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Dave Leisawitz, NASA GSFC. Technologies for Future Far-IR Telescopes and Interferometers. SPIRIT. CALISTO. SPICA. Future Far-IR Missions. SPICA – the Space Infrared Telescope for Cosmology and Astrophysics, led by Japan - PowerPoint PPT Presentation
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Technologies for Future Far-IR Telescopes and Interferometers
Dave Leisawitz, NASA GSFC
SPICA
SPIRIT
CALISTO
D. Leisawitz - COPAG Workshop - Austin AAS 219 2
Future Far-IR Missions• SPICA – the Space Infrared Telescope for Cosmology and
Astrophysics, led by Japan
• SPIRIT – the Space Infrared Interferometric Telescope, studied as a candidate Origins Probe (comparable to FIRI – the Far-Infrared Interferometer in Europe)
• SAFIR – Single Aperture Far-IR Telescope. A refined version, CALISTO, the Cryogenic Aperture Large Infrared Space Telescope Observatory, was proposed for technology devopment to the Decadal Survey
8 Jan 2012
The Far-IR Community is unified in its endorsement of US involvement in these missions.
D. Leisawitz - COPAG Workshop - Austin AAS 219 3
NWNH Recommendations
• Science goals that require more capable far-IR missions than any developed to date
• US participation in SPICA (budget caveat)
• Technology development for single-aperture (SAFIR/CALISTO) and interferometric (SPIRIT) far-IR missions
8 Jan 2012
D. Leisawitz - COPAG Workshop - Austin AAS 219 4
Compelling Science Goals
8 Jan 2012
• How do the conditions for planetary habitability arise during planet formation? (“follow the water”)
• Find and characterize exoplanets by imaging and measuring the structures in protoplanetary and debris disks.
• How did high-redshift galaxies form and merge to form the present-day population of galaxies? (How did a hot, smooth universe give rise to the Milky Way?)
• When and how did the first stars form and enrich the intergalactic medium?
SAFI
R/CA
LIST
OSP
IRIT
D. Leisawitz - COPAG Workshop - Austin AAS 219 58 Jan 2012
Water, water everywhere! (Some gaseous, some solid.)
How do the conditions for planet habitability arise during planet formation?
D. Leisawitz - COPAG Workshop - Austin AAS 219 68 Jan 2012
Kuchner et al. Eps Eri model scaled to 30 pc
Jang-Condell protoplanetary disk structure
Find and characterize planets by detecting lumps of gravitationally trapped dust in debris disks.
Detect and characterize newborn planets in protoplanetary disks.
14 May 2011 6D. Leisawitz - Far-IR Space Opportunities and SPIRIT
D. Leisawitz - COPAG Workshop - Austin AAS 219 78 Jan 2012
How did high-z galaxies form and merge to form the present-day population of galaxies?
D. Leisawitz - COPAG Workshop - Austin AAS 219 8
Herschel GOODS-N Deep Field
8 Jan 2012
D. Leisawitz - COPAG Workshop - Austin AAS 219 9
Derived Requirements (SPIRIT)• Sub-arcsecond angular resolution over the wavelength
range 25 – 400 mm (between JWST and ALMA)– Image protostellar and debris disks– Resolve the far-IR extragalactic background
• ~10 mJy continuum, 10-19 W/m2 line sensitivity– Detect low surface brightness debris disks– Measure SEDs and spectral lines of high-z galaxies
• >1 arcmin instantaneous FOV• Spectral resolution, R ~ 3000 (integral field
spectroscopy)
8 Jan 2012
D. Leisawitz - COPAG Workshop - Austin AAS 219 108 Jan 2012
To image protoplanetary and debris disks and definitively distinguish the emissions of individual high-z galaxies requires sub-arcsecond angular resolution. This capability is sorely lacking in the far-IR, where these objects are bright and their information content is great.
D. Leisawitz - COPAG Workshop - Austin AAS 219 118 Jan 2012
Sub-arcsecond angular resolution
Astronomical background-limited
sensitivity
Technology:• Detectors• Cryocoolers• Wide-field spatial-spectral interferometry• Low aereal density, possibly deployable primary mirror
Measurement requirements drive technology requirements
D. Leisawitz - COPAG Workshop - Austin AAS 219 128 Jan 2012
Technology Roadmap (SPIRIT)*
* A large single-aperture telescope also requires: large format, lower NEP detectors, though they needn’t be as fast (see Paul Goldsmith’s presentation), and a low aereal density primary mirror, possibly deployable.
D. Leisawitz - COPAG Workshop - Austin AAS 219 13
Cooling FIR Telescopes: Past and Future
Past:• IRAS• COBE• Spitzer• Akari•WISE• Herschel
8 Jan 2012
Past missions used expendable cryogens
Future:• SPICA• SAFIR/CALISTO• SPIRIT
Future missions will use cryocoolers
D. Leisawitz - COPAG Workshop - Austin AAS 219 14
Why use cryocoolers?
• Much less mass to launch• Greatly reduced volume relative to cryostat• Lower mass and volume means lower cost to
launch or more room for science payload• Mission lifetime not limited by expendable
cryogen
8 Jan 2012
D. Leisawitz - COPAG Workshop - Austin AAS 219 15
Technology Readiness
8 Jan 2012
With straightforward modifications, the JWST cryocooler (left) and the IXO CADR (right) will reach TRL 6 for SPIRIT.
D. Leisawitz - COPAG Workshop - Austin AAS 219 16
How much cooling power?
8 Jan 2012
(Left) Heat loads and cryocooler requirements are based on high-fidelity thermal models like this 106-node model of a SPIRIT telescope. (Right) Subscale cryothermal testing in a LHe shroud was used to validate the model. Dipirro et al. (2007)
D. Leisawitz - COPAG Workshop - Austin AAS 219 17
Cooling Requirements (SPIRIT)*
• For optical components, extend JWST cryocooler technology to enable cooling to 4 K with 180 mW heat lift at 18 K and 72 mW at 4K.
• For focal plane, need an ADR cryocooler operating from a base temperature of ~4K and cooling to 30 mK with a continuous heat lift of 5µW at 50 mK and 1 mW at 30 mK.
• Compactness, high efficiency, low vibration, and other impact-reducing design aspects are desired.
* More stringent requirements may pertain to a large single-aperture far-IR telescope with much larger focal plane arrays.
8 Jan 2012
D. Leisawitz - COPAG Workshop - Austin AAS 219 18
Wide-field Spatial-Spectral Interferometrysomething old and something new
8 Jan 2012
D. Leisawitz - COPAG Workshop - Austin AAS 219 198 Jan 2012
Wide-field Spatial-Spectral interferometry
We’ve been developing and gaining practical experience with this technique in the lab for the past decade
D. Leisawitz - COPAG Workshop - Austin AAS 219 20
Low aereal density mirror
8 Jan 2012
~10 kg/m2
~4 K
CALISTO
D. Leisawitz - COPAG Workshop - Austin AAS 219 21
Summary• In the far-IR, the drive toward sub-arcsecond angular resolution
coupled with the need for astronomical background-limited sensitivity translates into technology requirements for: – Far-IR detectors (Paul Goldsmith’s presentation)– Cryocoolers– Wide-field spatial-spectral interferometry– Low aereal density mirrors
• Most of the technology requirements are well understood• Recommendation: future investments in the technologies listed
above should be coordinated, sustained, and tied to the needs of studied single aperture and interferometric mission concepts
8 Jan 2012