IR Technology & IR Telescopes

1. Infrared detector technology  Early Thermocouples  devices which convert heat into electric current  In 1856 : used thermocouples to detect infrared radiation from the Moon.  Thermopiles (a group of thermocouples combined in one cell).  in 1948 : more sophisticated infrared studies of the Moon showed its surface was covered with a fine powder.

Infrared detector technology  In the early 1900's, infrared radiation was successfully detected from the planets Jupiter and Saturn and from some bright stars such as Vega and Arcturus.  Work in infrared astronomy remained at a low level until breakthroughs in the development of new, sensitive infrared detectors were achieved in the 1960's.

Infrared detector technology  1950 : Lead-sulphide (PbS) detectors to study infrared radiation in the 1 to 4 micron range.  it changes the resistance of the cell.  To increase the sensitivity of the PbS cell it was cooled to a temperature of 77 degrees Kelvin by placing it in a flask filled with liquid nitrogen.

Infrared detector technology  1961 : development of the germanium bolometer.  hundreds of times more sensitive than previous detectors and capable of detecting all infrared wavelengths.  measure its conductivity (a measure of how much electrical current flows through an object)  measure its conductivity (a measure of how much electrical current flows through an object)  works best at an extremely low temperature (much lower than liquid nitrogen).  cooled it to 4 degrees Kelvin with liquid helium

Infrared detector technology  continues to advance at a rapid rate  use InSb and HgCdTe detectors for the 1 to 5 micron range.  1980's breakthrough : development of infrared array detectors  In 1983 the IRAS mission used an array of 62 detectors.  now commonly use 256x256 arrays (that’s 65,536 detectors!).

2. Ground based telescopes 2. Ground based telescopes  1. On a high, dry mountain, above much of the water vapor which absorbs infrared.  2. Telescopes as well as our atmosphere emit infrared radiation

2.1 Two Micron Sky Survey  mid-1960's : Mount Wilson Observatory with 24 inch telescope using liquid nitrogen cooled PbS detectors which were most sensitive at 2.2 microns  covered approximately 75 percent of the sky (Dec > -33 deg.)and detected about 20,000 infrared sources  The brightest 5,500 of these sources (brighter than K=3.0) made up the first catalog of infrared stars = IRC.

2.2 Infrared telescopes on top of Mauna Kea 2.2 Infrared telescopes on top of Mauna Kea  the Mauna Kea Observatories (1967) above of water vapor at 4200 m above of water vapor at 4200 m  found that the centers of most galaxies emit strongly in the infrared, Quasars and other active galaxies were also found to be strong infrared emitters.  activate IR Ast.  Telescopes are modified for IR

2.3 DENIS  Southern sky from -88 to +2 with a 1m telescope at ESO, Chile.  observe simulteneously, using dichroic beam- splitters,  Gunn-i(0.82micron), and J(1.25 micron) and the Ks (2.15 micron) or short K-band with NICMOS array detectors  Epchtein et al. (1994, Science with Astronomical Near-Infrared Surveys, Kluwer, Dordrecht.)

2.4 2MASS  Survey the entire sky  J(1.25 micron), H (1.65 micron), and Ks (2.15 micron) or short K bands with 1.3 m dedicated telescopes at Mount Hopkins, Arizona, USA and Cerro Tololo, Chile.  Used NICMOS array detectors 

3. Rockets, Balloons, and Airplanes  1. A series of rocket flights (total 30 min) by the Air Force Cambridge Research Laboratory.  The first infrared all-sky map ; nearly 90% of the sky scanning at wavelengths of 4.2, 11, 20 and 27.4 microns.  2363 reliable infrared sources  2. balloon at 40Km : Goddard Institute of Space Sciences to survey the sky at 100 microns (1966).  120 bright infrared sources near the plane of our galaxy.

3. Rockets, Balloons, and Airplanes -cont  3. Kuiper Airborne Observatory : aircraft  over 20 years, fly at an altitude of 12 km  detect fainter infrared objects which cannot be observed well from the ground (such as interstellar clouds).  discover the rings of Uranus in  4. SOFIA - The Stratospheric Observatory For Infrared Astronomy : NASA’s new airborne observatory  an optical/infrared/sub-millimeter telescope mounted in a Boeing 747, 2009 : 8h/day 3days/week, for 20 years

3. Rockets, Balloons, and Airplanes -cont  3. Kuiper Airborne Observatory : aircraft  over 20 years, fly at an altitude of 41,000 feet  detect fainter infrared objects which cannot be observed well from the ground (such as interstellar clouds).  discover the rings of Uranus in  4. SOFIA - The Stratospheric Observatory For Infrared Astronomy : NASA’s new airborne observatory  an optical/infrared/sub-millimeter telescope mounted in a Boeing 747, 2009 : 8h/day 3days/week, for 20 years

4. Space IR Telescopes Past

4.1 IRAS - The Infrared Astronomical Satellite. 1977: an international collaboration by the Netherlands, United States and Great Britain to develop IRAS 1977: an international collaboration by the Netherlands, United States and Great Britain to develop IRAS  IRAS was successfully launched on January 25,  The telescope was housed in a dewar, filled with 127 gallons of liquid helium and contained 62 detectors.

IRAS  The entire telescope was cooled to a temperature of just a few degrees above absolute  The IRAS mission would last as long as the liquid helium did.  For the ten months, IRAS scanned more than 96 percent of the sky four times, providing the first high sensitivity all sky map at wavelengths of 12, 25, 60 and 100 microns.

IRAS  IRAS detected about 500,000 infrared sources, doubling the number of cataloged astronomical sources.  IRAS discoveries included a disk of dust grains around the star Vega, six new comets, and very strong infrared emission from interacting galaxies as well as wisps of warm dust called infrared cirrus which could be found in almost every direction of space.  IRAS also revealed for the first time the core of our galaxy, the Milky Way

4.2 COBE  In November 1989, NASA launched the COBE satellite to study both infrared and microwave characteristics of the cosmic background radiation (the remains of the extreme heat that was created by the Big Bang).  Over a ten month period, COBE mapped the brightness of the entire sky at several infrared wavelengths and discovered that the cosmic background radiation is not entirely smooth, showing extremely small variations in temperature.  These variations may have led to the formation of galaxies.

4.3 IRTS - The Infrared Telescope in Space 4.3 IRTS - The Infrared Telescope in Space  The Infrared Telescope in Space (IRTS), launched in March 1995, was Japan's first infrared satellite mission.  During its 28 day mission, IRTS surveyed about 7% of the sky with four instruments: A Near and Mid Infrared Spectrometer which covered wavelengths of 1.4 to 4 microns and 4.5 to 11 microns respectively, a Far Infrared Line Mapper which studied Oxygen and Carbon spectral lines at 63 and 158 microns, and a Far infrared Photometer which studied the sky at four bands centered at 150, 250, 400, and 700 microns.

4.4 ISO - Infrared Space Observatory  The European Space Agency launched the Infrared Space Observatory (ISO) in November which observed at wavelengths between 2.5 and 240 microns, not only covered a much wider wavelength range than IRAS but was also thousands of times more sensitive than IRAS and viewed infrared sources with much better resolution.  ISO took data for about 2.5 years (3 times times longer than IRAS).

ISO - Infrared Space Observatory  ISO contained instruments which measured details of both the shorter and longer wavelength regions of the infrared spectrum, an infrared camera which had two infrared arrays, and a photometer.  ISO has detected dry ice in interstellar dust and hydrocarbons in some nebulae.

4.5 MSX - The Midcourse Space Experiment  The Midcourse Space Experiment (MSX) was launched in April 1996 and lasted until its liquid helium coolant ran out in Feb  During its 10 months of operation, MSX gathered a vast amount of data at microns.  MSX had 30 times the spatial resolution as IRAS and surveyed areas of the sky which were missed by IRAS.

5. Active and future IR projects the development of adaptive optics for ground based work. & infrared missions

exciting discoveries by IR  exciting discoveries about  new planets orbiting nearby stars,  how planets, stars and galaxies are formed,  the early universe,  starburst galaxies,  brown dwarfs,  quasars and interstellar matter.

5.1 SWAS - The Submillimeter Wave Astronomy Satellite  SWAS is a NASA Small Explorer Project (SMEX) designed to study the chemical composition of interstellar gas clouds.  a complete radio telescope in space  was launched into low Earth orbit on December 05,  The primary objective is to survey water, molecular oxygen, carbon, and isotopic carbon monoxide emission in a variety of galactic star forming regions.

SWAS  SWAS focused on the following spectral lines:  (1) Water (H 2 O) at GHz  (2) Molecular oxygen (O 2 ) at GHz  (3) Neutral carbon (C I ) at GHz  (4) Isotopic carbon monoxide ( 13 CO) at  (5) Isotopic water (H 2 18 O) at GHz  The spacecraft made detailed 1 degree x 1 degree maps of at least twenty giant molecular and dark cloud cores during the first 2 years of the mission.

SWAS  June 28, 2005: SWAS Mission To Support Deep Impact  "Hibernating" since July 21, 2004, the SWAS mission has been reactivated to full science operations mode to provide support for the Deep Impact Mission.  The SWAS spacecraft has been taking data on Comet 9P/Tempel-1 since June 1, 2005 in order to establish the water production rate of the comet before the July 4 impact.  A plot showing ground-state water emission observed toward the comet during the period June , 2005.

water emission from the comet  monitor water emission from the comet through August 2005.

5.2 NICMOS - Near Infrared Camera and Multi-Object Spectrometer  Attached to the Hubble Space Telescope in February 1997  An infrared array consisting of 3 cameras and 3 spectrometers.  Provide spectra and high resolution images in the near infrared of regions in space.  Wavelengths: microns

5.3 Keck Interferometer  Began operation in 2001  the twin Keck Telescopes to form an interferometer.  use adaptive optics to remove the effects of atmospheric turbulence.  To detect planets around nearby stars in the infrared.  microns

5.4 Spitzer Space Telescope  Launched in August 2003,  Wavelengths: microns  consists of a 0.85 meter telescope, a camera, spectrograph and photometer.  much more sensitive than prior infrared missions and will study the universe at a wide range of infrared wavelengths.  protoplanetary and planetary debris disks, brown dwarfs and super planets, Ultraluminous galaxies and active galactic nuclei, and the early univers, the outer solar system, early stages of star formation and the origin of chemical elements.

5.5 IRIS (Infrared Imaging Surveyor)  Launch in years by the Japanese space agency ISAS.  have a near and mid infrared camera and a far infrared scanner.  study the formation and evolution of galaxies, star formation, interstellar matter and extra-solar systems.  Wavelengths: 2-25 microns and microns

5.6 The Herschel Space Observatory  Launched in > 3 years (14 May 2009 on board an Ariane 5 from ESA's Spaceport in Kourou, French Guiana. The launch took place at 15:12 CEST. Herschel, ESA's infrared space observatory was launched along with Planck )  European Space Agency's fourth "Cornerstone Mission". The 3.5 meter telescope performs photometry and spectroscopy in approximately the micron range.  discover how the first galaxies formed and how they evolved to give rise to present day galaxies like our own, also study clouds of gas and dust where new stars are being born, disks out of which planets may form and cometary atmospheres packed with complex organic molecules.

5.7 Kepler  Launched on 06 March 2009, 3.5 years + 2 years extending  uses high-precision photometry to search for transiting exoplanets around main sequence stars.  detect earth-like planets and its primary mission is to determine the frequency of earth-sized planets around other stars.

5.8 WISE -The Wide-field Infrared Survey Explorer 5.8 WISE -The Wide-field Infrared Survey Explorer  launched on 14 December  all-sky survey from 3 to 25 microns which is up to 500 times more sensitive than the IRAS survey.  find the most luminous galaxies in the Universe, the closest stars to the Sun, detect most main belt asteroids larger than 3 km, and extend the 2MASS survey into the thermal infrared.  Studies from the evolution of protoplanetary debris discs to the history of star formation in normal galaxies.

WISE - Preliminary Data Release  NASA's Wide-field Infrared Survey Explorer mapped the sky at 3.4, 4.6, 12, and 22 μm in 2010 with an angular resolution of 6.1" 6.4" 6.5" & 12.0" in the four bands.  WISE achieved 5σ point source sensitivities better than 0.08, 0.11, 1 and 6 mJy in unconfused regions on the ecliptic in the four bands.

5.9 PLANCK  14 May 2009 on board an Ariane 5 from ESA's Spaceport in Kourou, French Guiana. The launch took place at 15:12 CEST. Planck was launched along with Herschel, ESA's infrared space observatory.  far IR-submillimeter mission.  measure the intensity and polarization of the sky over a range of frequencies from 30 to 857 GHz (wavelengths 1 cm to 350 microns).  anisotropies of the Cosmic Background Radiation over the entire sky with exceptional resolution and sensitivity.

5.10 The James Webb Space Telescope  Launch planned for 2013  an infrared space mission :extremely good sensitivity and resolution, giving us the best views yet of the sky in the near- mid infrared.  study the early universe and the formation of galaxies, stars and planets.  0.5 to 20 microns

5.11 TPF (The Terrestrial Planet Finder)  Launch date - ?  long baseline interferometer space mission  very precise position measurements  detect terrestrial planets (small and rocky planets - like Mercury, Venus, Earth and Mars) outside our solar system and orbiting other stars.  detect several molecules which can indicate how earth-like these planets are.  Wavelengths: 7-20 microns (the best range for searching for Earth-like planets

5.12 Darwin (space infrared interferometer project)  Start : 2015? European Space Agency's infrared interferometer space mission  search for Earth-like planets around nearby stars, and to search for signs of life on these planets by studying infrared spectral lines in their atmospheres.  consist of about 6 individual telescopes combined as an interferometer about 100 yards across and would orbit between Mars and Jupiter, beyond the zodiacal dust which radiates infrared light at the wavelengths which will be used to search for planets.  Wavelengths: Not yet defined - near infrared

Beginning of a Golden Age for IR Astronomy!  NASA & ESA have several missions aimed at infrared astronomy: SOFIA, Spitzer, Herschel, Planck, JWST.  Spitzer Space Telescope is in operation, but the IR spectra are relatively low-resolution.  SOFIA (Stratospheric Observatory for Infrared Astronomy) is an airplane-based observatory, which should allow for updates to instruments periodically.  The Herschel Space Observatory is mainly an ESA endeavor with some NASA involvement; Launched in 2009 along with Plank, Far IR-Submillimeter Mission for anisotropies of the Cosmic Background.  James Webb Space Telescope (JWST) is scheduled for launch in 2013.