mex-els-all.xml
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<?xml version="1.0" encoding="UTF-8"?>
<Spase xmlns="http://www.spase-group.org/data/schema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.spase-group.org/data/schema http://amda.irap.omp.eu/public/schemas/spase-2_3_1.xsd">
<Version>2.3.1</Version>
<NumericalData>
<ResourceID>spase://CNES/NumericalData/CDPP-AMDA/MEX/ELS/mex-els-all</ResourceID>
<ResourceHeader>
<ResourceName>electron energy spectra : 16 anodes</ResourceName>
<ReleaseDate>2016-10-15T09:46:00</ReleaseDate>
<Description>Level2 data. This dataset is generated directly from the MEX telemetry with IRAP software</Description>
<Acknowledgement>The Mars Express ASPERA team, S.Barabash, Swedish
Institute of Space Physics, PI, and the European Space Agency</Acknowledgement>
<Contact>
<PersonID>spase://SMWG/Person/Stas.Barabash</PersonID>
<Role>PrincipalInvestigator</Role>
</Contact>
<Contact>
<PersonID>spase://CNES/Person/Rudy.Frahm</PersonID>
<Role>GeneralContact</Role>
</Contact>
<Contact>
<PersonID>spase://CNES/Person/Elena.Budnik</PersonID>
<Role>TechnicalContact</Role>
</Contact>
</ResourceHeader>
<AccessInformation>
<RepositoryID>spase://SMWG/Repository/CNES/CDPP-AMDA</RepositoryID>
<Availability>Online</Availability>
<AccessRights>Open</AccessRights>
<AccessURL>
<URL>http://amda.cdpp.eu</URL>
</AccessURL>
<Format>Text</Format>
<Acknowledgement> AMDA is a science analysis system provided by the Centre de Donnees de la
Physique des Plasmas (CDPP) supported by CNRS, CNES, Observatoire de Paris and
Universite Paul Sabatier, Toulouse
</Acknowledgement>
</AccessInformation>
<ProviderName>IRAP</ProviderName>
<InstrumentID>spase://CNES/Instrument/CDPP-AMDA/MEX/ELS</InstrumentID>
<MeasurementType>ThermalPlasma</MeasurementType>
<TemporalDescription>
<TimeSpan>
<StartDate>2003-06-23T18:42:48Z</StartDate>
<StopDate>2018-09-05T09:21:05Z</StopDate>
</TimeSpan>
<CadenceMin>PT1S</CadenceMin>
<CadenceMax>PT64S</CadenceMax>
</TemporalDescription>
<ObservedRegion>Mars</ObservedRegion>
<Caveats><!--
* Concerning ELS NEV Data :Before 2003/190 (09 July 2003), operational engineering tests were being executed on the ELS instrument. Before 2100 hours on that date,
the ELS science data should be all zero (except for day 2003/183,
02 July 2003, between 0100 hours and 0200 hours). For all times other
than the 2003/183 (2003-07-02) time listed above, ELS was undergoing the
Near Earth Verification tests. These tests adjusted the ELS instrument
voltages and the ELS science data was monitored to be sure that the
science data were all zero. If ELS science data had not been zero, it
would have been an indication that there was something wrong with the
instrument. Thus, the zeroes in the ELS science data are normal and
expected during these times.
The exception for day 2003/183 (02 July 2003) between 0100 hours and 0200 hours was when the deflection plates were not stepping and the
instrument voltages were increased such that a science signal could be seen. Since the ELS was not sweeping but held at a fixed value, there
should be science data only at one energy (although the numeric value for
each sector should be different). Science data values should show in all
sectors of ELS, not just in sector zero. Tests were to include sweeping
of the deflection plates at this time, but a small bug in the operations
software prevented sweeping. This was not fixed until after 2100 hours
on day 2003/190 (09 July 2003).
* Concerning ELS January 2004 Data: The Mars Express commissioning period for ASPERA-3 occurred in January 2004. Since operational engineering tests were being executed on the ELS instrument during this time, some of the ELS science data are all zeroes. The zeroes are normal and expected during January 5, 12, and 14, 2004. If the ELS science data had not been zero during these times, it would have been an indication that there was something wrong with the instrument.
* Note on Noise Levels: The ELS sectors which view across the spacecraft and into the spacecraft
body measure electrons escaping the spacecraft either due to outgassing by
the spacecraft, emissions from the spacecraft surfaces, scattered primary
electrons reflected from the spacecraft, or secondary electrons that had
been absorbed and then re-emitted by the spacecraft. From launch until
about mid-2004, spacecraft outgassing is observed as an increase in the
background values to higher than normal levels in those sectors which view
across the spacecraft.
These background levels of each sector are known to vary in time. This
is caused when some ELS sectors view across the spacecraft or at spacecraft
objects. In launch configuration, ELS sectors 15, 14, 13, 12, 1, and 0
view over the spacecraft. In addition ELS sector 1 includes a spacecraft
sun sensor within its field of view, and ELS sector 13 views the spacecraft
solar array attachment arm. The ELS was in its launch configuration until
January 24, 2006 when the scanner platform was activated. After this date,
the angle which the scanner is rotated determines the degree of blockage by
the spacecraft for each sector.
The scanner angle is set at 90 deg for the launch configuration (this is
0 deg in the Unit Reference Frame). When the scanner rotates, it moves
toward the 0 deg position (+90 deg in the Unit Reference Frame). At this
time, ELS sectors 15, 14, 13, and part of sector 12 rotate to view the
spacecraft body. ELS sector 0 and 12 view across the spacecraft. The
scanner then rotates toward its 180 deg position (-90 deg in the Unit
Reference Frame) when active. As the scanner rotation passes the 90 deg
position, ELS sectors 0, 1, 2, and part of sector 3 view the spacecraft
body. ELS sector 15 and 3 view across the spacecraft.
It should also be noted that the relative calibration factors (relative
efficiency coefficients for Anode 13 in CALINFO.TXT) indicate that the
sensitivity of sector 13 is lower than the rest of the sectors by a factor
of about 2 or 3. A rough estimate of the orientation of the particle
entrance geometry to the MCP indicated that the electrons in this sector
penetrate deeper into the MCP chevron than the other sectors. This means
that there are fewer electrons generated by the MCP during the cascade
(electron multiplication) process. Thus, this intensity difference has
been compensated for by the relative calibration factors for this sector.
* Note on Artificial Peaks in Spectra: At about 150 eV, there is an artificial effect which is caused by the
transition between control states of the ELS power supplies. This
artificial effect appears as a peak, drifting in amplitude, shape, and
affected energy range. The artificial peak occurs because the controlling
signal to ELS exceeds its designed specifications and exhibits enough
drift so that the controlling voltage sent to ELS does not accurately
reflect the control voltage reported by the ASPERA-3 Main Unit. This
results in an error in the measurement energy which occurs at the lowest
control voltage (where the drift is a larger part of the control signal).
The flux measured at the expected energy is actually measured at a lower
energy than expected (where the flux is slightly higher). The region
affected by the artificial spike at about 150 eV rarely exceeds 200 eV.
The ELS stepping power supply has two ranges. The stepping voltage
value is controlled by an analog signal sent to ELS by the ASPERA-3 Main
Unit. The power supply range is controlled by a digital bit. ELS converts
the analog control voltage into a voltage across its deflection plates
which relates to the particle energy. Thus, an error in the control
voltage translates into an error in the particle energy.
ELS has a voltage monitor that reports every sample, but it is accessed
by the ASPERA-3 main unit only about every 32 sec. ELS was to use the
monitor value along with the science data value to correct for any drift
within the sweep voltage. Unfortunately due to telemetry restrictions,
a decision was made to not telemeter the step voltage monitor the same
time as the science data, so no correction can be determined between the
voltage monitor drift and the energy shift observed in the science data.
This same effect is likely to be hidden in the low range deflection,
below about 10 eV. Its existence and magnitude can not be accurately
assessed because the ASPERA-3 main unit does not sample the simultaneous
sweep, monitor, and science data for ELS. An artificial spike is noticed
at about 150 eV because any drift in the control voltage is a larger
fraction on the low voltage side of the high range and a smaller fractional
fluctuation on the higher voltage side of the low range. The ELS sweep is
a decay step from its highest voltage value to its lowest voltage. The
spike is seen by the observer because it is highlighted by the transition
between the sweep high range (larger fractional error) to the low range
(smaller fractional error). -->Data gap 2015-05-24 - 2015-07-01</Caveats>
<Parameter>
<Name>counts : per anode ##anode##</Name>
<ParameterKey>mex_els_spec</ParameterKey>
<Description>energy spectrogram of electron counts</Description>
<Ucd>phys.count;phys.electron</Ucd>
<Units>cnts</Units>
<RenderingHints>
<DisplayType>Spectrogram</DisplayType>
</RenderingHints>
<Structure>
<Size>128</Size>
</Structure>
<Particle>
<ParticleType>Electron</ParticleType>
<ParticleQuantity>Counts</ParticleQuantity>
</Particle>
</Parameter>
<Parameter>
<Name>counts : sum over anodes</Name>
<ParameterKey>mex_els_spec_sum</ParameterKey>
<Description>energy spectrogram of electron counts</Description>
<Ucd>phys.count;phys.electron</Ucd>
<Units>cnts</Units>
<RenderingHints>
<DisplayType>Spectrogram</DisplayType>
</RenderingHints>
<Structure>
<Size>128</Size>
</Structure>
<Particle>
<ParticleType>Electron</ParticleType>
<ParticleQuantity>Counts</ParticleQuantity>
</Particle>
</Parameter>
</NumericalData>
</Spase>