EChO: Exoplanet Characterisation Observatory Ignas Snellen (Leiden) on behalf of the EChO Study Science team: Pierre Drossart (FR), Christophe Lovis (CH), Oliver Krause (DE), Giuseppina Micela (IT), Marc Ollivier (FR), Ignasi Ribas (ES), Ignas Snellen (NL), Bruce Swinyard (UK), Giovanna Tinetti (UK), Kate Isaak (ESA-ESTEC, EChO study scientist)
EChO: Exoplanet Characterisation Observatory • Dedicated mission to characterise exoplanet atmospheres through spectroscopy in the visible – MIR • Primary science objectives: • Study exoplanetary chemistry • Characterise an exoplanet’s climate • Constrain atmospheric escape processes • Constrain formation of exoplanets
• EChO target sample: • planet sizes (Jupiters super Earths) • equilibrium temperatures (hot temperate) • host spectral types Ignas Snellen/EChO Science study team
Leiden 22 October, 2012
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Measurement principles
HAT-P7b observed by Kepler (Borucki et al, 2010)
transmission (sounding the terminator) in primary eclipse (transit) emission and reflected light around secondary eclipse (occultation) Orbital phase Exoplanet/host contrast 10-2 – 10-5 0.55 – 11 um (0.4 – 16 um goal) wavelength coverage Instantaneous spectral coverage over full range Ignas Snellen/EChO Science study team
Leiden 22 October, 2012
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EChO: Measurement principles - spectroscopy
Spectral features of key molecules fall into the EChO band: eg. H2O, CO, CO2, CH4, NH3 in addition to hydrocarbons, Ozone, H3+
Ignas Snellen/EChO Science study team
Leiden 22 October, 2012
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Spacecraft design Solar array 1.2 m Cassegrain design 5m
Thermal shields
TOB Spectrometer; FGS
SVM • • • • • •
IOB 2011 ESA CDF study –
Cosmic Vision M3 candidate for European mission Puig et al. SPIE 8146, (2011) 1.2m diameter telescope Science payload: 0.4 – 16 um spectrometer Quasi halo orbit around L2 thermally stable environment 5 year mission lifetime Launch on Soyuz in 2024, with an option for 2022 as a back-up for L-class JUICE Ignas Snellen/EChO Science study team
Leiden 22 October, 2012
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EChO timeline
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Call for Mission Proposals in 2010 => SSAC recommended 4 mission candidates
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Start of assessment study (Phase 0/A)
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Spring 2011: Appointment of EChO science study team
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Mid-2011: ESA Internal Concurrent Design Facility study.
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Oct 2011:
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Call for instrument consortia 2 parallel studies (nationally funded) led by Germany (Oliver Krause, MPIA) and UK (Giovanna Tinetti, UCL)
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ITT for Industry to study mission 2 x parallel system-level studies
Sept 2012: •
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Instrumentation AO
Feb 2013: •
Selection of Instrument teams
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End 2013: Down-selection and progression into Phase A/B1
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2015: Adoption of the M3 mission and start of Phase B2/C/D
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Launch in 2024 (option for 2022 as a back-up for L-class JUICE)
Ignas Snellen/EChO Science study team
Leiden 22 October, 2012
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Key science requirements
Science requirement
Value: requirement (goal)
< 1 micron: monitoring stellar activity (e.g. stellar spots) + in favorable cases the optical albedo of hotter planets as well as Rayleigh scattering . 1- 5 micron: characterization of hot/warm planets. Hosts fundamental key transitions of many of the EChO target molecules. 5 – 11 micron: characterization of cooler planets + retrieval of thermal profile for hot ones 11 – 16 micron: CO2 feature that is key to retrieving thermal profile of temperate planets + strong features of HCN and hydrocarbons.
Wavelength coverage
0.55 – 11 micron (0.4 - 16 micron)
Resolving power
R≥300 for λ5 micron
Photometric stability
The EChO instrument and satellite systems shall not induce noise or disturbance in the frequency band of 2.8x10‐5 Hz to 4mHz that raises the fundamental white noise floor in this band by more than 10% following post processing and extraction of the wavelength dependent transit signal. Goal: 3.8x10‐6 Hz to 16mHz
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Ignas Snellen/EChO Science study team
Comment
R~300 in NIR to detect/separate molecules, constrain abundances and thermal profile. R~30 in MIR to separate and detect individual molecular bands
For orbital phase measurements.
Leiden 22 October, 2012
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Key science requirements Science requirement
Value: requirement (goal)
Comment
Cadence
90 seconds (30 seconds)
Sensitivity/ signal-to-noise
Various
Photon noise limited performance relative to the target sample, with the instrumental noise ≤ TBC fraction of the photon noise of the faintest sizing sources.
40% of the sky should be accessible at any one time. The same 40% should be accessible over a period of ~10 hrs. The complete sky should be accessible within a year (TBC). A source at the ecliptic should be observable for 40% of the mission lifetime
It should be possible to access as many of all the possible transits for the most challenging targets (e.g. Super Earth) during the course of the mission.
Sky visibility
To enable recovery of the transit ingress and egress in the most favourable targets
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Ignas Snellen/EChO Science study team
Leiden 22 October, 2012
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Status of the payload design: UCL/RAL-led instrument •
Consortium with UK/France/Italy/Spain/MPS-Germany/Poland/Ireland/Denmark 4 modules, 1 common FoV: • Cross-dispersed spectrometers (to avoid overlapping diffraction orders) for the visible and nearIR module fed by two fibers. • A grating-based dispersive spectrometer for the short-wave IR module. • Two prism-based dispersive spectrometers for the mid-wave IR module. • A static FTS or prism-based dispersive spectrometer for the long-wave IR module.
Ignas Snellen/EChO Science study team
Leiden 22 October, 2012
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Status of the payload design: MPIA-led instrument •
Consortium with Germany/Austria/Netherlands/Switzerland/Belgium.
6 channel grating spectrograph with all-reflective optics: • Splits at 0.4 - 0.75 - 1.36 - 2.61 5.08 - 8.8 – 16 micron • Common 30” x 13’’ FoV • R from 300 to 600 • Detectors baselined: • 0.4–9 micron HgCdTe • 9-16 micron Si:As with active coolers
650 mm
Ignas Snellen/EChO Science study team
Leiden 22 October, 2012
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The EChO Sample Hypothetical (expected in 2024) Mission Reference Sample
Ignas Snellen/EChO Science study team
Leiden 22 October, 2012
Currently Available Sample (2012)
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Summary
• EchO is a dedicated mission to characterise exoplanet atmospheres through spectroscopy in the visible – MIR spectral range • It is optimized for broad instantaneous wavelength coverage and photometric stability • Technical and scientific definition ongoing in course of the current assessment phase – to be completed with the assessment study report (“Yellow Book”) for the M3 down selection process 2013
Acknowledgements: •
Ludovic Puig (study manager), Martin Linder (payload manager), Isabel Escudero Sanz (optics expert), Pierre-Elie Crouzet (detector expert) + other ESTEC D/TEC expert
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Instrument teams
Ignas Snellen/EChO Science study team
Leiden 22 October, 2012
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