Mission Overview René Laureijs G. Racca, L. Stagnaro, J.C. Salvignol, J. Hoar (ESA) Y. Mellier and the EC Synergistic Science with and the SKA Oxford 16 September
Outline Setting the scene Science Objectives and driving requirements Mission Implementation Organisation Project outlook and Conclusions R. Laureijs, et al SKA and 2013-09-16 Slide 2
Where do we stand? March 2007: Call for mission ideas by ESA March 2008: the Concept Advisory Team named for the European dark energy mission. Oct. 2011: was selected by the Science Programme Committee (SPC) of the member states of the European Space Agency to be the second Medium Class (M2) mission of the Cosmic Vision programme. June 2012: the implementation of the mission was approved by the SPC. Dec. 2012: ESA selected Astrium (Toulouse) as the lead contractor for the Payload Module (PLM) July 2013: ESA selected Thales Alenia Space (Turin) as the prime contractor for the system and Service Module (SVM) March 2020: Scheduled launch date Sep 2026: End of nominal mission R. Laureijs, et al SKA and 2013-09-16 Slide 3
Main Actors Science Programme of ESA Cosmic Vision 2015-2025 Advisory Structure SPC ESA Science directorate (Mission) Consortium - selected in 2011 EC Lead: Y. Mellier Provision of science requirements, instruments, science ground segment Multi-Lateral Agreement between ESA and EC funding agencies since 2012 ESA Project Team formed in 2012 Project Manager: G.Racca Science Team 12 representative scientists Industry TAS (Turin) prime contractor since 2013 NASA Memorandum of Understanding since 2013 R. Laureijs, et al SKA and 2013-09-16 Slide 4
Scientific Objectives Issue What is Dark Energy: w Beyond Einstein s Gravity: γ The nature of dark matter: m ν The seeds of cosmic structure: f NL s Targets Measure the DE equation of state parameters w p and w a to a precision of 2% and 10%, respectively, using both expansion history and structure growth. Distinguish General Relativity from modified-gravity theories, by measuring the growth rate exponent γ with a precision of 2%. Test the Cold Dark Matter paradigm for structure formation, and measure the sum of the neutrino masses to a precision better than 0.04eV when combined with Planck. Improve by a factor of 20 the determination of the initial condition parameters compared to Planck alone. n (spectral index), σ 8 (power spectrum amplitude), f NL (non-gaussianity) R. Laureijs, et al SKA and 2013-09-16 Slide 5
Scientific Requirements Optimize the mission for two complementary dark energy probes: galaxy clustering and weak lensing; Wide survey: > 15,000 deg 2 (36% of the total sky) Deep survey: > 40 deg 2, 2 mag deeper than wide survey Weak Lensing: Shapes and shear of galaxies with a density of >30 galaxies/arcmin 2. Very high image quality, high stability (ellipticity, FWHM, R 2 ) Minimise Systematics σ sys < 10-7 Redshift range 0<z<~2, accuracy dz/z ~ 0.04 Galaxy clustering: Redshifts for >3500 galaxies/deg2 Redshift range 0.7 < z <2.05, accuracy dz/z < 0.001.Line Flux limit < 3 10-16 erg cm -2 s -1. R. Laureijs, et al SKA and 2013-09-16 Slide 6
Why space? Stable environment diffraction limited PSF in the visual Low NIR background Stable and small PSF in the NIR Homogeneous dataset, able to minimize and control sources of systematic error Ability to access a large survey area Caveat: space weather But: don t forget cosmics R. Laureijs, et al SKA and 2013-09-16 Slide 7
Mission Constraints M mission Before approval, all subsystems/components at technology readiness level TRL 5 Soyuz ST-2.1B Carrier Launch from Kourou satellite mass 2160 kg (for L2) Duration: 6 years nominal science + 6 months commissioning and performance verification Data rate < 850 Gbit/day K band downlink transmission for the science data X band for the housekeeping and spacecraft commanding Spacecraft components build by European Industries R. Laureijs, et al SKA and 2013-09-16 Slide 8
Ground based data cannot meet the photo-z requirement dz/z ~ 0.04 without ground based data. The availability of ground based photometry data is essential for meeting the science objectives: g,r,i,z imaging photometry down to ~24 mag Need same coverage as the survey (15,000 deg 2 ) Need 10 4-10 5 spectra down to AB=24 mag to calibrate the photo-z photometry. The provision of these data is the responsibility of the EC, see presentation by Y. Mellier Southern hemisphere: DES data Northern Hemisphere: negotiations in progress R. Laureijs, et al SKA and 2013-09-16 Slide 9
Requirements flow down A large effort is put in the flow of the top level science requirements down to the main sub-systems, with a traceable and justified budgeting Top level science requirements (Level 2) have been flown down do: Spacecraft requirements Payload/Instrument requirements Ground Data processing requirements Ground Segment requirements The budgeting includes Operational constraints/requirements Calibration requirements Top Level Requirements Performance Budgeting Survey Calibration spacecraft Ground segment Telescope/ instruments Data processing R. Laureijs, et al SKA and 2013-09-16 Slide 10
Payload Module Telescope: Korsch 3-mirror anastigmat (TMA), FoV > 0.54 deg 2 Primary mirror: 1.2 m diameter All lightweight SiC telescope, isostatic design Focussing mechanism on the secondary mirror SiC Optical bench and payload cavity are passively cooled down to 150 K thermal design Dichroic for simultaneous visual and near-infrared measurements: Reflection for the visual beam Transmission for the infrared beam Accommodation for the VIS and NISP instruments PLM industrial contractor: Astrium Toulouse R. Laureijs, et al SKA and 2013-09-16 Slide 11
PLM design R. Laureijs, et al SKA and 2013-09-16 Slide 12
Payload Module: Instruments NISP: Slitless-Spectrometer/Photo-imager 16 HgCdTe sensors (H2RG Teledyne) at 90-100 K, 0.92<λ<2.0 micron Pixel: 0.3 0.3 arcsec 4 Grisms (blue and red with two orientations each), λ/ λ>250 3 filters: Y, J, H VIS: Visual imager 36 CCDs (CCD273 e2v), single filter 0.55 < λ < 0.9 micron Pixel: 0.1 0.1 arcsec Shutter Calibration unit VIS, NISP Common field of view ~0.54 deg2 Instruments are provided by the EC see presentation by Y. Mellier Sensors are procured by ESA R. Laureijs, et al SKA and 2013-09-16 Slide 13
PLM Testing ESA has requested the preparation of on-ground PLM tests to verify the optical performance of the telescope with instruments (psf, straylight, etc) TAS will provide a test chamber with collimator. Possible set-up R. Laureijs, et al SKA and 2013-09-16 Slide 14
Mission and Spacecraft Mission Soyouz-Fregat ST-2.1B carrier, ~2160 kg spacecraft mass to L2, with line of sight nearly 90 degrees from Sun, to ensure thermal stability Mission is scoped to a nominal lifetime of 6 years + cruise + commissioning Spacecraft Attitude and Orbit Control System includes a Fine Guidance Sensor near the (visual) instrument s focal plane; pointing stability = 20 mas << size of smallest pixel of 0.1 during one exposure 4 hours daily communication window with K-band to receive 850 Gbit/day compressed science telemetry R. Laureijs, et al SKA and 2013-09-16 Slide 15
Spacecraft Reaction wheels operated in Stop and Go unique! Cold gas for fine pointing actuation Gaia heritage K-band transponder a first for ESA R. Laureijs, et al SKA and 2013-09-16 Slide 16
Orbit and operation Direct transfer into L2 short cruise phase Lissajous of +/- 33 degrees Two available ground stations Cebreros (Spain) and Malargüe (Argentina) R. Laureijs, et al SKA and 2013-09-16 Slide 17
Ground Segment data flow MOC Commanding Telemetry Ground Station Data Products General Community Observation Planning MOGS Instrument Commanding Satellite Telemetry SOC Raw TM Level 1 Public Data Archive Mission Data Products Instrument Maintenance and (Calibration) Operations SGS EMC SDC Processing Group 1 SDC Processing Group 2 IOT 2 IOT 1 SDC SDC SDC Processing SDC Processing Group N Processing Group Processing Group 4 Group 3 R. Laureijs, et al SKA and 2013-09-16 Slide 18
Surveys Wide Survey: s primary wide survey aims at covering 15,000 deg 2, i.e. the entire extragalactic sky. Δ(M1-M2) < 20 nm implies ΔSAA<5 degrees Deep Survey: s additional deep survey covers ~40 square degrees. This survey is 2 mag deeper than the wide survey. Open Surveys The instrument and pointing capabilities offer the possibility to carry out additional surveys, during or after the nominal mission. R. Laureijs, et al SKA and 2013-09-16 Slide 19
reference survey Ecliptic plane Avoided: Ecliptic plane (zodiacal light) and low (<30 deg) galactic latitudes Different colours indicate different survey years Calibration fields along the galactic plane R. Laureijs, et al SKA and 2013-09-16 Slide 20
Calibration observations Total time: ~10% of nominal mission Calibration data can be used for science Noise Bias Calibration Sample 4% VIS Color Gradient Observations 4% VIS Absolute Standards Observations 1% NISP-P Survey Self-Calibration 18% NISP-P Absolute Standards Observations 2% VIS PSF Model 1 23% Photo-z Training Sample 14% Courtesy: J. Amiaux, EC Survey WG & EC Calibration WG R. Laureijs, et al SKA and 2013-09-16 Slide 21 NISP-S Purity Sample 23% NISP-S Absolute Standards Observations 10% NISP-S Planetary Nebula Observations 1%
Overall Project Organisation ESTEC Noordwijk ESOC Darmstadt ESAC Madrid R. Laureijs, et al SKA and 2013-09-16 Slide 22
Science Team Also: A. Cimatti, E. Martin, J. Rhodes R. Laureijs, et al SKA and 2013-09-16 Slide 23
Working Groups involving ESA, Consortium and other parties System Engineering working group requirements flow down science performance Survey working group Calibration Working group Ground segment Engineering working group Data management working group Detector working groups NIR detectors CCDs Archive Users group R. Laureijs, et al SKA and 2013-09-16 Slide 24
Science Ground Segment R. Laureijs, et al SKA and 2013-09-16 Slide 25
Data Flow R. Laureijs, et al SKA and 2013-09-16 Slide 26
Machinery VIS and NIR observer of stars and galaxies ExternalPhotometry External Spectra VIS Imaging NIR Photometry NIR Spectroscopy Other probes Cosmic Shear survey Galaxy Redshift survey Dark Matter and Galaxy Power Spectra with look back time Planck Cosmo. Simul. Cosmological explorer of gravity and fundamental physics Legacy Science R. Laureijs, et al SKA and 2013-09-16 Slide 27 Courtesy: Y. Mellier
Data release plan Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Start of nominal mission Q1 DR1 Q2 DR2 Q3 Q4 ~2,500 ~7,500 deg 2 deg 2 DR3 ~15,000 deg 2 The survey will be released in three parts, each with a delay of 14 months from the end of the data taking: DR1 provides the first year s survey data DR2 provides the survey data from years 1-3 DR3 provides the survey data from the entire mission The four quick-releases (Level-Q, no core science) will be in years when there are no survey data releases: Q1 to Q4 after 2 months and 1, 3, 5, and 6 years. The Level-Q release products will be processed with the best available calibration and software at the time. Level-Q contents to be proposed by the EST to the Advisory Structure R. Laureijs, et al SKA and 2013-09-16 Slide 28
Project Schedule/Milestones M-RR: Feb 2014 M-PDR: May 2015 M-CDR: May 2017 Instruments delivery: July 2017 System Validation Test 1: Nov 2018 M-FAR: August 2019 Launch: March 2020 M-CRR: July 2020 Data Release 3: Sep 2027 R. Laureijs, et al SKA and 2013-09-16 Slide 29
Conclusions is an approved mission. The Survey has an immense scientific value: Cosmology, Fundamental Physics, and Legacy for all Astronomy is a feasible mission: no technical (high TRL) and programmatic show stoppers however, there are still many challenges. The Consortium consists of more than 100 institutes and is well organised. It is fully equipped to support the mission and its science return. Funding is secured, project is on track! R. Laureijs, et al SKA and 2013-09-16 Slide 30
Thanks for your attention! R. Laureijs, et al SKA and 2013-09-16 Slide 31