SOFIA Observations of Stellar Occultations, Extra-solar Planets, Asteroids, and Comets

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SOFIA Observations of Stellar Occultations,
Extra-solar Planets, Asteroids, and Comets
by R. D. Gehrz1, E. E. Becklin2, I. de Pater3, E.
W. Dunham4, C. E. Woodward1, and M. S.
Kelley5 1Department of Astronomy, University of
Minnesota, 2Universities Space Research
Association, NASA Ames Research Center,
3Astronomy Department, University of California
Berkeley, 4Lowell Observatory, 5Department of
Physics, University of Central Florida
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Outline

• SOFIA Heritage and Context
• SOFIA Description and Status Report
• SOFIA Performance Specifications
• SOFIA and Solar System Research
• SOFIA Schedule
• Opportunities for International Collaboration
  on SOFIA
• Summary

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SOFIAs Heritage and Context
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The History of Flying Infrared Observatories
1999
1967
2002
1967
2003
1977
1974
NASA Spitzer Space Telescope
NASA Kuiper Airborne Observatory (KAO)
NASA Lear Jet Observatory
2006
2006
2009
1995
NASA/DLR Stratospheric Observatory for Infrared
Astronomy (SOFIA)
1983
ESA Infrared Space Observatory (ISO)
NASA Infrared Astronomical Satellite (IRAS)
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SOFIA and its Companions in Space
HERSHCEL
2008/9
2003
JWST
SOFIA
2013
2009
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SOFIA and Major IR Imaging/Spectroscopic Space
Observatories
0.3
1000
SPICA
?
AKARI
SAFIR
SOFIA
Herschel
3
100

Frequency (THz)
WISE
JWST
SPITZER
Wavelength (µm)
30
10
Warm Spitzer
1
2005
2010
2015
2020
2025
Ground-based Observatories
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SOFIA and Herschel Compilemtarity, Synergism
A comparison between SOFIA First Generation SIs
and Herschel SIs

• Similar instrumentation at relatively unexplored
  long wavelengths
• SOFIA will complement and supplement Herschel
  observations
• SOFIAs long life and accessibility will
  encourage the development and application of new
  technologies

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SOFIA Status Report
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NASA/DLR SOFIA Overview

• 2.5 m telescope in a modified Boeing 747SP
  aircraft
• Imaging and spectroscopy from 0.5 ?m to 1.6 mm
• Emphasizes the obscured IR (30-300 ?m)
• Service Ceiling
• 39,000 to 45,000 feet (12 to 14 km)
• Above gt 99.8 of obscuring water vapor
• Joint Program between the US (80) and Germany
  (20)
• First Light Science in 2009
• 20 year design lifetime can respond to changing
  technology
• Ops Science at NASA-Ames Flight at Dryden FRC
  (Palmdale- Site 9)
• Deployments to the Southern Hemisphere and
  elsewhere
• gt120 8-10 hour flights per year

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The Advantages of SOFIA

• Above 99.8 of the water vapor
• Transmission at 14 km gt80 from 1 to 800 µm
  emphasis
• on the obscured IR regions from 30 to 300
  µm
• Instrumentation wide variety, rapidly
  interchangeable, state-of-the art SOFIA is a
  new observatory every few years!
• Mobility anywhere, anytime
• A near-space observatory that comes home after
  every flight
• Twenty year design lifetime

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SOFIA The Observatory
open cavity (door not shown)
Educators work station
pressure bulkhead
scientist stations, telescope and instrument
control, etc.
TELESCOPE
scientific instrument (1 of 9)
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Nasmyth Optical Layout
Observers in pressurized cabin have ready access
to the focal plane
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The Un-Aluminized Primary Mirror Installed
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Four First Light Instruments
Working/complete HIPO instrument in Waco on
SOFIA during Aug 2004
Working/complete FLITECAM instrument at Lick in
2004/5
Working FORCAST instrument at Palomar in 2005
Successful lab demonstration of GREAT in July 2005
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SOFIA Airborne!
26 April 2007, L-3 Communications, Waco Texas
SOFIA takes to the air for its first test flight
after completion of modifications
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SOFIA Performance Specifications
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SOFIA First Generation Spectroscopy
SOFIAs 8 arcmin diameter FOV accommodates very
large detector arrays

• FORCAST

SAFIRE
JWST

• SPITZER IRS

HAWK
MIPS
IRAC
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Photometric Sensitivity
SOFIA is as sensitive as ISO
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Angular Resolution
SOFIA is diffraction limited beyond 25 µm (?min
?/10 in arcseconds) and can produce images
three times sharper than those made by Spitzer
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Planetary System Researchwith SOFIA
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SOFIA Addresses Key Questions in Planetary
Science

• What are dwarf planets?
• How do they relate to solar system formation?
• What is the nature of Comet nuclei
• What are the properties of Extra-Solar Planets?
• Are biogenic molecules made in space?
• Are they in other solar systems?

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Small Bodies and Comets as the Rosetta Stones
of the Solar System

• They are the remaining planetesimals from the
  epoch of planet formation in the primitive Solar
  nebula
• Occultations yield the physical properties of
  small bodies.
• IR spectroscopy of material released from comet
  nuclei
• during perihelion passage samples the content
  of the
• primitive Solar System
• IR imaging and spectroscopy of debris disks
  enables
• comparisons with extra-solar planetary sytems
• S

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Many SOFIA Planetary Science Observations Involve
Targets of Opportunity

• Bright Comets at Perihelion Passage
• Occultations by Outer Solar System Bodies
• Extra-Solar Planet Transits

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Occultation Astronomy with SOFIA
How will SOFIA help determine the properties of
small Solar System bodies?

• Occultation studies probe sizes, atmospheres,
  satellites, and rings of small bodies in the
  outer Solar system.
• SOFIA can fly anywhere on Earth to position
  itself in the occultation shadow. Hundreds of
  events are available per year compared to a
  handful for fixed ground and space-base
  observatories.

Earth
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Occultations and Atmospheres
This occultation light curve observed on the KAO
(1988) probed Plutos atmosphere J. L. Elliot
et al., Icarus 77, 148-170 (1989)

• Occultation studies with SOFIA will probe the
  sizes, atmospheres, and possible satellites of
  newly discovered planet-like objects in the outer
  Solar system.
• The unique mobility of SOFIA opens up some
  hundred events per year for study compared to a
  handful for fixed observatories.

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Occultations Rings and Moons
This occultation light curve observed on the KAO
in 1977 shows the discovery of a five ring system
around Uranus J. L. Elliot, E. Dunham, and D.
Mink, Nature 267, 328-330 (1977)

• Occultation studies with SOFIA will probe the
  sizes, atmospheres, and possible satellites of
  newly discovered planet-like objects in the outer
  Solar system.
• The unique mobility of SOFIA opens up some
  hundred events per year for study compared to a
  handful for fixed observatories.

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Extra-solar Planet Transits
How will SOFIA help us learn about the
properties of extra-solar planets?

• Today, over 268 extra-solar planets are known,
  and with more than 21 transiting their primary
  star. Transit observations can
• Provide good estimates for the mass, size and
  density of the planet
• May reveal the presence of, satellites, and/or
  planetary rings

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SOFIA and Extra-solar Planet Transits
G. E. Ballester, D. K. Sing F.Herbert, 2007,
Nature, 445, 511.
Expected SOFIA performance comparable to this HD
209458b transit with HST STIS
HD 209458b transit artists concept
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SOFIA and Extra-Solar Planetary Systems
What can SOFIA tell us about debris disks?
850 µm
JCMT beam

• SOFIA imaging and spectroscopy can resolve disks
  to trace the evolution of the spatial
  distribution of the gaseous, solid, and icy gas
  and grain constituents
• SOFIA can shed light on the process of planet
  formation by studying the temporal evolution of
  debris disks

53 µm
88µm
Debris disk around e Eridanae
SOFIA beam sizes
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Observing Comets in the IR with SOFIA

• Comet nuclei, comae, tails, and trails emit
  primarily at the thermal IR wavelengths
  accessible with Spitzer (3-180 ?m)
• Emission features from grains, ices, and
  molecular gases
• occur in the IR
• IR Space platforms (Spitzer, Herschel, JWST)
  cannot view
• comets during perihelion passage due to
  pointing constraints

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SOFIA and Comets Mineral Grains
What can SOFIA observations of comets tell us
about the origin of the Solar System?
ISO Data

• Comet dust mineralogy and physical properties
• Comparisons with IDPs
• Comparisons with meteorites
• Comparisons with Stardust
• Only SOFIA can get these observations

Spitzer Data
The vertical lines mark features of
crystalline Mg-rich crystalline olivine
(forsterite)
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SOFIA and Comets Gas Phase Constituents
What can SOFIA observations of comets tell us
about the origin of the Solar System?
ISO Data

• Comet dust mineralogy and physical properties
• Comparisons with IDPs
• Comparisons with meteorites
• Comparisons with Stardust
• Only SOFIA can get these observations

Hale-Bopp spectrum shows H20 (2.7 µm), CO2 (4.26
µm), and CO (4.65 µm). Crovisier et al. 1997
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SOFIA and Comets Protoplanetary Disks
What can SOFIA observations of comets tell us
about the origins of our Solar System and other
solar systems?
ISO Observations Adapted from Crovisier et al.
1996, Science 275, 1904 and Malfait et al. 1998,
AA 332, 25
Image of Solar System IDP (Interplanetary Dust
Particle)
50 microns
Disk System
ISO Data
Solar System Comet

• The silicate features in HD 100546 and C/1995 O1
  Hale-Bopp are well-matched, suggesting that the
  grains in the stellar disk system and the small
  grains released from the comet nucleus are similar

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Schedule
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SOFIA Schedule (Major Milestones)

• First Re-Flight Occurred April 07
• Ten Closed Door Flights Finished
  Dec 07
• Mirror coated Finished Summer
  08
• Door Drive Delivered
  Summer 08
• Open Door Flights at Palmdale Winter 09
• First Science 09
• Next Instrument call
  10

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Early General Observer Opportunities

• Early Short Science in 2009 with FORCAST (US
  5-40 µm imager)
• and GREAT (German heterodyne 60 to 200 µm
  Spectrometer)
• Proposals are in and teams are being selected
• Very limited number of flights (3)
• GOs will not fly
• Early Basic Science for GOs in 2009 with FORCAST
  and GREAT
• Call in Dec 2008
• Longer period (15 Flights)
• Call will be for GO Science

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Next Call For New Instruments

• The next call for instruments will be at First
  Science FY 10
• There will be additional calls every 3 years
• There will be one new instrument or upgrade per
  year
• Funding for new instruments and technology is
  10 M/yr

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Partnership Opportunity on SOFIA

• NASA is funding 80 of the program and the German
  space agency (DLR) is funding 20 of the program
• The NASA Science Mission Directorate is open to
  considering proposals for participation as a
  partner in the United Statess share of the
  operations phase of the SOFIA Mission by domestic
  and international governments, agencies,
  universities, organizations, and research
  foundations

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Summary

• The Program is making progress!
• Aircraft structural modifications complete
• Telescope installed, several instruments tested
  on ground observatories
• Full envelope closed door flight testing is
  complete.
• door motor drive, coated primary mirror are being
  installed during summer of 08
• First science will be in early 09
• SOFIA will be one of the primary observational
  facilities for far-IR and submillimeter astronomy
  for many years
• See our WEBSITE at www.sofia.usra.edu

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Backup
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The Initial SOFIA Instrument Complement

• HIPO High-speed Imaging Photometer for
  Occultation
• FLITECAM First Light Infrared Test Experiment
  CAMera
• FORCAST Faint Object InfraRed CAmera for the
  SOFIA Telescope
• GREAT German Receiver for Astronomy at Terahetz
  Frequencies
• CASIMIR CAltech Submillimeter Interstellar
  Medium Investigations Receiver
• FIFI-LS Field Imaging Far-Infrared Line
  Spectrometer
• HAWC High-resolution Airborne Wideband Camera
• EXES Echelon-Cross -Echelle Spectrograph
• SAFIRE Submillimeter And Far InfraRed Experiment

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SOFIAs 9 First Generation Instruments
4.5-28.3
Listed in approximate order of expected
in-flight commissioning Operational (August
2004)
Uses non-commercial
detector/receiver technology
Science