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- The Polar Ionospheric X-ray Imaging Experiment (PIXIE) onboard the POLAR
spacecraft is described. The PIXIE instrument will measure the spatial
distribution and temporal variation of x-ray emissions in the energy range 3 to
60 keV from the earth's atmosphere. From these x-ray measurements, the
morphology and spectra of energetic electron precipitation and its effects upon
the atmosphere can be derived.
The Polar Ionospheric X-ray Imaging Experiment (PIXIE) will provide global
measurements of the spatial distribution and temporal variation of
bremsstrahlung x-ray emissions from the earth's atmosphere. From these x-ray
measurements, the morphology and spectra of energetic electron precipitation
and the effects upon the atmosphere can be derived. The measurements can be
used to estimate the total rate of electron energy deposition and the energy
distribution of the precipitating electrons. The electron energy distribution
can then be used to compute the altitude profile of ionization and electrical
conductivity. All of these quantities will be derived for the entire auroral
zone simultaneously. PIXIE x-ray measurements can be made on the day side of
the earth as well as the night, and the precipitating electron intensities and
energy spectra can be derived from the x-ray images. These are unique
capabilities that cannot be duplicated by optical or UV devices. Images of
atmospheric bremsstrahlung emission will be obtained over the energy range of 3
to 60 keV with good spatial and energy resolution, and with sufficient time
resolution (a few minutes) to generate movies of the dynamical variations of
auroral luminosities and associated atmospheric effects.
The design of an instrument for mapping bremsstrahlung x-rays and the plans for
on-orbit operations and data analysis should be based on actual measurements of
bremsstrahlung x-rays at satellite altitudes. For these purposes, we have
formulated representative spectra and intensities based on the only existing
sets of satellite bremsstrahlung data. (These data were acquired by the
Lockheed and Aerospace groups - Imhof et al., 1974, 1981, 1985; Datlowe et al.,
1988; Mizera et al., 1978, 1984; Gorney, 1987) . Previous instruments viewed a
relatively small region below a low-altitude spacecraft and, therefore, do not
give a global picture, but the data can be taken as representative of certain
classes of auroral events. The two physical parameters that are crucial in
determining global upper atmospheric processes are the total energy input to
the high latitude regions of the atmosphere and the spectrum of the
precipitating electron fluxes which provide a highly variable and significant
portion of that energy. Based on our data taken from low-altitude polar
orbiting satellites, bremsstrahlung x-rays can be used to deduce these
parameters.
For more information, see:
http://pixie.spasci.com/
and
http://pwg.gsfc.nasa.gov/polar/polar_inst.shtml
Group: Instrument_Details
Entry_ID: PIXIE
Group: Instrument_Identification
Instrument_Category: Solar/Space Observing Instruments
Instrument_Class: X-Ray/Gamma Ray Detectors
Short_Name: PIXIE
Long_Name: Polar Ionospheric X-Ray Imaging Experiment
End_Group
Group: Associated_Platforms
Short_Name: POLAR
End_Group
Online_Resource: http://pixie.spasci.com/
Group: Instrument_Logistics
Instrument_Start_Date: 1996-02-24
Instrument_Owner: Lockheed Martin Missiles and Space Company
Instrument_Owner: Aerospace Corporation
End_Group
End_Group
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