* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download HabEx`s Three Graces of general asrophysics: Paul Scowen
Survey
Document related concepts
Lovell Telescope wikipedia , lookup
Allen Telescope Array wikipedia , lookup
Hubble Space Telescope wikipedia , lookup
Optical telescope wikipedia , lookup
Arecibo Observatory wikipedia , lookup
Leibniz Institute for Astrophysics Potsdam wikipedia , lookup
Very Large Telescope wikipedia , lookup
CfA 1.2 m Millimeter-Wave Telescope wikipedia , lookup
Space Interferometry Mission wikipedia , lookup
Spitzer Space Telescope wikipedia , lookup
Reflecting telescope wikipedia , lookup
Transcript
The Habitable Exoplanet Imaging Mission (HabEx): Exploring our neighboring planetary systems. Community Chairs: Scott Gaudi (OSU/JPL) & Sara Seager (MIT) Study Scientist: Bertrand Mennesson (JPL) Study Manager: Keith Warfield (JPL) (This presentation extracted from material presented by Scott Gaudi, Keith Warfield, Gary Kuan, and HabEx STDT members at Nov. 10-11 face-to-face meeting) © 2016 California Institute of Technology. Government sponsorship acknowledged. CL#16-5499 The HabEx STDT. (mostly) HabEx Design Team at JPL Name Keith Warfield Bertrand Mennesson Gary Kuan Stefan Martin Joel Nissen Rhonda Morgan Stuart Shaklan Doug Lisman David Webb Eugene Serabyn John Krist Alina Kiessling Bala Balasubramanian Phil Stahl Steve Warwick Shouleh Nikzad John Hennessy Fang Shi Role Study Lead Study Center Scientist Design Lead Optics Lead Systems & Structures; Stability DRM & science yield starshade & coronagraph expert Starshade expert Starshade expert coronagraph expert coronagraph expert associate center scientist coatings expert MSFC - Telescope Northrup Grumman - Starshade expert Detectors Lead detectors expert LOWFSC expert consultant jpl.nasa.gov HabEx General Goals. 1. “Develop an optimal mission concept for characterizing the nearest planetary systems, and detecting and characterizing a handful of ExoEarths.” 2. “Given this optimal concept, maximize the general astrophysics science potential without sacrificing the primary exoplanet science goals.” • Optimal means: – Maximizing the science yield while maintaining feasibility, i.e., adhering to to expected constraints. • Constraints include: – Cost, technology (risk), time to develop mission. • Thus some primary lower-level goals include: – Identify and quantify what science yields are desired and optimal. – Identify and quantify the range of potential constraints. HabEx Science Goals. • Exploration-based: – How many unique planetary systems can we explore in great detail, determine “their story”, including finding and characterizing potential habitable worlds? – HabEx will explore N systems as systematically and completely as possible. – Leverage abundant pre-existing knowledge about our nearest systems, acquire as much additional information as possible. – Take the first step into the unknown! • Search for Potentially Habitable Worlds – Detect and characterize a handful of potentially habitable planets. – Search for signs of habitability and biosignatures. • Optimized for exoplanet imaging, but will still enable unique capabilities to study a broad range of general astrophysics topics. Exploration approach: The case of 40 Eridani A Constraining the presence of a habitable planet • K0 star at 5 pc distance; B and C components orbit each other 80 away • HZ lies at 0.13 separation. An earth mass planet there: – – – – Would induce 12 cm/sec of stellar reflex motion Has a 0.4% probability of ever transiting Would induce 0.5 as of stellar astrometric wobble Won’t lens background stars (galactic latitude -38°) • In direct imaging, an Earth analog here would: – Appear at R magnitude 27.6, and with contrast to the star of 310-10 – Be separated from the star by 3 resolution elements as seen by a 3 meter telescope observing in V band – Provide photons enabling its discovery *and* spectral measurements of its physical/chemical/biological? conditions From Keith Warfield’s study of past decadal missions: • “All past missions prioritized by the Decadal Survey were thought to be under $ 3B” • Only allowed 3 “tooth fairies”, i.e. major technology development activities Paul Hertz Fiscal and technical constraints • ~$ 7B of free energy in NASA astrophysics budget through 2035; HabEx study goal is to not use it all HabEx Overview • Exploring our nearest planetary systems. • Detect and characterize potentially habitable planets, search for signs of habitability and biosignatures. • Enable a broad range of general astrophysics. • Study started spring 2016. 3 face-to-face STDT meetings so far, weekly design team meetings • Interim report due late 2017, final report early 2019. Planets with comparable brightness have very different spectra Cloud Scaled Brightness Sulfur species Venus Cool Neptune CH4 CH4 3-bar Earth O3 O3 Rayleigh Mars SO2 Surface Oxides Wavelength [nm] Ty Robinson CH4 CH4 Earth observed in the optical Feng, Robinson, et al. (in prep.) Why go into the near-IR Ty Robinson O3 H2O H O 2 O2 H2O O2 H2O O2 CO2 H2O H2O H2O CO2 Why go into the UV for HZ planets Venus Earth CO2 Ty Robinson O3 Mars Earth twins 4-m HabEx Coronagraph 5 pc λ/Δλ = 7 Ty Robinson Venus twins 4-m HabEx Starshade 5 pc λ/Δλ = 7 Ty Robinson General Astrophysics • Consider what will be or has been available: – HST – JWST, WFIRST – Ground-based ELTs • UV for >2.5m aperture provides a novel capability Paul Scowen General Astrophysics Themes. • • • • • • Hubble Constant Escape Fraction Cosmic Baryon Cycle Massive Stars & Feedback Stellar Archaeology Dark Matter HabEx’s Three Graces of general asrophysics: Paul Scowen, Rachel Somerville, Dan Stern General Astrophysics Capabilities Matrix. Science driver Hubble Constant Escape Fraction Cosmic Baryon Cycle Massive Stars/Feedback Stellar Archaeology Dark Matter observation wavelength spatial resolution spectral resolution FOV aperture effective aperture exp. time image Cepheid variable stars in SN Ia host galaxies UV imaging of star forming galaxies optical-near-IR (!.6 micron) UV, preferably down to 912A diffraction limited diffraction limited preferred N/A 3' >=4m R ~ 1000-3000 few arcmin >=4m spectroscopy of absorption lines in background QSO or galaxies; UV imaging UV imaging and spectroscopy of massive stars in the Galaxy and nearby galaxies UV, imaging down to 115nm sufficient, spectroscopy down to 92nm preferred 10mas R=1,000-40,000 (grating turret) 10' >6m UV, 120-160nm spectroscopy; 1101000nm imaging R=10,000 10-30' >4m N/A 10' 4-8m ? 10' >=8m diffraction limited; 0.04" at 300nm resolved photometry of individual stars in nearby galaxies optical (500-1000nm) diffraction limited integrated photometry + radial velocities and proper motions of stars in Local Group dwarf galaxies optical (500-1000nm) diffraction limited other 20 ks/galaxy few ks/galaxy >3x10^4 cm^2 in the UV - implies 10% (throughput + DQE) in the UV for a 6m telescope 300-2000s 100 hours/galaxy MOS capabilities beneficial over a field as large as 20x20' large number of broad, medium and narrow filter bands; spectroscopic angular resolution 5 mas this science can be done with smaller aperture telescopes, but a significant jump in capability occurs at around 8m astrometric accuracy of <40 m arcsec/yr -> UV Spectrometer and UVOIR imager. HabEx’s Three Graces of general asrophysics: Paul Scowen, Rachel Somerville, Dan Stern HabEx configuration for 4 meter monolith First architecture option • 4-meter monolithic primary mirror, off-axis, unobscured • Waveband: 120nm – 1m – (stretch: 90nm – 2m) • • • • • • Starshade(s) Active vs. passive stability Coronagraph 10 arcmin^2 imager 30,000 spectrograph Diffraction limited @ 400nm – (stretch 250nm) jpl.nasa.gov Assessing UV compatibility with coronagraph: polarization effects Effects of telescope f number and mirror coatings • Considered: – f/1.5 , f/2.0 , f/2.5 – Coating: • Protected Silver Coating (all optics) • Standard Protected Aluminum coating on Telescope optics (PM, SM, TM) and protected silver coating on all other optics – Coronagraph Architecture (chosen for convenience & sensitivity): • Hybrid Lyot Coronagraph (HLC) design from Exo-C probe study • Vector Vortex charge 6 design • Analysis: – Two linear polarization states (+45deg, -45deg) input to Telescope – Wavefront phase and amplitude maps at exit pupil passed as input to coronagraph – Coronagraph Analysis: • Electric Field Conjugation (EFC), PROPER, Deformable Mirror (DM) jpl.nasa.gov Effect of Coronagraph Type, mirror coatings John Krist & Stefan Martin jpl.nasa.gov Coating options to extend UV below 120nm Reflective coating options for telescope • Protected Silver Quantum Coatings Protected Silver FSS99-500* – FSS99-600 from Quantum Coatings or similar, TRL-9 • Standard Protected Aluminum – Aluminum with MgF2 overcoat, like HST, TRL-9 *http://www.quantumcoating.com/fss99 • UV Enhanced Protected Aluminum – Aluminum with MgF2/LiF overcoats, in development, ~TRL-3 – Aluminum with AlF3/LiF overcoats, in development, ~TRL-3 Kunjithapatham Balasubramanian ; John Hennessy ; Nasrat Raouf ; Shouleh Nikzad ; Michael Ayala ; Stuart Shaklan ; Paul Scowen ; Javier Del Hoyo and Manuel Quijada " Aluminum mirror coatings for UVOIR telescope optics including the far UV ", Proc. SPIE 9602, UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VII, 96020I (September 22, 2015); doi:10.1117/12.2188981; http://dx.doi.org/10.1117/12.2188981 jpl.nasa.gov Exo-C Coronagraph Low-Order Sensitivity Contrast change with 100 pm RMS WFE (550 nm) 10-7 10-7 10-8 Spherical 10-9 Coma 10-9 Coma 10-10 Focus Trefoil -11 10 PIAA 10-8 RMS contrast RMS contrast Spherical HLC Astigmatism 10-12 10-10 Focus Trefoil Astigmatism 10 -11 Tilt 10-12 Tilt 10-13 10-13 IWA 10-14 2 4 6 /D lλ/D 8 10 12 2 10-7 VVC charge 4 RMS contrast Coma Astigmatism Trefoil -12 10 10 12 14 VVC charge 6 Trefoil 10-10 10-11 Astigmatism 10-12 Focus 10-13 10-14 8 /D lλ/D 10-9 Tilt 10-11 6 IWA 10-8 RMS contrast 10-8 10-10 4 10-7 Spherical 10-9 IWA 10-14 Coma Spherical 10-13 Tilt IWA 2 10-14 4 6 8 /D lλ/D 10 12 14 2 Focus 4 6 8 l/D λ/D 10 12 14 Telescope stability Laser Metrology for Active Rigid Body Motion Control • • Existing JPL technology, TRL-9 expected by 2019 Performance: • • < 6 nm RMS Gauge Noise @ 1 kHz < 5 nm/°C Thermal Drift • 10mK temp stability < 50 pm gauge error drift Stuart Shaklan, Metrology System for the Terrestrial Planet Finder Coronagraph , Proceedings of SPIE Vol. 5528 • Low order wavefront sensor would supply information on a restricted set of disturbances jpl.nasa.gov Architecture – Initial Round • Aperture trade – STDT selected 4m unobscured and 6.5m on-axis telescope designs for study – Decision based partly on an assessment of science per dollar, partly on an assessment current industry mirror capabilities, and JWST leverage value • GA instrument trade – STDT general astrophysics members identified 6 high-value instruments for evaluation by the whole STDT – Discussions within the STDT reduced the instruments for evaluation to two: UV spectrograph and a UV/VIS/NIR camera – Both instruments sent to Team X for rough design • Team X identified new technologies, liens generated on the flight system and operations, and cost for both candidates – STDT will select the best option for integration into the concept design • L2 assumed as the orbit – Earth trailing/leading limits life and starshades must co-launch – Earth orbits are unattractive due to thermal and field-of-regard considerations – L2 orbit size remains a small trade. Presently assuming a WFIRST-like orbit. Architecture – Second Phase • 5 unique architectures (so far) being evaluated for 4m design – Additional variations based on extended bandpass (both in the blue and the red) – Will repeat for 6.5m when we reach that design • Using high-level assessments for performance, cost and risk – Using Stark’s yield analysis (performance), ghosting the CATE (cost), counting new technologies (risk) TRADE STATEMENT: Recommend a 4m exoplanet direct detection architecture for HabEx study concept development Description Architecture Trades MUSTS Technical M1 M2 M3 M4 Can search the HZ of XX nearby stars Can spectrally characterize planets from 400nm -1000nm Can spectrally characterize planets to >RXX resolution Operational for 5 years or more Schedule M5 Ready for KDP-A by 2025 Evaluation Cost M6 Total estimated cost will be less than $XXB WANTS (DISCRIMINATORS) Weights Technical W1 W2 W3 W4 W5 Spectrally characterize to XXnm in IR Spectrally characterize to XXnm in UV Minimize number of new technologies Maximize characterization of all planet types Maximize characterization of HZs Schedule W6 Reach TRL 5 at earliest possible date Cost Risk Evaluation W7 Minimize cost RISKS R1 R2 R3 OPPORTUNITIES O1 O2 25 1 2 3 4 5 Starshade Only Corongraph Only S&C 2 Starshades S & 10-9C Starshade Trades • Size – Depends strongly on IWA and longest desired wavelength of operation. IWA will be ~70 mas, max = 1.0-1.7 m – Currently working starshade sizing which is a function of the above and the desired bandpass – Starshade must fit in 5m fairing to allow second (or followon) launches – Minimizing dry mass will extend the delta-V and improve yield • Deployment Method – Will also evaluate NGAS and JPL deployment methods for use in the 4m and 6.5m concepts • Overall concept cost and technical readiness will be the criteria Team X Results – UV Spectrograph Study leads to mass, power, dimensional constraints for the mission architecture Camera Study Requirements • Imager (“HabEx Workhorse Camera”) – 2 channel – UV/optical and near-IR – with a suite of filters. • Spectrometer (“HabEx UV Instrument”; see 1817 Study Report) – Slit spectroscopy – A micro-shutter array (as per NIRSpec on JWST). Again, covering UV, optical, and near-IR wavelengths. • Spectral Range: 150-2000 nm – Diffraction limited at 400 nm • Spectral Resolution: – Moderate resolution spectroscopy, R~2000 • FOV: 3 x 3 arcminute 9/24/2015 28 Waveband: 120nm – 1m Detectors • UV spectrograph: (100nm – 350nm) – micro-channel plate • General Astrophysics Imager: (150nm – 2m) – CCD (high TRL) – HgCdTe (high TRL) • Coronagraph & Starshade: (150nm - 1m) – micro-channel plate (high TRL, GALEX) ? – EMCCD (WFIRST), (250nm – 1m) – HgCdTe (1m - 1.7m) (current devices are too noisy) jpl.nasa.gov Work together - meet in the middle 30 Difference between LUVOIR and HabEx? • • • • Both LUVOIR and HabEx have two primary science goals • Habitable exoplanets & biosignatures • Broad range of general astrophysics The two architectures will be driven by difference in focus • For LUVOIR, both goals are on equal footing. LUVOIR will be a general purpose “great observatory”, a successor to HST and JWST in the ~ 8 – 16 m class • HabEx will be optimized for exoplanet imaging, but also enable a range of general astrophysics. It is a more focused mission in the ~ 4 – 8 m class Similar exoplanet goals, differing in quantitative levels of ambition • HabEx will explore the nearest stars to “search for” signs of habitability & biosignatures via direct detection of reflected light • LUVOIR will survey more stars to “constrain the frequency” of habitability & biosignatures and produce a statistically meaningful sample of exoEarths The two studies will provide a continuum of options for a range of futures 31 Yields: ExoEarths Chris Stark 2015 Interpolation • HabEx • • • • • 4m monolith off axis 6.5m segmented on or off axis 2-3 instruments (coronagraph, up to 2 GA instruments) Likely starshade(s) DI λ: 400-1000 nm (stretch ~200-1700nm) • LUVOIR • • • • • ~9m segmented 16m segmented on axis 4-5 instruments (or instrument bays) Starshade as a future option DI λ: 400- 2500 nm 33 jpl.nasa.gov