Technical challenges and solutions:

1. SIGNALS AC-BIAS DETECTORS MIXER LC FILTERS SUM SQUID DOWN SHIFT + FILTER DEMUX + SIGNAL PROCESSING LNA PHASE SHIFT UP SHIFT SUB-GROUP P.R. Roelfsema, F.P. Helmich (SRON NetherlandsInstituteforSpace Research, Groningen, The Netherlands), B.S. Swinyard (UCL, London, UK), J. Goicoechea (CAB-CSIC/Inta, Madrid, Spain) onbehalf of the SPICA-SAFARI consortium Exoplanetarysystemswith SAFARI We present the science capabilities for a far-IR instrument to be flown on the Japanese SPICA satellite. The development is being undertaken by a consortium of European, Canadian and Japanese institutes, SPICA is a Mission of Opportunity in ESA’s Cosmic Vision Program with an expected launch in FY 2018. SAFARI – SpicA FAR-infrared Instrument – is an imaging spectrometer with both spectral and photometric capabilities covering the ~34-210mm waveband. While SAFARI is a highly versatile instrument we highlight some of the science questions that will be addressed in the field of exoplanets and planet formation. Put logo & name of presente here SPICA – the nextfar-IRmission • From gas and dust to planets • Protoplanetary disks: from ices to oceans • Tracing the presence of stellar far-IR photometric excesses (due to dusty disks similar to our Kuiper Belt) out to ~150 pc. • Providing a comprehensive inventory of stars with circumstellar disks for future planet imaging facilities • Study the transition from protoplanetary to debris disks, → prime importance due to its link with planet formation. • Resolving the "snow line" (water ice) in nearby “Vega” disks • Access to the main gas coolants & key chemical species (eg. water, oxygen, organics) in proto-planetary disks. • Access to a keywaveband • Opening astrophysical research to λ’s blocked by the atmosphere but the emission peak of exo-zodiacal dust and cool bodies. • A successor to Spitzer and Herschel • Herschel: passively cooled (~80 K), sensitivity limited. • Spitzer: poor angular resolution due to modest mirror size. • Complementary to optical telescopes • Unique spectroscopic toolkit in many astrophysical environments: oxygen, ammonia, water ice and vapor, deuterated reservoirs: HD and a plethora of atomic and ionic fine structure lines. • Emission from dusty disks & cool bodies as well as obscured phenomena • SPICA (< 5 K)→“Cooled Herschel”: • Much lower background → deep spectroscopy possible • Imaging instead of point-source observations • No cryogenics → Long lived mission The ISO spectrum towards the young star HD142527 (Malfait et al.) showing the components of the MIR/FIR disk emission. Water ices can be detected through the 43/62m emission features. Diagram showing where radiation arises from in a protoplanetary disk and why the mid- and far-IRtogether are essential to understanding the full picture of the role of gas disks in the formation of planetary systems and the primordial chemistry that leads to the emergence of life. SAFARI: ~34-210 mm NH3, PH3, … Image of Vega debris disk at 70um with Spitzer (Su et al. 2005). Spatial resolution equivalent to ~23 AU will be enough to detect the expected “snow-line” region at 42 AU with SPICA. Jupiter’s far-IR spectrum between 47 and 100 micron from ISO/LWS (black) and model (red; Burgdorf et al.) • SAFARI Instrument concept: • Imaging Fourier Transform Spectrometer FTS • Wavelength coverage of ~34-210mm (using 3-detector arrays, Fl/2 sampling) • Range not covered by JWST or ALMA! • Field of view of 2’ x 2’ • Spectroscopy R up to ~2,000 at 100 μm • Photometry(R~3) • Sensitivity: • Unresolved lines 5s-1hr: few x 10-19 W/m2 • Photometry5s-1hr : <50mJy • Filter options for photometry under study • Exoplanet research in the far-IR • 2 orders of magnitude higher sensitivity than Herschel/PACS to detect and characterize zodiacal backgrounds in a statistical sample of stars (~105 Sun-like stars at d<180 pc). • Key to prioritising Earth-like candidates for future missions. • Complement to SPICA‘s mid-IR coronagraph and spectrometer. • Very stable detectors and efficient, high cadence and high S/N observations to perform transit photometry and low-R spectroscopy in the far-IR. • EPs around cool stars ? Spectral signatures (water/ice?, HD?) 24µm HD 209458b primary eclipse with Spitzer (Richardson et al). Transit studies possible in the far-IR Left: Fit to HD 209458b “hot Jupiter” MIR fluxes inferred from a secondary transit with Spitzer (Swain et al. 2008a) around a G0 star (d ～ 47 pc, in black) and interpolation to d = 10 pc (red). The expected emission of a Jupiter-like planet at 5 pc is shown in blue (reflected emission neglected). 5σ-1hr photometric sensitivities of SPICA/MIR instruments (cyan) and SAFARI (blue, magenta and red) are shown. Dashed lines show sensitivities in spectrophotometric mode (R ~25).SAFARI can potentially extract their FIR spectrum for the first time. Middle: Flux from the host star at different distances. Right: Planet-to-star contrast. Example of far-IR HD and H2O lines towards Uranus & Neptune (Fouchet; Feuchtgruber et al.) Technical challenges and solutions: Detectors: The required sensitivity, dynamic range and array formats are all challenging for the currently available technology. TES detectors arrays with lithographic LC filters , squids and frequency multiplexed read-out are chosen for SAFARI. The optical coupling is done with horn arrays Cooler technology: a hybrid sorption cooler/ADR is under development for the low temperatures the detectors are operated on (50 -150 mK) Broadband beam splitters and filters: ~3 octave bandwidth required. Cryo-mechanisms: The Fourier Transform Spectrometer mechanism and the filter wheels are being qualified now 500 m