DAViNCI 1 M. Shao, B. M. Levine, G. Vasisht (JPL), B. F. Lane (Draper Labs), M. Clampin, R. Lyon (NASA/GSFC), V. Tolls (CfA), R. Woodruff, G. Vasudevan (Lockheed-Martin), R. Samuele (Northop Grumman), K. Havey (ITT), O. Guyon (U. Arizona/Subaru) Baltimore 2009 Dilute Aperture Visible Nulling Coronagraphic Imager (DAViNCI) © 2008 California Institute of Technology. Government sponsorship acknowledged.

DAViNCI 2 July 7, 2016 Outline DAViNCI is an Astrophysics Strategic Mission Concept study Focuses on imaging of Earth-like planets Sample of 150 nearby target stars in 5 yr Spectroscopy of 15 planets Study focuses on -Payload design and identification of key technologies VNCs may be attractive from a cost standpoint Results of the study will be reported to the Decadal Review

DAViNCI 3 July 7, 2016 Outline Instrument and Mission Overview -Four 1.1 m telescopes, square array, inside of a 4.5 m structure. A dilute aperture VNC. Collecting area equal to a 2.2 m telescope. -Cost roughly equal to a 2.5 m coronagraph. DAViNCI Scientific capability -38 mas IWA at 800 nm (also nm) Imaging capability equal to 8 m 2λ/D coronagraph, or 76 m occulter at 166,000 km (50 m at 72,000 km). Tries to beat some of the steep IWA -n laws associated with coronagraphs and occulters -Science instrument 0.5 um to 1.7 um, 25% BW at a time. Imager R = 80 spectrometer

DAViNCI 4 July 7, 2016 DAViNCI: Principle of Operation Θ 2 Null Θ 4 Null

DAViNCI 5 7/7/2016 T1 T2 T3 T4 D w B D = 1.1 m B = 1.5 m  = 20% w = 0.02 m D = 1.1 m B = m  = 20% w = 0.02 m 1.0 arcsec Sampling = mas 2048 x 2048 grids V-band:  = nm Transmissions Rotated by 45 degrees from apertures R. Lyon 1/26/09

DAViNCI 6 July 7, 2016 Payload has 4 on-axis telescopes with dual VNCs ITT NextView telescopes with 1.1 diameter M1s OTA wavefront 60 nm Two Modified Mach-Zehnder Nullers (10 -9 ) with segmented DMs One Michelson X-combiner with segmented DM Spatial filter fiber array Post-Coronagraphic Wavefront Sensors for active speckle cancellation 1.7 micron cutoff material science focal plane Spectral range of microns (R = 4 and 80) Guiding and pupil alignment optics/cameras Instrument: Salient Features Segmented DM technology demonstrator Design of a Single Mode Fiber Array from Fiberguide Industries. Left: Array of 217 fibers in a hexagonal.

DAViNCI 7 July 7, 2016 DM3 Fiber Bundle Array Phase Plates Null Beam Combiner Assembly Instrument Layout DM1 T1 / T2 Nuller Bright T1-2 Dark T3-4 Dark Science Camera WFS Camera1 Phase stepping dither Shutters DM Control Single fibers with matched properties as the fiber bundle Lens compensator Phase Plates DM2 T3 / T4 Nuller Bright Shutter Phase Plates WFS Camera2 DM Control Pupil Remap Lens To Pupil Geom Mechanism ACS Camera Pupil Geom. Camera ACS Camera output with pupil camera allows Phase diversity WFS as well! Filters Translation Stage slit Beam launcher Dichroic mirror

DAViNCI 8 July 7, 2016 DAViNCI Spacecraft Sun shade Spacecraft in 5m Fairing 4 x 1.1m telescopes based on NextView CRS Three-axis stabilized spacecraft bus Sun Shade provides thermal insulation, while allowing the target to be observed within 45 deg of the Sun, any target is observable 75% of the time. wet mass 4400 kg

DAViNCI 9 July 7, 2016 Observing Strategy Project transmission Pattern on sky with B1 Project transmission Pattern on sky with B2 Execute 90 deg. Spacecraft roll(s)

DAViNCI 10 July 7, 2016 DAViNCI Science capability Max star-planet separation > 1.2xIWA 4x1.1m DAViNCI and 8m telescope with 2λ/D Coronagraph 4m telescope with 2λ/D Coronagraph # Stars ~ IWA -3 2m telescope with 2λ/D Coronagraph

DAViNCI 11 July 7, 2016 Target Selection

DAViNCI 12 July 7, 2016 Team X Mission Study Costs

DAViNCI 13 July 7, 2016 Technology Status/ Near Future Plans DAViNCI Technology is at well understood readiness levels (TRLs) Pathway for technologies maturation Picture suborbital mission – broadband nulling demonstration VNC testsbed at Goddard (EPIC) VNC imaging testbed at JPL called APEP -In vacuum -VNC, science camera, waverfront sensor -DMs driven by 16-bit electronics

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DAViNCI 15 July 7, 2016 Team X Mission Study Summary Flagship Class Mission High Level Mission Description -Launch Vehicle: Atlas V 521 -Orbit: Earth-Trailing -Launch Date: Mission Lifetime: 5 years -Observation strategy: Planet Detection Planet Spectroscopy Instrument Description -4 element dilute aperture imaging interferometer using (‘COTS’ telescopes) on (Dual) Variable baselines -Dual nullers for deep and wide null with imager and (R=80) spectrometer

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DAViNCI 17 July 7, 2016 Dual Baselines

DAViNCI 18 July 7, 2016 Summary We have studied a dilute aperture VNC as an Exo-Earth Imager Images HZs of 150 nearby stars at reasonable cost. -Very high angular resolution (Small IWA, 38mas) in a compact package -IWA similar to that for an aggressive coronagraph on an 8 m telescope -Low resolution spectroscopy to 1.6 um for targets. -Leverages technology from SIM, Coronagraph testbeds and current ground based ExAOC projects Technology preparation: Imaging testbeds ongoing From a cost/performance vantage the dilute aperture concept is attractive DAViNCI directly addresses Astrobiology Goal 1 in Exoplanet Science Priorities (Task force chaired by Lunine)

DAViNCI 19 July 7, 2016 Deep Laser Null 1.23x10 -7 Suppression 8/22/06 R. Samuel. Experiment in vacuum chamber shut but at 1 Atm Rms vibration and drift over ~15 sec is ~60pm Amplitude fluctuations < 0.05% 1x /airy spot TPF goal DAVINCI requirement 1.2x10 -7 suppression Needed for ~ contrast

DAViNCI 20 July 7, 2016 Number of Targets vs Inner Working Angle Put a 1 Mearth planet at mid- HZ (1AU*sqrt(lum)) every star. Contrast limit 6e-11 (Earth-Sun is 1.2e-10) Brightness of planet < 31.2mag 780nm (oxygen line) Volume ~ IWA -3 Davinci 4m 2 /D Coronagraph Or large external occulter If the max planet separation is just barely larger than the IWA, we can’t really measure its spectra. (If the planet is visible only 3 days/yr, and it take 30 days to detect O 2 in the spectra, it will take 10yrs.)

DAViNCI 21 July 7, 2016 Planet Orbit can’t be Just = IWA Planet orbit 20% larger than IWA only detectable ~10% of year. We crudely estimate that the max star planet separation has to be > 20% larger than the IWA for meaningful science to be possible. Davinci 25~30 Stars vs ~160 stars IWA*1.2 < Max star-planet sep

DAViNCI 22 July 7, 2016 Images are In e - /sec/pixel Solar 10 pc DAViNCI rotated to place Earth on transmission maxima C. Stark’s Model for ExoZodi 3.5 asec B = 1.5 m  = 13.7 mas B = 1.5 m  = 27.4 mas B = 2.0 m  = 13.7 mas B = 2.0 m  = 27.4 mas

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DAViNCI 24 July 7, 2016 Cost Advantages of Dilute/Segmented Aperture Telescopes Mulitple telescopes are cheaper -Telescopes #2,3,4 are ~ 50% of the cost of #1. -If cost ~ D 2.5 then 4 1.1m’s is less than ½ the cost of a 2.2m. -DAViNCI telescopes are On-Axis (not off-axes unobscured) Technology for diffraction limited segmented and dilute aperture telescopes was demonstrated on Keck >10 years ago. (JWST) -Technology for SIM (picometer level dilute aperture telescope/interferometer in space) is also in hand. -There is a known ~fixed cost for the metrology and structure/mechanisms for DAViNCI. Instrument (Nulling coronagraph) is roughly the same complexity/cost of a Lyot coronagraph with DM’s for phase and amplitude control. -DAViNCI instrument is more expensive because of the very wide 0.5um ~ 1.7um wavelength coverage. (rather than 0.5um~0.8um) Spacecraft -(Vibration) requirements similar to other coronagraphs -Thermal stability requirements ~100X less sensitive than coronagraphs that use telescope rotation for speckle subtraction. (Post coronagraph inteferometer)

DAViNCI 25 July 7, 2016 DAViNCI: Principle of Operation Spectromete r Spectrometer FPA Imager FPA OTA Pupil Relay Beam Combiner Compressor primary mirror Compressor secondary mirror Θ 2 Null Θ 4 Null