ExoMars Orbiter Polarisation Spectrometer EOPS

1
ExoMars Orbiter Polarisation Spectrometer (EOPS)

• Opportunity for making a Dutch impact in
  Planetary Exploration
• December 1, 2004

2
Introduction

• ExoMars Mission background
• Orbiter payload opportunity
• Science Case for a Polarisation Spectrometer on
  the ExoMars Orbiter
• EOPS instrument development
• Outlook

3
ExoMars mission background (1)

• Search for signs of extant/extinct life on Mars
• Landing a Rover with Pasteur payload on the
  surface of Mars
• ExoMars Orbiter serves as data-relay for rover
• ExoMars rover has lifetime in the order of months
  upto a year
• Current launchdate 2009

4
ExoMars mission background (2)

• Three consortia have performed a phase A1 study
  for the ExoMars mission
• Alenia Spazio (Italy) with subcontractors OHB
  (Germany), GMV (Spain), SEA (UK), SSC (UK) and
  Laben (Italy).
• Alcatel Space (France) with subcontractors Deimos
  (Spain), ETCA (Belgium), Fluid Gravity
  Engineering (UK), Kayser Threde (Germany), Laben
  (Italy), MD Robotics (Canada), NGC Aerospatiale
  (Canada), QinetiQ (UK), Vorticity (UK).
• EADS Astrium (France) with subcontractors Astrium
  Ltd. (UK), EADS LV (France) and SAS (Belgium).
• Currently, a phase A2 is under study (by at least
  Alenia Spazio) which will run till May 2005

5
ExoMars Orbiter Payload opportunity

• ExoMars Mission definition includes provisions
  for a payload on-board the orbiter
• Mass 20 kg TBC
• Nadir pointed
• Maximum power use 45 W
• Data rate 1 Gbit/day
• Absolute payload pointing accuracy (during
  imaging) 20 arcsec
• Orbit parameters are not fixed (May 2005).
  Options studied
• Periapsis 300 km, apoapsis 6300 km (Mars
  Express equivalent)
• Periapsis 500 km, apoapsis 8919 km (ESA/ESTEC
  CDF Study Report ExoMars 09, August 2002)
• Circular orbit with altitude 550 km (ExoMars
  orbiter with MSR RVE (Rendez Vous Experiment))
• Circular orbit will not cover the poles
  (inclination of 50.7 degrees)
• Preferred option The highly elliptic orbit
  options are polar global coverage within at
  least a few days is guaranteed (including poles)

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Science Case for EOPS (1)

• Main instrument products
• Water-vapour Indication for possible presence of
  sub-surface water reservoirs
• Methane Ammonium Indication for possible
  presence of micro-bacteriological material
• Sulphur-dioxide Indication for possible volcanic
  activity and presence of hydro-thermic vents
• Dust properties of the atmosphere key factor in
  thermal balance of atmospheres and lifetime of
  the ExoMars rover
• Search for signs of extant/extinct life on Mars
  from Mars Orbit, in synergy with the Exomars
  rover
• Obtain polarisation and absolute flux information
  of the reflected sun irradiance from the Martian
  atmosphere
• Doing climate research on Mars is relevant for
  knowledge of Earths climate. The Mars atmosphere
  is a relatively simple system compared to Earths
  atmosphere and specific effects can be studied in
  an isolated case (comparitive planetology).
• Prepare instrumentation for search of signs of
  life on exoplanets (DARWIN)

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Science Case for EOPS (2)

• PFS on MEX has shown correlation between
  water-vapour and methane
• EOPS will provide confirmation, with lower
  detection limits and higher ground-resolution
• (source http//www.esa.int/esaCP/SEMAK21XDYD_inde
  x_0.html)

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EOPS instrument development (1)

• Based on strong instrument heritage
• OMI (GOME, SCIAMACHY)
• Planetary Fourier Spectrometer (PFS) on-board MEX
  VEX
• PACE
• Instrument trade-offs to be performed
• Multi-telescope vs single telescope (alignment
  vs polarisation calibration)
• Prism vs Grating vs Interferometer
• CCD vs CMOS
• Instrument keywords
• Miniaturization
• Employable for all planetary atmospheres (Earth,
  Venus, Titan, ..)

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EOPS instrument development (2)

• Possible instrument configuration
• 3 OMI telescopes with differently aligned
  polarisers (S, P, 45 degrees) in crosspoint of
  FOV just before primary telescope mirror
• 3 slits imaged with same collimator and camera on
  CMOS 2d-detector (spectral x spatial). Delicate
  baffling required for elimination of straylight
  ghosts.
• Possible suppliers of CMOS detectors
• Sofradir
• Rockwell
• Miniaturisation
• Use of immersed gratings in echelle mode
• Optimization of spectral windows

Spectrometer
Command

Detector
DataHandling Unit
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Outlook

• Dutch role in Mars exploration appeals to the
  society in general.
• Dutch role in Mars Exploration will increase
  interest in technical studies
• Opportunities for International Partnerships
• Italy is main contributor to Aurora programme
• Possible partnerships
• Institutes IFSI, IRSPS, TBD
• Industry Alenia Spazio, Galileo Avionica (who
  built GOME)
• Need for urgent team build-up launch is
  prospected in 2009!
• 0.5 year feasibility study should minimally
  deliver
• Science Requirements
• Signal to noise analysis
• Instrument baseline (telescope, spectrometer,
  detectors)
• Critical items listing (immersed grating in
  echelle mode, polarisers, )
• Development plan