************************************ AE-E **************************
************* BRIEF DESCRIPTIONS OF THE SATELLITE AND EXPERIMENTS **
************************************ AE-E **************************
Spacecraft Common Name- AE-E
NSSDC ID- 75-107A
Launch Date- 11/20/75              Weight-      735. KG
Orbit Parmeters
   Orbit Type- Geocentric          Epoch Date-      1975-11-25
   Orbit Period- 117.29  min       Inclination-       19.7 DEG
   Periapsis-    156. KM_ALT       Apoapsis-      2983. KM_ALT
The  purpose  of  the  AE-E  mission  was  to  investigate  the
chemical  processes and energy transfer mechanisms that control
the  structure  and  behavior  of  the  earth's  atmosphere and
ionosphere  in the region of high absorption of solar energy at
low  and  equatorial  latitudes.  The  simultaneous sampling at
higher  latitudes  was carried out by the AE-D spacecraft until
its  failure  on  January  29, 1976, and then by AE-C, until it
reentered  on December 12, 1978. The same type of spacecraft as
AE-C  was  used, and the payload consisted of the same types of
instruments  except  that the low-energy electron and UV nitric
oxide   experiments   were   deleted   and   a  backscatter  UV
spectrometer  was  added  to  monitor  the ozone content of the
atmosphere.  The  two  experiments  that were deleted were more
appropriate  for  the  high-latitude regions. The perigee swept
through  more  than six full latitude cycles and two local time
cycles  during  the  first year after launch when the orbit was
elliptical  and  the  perigee height was varied between 130 and
400 km. The circularization of the orbit around 390 km was made
on  November  20,  1976  and  the spacecraft was raised to this
height  whenever it would decay to about 250 km. By end of 1977
data were only acquired for one orbit each day.  AE-E reentered
on  June  10, 1981. More details can be found in A. Dalgarno et
al., Radio Sci., v. 8, n. 4, p. 263, 1973.
--------------------------------- AE-E,BRACE -----------------------------------
Investigation Name- Cylindrical Electrostatic Probe (CEP)
NSSDC ID- 75-107A-01
Personnel
   OI - R.F. THEIS                          NASA-GSFC
   OI - A.   DALGARNO                       SAO
   PI - L.H. BRACE                          NASA-GSFC
Brief Description
The  CEP  consisted  of  two  identical instruments designed to
measure electron temperatures, electron and ion concentrations,
ion  mass,  and  spacecraft  potential.  One probe was oriented
along the spin axis of the spacecraft (usually perpendicular to
the  orbit  plane),  and  the  other radially, so that it could
observe  in the direction of the velocity vector once each 15-s
spin   period.   Each   instrument  was  a  retarding-potential
Langmuir-probe  device  that  produced  a current-voltage (I-V)
curve  for  a  known  voltage  pattern placed on the collector.
Electrometers  were used to measure the current. There were two
systems of operation (one with two modes and another with three
modes)  using collector voltage patterns between plus and minus
5  volts.  Most modes involved an automatic or fixed adjustment
of  collector  voltage limits (and/or electrometer output) such
that  the  region  of interest on the I-V profile provided high
resolution.  Each  system was designed for use with only one of
the  probes,  but they could be interswitched to provide backup
redundancy.  The  best measurements in the most favorable modes
provided  1-s time resolution; electron temperature between 300
and  1.E4  deg  K  (10% accuracy); ion density between 1.E4 and
1.E7 ions/cc (10-20% accuracy); electron density between 50 and
1.E6  electrons/cc;  and  ion mass at ion densities above 1.E4.
Each probe had a collector electrode extending from the central
axis  of  a  cylindrical guard ring. The 2.5-cm-long guard ring
was  at  the  end  of  a 25-cm boom, and the collector extended
another  7.5  cm  beyond  the  guard ring. The boom, guard, and
collector  were  0.2  cm in diameter. More detailed information
can  be found in L. H. Brace et al., Radio Sci., v. 8, n. 4, p.
341, 1973.
-------------------------------- AE-E,CHAMPION ---------------------------------
Investigation Name- Atmospheric Density Accelerometer (MESA)
NSSDC ID- 75-107A-02
Personnel
   OI - F.A. MARCOS                         USAF GEOPHYS LAB
   PI - K.S. CHAMPION                       USAF GEOPHYS LAB
Brief Description
The  Miniature  Electrostatic  Analyzer (MESA) obtained data on
the  neutral density of the atmosphere in the altitude range of
120  to  400  km, by the measurements of satellite deceleration
due  to  aerodynamic  drag,  which  is directly proportional to
atmospheric   density.   The   instrument  consisted  of  three
single-axis  accelerometers,  mounted mutually at right angles,
two in the spacecraft X-Y plane and the other along the Z-axis.
The  instrument  determined  the  applied acceleration from the
electrostatic  force  required  to  recenter  a proof mass. The
output  of  the device was a digital pulse rate proportional to
the  applied  acceleration.  The sample time of each instrument
was  0.25  s.  The  measurements  allowed  determination of the
density  of the neutral atmosphere, monitored the thrust of the
Orbit-Adjust Propulsion System (OAPS), determined the satellite
minimum  altitude,  measured spacecraft roll, and provided some
attitude-sensing information. Spacecraft nutations of less than
0.01  deg  were monitored. The instrument had three sensitivity
ranges: 8.E-3 earth's gravity (G) in OAPS monitor mode; 4.E-4 G
between  120  km  (plus  or minus 2%) and 280 km (plus or minus
10%);  and 2.E-5 G between 180 km (plus or minus 2%) and 400 km
(plus  or  minus 10%). Numbers in parentheses represent errors.
There  may  be a systematic error of up to plus or minus 5% due
to   drag  coefficient  uncertainty.  The  highest  measurement
altitude  was determined assuming the instrument could sense to
0.2% of full scale. More details can be found in K. S. Champion
et al., Radio Sci., v. 8, n. 4, p. 297, 1973.
-------------------------------- AE-E,DOERING ----------------------------------
Investigation Name- Photoelectron Spectrometer (PES)
NSSDC ID- 75-107A-03
Personnel
   OI - C.O. BOSTROM                        APPLIED PHYSICS LAB
   PI - J.P. DOERING                        JOHNS HOPKINS U
Brief Description
This  experiment  was  designed  to  provide information on the
intensity,  angular distribution, energy spectrum, and net flow
along  field  lines,  of  electrons  in  the  thermosphere with
energies  between 1 and 500 eV. The instrument consisted of two
identical   oppositely   directed  hemispherical  electrostatic
analyzers,  and contained 30 operating modes. Each spectrometer
had  a  relative  energy resolution of plus or minus 2.5% and a
geometric factor on the order of 0.001 sq cm-sr, independent of
electron   energy.   Three  separate  energy  ranges  could  be
measured: 0 to 25, 0 to 100, and 0 to 500 eV. Measurements from
these  intervals  could  be  sequenced  in five different ways.
Data   could   be  taken  from  either  sensor  separately,  or
alternately  with  time  resolution  varying  from 0.25 to 8 s.
There  were two deflection voltage scan rates determined by the
spacecraft clock. This voltage was changed in 64 steps, and was
done  at  4  or 16 steps per telemetry frame. With 16 frames/s,
this  allowed a choice of either one 64-point spectrum, or four
16-point spectra in one second. The longest (8 s) cycle of data
involved  observations  using  increasing voltage steps for the
lowest,  middle,  lowest,  then  highest energy ranges (in that
order)  for  1  s  each.  A repeat for decreasing voltage steps
completed  the  cycle.  A  more  detailed  description  of this
experiment  is found in J. P. Doering et al., Radio Sci., v. 8,
n. 4, p. 387, 1973.
--------------------------------- AE-E,HANSON ----------------------------------
Investigation Name- Retarding Potential Analyzer/Drift Meter
NSSDC ID- 75-107A-04
Personnel
   OI - S.   SANATANI                       U OF TEXAS, DALLAS
   OI - D.R. ZUCCARO                        U OF TEXAS, DALLAS
   OI - C.R. LIPPENCOTT                     U OF TEXAS, DALLAS
   PI - W.B. HANSON                         U OF TEXAS, DALLAS
Brief Description
This  experiment  was  designed  to  determine vector ion drift
velocities,   ion  concentration  and  temperature,  total  ion
concentration   roughness,   and   spacecraft   potential.  The
experiment  consisted  of  a  retarding potential analyzer with
four  planar  sensor heads. The sensor heads were spaced nearly
equally  around the satellite equator. Since the satellite spin
axis  was  perpendicular  to the orbit plane, these heads could
observe along the spacecraft velocity vector in either the spin
or  despun  mode  of  the spacecraft. Three of the sensor heads
were  similar.  They  had  two  grounded  entrance  grids,  two
retarding  grids,  a  suppressor  grid,  a  shield  grid, and a
collector. A linear sweep voltage (32 or 22 to 0 V, up or down)
was  normally  applied  to  the  retarding  grids  in  0.75  s.
Interpretation   of   the  resulting  current-voltage  profiles
provided   the   ion   temperature,   the   ion   and  electron
concentration,  some  ion  composition information, and vehicle
potential  and  plasma  drift velocity parallel to the velocity
vector. With the retarding grid at constant zero volts, current
changes  could  be observed for 3-s periods to obtain gradients
of  ion  concentration.  Electron parameters were measured in a
manner  similar  to ions. Ions in mass ranges 1 to 4, 14 to 16,
24  to  32  and  greater  than  40  atomic  mass units could be
identified.  The  fourth  sensor  head  was  for  the ion-drift
velocity  measurements, and consisted of four grounded grids, a
negatively   biased   suppressor   grid,   and  a  four-segment
collector.  Differences  in  the  collector  segments' currents
provided  ion-drift  directional  component  information.  More
details  of  this  experiment  are available in W. B. Hanson et
al., Radio Sci., v. 8, n. 4, p. 333, 1973.
--------------------------------- AE-E,HEATH -----------------------------------
Investigation Name- Extreme Solar UV Monitor (ESUM)
NSSDC ID- 75-107A-05
Personnel
   OI - J.F. OSANTOWSKI                     NASA-GSFC
   PI - D.F. HEATH                          NASA-GSFC
Brief Description
The  Extreme  Solar  Ultraviolet Monitor (ESUM) experiment made
absolute  broadband  spectro-radiometric  measurements  of  the
solar  EUV  flux  from  200 A to Lyman-alpha at 1216 A and made
precise   measurements   of   the   temporal  variability.  The
instrument   consisted   of   two   identical   windowless  EUV
photodiodes  with  aluminum  oxide  cathodes and a filter wheel
containing  two  sets  of  unbacked metallic filters (aluminum,
tin,  indium)  and  an  open  position.  A  visible light diode
measured  the pinhole transmittance of the filters to determine
the  white  light  background. The tilt angle of the instrument
relative  to  the  +Z  spacecraft  axis  was  optimized for the
maximum  viewing  time  of  the sun in both spinning and despun
spacecraft  modes. The instrument field of view was 60 deg. The
nominal  bandwidths in Angstroms for 50% of the signal were 270
to  550,  570  to  584, 800 to 935, and 1216 A. More experiment
details can be found in D. F. Heath and J. F. Osantowski, Radio
Sci., v. 8, n. 4, p. 361, 1973.
------------------------------ AE-E,HINTEREGGER --------------------------------
Investigation Name- Solar EUV Spectrophotometer (EUVS)
NSSDC ID- 75-107A-06
Personnel
   OI - C.W. CHAGNON                        USAF GEOPHYS LAB
   OI - D.E. BEDO                           USAF GEOPHYS LAB
   OI - L.A. HALL                           USAF GEOPHYS LAB
   OI - J.E. MANSON                         USAF GEOPHYS LAB
   PI - H.E. HINTEREGGER                    USAF GEOPHYS LAB
Brief Description
The   Extreme  Ultraviolet  Spectrometer  (EUVS)  was  used  to
observe  the variations in the solar EUV flux in the wavelength
range  from  140  to  1850 A and the atmospheric attenuation at
various   fixed   wavelengths.   This   provided   quantitative
atmospheric  structure  and  composition  data.  The instrument
consisted of 24 grazing-incidence grating monochromators, using
parallel-slit    systems    for    entrance   collimation   and
photoelectric  detectors  at  the  exit  slits. Twelve of these
monochromators  had  wavelength  scan capability, each with 128
selectable wavelength positions, which could also automatically
step  scan through these positions. The other 12 monochromators
operated  at fixed wavelengths with fields of view smaller than
the  full  solar  disk  to  aid  in  the atmospheric absorption
analysis.  The  spectral  resolution  varied  from  2  to  54 A
depending  upon  the  particular  instrument. The field of view
varied   from  60  x  60  down  to  3  x  6  arc  min.  All  24
monochromator-entrance  axes  were co-aligned parallel. A solar
pointing system could point to 256 different positions, execute
a  16-step  one-dimensional scan or a full 256-step raster. The
time  resolution  varied  from  0.5  s  for  observing 12 fixed
wavelengths  up  to  256 s for programming the EUVS through all
possible  modes. More details can be found in H. E. Hinteregger
et al., Radio Sci., v. 8, n. 4, p. 349, 1973.
---------------------------------- AE-E,NIER -----------------------------------
Investigation Name- Open-Source Neutral Mass Spectrometer
NSSDC ID- 75-107A-07
Personnel
   OI - W.E. POTTER                         U OF MINNESOTA
   OI - K.   MAUERSBERGER                   U OF MINNESOTA
   PI - A.O. NIER                           U OF MINNESOTA
Brief Description
The  objective  of this experiment was to contribute to a study
of  the chemical, dynamic, and energetic processes that control
the  structure  of the thermosphere by providing direct in situ
measurements  of  both  major  and  minor  neutral  atmospheric
constituents  having  masses  in  the range from 1 to 48 atomic
mass  units  (u).  A  double-focusing, Mattauch-Herzog magnetic
deflection  mass  spectrometer  with  an  impact ion source was
flown.  Two  ion  collectors  were  included  to  measure  ions
differing  in  mass by a factor of 8; i.e., the two mass ranges
covered  were  1  to  6  and  6  to 48 u. In the ion source the
neutral  species  were ionized by means of electron impact. The
electron  energies  were selectable; 75 eV for the high-eV mode
and  25  eV  for the low-eV mode. At altitudes greater than 380
km,  ion  currents  were  measured with an electron multiplier.
Counts   were  accumulated  for  1/20  s  before  automatically
switching  to  a  different  mass  number.  While complete mass
spectra  could  be  swept, in the common mode of operation peak
stepping  was employed; readings on principal peaks in the mass
spectrum  were  repeated approximately every 0.5 s and on other
species  less frequently. Data below 380 km were measured using
an  electrometer.  In addition to the peak stepping mode, there
were  several  other  operating  modes  which  were selected by
ground  command.  In  the  fly-through  mode, ambient particles
striking  the  ion  source  retained energies less than 0.1 eV,
which was not high enough to overcome the negative space charge
potential   holding   the  ions  in  the  beam.  Those  ambient
particles  that  did  not  strike the ion source retained their
incoming energy of several eV after ionization and escaped into
the  acceleration  region  of  the  analyzer.  More  experiment
details can be found in A. O. Nier et al., Radio Sci., v. 8, n.
4, p. 271, 1973.
--------------------------------- AE-E,HEDIN -----------------------------------
Investigation Name- Neutral Atmosphere Composition (NACE)
NSSDC ID- 75-107A-08
Personnel
   OI - G.R. CARIGNAN                       U OF MICHIGAN
   OI - C.A. REBER                          NASA-GSFC
   PI - A.E. HEDIN                          NASA-GSFC
Brief Description
This  experiment  measured in situ the spatial distribution and
temporal   changes   of   the  concentrations  of  the  neutral
atmospheric  species.  In  addition,  new  insight into in situ
measurement  techniques  was obtained from comparisons of these
measurements   with   those   obtained   from   other   onboard
experiments;  namely,  open  source  spectrometer (75-107A-07),
solar  EUV  spectrometer  (75-107A-06), and atmospheric density
accelerometer  (75-107A-02). The mass-spectrometer sensor had a
gold-plated   stainless  steel  thermalizing  chamber  and  ion
source,  a  hyperbolic rod quadrupole analyzer, and an off-axis
electron multiplier. When operating in the "normal" format, the
analyzer  measured  all masses in the range 1 to 44 atomic mass
units  with emphasis on hydrogen, helium, oxygen, nitrogen, and
argon.  Another  format  was  optimized  for  minor constituent
studies   of   gas  species  in  the  measured  range.  Spatial
resolution  was  determined primarily by the mode of spacecraft
operation. In orbit, the presealed spectrometer was opened, and
the  atmospheric  constituents  passed  through  a  knife-edged
orifice   into  the  thermalization  chamber  and  ion  source.
Selected  ions  left  the  quadrupole  analyzer  through a weak
focusing lens and were accelerated into an electron multiplier,
where  they  were turned 90 deg to strike the first dynode. The
spectrometer had a resolution of better than 1 u for all masses
between  1  and  44,  and  the measurement system had a planned
dynamic  range  of  approximately 1.E8. There was provision for
the instrument orifice to be covered during spacecraft thruster
operations.  More experiment details can be found in D. T. Pelz
et al., Radio Sci., v. 8, n. 4, p. 277, 1973.
-------------------------------- AE-E,SPENCER ----------------------------------
Investigation Name- Neutral Atmosphere Temperature (NATE)
NSSDC ID- 75-107A-09
Personnel
   OI - G.R. CARIGNAN                       U OF MICHIGAN
   OI - H.B. NIEMANN                        NASA-GSFC
   PI - N.W. SPENCER                        NASA-GSFC
Brief Description
This   experiment   was   designed   to   measure  the  kinetic
temperature  of  the  neutral  atmosphere  by  determining  the
instantaneous  density  of  molecular  nitrogen  in a spherical
chamber   coupled  to  the  atmosphere  through  a  knife-edged
orifice.  Analysis  of  the measured molecular nitrogen density
variation over a spin cycle with a knowledge of the satellite's
motion  and  orientation  led to a determination of the ambient
temperature,  independent  of scale height. Measurements of the
ambient  neutral  composition were obtained when the instrument
was commanded into the appropriate mode. Approximate values for
the  meridional  wind were obtained from the measurement of the
"stream"  position  relative  to  the  satellite  velocity.  An
alternate   measurement   of   neutral   temperature  was  also
undertaken,  using a baffle inserted in front of the orifice to
intercept  a  portion  of  the gas particle stream entering the
chamber.  When the satellite was in the despun mode, the baffle
was  made  to  oscillate  in  a  stepwise  fashion  in order to
interrupt  the  particle  stream  seen by the orificed chamber.
These  chamber density variations were interpreted to yield the
neutral gas kinetic temperature too. A dual-filament ion source
sampled  the  thermalized molecular nitrogen in the chamber and
produced  an  ion  beam  density  proportional  to the nitrogen
chamber  density.  From  the source, this ionized nitrogen beam
was  directed  into  a quadrupole analyzer, tuned to pass those
particles  with  a  mass-to-charge  ratio  of 28. The beam then
struck  an  electron  multiplier,  and  the  output pulses were
amplified  and  counted.  The sensor was vacuum-sealed prior to
launch and opened to the atmosphere after the spacecraft was in
orbit.  More  experiment  details can be found in N. W. Spencer
et al., Radio Sci., v. 8, n. 4, p. 287, 1973.
-------------------------------- AE-E,BRINTON ----------------------------------
Investigation Name- Bennett Ion-Mass Spectrometer (BIMS)
NSSDC ID- 75-107A-10
Personnel
   OI - H.A. TAYLOR                         NASA-GSFC
   OI - M.W. PHARO                          NASA-GSFC
   PI - H.C. BRINTON                        NASA HEADQUARTERS
Brief Description
This  experiment  was  flown  to measure, throughout the orbit,
the individual concentrations of all thermal ion species in the
mass  range  1  to  72 atomic mass units (u) and in the ambient
density  range  from  5  to  5.E6  ions/cc.  The mass range was
normally scanned in 1.7 s, but the scan time per range could be
increased  by command. Laboratory and inflight determination of
spectrometer   efficiency  and  mass  discrimination  permitted
direct   conversion   of   measured  ion  currents  to  ambient
concentrations.  Correlation  of  these  measured data with the
results  from  companion  experiments, CEP (75-107A-01) and RPA
(75-107A-04)  permitted  individual  ion  concentrations  to be
determined  with  high  accuracy. The experiment's four primary
mechanical  components  were  guard ring and ion-analyzer tube,
collector and preamplifier assembly, vent, and main electronics
housing.  A  three-stage  Bennett tube with 7- to 5-cycle drift
spaces  was  flown; it was modified to permit ion concentration
measurements  to  be  obtained  at  low  altitudes. The balance
between  ion-current  sensitivity  and  mass  resolution  in  a
Bennett  spectrometer  may  be  altered by changing appropriate
voltages.  These  voltage changes were controlled independently
by  ground  command for each one of the three mass ranges: 1 to
4,  2  to 18, and 8 to 72. More complete experiment details can
be  found  in  H. C. Brinton et al., Radio Sci., v. 8, n. 4, p.
369, 1973.
---------------------------------- AE-E,HAYS -----------------------------------
Investigation Name- Visible Airglow Photometer (VAE)
NSSDC ID- 75-107A-11
Personnel
   OI - G.R. CARIGNAN                       U OF MICHIGAN
   OI - G.G. SHEPHERD                       YORK U
   OI - J.C. WALKER                         U OF MICHIGAN
   PI - P.B. HAYS                           U OF MICHIGAN
Brief Description
This   experiment  provided  detailed  data  on  the  rates  of
excitation  of  the  atomic  and  molecular constituents of the
thermosphere. The wavelength range, expressed in Angstroms, was
measured  in  pairs:  7319  and  6563,  5300 and dark, 5577 and
7319,  2800  and  5200,  6300 and 5577, calibrate and 2800, and
6563  and  6300.  A  photometer  was  used  which contained two
separate  optical  channels,  a narrow field of view and a wide
field  of  view.  Spectral  selection  was  accomplished with a
filter wheel that contained six interference filters and a dark
and  calibrate  position. The two channels were separated by 90
deg.  One channel had a 3-deg half-angle cone field of view for
high  sensitivity and pointed normally toward the local zenith.
The  second  had a field of view of 0.75-deg half cone for high
spatial resolution, pointing tangentially to the surface of the
earth  when  the  satellite  was  in  the  oriented  mode. Both
channels  were  protected from stray light contamination during
the  daytime  with  multistage  baffle  systems.  Filters  were
operated  in  several  modes. The two separate optical channels
were  monitored at time intervals consistent with their angular
resolution in the spinning mode. More experiment details can be
found  in  P.  B.  Hays et al., Radio Sci., v. 8, n. 4, p. 369,
1973.
--------------------------------- AE-E,HEATH -----------------------------------
Investigation Name- Backscatter UV Spectrometer (BUV)
NSSDC ID- 75-107A-16
Personnel
   PI - D.F. HEATH                          NASA-GSFC
Brief Description
The  backscatter  ultraviolet  instrument  (BUV)  monitored the
spatial  distribution  of  atmospheric  ozone  by measuring the
intensity  of  the  UV radiation backscattered from the earth's
atmosphere.   To   obtain  this  ozone  distribution,  the  BUV
subsystem  measured direct solar radiation and backscattered UV
radiation  from  the  daytime  sun-illuminated  atmosphere. The
instrument  consisted  of  a spectrometer (monochromator) and a
photometer.  The  monochromator  measured  the  intensity of UV
radiation  backscatter and reflected radiation from the earth's
atmosphere  in  12  wavelengths (2555 to 3398 A) in which ozone
attenuation  occurs.  The  photometer measured the reflected UV
radiation  in  a single wavelength span in which attenuation by
ozone does not occur. The BUV had four operating modes.