PowerPointPrsentation

1
SESAMEStatus and On-Comet Science K.
Seidensticker1, H.-H. Fischer2, K. Thiel2, I.
Apathy3, W. Schmidt4 and the SESAME team 1DLR
(Köln) , 2University of Köln, 3KFKI (Budapest),
4FMI (Helsinki)
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Outline of Talk

• Flight operation
• Payload checkout 6
• Software
• Flight SW, EGSE-SW
• Operation planning for 2008
• SESAME On-Comet operation aspects
• Funding and personnel
• Conclusions

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SESAME PC 6 Activities
4
PC 6 New Temperature Measuring Method

• Left Old method no temperature
  valuesaccessible lt -104.5C
• Below New method with two voltage references
  temperatures (voltages) are given in columns 4
  and 6 a calibration during Steins Fly-By is
  planned.

5
PC 6 SD2 Drill Rotation Test

• CASSE time series data from three feet three
  axes each example foot -Y, x

(a) Before drilling starts predominantly
vibration caused by Orbiter reaction wheels
FFT
(b) After start of SD2 drill motor
FFT
6
PC 6 CASSE Trigger Event (IDP ?)
During the 2. CASSE Triggered Mode sequence of
the new ExtAFT (29. September 2007) an event
eceeded the trigger level of 20 (ADC values) on
the X foot, ACC y-axis

• Complete time series with 5980 samples
• Most of the noise is caused by vibrations
  excited by the orbiter reaction wheels
• Red lines indicate full y-scale.

Enlarged view (around t 100 ms) of complete
time series above x and z axes also show tiny
signals thermal cracking or IDP?
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PC 6 PP Active Mode (1)
SESAME software version FM-2 introduced
wavelet-based data reduction. First use of
transmitter electrodes in the X foot and at the
MUPUS PEN.

• A 1 kHz signal was injected with 20 Vp-p the
  response was monitored via Y and Y feet
  sensors. The red lines mark the start of an
  injected sine wave in order to estimate the phase
  shift between current and response voltage.

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PC 6 PP Active Mode (2)
The FFT spectrum (TX) shows the injected 1 kHz
current and higher harmonics. The receiver (RX)
registered additionally a component at about 60
Hz. PP-AM injects 20 frequencies with different
amplitudes (5, 10 and 20 V) each and analyzes the
responses.
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PC 6 PP Passive Mode
First use of PP Passive Mode foreseen for plasma
waves detection during descent
The potential difference between the Y and Y
sensors is sampled with 40 kHz for 0.2 s. The
lowest frequency bin contains also offset
components, the highest contains digital
noise. The left panel shows the command
parameters Langmuir Probe flag 65535 means no
plasma wave detected.
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PC 6 New Flight Software FM-2

• Major upgrades implemented / planned for SW FM-2
• CASSE Implementation of Triggered Mode
  detection of external signals like cometary
  quakes and MUPUS-PEN insertion
• CASSE Fixing of wrong channel assignment(due to
  FPGA program flaw missing reset) (postponed to
  FM-3)
• CASSE New temperature measuring mode
  calibration U vs. T pending
• DIM Autonomous measuring depending on dust flux
  and sensor status (implemented, but further
  ground tests needed)
• PP Improved data sampling strategy on-board
  data evaluation for active and passive modes
  wavelet filtering of time series
• General HK data content improved time-stamp
  includedscience data processing revised
• FM-2 successfully uploaded during PC 6
  (September 2007)

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SESAME EGSE Software

• EGSE software AliBaba for SESAME
• Goals
• Parsing of rolbin-files and formatting of SESAME
  science and HK records
• Quick-look data check (science data and HK) and
  export
• Applicable for all hardware versions in use (FM,
  GRM, EGSE)
• Browsing on telemetry level
• Version 1.5.2 released
• Fully qualified for all PC 6 SESAME procedures
  and flight software version FM-2
• Recently implemented AliBaba upgrades
• Improved presentation and analysis of PP and DIM
  data
• Display of CASSE Triggered Mode
• Presentation of revised health-check and
  housekeeping data
• Improved service for lab operation handle
  increasing file size during measurements

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SESAME Planning for PC 8

• Participation in Flywheel test (SES_7)
• Flywheel operation not representative for descent
  (CVP repetition?)
• But should help to prepare SESAME instruments for
  descent test (PC 12?)
• CASSE Measurement during SD2 Drill Test (SES_8
  and SES_14)
• Repetition of PC 6 tests planned by SD2 team
• Additional inter-foot sounding by CASSE in order
  to characterize landing gear and sole actuators
  and receivers
• Vibration measurements during Orbiter Wheel
  Offloading (SES_9)
• Test of CASSE Triggered Mode
• Improved frequency resolution compared to PC 4
• Thermal test of Philae soles (SES_10)
• Part 1 Preparation of thermal calibration during
  Steins fly-by (PC 8 without solar illumination
  of soles, solar distance ca. 2 AU)
• Measure temperatures of all CASSE sole sensors
  being heated by CASSE accelerometers with new
  method.

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SESAME Planning for Steins Fly-By

• Vibration measurements during Orbiter Wheel
  Offloading (SES_9)
• 24 h before Close Approach
• Can be cancelled if PC 8 operation is possible
  and successful
• Thermal test of Philae soles (SES_10)
• Part 2 Measure temperatures of all CASSE sensors
  with old and new method
• Get temperature data from soles illuminated by
  sun and being in shadow
• Obtain new calibration curve (voltages vs.
  temperature)
• Later on Try to model dynamic thermal behavior
  of soles for on-comet application
• Operate CASSE and DIM in a dusty environment
  (SES_11)
• Search with CASSE (Triggered Mode) and DIM (Burst
  Continuous Mode) for dust particles when Philae
  attitude is favorable (around Close Approach)

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CASSE Science Objectives and Measurements

• Science Objectives
• LSE-CAS-O1 Determine elastic properties of
  cometary surface layer
• LSE-CAS-O2 Determine macro-structure of surface
  layer (layering, inhomogeneities)
• LSE-CAS-O3 Locate and analyze micro-seismic
  events
• Measurements
• LSE-CAS-M1 Determine longitudinal and shear wave
  velocities by active sounding from foot to foot
• LSE-CAS-M2 Generate reflection and refraction
  seismograms by active sounding (CASSE and
  MUPUS-Pen)
• LSE-CAS-M3 Register external signals with
  several sensors (Passive triggered listening)
• Relation to other Instruments
• MUPUS Use MUPUS-PEN hammering as external
  vibration source
• SD2 Use SD2 drilling as external vibration
  source (TBD)

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Experiment with MUPUS-PEN Simulator

• Accelerometer signal of z-axis (pointing to PEN)
  in 35 cm distance from insertion point

Simulator hammering on an ice-block (WDL
503070 cm3) in the DLR Cold Lab (Chr. Krause)
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DIM Science Objectives and Measurements

• Science Objectives
• LSE-DIM-O1 Study the fluxes and dynamics of
  near-surface cometary particle flow
• LSE-DIM-O2 Determine physical properties of
  cometary grains
• LSE-DIM-O3 Contribute to the understanding of
  cometary activity and the formation of cometary
  mantles
• Measurements
• LSE-DIM-M1 Measure parameters of the electrical
  signal caused by particle impact on
  piezo-electric plate
• LSE-DIM-M2 Determine average signal height in
  case single impacts can not be discriminated
• LSE-DIM-M3 Determine flow rate and direction as
  well as temporal variations
• Relation to other Instruments
• GIADA Correlate DIM data with GIADA
  observations (TBD)

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PP Science Objectives and Measurements

• Science Objectives
• LSE-PP-O1 Determine electrical properties of the
  cometary surface matter and its evolution
• LSE-PP-O2 Monitor electron density variation
  and the comets outgassing activity
• Measurements
• LSE-PP-M1 Inject alternating currents of
  different frequencies into the cometary surface
  and monitor variations of induced electrical
  potential (active mode)
• LSE-PP-M2 Monitor potential difference
  variations (passive mode)
• Relation to other Instruments
• ROMAP Compare permeability measurements
• MUPUS PP electrode deployment temperature of
  surface matter
• APXS PP electrode deployment surface
  composition
• CIVA Observation of MUPUS-Pen and Philae soles

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Open issues during the cruise phase

• Until hibernation development and test of
  additional measurement and operation methods gt
  further upgrades of flight and EGSE software
• Development of software planning tool for command
  generation and resource calculation
• Ongoing calibration (in space and on Earth) of
  SESAME instruments and development of analysis
  programs
• Detailed planning and testing of 67P/C-G
  operation phases(S-D-L, FSS and long-term
  science)
• Archiving (PDS), documentation, knowledge
  management

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Long-term SESAME Planning
PC 6 FM-2 Upload PC 8 Flywheel test therm.
calibration Steins Fly-By Thermal
Calibration PC 10 FM-3 Upload PC 12
Flywheel Test, IF-Test, FM-3.5 Upload? Lutetia
Fly-By Search for IDPs? 2014 FM-4
Upload?
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Readiness for FSS and long-term science

• SESAME is not fully ready
• CASSE
• Basic operation modes are operational
• Increase on-board autonomy (e.g. trigger level
  setting, averaging)
• Correction or compensation of hardware problems,
  e.g. missing H/W reset or varying offsets
• DIM
• Basic operation modes are operational
• Autonomous Mode is implemented, but ground
  validation is pending
• PP
• Final functionality is operational
• Determine stray capacitances after separation
  from orbiter (PP-AM)

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Long-term science goals and operation

• Goals Evolution of surface properties and
  cometary activity with rotational and orbital
  phase
• Basic operation modes and sequence have been
  defined for RSOC commissioning test (2004)
• Operation sequence has to be upgraded using
  capabilities of new flight software version FM-2
  (and planned features of FM-3 software)
• Operation (duration about 1 h) should be
  conducted twice to once per comet week at special
  local times (sunrise, noon, sunset and midnight).

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Funding and Personnel

• CASSE / SESAME
• Large changes at DLR possible people and test
  units relocation?
• Personnel (DLR) K. Seidensticker (PI), K.
  Gusbeth (student, Ground S/W),Univ. Köln K.
  Thiel, H.-H. Fischer (until 15.1.2008!) (both
  Co-Is, Flight S/W, operation)
• DIM
• Personnel (KFKI AEKI) I. Apáthy (PI), A. Péter
  (engineering) (both retired!)
• A. Juhász (Co-I, KFKI RMKI) diploma student
• PP
• In-house funding for Rosetta support, external
  funding for special activities on application?
• Personnel FMI W. Schmidt (PI), M. Genzer
  (operations), J. Ryno (S/W support) Co-Is
  ESTEC H. Laakso, R. Trautner CETP M. Hamelin

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A difficult way to 67P/C-G Conclusions

• Slow progress due to limited resources
• Software (flight and ground) upgrades are needed
  forefficient use of hardware and telemetry
  limitations
• Improving analysis methods, e.g.
• CASSE Identification of wave types analysis of
  seismograms
• DIM More precise impact model
• PP More calibration work
• Complex permittivity vs. ice concentration,
  composition, temperature
• Preserve the knowledge!
• Upgraded definition of SESAME comet science
  operations(SDL, FSS and long-term)