 30 1.6 0.8
E2Uncompressed Housekeeping (in Bytes)
350 2800 600 4.6 2.3
Total Telemetry After Compression (bits/s)
200.0 100.0
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Strofio: Analysis of Mercury’s Exosphere
Data Products and DeliveryTable 3: Strofio Data Product Summary Data Level
Responsibility Description Time Lag
L-0b BMOC Input telemetry stream Immediately
L-1b SGS (ESOC Science Ground Segment)
Raw time-ordered data, checksum validated data in scientific units, including label files
Immediately
L-2 SGS (1) Strofio GDS (2)
Time-ordered and calibrated data, including attitude and ephemeris information and label files
Immediately (1)
After reprocessing (2)
L-3 Strofio GDS Higher-order Strofio data (e.g., time-ordered mass histograms, densities organized by latitude and longitude), complementary SERENA and BepiColombo (MPO and MMO) data, relevant theoretical models of the surface-exosphere-magnetosphere interactions, appropriate laboratory measurements and modeling.
As available
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Strofio: Analysis of Mercury’s Exosphere
BACKUP SLIDESMission Operations & Data Analysis
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Strofio: Analysis of Mercury’s Exosphere
Science Overview
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Strofio: Analysis of Mercury’s Exosphere
135°
45°
315°
225°
180°
170°
60°
300°
315°
45°
190°
Aphelion = 32 days
Reduced P/L ops.8 days (120 W)
during GS with Ka
Reduced P/L ops.4 days (120 W)
during GS with Ka
Full P/L ops.27 days (179 W)
Full P/L ops.27 days (179 W)
Reduced P/L ops.4 days (120 W)
during GS with Ka
Reduced P/L ops.16 days
111 W outside GS contact5 W during GS with X
(no Ka band during this period)
Terminator = 20 days
Terminator = 20 days
Perihelion = 16 days
MPO Timeline (from ESA)
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Strofio: Analysis of Mercury’s Exosphere
Orbit Definition
RadiatorFrom EID-A sec 2.4.6.2
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Strofio: Analysis of Mercury’s Exosphere
Timeline Assumptions
Launch 7/19/2014
Perihelion 5/12/2020
11/13/2020 Orbit insertion
Aphelion 6/25/2020
7/21/2020 Start of commissioning
Perihelion 8/8/2020
2/19/2021 Start Science Ops
Aphelion 9/21/2020
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Strofio: Analysis of Mercury’s Exosphere
Exospheric Asymmetries dawn/dusk
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Strofio: Analysis of Mercury’s Exosphere
Timeline of Flight Operations