CORSAIR Calibrated Observations of Radiance Spectra in the Far-Infrared Marty Mlynczak NASA Langley Research Center

The CORSAIR Team NASA Langley –Marty Mlynczak, PI –Sharon Graves, PM –Richard Cageao –Dave Johnson –Nurul Abedin –Dave Kratz –Xu Liu ITT –David Jordan Raytheon Vision Systems –Jinxue Wang Space Dynamics Laboratory –Gail Bingham –Harri Latvakoski NIST –Simon Kaplan JPL –Kevin Bowman

Far-IR Sensors and Science at Langley Timeline of Projects FIRST Instrument –IIP 2001 INFLAME Instruments –IIP 2004 NRC White Paper –Decadal Survey Call 2005 CERES/AIRS –EOS recompetion, 2005 FIDTAP –ATI 2006 FORGE –Radiation Sciences Program 2006 CORSAIR –IIP 2007

CORSAIR -- Outline Background on the Far-Infrared –Definitions and Science –The FIRST Project Elements of the CORSAIR IIP Project –Detectors –Blackbody Radiance Standards –Broad Bandpass Beamsplitters Some Thoughts on The Way Forward –Instrument Modeling –Calibration Demonstration Unit –Atmospheric Observations

Earth’s Infrared Radiance Spectrum

Compelling Science of the Far-Infrared FIRST - Science Flights 6/2005; 9/2006 Demonstrated far-IR interferometer technologies Measurement of Cirrus Opt. Depth Collins and Mlynczak, 2001 Mlynczak et al., 1998 Yang et al., 2003

FIRST: Technology and Science First complete infrared spectrum of Earth FIRST Focal Plane Array Technology Development through IIP Partners: SDL; SAO Effects of middle troposphere temp erature Mlynczak et al., 2006 Harries et al., 2008

The CORSAIR Project

CORSAIR - Overview FIRST demonstrated: –High throughput FTS (0.47 cm 2 sr) –Far-IR beamsplitter –Cryogenic Focal Plane Design CLARREO Requires: –Far-IR detectors operating above liquid helium temperatures –Far-IR blackbodies traceable to SI standards –Broad bandpass beamsplitters (5 to 50  m) CORSAIR IIP to demonstrate these technologies at TRL-6

CORSAIR - Major Technology Elements Passively Cooled Detectors (Raytheon Vision Systems) –Antenna Coupled Terahertz Devices –Potential for 100 to 1000 times more sensitive (D*) than pyroelectric –Substantial prior DARPA and Homeland Security investment –Detectors evaluated in Year 3 in Langley SI Traceable Blackbodies in Far-IR (SDL; NIST) –Flight prototype blackbody w/ well-characterized emissivity –On-orbit, SI-traceable temperature measurement for blackbody –On-orbit emissivity monitor in far-IR Broad Bandpass Beamsplitters (ITT) –Cover 5 to 50  m region in 1 beamsplitter –Potentially enables 1 instrument to cover CLARREO range

Antenna-Coupled Technology Far-IR Energy Couples to Antenna Optimized for Specific LW Band & Bandwidth Antenna Passes Current to the Detector (Diode) Detector Connects to ROIC through Conducting Leads ROIC Reads Out Resistance for Each Pixel & Multiplexes Output D* above 1e+10 cm sqrt(Hz)/W predicted LW Pixel with MicroAntenna Antenna Captures LW Radiation Energy Coupled to Detector LW Power Flows from Antenna to Detector Detector Element Bowtie Antenna Connections to Readout Circuitry

Requirements and Project Milestones Spectral Range: 15 to 50  m Specific Detectivity: 1e + 10 cm sqrt(Hz)/W Bandwidth: Greater than 3:1 NEP: Less than 2e-11 W/sqrt(Hz) Sampling Frequency: 2 kilohertz Operating Temperature: 285 to 295 Kelvin Dark Current Shot Noise: 4 picoamperes/sqrt(Hz) Critical Design Review: March 2009 Detector Lot 1 Fab. and Test: August 2009 TRL 4 Detector Lot 2 Fab. and Test: September 2010 TRL 5 Detectors Delivered to Langley: October 2010 Testing in FIRST completed: August 2011 TRL 6

CORSAIR Far-IR Blackbodies No SI-traceable standards currently exist for Far-IR SDL, NIST, and Langley will work to develop SI-traceable BB sources for the Far-IR Approach –Install phase change cells on FIRST LW Calibration Source (LWIRCS) –NIST/SI certify LWIRCS in NIST LBIR facility –Develop CLARREO flight demo Far-IR blackbody Include Far-IR emissivity monitor –Calibrate against LWIRCS Flight demo Blackbody to be delivered to Langley –SI traceable temperature via phase change cells and calibration against LWIRCS –Emissivity monitoring to better than 3 parts in 10,000

Far-Infrared Spectrum in Brightness Temperature

Effects of Emissivity Error on Far-IR Calibration Emissivity must be known better than 3 parts in 10,000  0 =

Effects of Emissivity Error on Far-IR Calibration  0 = Emissivity must be known better than 3 parts in 10,000

FIRST LWIRCS LWIRCS to be calibrated at the NIST LBIR facility Will be SI-traceable radiance standard upon completion

Project Requirements and Milestones SI-traceable LWIRCS (0.1 K, 3-  ) Design and build flight demo blackbody –Incorporate emissivity monitor to 3 parts in 10,000 Spectral range of BB: 15 to 50  m minimum LWIRCS calibration at NIST LBIR:April 2009TRL 6 –(SI-traceable far-IR calibration standard) Flight demo BB Design ReviewDec Flight demo BB development:July 2010TRL 5 Flight demo BB testing and eval:July 2011TRL 6 Delivery of far-IR BB to Langley: August 2011 –(SI-traceable, PCM cells, emissivity monitor)

CORSAIR Broad Bandpass Beamsplitters CLARREO Requirement in Decadal Survey –Interferometer covering 5 to 50  m Presents challenges in –Detectors –Optical coatings –Beamsplitters CORSAIR will develop and demonstrate a single beamsplitter capable of passing the entire CLARREO range with minimal absorption and maximum efficiency

Project Requirements and Milestones Wavelength Range: 5 to 50  m R-T Product: 4[R] [T] = 1.0, 5 to 50  m Beamsplitter Design3/2009 Computer Model Development6/2009 Design Review7/2009 Fabricate first beamsplitter9/2009 TRL 4 Develop Test Setups12/2009 Fabricate Beamsplitters4/2010 Test Beamsplitters8/2010 TRL 5 Beamsplitters Thermal cycling1/2011 Comprehensive Test and Evaluation6/2011 TRL 6 Delivery of Beamsplitters to Langley9/2011

The Way Forward

Model, Build, Measure. Repeat. There is no equivalent atmospheric measurement heritage in the far-IR as there is in the mid-IR (e.g, S-HIS; NAST-I; AIRS, IASI, etc.) Achieving Far-IR accuracy for CLARREO will require us to do the following in addition to developing component technologies: –1. Develop detailed instrument model as part of instrument design process –2. Build a “Calibration Demonstration Unit” to show SI-traceability of system and validity of instrument model –3. Conduct “viable” atmospheric measurements and intercomparisons amongst various extant instruments There are 4 Far-IR instruments worldwide: –FIRSTTAFTS REFIR AERI-ER Must continue to measure the far-IR spectrum and validate knowledge of calibration in all respects Example: RHUBC/FORGE Campaign, Atacama Desert, Chile, in 2009

RHUBC/FORGE Campaign Details RHUBC-II/FORGE –1 Aug - 31 Oct 2009 –Cerro Toco or Chajnantor Plateau, Chile. 5.1 km altitude (17,000 feet) –Minimum PWV: 0.1 mm (anticipated) –Key instrumentation: Infrared FTS: FIRST, AERI-ER, REFIR-PAD, TAFTS(?) Microwave Radiometers: MP-183, RS-92, MPL, GVR RS-92 radiosondes

CORSAIR Summary The far-IR spectrum is a frontier in climate sensing Substantial strides to date in achieving technologies required for routine, extended space-based far-IR observations CORSAIR will develop and demonstrate several remaining technologies at TRL 6 (from TRL 3) –Antenna coupled detectors for Far-IR –SI Traceable Blackbodies for Far-IR –Broad bandpass beamsplitters IIP’s need to be complemented with on-going measurements to develop “working knowledge” of far-IR hardware and calibration

Public Service Announcements Appearing in Rev. Geophys. imminently: Harries, J., B. Carli, R. Rizzi, C. Serio, M. Mlynczak, L. Palchetti, T.Maestri, H. Brindley, and G. Masiello (2008), The Far-Infrared Earth, Rev.Geophys., 46, doi: /2007RG Please see poster by Mark Muzilla et al. on some exciting new detector technology for the far-IR