This is an artist's impression of AIM above the Earth. Credit: NASA.{{free media}}
The clean room is used to keep particulate matter from short-circuiting AIM satellite sensitive systems. Credit: NASA.{{free media}}

"The scientific purpose of the Aeronomy of Ice in the Mesosphere (AIM, [NSSDC/COSPAR ID: 2007-015A]) mission is focused on the study of Polar Mesospheric Clouds (PMCs) that form about 50 miles [60 km] above the Earth's surface in summer and mostly in the polar regions. The overall goal is to resolve why PMCs form and why they vary."[1]

"AIM will measure PMCs and the thermal, chemical and dynamical environment in which they form. This will allow the connection to be made between these clouds and the meteorology of the polar mesosphere. This connection is important because a significant variability in the yearly number of noctilucent ("glow in the dark") clouds (NLCs), one manifestation of PMCs, has been suggested as an indicator of global change."[1]

"The AIM scientific objectives will be achieved by measuring near simultaneous PMC abundances, PMC spatial distributions, cloud particle size distributions, gravity wave activity, cosmic dust influx to the atmosphere needed to study the role of these particles as nucleation sites and precise, vertical profile measurements of temperature, H2O, OH, CH4, O3, CO2, NO, and aerosols. AIM carries three instruments: an infrared solar occultation differential absorption radiometer, ... (Solar Occultation for Ice Experiment, SOFIE); a panoramic ultraviolet imager (Cloud Imaging and particle Size Experiment, CIPS); and, an in-situ dust detector (Cosmic Dust Experiment, CDE)".[1]

"The solar occultation for ice experiment (SOFIE) is an infrared radiometer experiment that uses a differential absorption technique in solar occultation (sunrise and sunset). SOFIE measures absorption of sunlight in eight spectral regions between 0.25 and 5.3 mm. The specific wavelengths are chosen to provide altitude profiles of temperature, polar mesospheric clouds (PMCs), water vapor, Carbon Dioxide, Methane, Nitric Oxide, Ozone and aerosol absorption."[2]

"The cloud imaging and particle size experiment (CIPS) is a UV panoramic imager that uses intensified CCD cameras to image the Polar Mesospheric Clouds (PMC) latitude versus longitude distribution. It provides nadir imaging with a 120 degrees by 80 degrees field of view (1140 by 960 km) with at least 3 km spatial resolution at 83 km. CIPS observes the backscattered radiance from PMCs (near 82 km altitude) to derive the morphology of PMCs and the cloud particle sizes. Rayleigh scattering from the background near 50 km altitude is used to measure gravity wave activity. Multiple exposures of individual cloud elements provide a measurement of the scattering phase function and detect spatial scales ~2 km. The Ultraviolet bandpass (265 plus or minus 5 nm) maximizes cloud contrast."[3]

"The cosmic dust experiment (CDE) is an in-situ dust detector that measures the influx of dust particles into the upper atmosphere (the PMC region). The CDE is mounted on the zenith side of the spacecraft, with a very wide field of view looking away from the Earth."[4]

## Emissions

The "discovery of the anomalous dust-correlated microwave emission (AME) in the galaxy [was] by Leitch et al (1997) [18] [Characteristics include]

1. the AME constitutes a foreground emission to cosmic microwave background (CMB) radiation. [...]
2. it provides a window into the properties of small grains, which play crucial roles for the physics and chemistry of the ISM.
3. [It is a] diffuse and localized AME"[5]

"In the case of electric dipole radiation, the associated fluctuation in angular momentum is due to absorption of and decays stimulated by microwave photons (dominated by Cosmic Microwave Background (CMB) photons in the diffuse ISM)."[5]

"The [warm ionized medium] WIM is characterized by a large gas temperature T ≈ 8000 K, and a fully ionized gas at low density, nH+ ≈ 0.1 cm-3. Collisions with ions provide the dominant excitation mechanism. Grains are mostly negatively charged due to the high rate of sticking collisions with high-velocity electrons. For a coronene molecule, the characteristic time between ion collisions and the characterstic rotational damping time at the peak angular momentum τrot = √ττed turn out to be comparable6, of order a few years."[5]

The "peak emissivity is enhanced by about 23% for the WIM [and only 11 % for the warm neutral medium (WNM)], although the peak frequency remains unchanged."[5]

"A more important effect on the spectrum is that of increasing the characteristic internal temperature Tω, which makes the grains wobble rather than simply spin about their axis of greatest inertia."[5]

For triaxiality there is an "additional enhancement of the peak frequency and total power by up to the same factors (~ 30 % and 2, respectively) for a large internal relaxation temperature and highly elliptical grains."[5]

## Cosmic rays

Notation: let the symbol GZK represent Greisen-Zatsepin-Kuzmin.

Based on interactions between cosmic rays and the photons of the cosmic microwave background radiation (CMB) ... cosmic rays with energies over the threshold energy of 5x1019 eV interact with cosmic microwave background photons ${\displaystyle \gamma _{\rm {CMB}}}$ to produce pions via the ${\displaystyle \Delta }$ resonance,

${\displaystyle \gamma _{\rm {CMB}}+p\rightarrow \Delta ^{+}\rightarrow p+\pi ^{0},}$

or

${\displaystyle \gamma _{\rm {CMB}}+p\rightarrow \Delta ^{+}\rightarrow n+\pi ^{+}.}$

## Beta particles

"The attenuation of photons in the microwave background via the process

${\displaystyle \gamma +\gamma (3^{o}K)\rightarrow e^{+}e^{-}}$

is strongly energy dependent, with a minimum attenuation length of ≈ 7 kpc around 2.5 PeV, as determined by the threshold for e+e- production (Gould and Schreder, 1966; Jelley, 1966)."[6]

## Electrons

A "PeV energy photon cannot deliver information from a source at the edge of our own galaxy because it will annihilate into an electron [positron] pair in an encounter with a 2.7 Kelvin microwave photon before reaching our telescope."[7]

"In general, energetic photons above a threshold E given by

${\displaystyle 4E\epsilon \sim (2m_{e})^{2},}$

where E and ε are the energy of the high-energy and background photon, respectively. [This] implies that TeV-photons are absorbed on infrared light, PeV photons on the cosmic microwave background and EeV photons on radio-waves".[7]

"Each [optical module] OM contains a 10 inch [photo-multiplier tube] PMT that detects individual photons of Cerenkov light generated in the optically clear ice by muons and electrons moving with velocities near the speed of light."[7]

"Radio Cerenkov experiments detect the Giga-Hertz pulse radiated by shower electrons produced in the interaction of neutrinos in ice."[7]

"Above a threshold of ≃ 1PeV, the large number of low energy(≃ MeV ) photons in a shower will produce an excess of electrons over positrons by removing electrons from atoms by Compton scattering. These are the sources of coherent radiation at radio frequencies, i.e. above ∼ 100MHz."[7]

## X-rays

This ROSAT image is an Aitoff-Hammer equal-area map in galactic coordinates with the Galactic center in the middle of the 0.25 keV diffuse X-ray background. Credit: The Max Planck Institute for Extraterrestrial Physics, Snowden et al. 1995, ApJ, 454, 643; Imagine the Universe! is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.
This 0.75 keV diffuse X-ray background map from the ROSAT all-sky survey in the same projection as the SXRB and neutral hydrogen. The image shows a radically different structure than the 0.25 keV X-ray background. At 0.75 keV, the sky is dominated by the relatively smooth extragalactic background and a limited number of bright extended Galactic objects. Credit: The Max Planck Institute for Extraterrestrial Physics, Snowden et al. 1995, ApJ, 454, 643; Imagine the Universe! is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

In addition to discrete sources which stand out against the sky, there is good evidence for a diffuse X-ray background.[8] During more than a decade of observations of X-ray emission from the Sun, evidence of the existence of an isotropic X-ray background flux was obtained in 1956.[9] This background flux is rather consistently observed over a wide range of energies.[8] The early high-energy end of the spectrum for this diffuse X-ray background was obtained by instruments on board Ranger 3 and Ranger 5.[8] The X-ray flux corresponds to a total energy density of about 5 x 10−4 eV/cm3.[8] The ROSAT soft X-ray diffuse background (SXRB) image shows the general increase in intensity from the Galactic plane to the poles. At the lowest energies, 0.1 - 0.3 keV, nearly all of the observed soft X-ray background (SXRB) is thermal emission from ~106 K plasma.

By comparing the soft X-ray background with the distribution of neutral hydrogen, it is generally agreed that within the Milky Way disk, super soft X-rays are absorbed by this neutral hydrogen.

There is an “extensive 1/4 keV emission in the Galactic halo”, an “observed 1/4 keV [X-ray emission originating] in a Local Hot Bubble (LHB) that surrounds the Sun. ... and an isotropic extragalactic component.”[10] In addition to this “distribution of emission responsible for the soft X-ray diffuse background (SXRB) ... there are the distinct enhancements of supernova remnants, superbubbles, and clusters of galaxies.”[10]

X-rays in the 0.5 to 5 keV (80 to 800 aJ) range, where most celestial sources give off the bulk of their energy, can be stopped by a few sheets of paper; ninety percent of the photons in a beam of 3 keV (480 aJ) X-rays are absorbed by traveling through just 10 cm of air.

## Dark nebulae

"The 111 → 110 rotational transition of formaldehyde (H2CO) [occurs] in absorption in the direction of four dark nebulae. The radiation ... being absorbed appears to be the isotropic microwave background".[11] One of the dark nebulae sampled, per SIMBAD is TGU H1211 P5.

## Galileo Orbiter

This is an image of the Energetic Particles Detector (EPD) aboard the Galileo Orbiter. Credit: NASA.

The Energetic Particles Detector (EPD) aboard the Galileo Orbiter is designed to measure the numbers and energies of electrons whose energies exceed about 20 keV. The EPD [can] also measure the direction of travel of [electrons]. The EPD [uses] silicon solid state detectors and a time-of-flight detector system to measure changes in the energetic [electron] population at Jupiter as a function of position and time.

"[The] two bi-directional, solid-state detector telescopes [are] mounted on a platform which [is] rotated by a stepper motor into one of eight positions. This rotation of the platform, combined with the spinning of the orbiter in a plane perpendicular to the platform rotation, [permits] a 4-pi [or 4π] steradian coverage of incoming [electrons]. The forward (0 degree) ends of the two telescopes [have] an unobstructed view over the [4π] sphere or [can] be positioned behind a shield which not only [prevents] the entrance of incoming radiation, but [contains] a source, thus allowing background corrections and in-flight calibrations to be made. ... The 0 degree end of the [Low-Energy Magnetospheric Measurements System] LEMMS [uses] magnetic deflection to separate incoming electrons and ions. The 180 degree end [uses] absorbers in combination with the detectors to provide measurements of higher-energy electrons ... The LEMMS [provides] measurements of electrons from 15 keV to greater than 11 MeV ... in 32 rate channels."[12]

## Cosmic microwave backgrounds

Fluctuations in the cosmic microwave background are shown in this COBE all-sky image. Credit: NASA.
This is a detailed, all-sky picture of the microwave background created from nine years of WMAP data. Credit: NASA / WMAP Science Team.
This graph shows the power density spectrum of the extragalactic or cosmic gamma-ray background (CGB). Credit: pkisscs@konkoly.hu.

Compare the COBE all-sky CMB at right with the map from WMAP.

"The cosmic microwave background fluctuations are extremely faint, only one part in 100,000 compared to the 2.73 degree Kelvin average temperature of the radiation field."[13]

[B]ackground radiation may simply be any radiation that is pervasive, whether ionizing or not. A particular example of this is the cosmic microwave background radiation, a nearly uniform glow that fills the sky in the microwave part of the spectrum; stars, galaxies and other objects of interest in radio astronomy stand out against this background.

The image at the top shows the "detailed, all-sky picture of the infant universe created from nine years of WMAP data. The image reveals 13.77 billion year old temperature fluctuations (shown as color differences) that correspond to the seeds that grew to become the galaxies. The signal from the our Galaxy was subtracted using the multi-frequency data. This image shows a temperature range of ± 200 microKelvin."[14]

In the figure at right, CUVOB stands for the cosmic ultraviolet and optical background.

The diffuse extragalactic background light (EBL) is all the accumulated radiation in the Universe due to star formation processes, plus a contribution from active galactic nuclei (AGNs). This radiation covers the wavelength range between ~ 0.1-1000 microns (these are the ultraviolet, optical, and infrared regions of the electromagnetic spectrum). The EBL is part of the diffuse extragalactic background radiation (DEBRA), which by definition covers the overall electromagnetic spectrum. After the cosmic microwave background, the EBL produces the second-most energetic diffuse background, thus being essential for understanding the full energy balance of the universe.

"The observations were made using two arrays of radio telescopes – the Cosmic Background Interferometer (CBI) in Chile and the Very Small Array (VSA) in Tenerife. The experiments have produced the sharpest measurements ever of the temperature variations in the cosmic microwave background. These variations trace the fluctuations in the distribution of primordial matter that seeded the formation of large-scale structure in the universe."[15]

## Low noise amplifiers

The QUIET module is a pseudo-correlation receiver comprising low noise amplifiers, phase shifters, detector diodes, and passive components. Credit: Immanuel Buder and the QUIET collaboration.{{fairuse}}
These are schematic views of a QUIET cryostat shown with a 91 element array of W-band modules. Credit: Immanuel Buder and the QUIET collaboration.{{fairuse}}
An illustration of the QUIET telescope on the Cosmic Background Imager mount. Credit: Immanuel Buder and the QUIET collaboration.{{fairuse}}
The site for the QUIET telescopes is the Chajnantor scientific reserve in Chile. Credit: Immanuel Buder and the QUIET collaboration.{{fairuse}}
The QUIET cosmic microwave background (CMB) polarization telescope has its dome lowered at the Llano de Chajnantor Observatory in Atacama, Chile. Credit: Joezuntz.{{free media}}

At right is an image of the QUIET module, a pseudo-correlation receiver comprising low noise amplifiers, phase shifters, detector diodes, and passive components. On the left is the first QUIET module which includes the "low noise amplifiers[, an] InP monolithic microwave integrated circuit (MMIC) high electron mobility transistor (HEMT) amplifiers."[16] The upper right shows "an earlier prototype 90 GHz module. The modules are 1.25 x 1.14."[16] The lower right is "the interior of a (2 x 2) 40 GHz module."[16]

"Both Q and U are measured simultaneously by a single QUIET module with the introduction of an appropriate optical element: a circularly polarized orthomode transducer (OMT)."[16]

At second right are schematic views "of a QUIET cryostat shown with a 91 element array of W-band modules."[16]

"The horns are held at ≈ 20 K and shielded from 300K radiation by a radiation shield (shown only in the figure on the left) held at ≈ 80 K on the top and sides and the aluminum plate (also 80K) on the bottom."[16]

The third right image is of the QUIET telescope. "The 2m design [...] accommodates 400 W-band receivers or 100 Q-band receivers, with each mirror machined as a single piece. [The] three 2m systems, [are] accommodated on the CBI platform as indicated in [the third right image]. The design uses two reflectors of approximately equal size in a crossed arrangement, and is known as a side fed Cassegrain (or crossed Dragone system). The primary mirror is parabolic and the secondary is a concave hyperboloid. By correctly selecting the angle between the two reflectors, a system that has a wide field of view with minimal cross-polarization results."[16]

"The site [in the image on the left] for the QUIET telescopes [in the second left image with its dome down] is the Chajnantor scientific reserve in Chile, at an altitude of 5080 m. This site is recognized as one of the best in the world for millimeter and submillimeter astronomy. The site belongs to the state of Chile and is leased to the international Atacama Large Millimeter Array project (ALMA)."[16]

## Microwave telescopes

The Planck telescope was launched in 2009 to observe the Cosmic Microwave Background Radiation. Credit: ESA.

"The basic scientific goal of the Planck mission is to measure [cosmic microwave background] CMB anisotropies at all angular scales larger than 10 arcminutes over the entire sky with a precision of ~2 parts per million. The model payload consists of a 1.5 meter off-axis telescope with two focal plane arrays of detectors sharing the focal plane. Low frequencies will be covered by 56 tuned radio receivers sensitive to 30-100 GHz, while high frequencies will be covered by 56 bolometers sensitive to 100-850 GHz."[17]

## Wilkinson microwave anisotropy probe

This is a spacecraft diagram of WMAP. Credit: NASA.

"The Wilkinson Microwave Anisotropy Probe (WMAP) is a Medium-class Explorer (MIDEX) mission designed to elucidate cosmology by producing full-sky maps of the cosmic microwave background (CMB) anisotropy."[18]

## Explorer 66

This is a diagram of Explorer 66, the COBE spacecraft. Credit: NASA.

The Cosmic Background Explorer (COBE) has aboard a differential microwave radiometer (DMR) labeled in the diagram at right.

## The E and B experiment

The E and B Experiment (EBEX) will measure the cosmic microwave background radiation of a part of the sky during two sub-orbital (high altitude) balloon flights. It is an experiment to make large, high-fidelity images of the CMB polarization anisotropies. By using a telescope which flies at over 42,000 metres high, it is possible to reduce the atmospheric absorption of microwaves to a minimum. This allows massive cost reduction compared to a satellite probe, though only a small part of the sky can be scanned and for shorter duration than a typical satellite mission such as WMAP.

EBEX was launched on 29 December, 2012, near McMurdo Station in Antarctica.[19][20]

"EBEX is meant to hone in on one specific feature of the CMB light that's been predicted, but never seen — a signature called B-type polarization, thought to have been produced by the gravity waves created by the universe's extremely rapid infant expansion, which happened even before the CMB light was released."[21]

## Cosmic Anisotropy Telescope

This is a stitched panorama of the Cosmic Anisotropy Telescope (CAT) enclosure at the Mullard Radio Astronomy Observatory, Cambridgeshire in June 2014. Credit: Cmglee.

The Cosmic Anisotropy Telescope (CAT), built in the mid 1990s, was the first interferometer to measure fluctuations in the cosmic microwave background (CMB). Its first results, published in 1996, were the highest resolution CMB detection at that time, and showed that the rise in fluctuation power towards scales of ~1 degree (l ~ 200) measured by the Saskatoon experiment were matched by a decline in power at smaller angles (l = 500-700), thus showing the existence of the long-predicted acoustic peak in the CMB power spectrum.

## Recent history

The image portrays a brief history of the detection of the microwave background. Credit: NASA.

The recent history period dates from around 1,000 b2k to present.

"Penzias and Wilson discovered the remnant afterglow from the Big Bang and were awarded the Nobel Prize for their discovery. COBE first discovered the patterns in the afterglow. WMAP will bring the patterns into much better focus to unveil a wealth of information about the history and fate of the universe."[22]

in the figure at the right, specifically the top left (TL) is the "Penzias and Wilson microwave receiver - 1965"[22], (TR) a "Simulation of the sky viewed by Penzias and Wilson's microwave receiver - 1965"[22], (ML) "COBE Spacecraft, Painting - 1992"[22], (MR) "COBE's view of early universe- 1992"[22], (BL) "WMAP Spacecraft, Computer Rendering - 2001"[22], and (BR) "Simulated WMAP view of early universe"[22].

## Hypotheses

1. The use of satellites should provide ten times the information as sounding rockets or balloons.

A control group for a radiation satellite would contain

2. a two-way communication system,
3. a positional locator,
4. an orientation propulsion system, and
5. power supplies and energy sources for all components.

A control group for radiation astronomy satellites may include an ideal or rigorously stable orbit so that the satellite observes the radiation at or to a much higher resolution than an Earth-based ground-level observatory is capable of.

## References

1. Dieter K. Bilitza (August 16, 2013). Aeronomy of Ice in the Mesosphere. Washington, DC USA: National Space Science Data Center, NASA. Retrieved 2014-01-08.
2. Mark Hervig (August 16, 2013). Aeronomy of Ice in the Mesosphere. Washington, DC USA: National Space Science Data Center, NASA. Retrieved 2014-01-08.
3. Cora E. Randall (August 16, 2013). Aeronomy of Ice in the Mesosphere. Washington, DC USA: National Space Science Data Center, NASA. Retrieved 2014-01-08.
4. Mihaly Horanyi (August 16, 2013). Aeronomy of Ice in the Mesosphere. Washington, DC USA: National Space Science Data Center, NASA. Retrieved 2014-01-08.
5. Yacine Ali-Haïmoud (2013). "Spinning dust radiation: a review of the theory". Advances in Astronomy 2013 (462697). doi:10.1155/2013/462697. Retrieved 2014-10-19.
6. Thomas K. Gaisser (1990). Cosmic Rays and Particle Physics. Cambridge University Press. pp. 279. ISBN 0521339316. Retrieved 2014-01-11.
7. Francis Halzen; Dan Hooper (June 12, 2002). "High-energy neutrino astronomy: the cosmic ray connection". Reports on Progress in Physics 65 (7): 1025-107. doi:10.1088/0034-4885/65/7/201. Retrieved 2014-02-08.
8. Morrison P (1967). "Extrasolar X-ray Sources". Ann Rev Astron Astrophys. 5 (1): 325–50. doi:10.1146/annurev.aa.05.090167.001545.
9. Kupperian JE Jr, Friedman H (1958). "Experiment research US progr. for IGY to 1.7.58". IGY Rocket Report Ser. (1): 201.
10. S. L. Snowden; R. Egger; D. P. Finkbiner; M. J. Freyberg; P. P. Plucinsky (February 1, 1998). "Progress on Establishing the Spatial Distribution of Material Responsible for the 1/4 keV Soft X-Ray Diffuse Background Local and Halo Components". The Astrophysical Journal 493 (1): 715-29. doi:10.1086/305135. Retrieved 2012-06-14.
11. Patrick Palmer; B. Zuckerman; David Buhl; Lewis E. Snyder (June 1969). "Formaldehyde Absorption in Dark Nebulae". The Astrophysical Journal 156 (6): L147-50. doi:10.1086/180368.
12. Donald J. Williams (May 14, 2012). Energetic Particles Detector (EPD). Greenbelt, Maryland USA: NASA Goddard Space Flight Center. Retrieved 2012-08-11.
13. DMR Images. Greenbelt, Maryland USA: NASA Goddard Space Flight Center. 10 April 2013. Retrieved 19 October 2014.
14. David T. Chuss. Nine Year Microwave Sky. Greenbelt, Maryland USA: NASA Goddard Space Flight Center. Retrieved 2014-10-18.
15. Joseph Silk (2002). "Tuning in to the early universe". Physics World 15 (8): 27. doi:10.1088/2058-7058/15/8/27/meta. Retrieved 2017-07-27.
16. Immanuel Buder (30 December 2009). "QUIET Instrumentation". Chicago, Illinois: University of Chicago. Retrieved 2014-10-18.
17. David T. Chuss (April 18, 2008). The Planck Mission. Greenbelt, Maryland USA: Goddard Space Flight Center. Retrieved 2013-12-12.
18. G. Hinshaw; M. R. Nolta; C. L. Bennett; R. Bean; O. Doré; M. R. Greason; M. Halpern; R. S. Hill et al. (5 January 2007). "Three-Year Wilkinson Microwave Anisotropy Probe (WMAP1) Observations: Temperature Analysis". The Astrophysical Journal (Supplement Series) 170 (2): 288-334. doi:10.1086/513698. Retrieved 2014-10-19.
19. Blog post from a member of the EBEX science team describing the launch.
20. YouTube video of the EBEX launch.
21. Penzias Wilson; NASA (2003). A Brief History of Background Radiation, Microwave Sky Comparison, 1965 - 2003. Greenbelt, Maryland USA: NASA Goddard Space Flight Center. Retrieved 2014-10-18.