FUTURE SUBMILLIMETER MISSIONS

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FUTURE SUBMILLIMETER MISSIONS
Mike Fich Department of Physics and Astronomy
University of Waterloo (with slides from
Wolfgang Wild, Frank Helmich, Thijs de Graauw,
Dave Leisawitz, Matt Griffin, )
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Outline

• history older submm/far-IR missions
• current or recent submm/far-IR missions
• near-term (funded) missions
• long-term (unfunded!) missions
• prospects for new funding, Canadian planning
  process

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submm/Far-IR history

• IRAS 57 cm mirror (1 4 arcmin beam), 200 days
  in 1983, first all sky survey, 12/25/60/100 µm
  point source photometry plus 7-23 µm spectroscopy
• Spacelab 2 1985, mapped 60 of Galactic Plane
• KAO airborne, 91 cm mirror
• IRTS Mar 1995, 28 days, 7 of sky
• ISO 64 cm mirror, Nov 1995 May 1998, 1000x
  more sensitive than IRAS (two imagers, two
  spectrometers), 2.5 240 µm
• MSX 1996, 10 months, 4 26 µm

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SWAS

• 55 x 71 cm mirror (4 arcmin beam)
• H2O at 557 GHz, O2 at 487 GHz, CI at 492 GHz,
  13CO, H218O
• launched Dec 1998, hibernated July 2004
  (reactivated for Deep Impact)

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Odin

• a Swedish-Canadian-French satellite observatory
• launched 20 Feb 2001 with 2 to 3 year lifetime
• still going
• joint astronomy/aeronomy (ozone chemistry)
  mission
• primary astronomy targets are objects with water
  and oxygen
• 557 GHz ground state water line
• 119 GHz ground state O2 line

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The last view of ODIN as it goes into the rocket.
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Spitzer

• 85 cm mirror
• launched Aug 2003 (2.5 year mission)
• wavelengths of 3 180 micron
• three instruments
• IRAC, camera at 3.6, 4.5, 5.8, 8.0 µm
• MIPS, camera at 24, 70, 160 µm
• IRS, spectrometer 5.2 38 µm

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ASTRO-F (IRIS)

• repeat of IRAS all-sky survey with much higher
  sensitivity in 6 bands
• 69 cm mirror, 2 200 µm
• launched Feb. 2006, several year mission
• first images recently appeared on website (22
  May, 2006)

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the near-future (funded!)

• Herschel (launched with Planck)
• SOFIA

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Herschel Planned for launch in 2008 80 to 600
microns far-infrared submillimeter 3.5 meter
antenna ESA Cornerstone mission
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SOFIA (NASA Airborne Observatory)

• Funding restored by NASA 21 July 2006!
• 2.5 m mirror
• 1 655 microns
• set of 9 instruments

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The future not yet funded
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Science Reqmts for new missions

• frequencies not accessible from ground
• high resolution match to ALMA?
• significantly higher sensitivity (more collecting
  area, better detectors)
• spectroscopy requirements of R105 (velocity
  resolution of a few km/s)

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Future Mission Characteristics

• Cooled antenna (SPICA)
• Larger antenna (SAFIR)
• Interferometers comparable resolution to ALMA
• direct detection (more sensitive, but fewer
  cooled antennas, controlled baselines) (SPIRIT,
  SPECS)
• heterodyne (larger number of free-flying
  antennas) (ESPRIT)
• higher frequency (up to 6 THz, 50 microns)

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The need for BIG, COLD telescopes
COLD, because we need ?T4 low in far IR. A 4K
telescope is needed to achieve background-limited
operation and measure faint distant galaxies in
the early universe
BIG, because we need ?/D small in far IR. A 10m
telescope will provide 1 resolution in the far
infrared -- necessary for avoiding confusion
limits! Also large collecting area.
Spitzer
200 K Tel.
Orders of magnitude capabilitiy increase!
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HIFI (R104)
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The Far-IR Spatial Resolution Gap
JWST
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Interferometers Heterodyne vs. Direct Detection

• Heterodyne detect the signals at each antenna
  and then combine electronically
• Direct Detection combine beams, then detect
  signal
• sensitivity
• resolution
• technology challenges (cost and schedule)

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Heterodyne vs. Direct Detection

• The sensitivity comparison between direct and
  heterodyne detection systems is not
  straightforward, since much depends on the
  assumed parameters, such as
• Detector sensitivities (NEP)
• Optical efficiencies
• Physical temperature of telescope and optics
• Bandwidth

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Heterodyne vs. Direct-Detection
Direct detection requirements for very low
background levels 1. Low telescope temperature
(lt6K) 2. Instruments at low level (2 K) 3.
Detectors at very low level (lt .1 K) 4.
Telescope / structure / instruments under very
strict stray-light requirements Sensitivity of
direct detectors will (have to) be improved by
orders of magnitude
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Heterodyne vs. direct detection

• For R 104 heterodyne detection is usually more
  sensitive
• For R 102 direct detection is usually more
  sensitive if the telescope is cooled to 4 K.
• Telescope temperature has a large impact on
  direct detection sensitivity.

S/N vs. spectral resolution R at 1 THz (from B.
Jackson)
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Heterodyne Advantages

• Heterodyne detection (non)-requirements
• Not background limited 1. Telescope at ambient
  temp (80K)
• 2. Ambient temperature instruments
• 3. 4 K mixers 15 K pre-amps
• Warm electronics (warm IF and back-end
  spectrometers)
• No stray light problems
• Telescope design for low standing waves
  (gtgtoff-axis)
• No precise real-time optical path-length
  adjustments,
• compensation and control necessary
• High spectral resolution
• Additional
• Heterodyne technique allows signal copy/division

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heterodyne interferometer characteristics

• Large coherence length
• Lcoh ?2/?? c/?? ? 30 cm _at_ ? 100 µm (1 GHz
  band)
• Allows delay line corrections in correlator
  (electronically)
• Relaxs metrology requirements (knowledge instead
  of control)
• Electronic delay line
• Since the coherence length is large, only
  knowledge (instead of accurate control) of
  satellite locations required
• Rate of change in relative satellite position
  determines the metrology speed cycle
• Observing while moving (drifting satellites to
  fill u-v plane)

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some Direct Detection Limitations

• Everything must be cooled
• One must control the positions of the antennas to
  a high precision ? antennas must be connected
  together
• Practical limitation of beam combining perhaps
  maximum of 3?, 4? antennas limit to sensitivity
  (so make the antennas larger?), imaging speed and
  dynamic range

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Primary Scientific Objectives for SPECS/SPIRIT
(direct detection)

• Learn how planetary systems form from
  protostellar disks, and how they acquire their
  chemical organization
• Characterize the family of extrasolar planetary
  systems by imaging the structure in debris disks
  to understand how and where planets form, and why
  some planets are ice giants and others are rocky
• Learn how high-redshift galaxies formed and
  merged to form the present-day population of
  galaxies

These objectives drive the mission design
requirements
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Direct Detection Far-IR Interferometry
Dave Leisawitz NASA
Based largely on the NASA-sponsored study of
the Space Infrared Interferometric Telescope
(SPIRIT), a candidate Origins Probe mission
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Science objectives (ESPRIT heterodyne)

• A. Imaging water and molecular ions in star
  forming regions and proto-stellar/proto-planetary
  disks H2O, OH, OH, CH, CH, CH2, CH3,
• B. Imaging in important atomic fine-structure
  lines
• CII, NII, OI, OIII,
• C. Imaging in high excitation lines of CO, HCN,
  HCO, etc
• D. Follow-up on ISO-LWS, SWAS, ODIN, Herschel,

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Main characteristics of ESPRITMission

• ESPRIT mission concept for a free-flying
  sub-millimetre and far-infrared heterodyne space
  interferometer
• Exploratory Space Submm Radio Interferometric
  Telescope

Telescopes N 6 free-flying Telescope size
gt3.5 m Temperature ambient (90K) Proj.
Baselines 7- 200 - 1000 m Freq. range in
0.56 THz (600-50 µm) Inst. Bandw. gt4
GHz Angular Res. 0.02 arcsec (_at_100 µm) Spectr.
Res. 1 Km/s (_at_100 µm)
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Interferometer Conclusions

• We need both
• direct detectors more sensitive, but low freq.
  resolution, lower spatial resolution, large
  technology challenges
• heterodyne have inherent (quantum) limits to
  sensitivity at shortest wavelengths, but
  technology is close to ready
• ? build heterodyne interferometer first?

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Funding

• US funding for NASA in trouble
• Look to ESA for partnerships

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ESA Cosmic Vision Science themes(2015-2025)

• What are the conditions for life and planetary
  formation? This theme looks at the emergence of
  life not only in our Solar System but also in
  'exoplanets' orbiting other stars. This requires
  the study of how and where stars form, how
  planets emerge from this process, and the
  appearance of signs of life (bio-markers) in
  other stellar systems as well as our own.
• How does the Solar System work?This will be a
  global attempt to understand the Solar System as
  a whole, from the Sun to the limits of its sphere
  of influence, as well as the formation mechanisms
  of gaseous giants and their moons, and the role
  of small bodies and asteroids in the process of
  planetary formation.
• What are the fundamental laws of the Universe?A
  century after Einsteins theory of relativity was
  proposed, physics remains a vast field for
  investigation. The laws of physics as currently
  formulated do not apply at extreme conditions,
  and are not at all understood for the first
  fractions of seconds after the Big Bang. Some
  implications, like the behaviour of matter at
  extremely high temperatures and energies or the
  existence of gravity waves, still have to be
  explored.
• How did the Universe begin and what is it made
  of? The origin and early evolution of the
  Universe is still largely unknown. Less than 5
  of the mass of the Universe has been identified,
  the rest being composed of mysterious dark
  matter (23) and dark energy - one of the most
  surprising recent discoveries.

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IRSI DARWIN
XEUS
Aurora
SOLARORBITER
F 3
GAIA
LISA
JWST
BEPI COLOMBO
Fundamental Physics
LPF

ILWS
ROSETTA
HERSCHEL
VENUSEXPRESS
PLANCK
MARS EXPRESS
SMART 1
SOHO CLUSTER
CASSINI/HUYGENS
XMM NEWTON
INTEGRAL
Time ?
DSP
Solar/STP
Astronomy
Planetary
HST
ULYSSES
CLUSTER II
ISO
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Missions in preparation
Bepi-Colombo 2012
Lisa 2014
Corot (CNES-ESA) . 2006
Herschel-Planck 2007
JWST (NASA-ESA) 2011
Astro-F (Japan-ESA) 2006
Lisa- Pathfinder 2009
Gaia 2011-12
Venus Express . 2005
Solar Orbiter 2015
Microscope (CNES-ESA) 2008
2015
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From themes to proto-missions
What are the conditions for life planetary
formation ?
How does the Solar System work ?
From dust and gas to stars and planets
Solar-Polar Orbiter (Solar Sailor)
From the sun to the edge of the solar system
Far Infrared Interferometer
Helio-pause Probe (Solar Sailor)
Earth Magnetospheric Swarm
Jupiter Magnetospheric Explorer (JEP)
From exo-planets to biomarkers
The Giant Planets and their environment
Near Infrared Terrestrial Planet Interferometer
Jovian In-situ Planetary Observer (JEP)
Europa Orbiting Surveyor (JEP)
Life habitability in the solar system
Asteroids and small bodies
Kuiper belt Explorer
Mars In-situ Programme (Rovers sub-surface)
Near Earth Asteroid sample return
Mars sample and return
Terrestrial Planet Astrometric Surveyor
Looking for life beyond the solar system
Terrestrial-Planet Spectroscopic Observer
Terrestrial Planet Imaging Observer
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From themes to proto-missions
How did the Universe originate and what is the
Universe made of?
What are the fundamental laws of the Universe ?
The early Universe
Wide Field NIR Dark Energy Observer
Fundamental Physics Explorer Programme
Exploring the limits of contemporary physics
General Relativity Probes
CMB Polarization Surveyor
The Universe taking shape
Binary source Gravitational Surveyor
The gravitational wave Universe
Far Infrared Observatory
Next Generation X-ray Observatory
Big Bang Cosmic Gravitational Surveyor
The evolving violent Universe
Matter under extreme conditions
Gamma-ray Observatory
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COSMIC VISION 2015 - 2025
ESA Corridor Planning
Three programme slices
500,000
LOAN
450,000
REIMBURSEMENT
400,000
350,000
SO 15
GAIA 11
LISA-PF 08
300,000
PROGRAMME
PROGRAMME
PROGRAMME
LISA 200M 14
SLICE
SLICE
SLICE
2015 - 2018
2018 - 2021
2021 - 2025
Keuro (2005 EC)
250,000
H-P
BC 12
200,000
150,000
JWST 11
UNTIL VEX
100,000
D/SCI contingency
50,000
Basic activities
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Canadian Space Astronomy Workshop

• Thursday 23 Nov and Friday 24 Nov. 2006
• presentations of possible future missions
• poster presentations welcome
• sponsored by the Canadian Space Agency
• held at CSA headquarters in Montreal
• all Canadian astronomy researchers invited
  (faculty, post-docs, staff, and graduate
  students)
• http//www.space.gov.ca/CSAW

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the end
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FIR water lines
Moro et al, ApJ
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Relation to ALMAWhat ALMA cannot do

• ALMA will do important science in all fields of
  Astrophysics,
• However limited to frequencies lt 950 GHz
• limited to atmospheric windows (no H2O lines)
• WHAT DOES THIS MEAN FOR ALMA? Cant do
• Light molecular species with rotational
  transitions gt900 GHz
• H2O, OH, H3O, HD, CH
• in star forming regions, protostellar disks,
  PDRs, shocks
• and Oxygen chemistry
• High excitation lines of CO, HCN, HCO, CN,
• in Shocks, PDRs, PPNs, PNs
• Atomic fine structure lines OI, N, C
• in PDRs, Shocks, Galaxies, AGNs, quasars

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Measurement Capabilities in the Next Decade
SPIRIT resolution is 0.3(l/100 mm) arcsec over
the spectral range 25 to 400 mm (matches JWST)
SPIRIT will provide 100x better angular
resolution than the Spitzer Space Telescope. The
resolution is comparable to that of JWST, but at
wavelengths 10x longer.
SPIRIT will be as sensitive as the spectroscopic
instruments on Spitzer and Herschel, but it will
provide spectral resolution R 3000 at much
higher angular resolution. Quoted minimum
detectable line flux (MDLF) values are for a 105
sec exposure in all cases except 104 sec for
SOFIA.
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SPIRIT will have a view of the sky that permits
access to all of the relevant objects, from
Galactic star forming regions to extragalactic
deep fields
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Interferometer element linking
Free flying Interferometer-elements linking
requirements 1. Optical metrology for position
determination 2. Signal transport between
elements for correlation 3. Locking of all the
LOs (reference distribution) Design goal is to
have all three functions carried out by optical
means, using same optical components.