1. ISRO Mars Data Analysis Workshop
CU/LASP  GSFC  UCB/SSL  LM  JPL
ISRO Mars Data Analysis Workshop
Mars Atmosphere and Volatile EvolutioN (MAVEN) Mission
MENCA (MOM)
NGIMS (MAVEN)
MAVEN Science presentation (last updated 1/31/12)
Meredith Elrod
NGIMS/GSFC
Feb 23-26, 2016

2. NGIMS Instrument Overview
Overview of NGIMS function
Normal Operational modes
OSION (fast switching between OS ion & CS neutral modes)
OSNB (fast switching between CS & OS neutral modes)
Orbit segments and operation (Inbound warmup, periapsis, deep dip, Outbound background, Apoapsis CPT/calgas/Phobos)
NGIMS data products available
L1a (raw sci, hk, msg, mkr); l1b (osnb, osion, hk, msg, mkr)
L2(ion, cso, csn)—most commonly used for science integrated into KP product
KP insitu product (integration of Particles & Fields and NGIMS)
L3 (res-den, res-sht)
How to use l1b, l2 and l3 products
Background subtraction techniques and refinements
Determinations of Scale height & Temperature (neutral)
Fractionation Patters & cross sections (neutral)
Cross calibration with STATIC & LPW (ion)
L1b ->L2->L3
Documentation and help on PDS and contacts/help

3. Neutral Gas and Ion Mass Spectrometer (NGIMS) Paul Mahaffy, GSFC
Measurement Objectives:
Basic structure of the upper atmosphere (He, N O, CO, N2, NO, O2, Ar and CO2) and ionosphere from the homopause to above the exobase
Stable isotope ratios, and variations
Technical Details:
Quadrupole Mass Spectrometer with open and closed sources
Closed source measurements: non-reactive neutrals
Open source species: neutrals and ions
Mass range: Da
Mass resolution: 1 Da over entire mass range
Modes: scan entire spectra or adapt to fixed masses
Sensitivity: 10-2 (counts/s)/ (particles/cm-3)
Heritage from Galileo GPMS, Pioneer Venus ONMS, CASSINI INMS, Contour NGIMS
CAD drawing of NGIMS
Flight Quadrupole Housing

4. NGIMS schematic

5. Orbit Timing and Geometry
Modeling assumptions:
Slews are fixed 10 minute duration
Desat is typically 5 minutes, but can be longer if momentum accumulation is large due to atmospheric blooming

6. Standard Operations and products developed
Odd orbit
Fast switching between closed source neutral (CSN) and open source ion (osion) mode.
Allows for quick comparison between neutral and ion species within one orbit
Maintains same conditions for ion and neutral examinations
Limited neutral species can be computed in closed source mode: Ar, CO2, He, N2, CO
Even Orbit
Fast switching between closed source neutral (CSN) and open source neutral beaming (OSNB)
Allows for a complete computation of the neutral composition
Can compute the reactive species, requires comparison with closed source
Ar, CO2, He, N2, O2, O, CO, NO

7. Necessary Files L1a [v01_r02]: raw data, includes all warmup data
L1b [v07_r02**]: ephemeris, cleaned out faulty files associated with Comm passes, Gaps, updated some missing files.
L2_cso [v05_r02]:all products on a 1 second cadence, precision & quality flags: Ar, CO2, N2, He, O2, O, NO, CO
L2_csn [v05_r02]: all products on 1 sec cadence, precision & quality flags. Ar, CO2, N2, He (same orbit as ion)
L2_ion [v05_02]: all products on 1 sec cadence, ion density range from Precision & quality flag.
L3_res-den [v02_r02]: re-sampled densities, averaged over 10 km steps as a rolling average
L3_res-sht [v02_r02]: scale height temperatures. Computed on Inbound between km as slope of density vs alt.
NGIMS_TID_caveats: List of bad or missing TID/Orbits removed due to comm pass, data gaps, bad pointing etc. List by level.
**All files have r03 from 1 Oct 2015 – 14 Nov 2015** Due to SCLK adjustment

8. Level 1 files L1a/l1b
Raw data files (L1a) and flight ground calibration files (L1c)
Headers (sci): TIME, MKID, IP, TUNNING, MASS, COUNTS, DAC_ID, DAC_VOLTAGE
TIME: sclk time only
MKID: marker id
IP: Integration time period
TUNNING: same as focus mode: csn osnb, osnt, osion
MASS: (1-150 is unattenuated signal, is first attenuation, is second attenuation for all modes).
COUNTS: raw counts (NOT counts per second!)
DAC_ID & DAC_VOLTAGE refer to engineering lens marker settings (see SIS for details
OTHER Level 1 files: HSK, MKR, MSG
There are marker, message and housekeeping files available at both the raw and calibrated levels. See SIS for details

9. Level 2 products: Neutrals
Closed Source Neutrals v04_r03
L2_csn-abund
In closed source only produce Ar, CO2, He, N2, CO
Open Source Neutrals
L2_cso-abund (Same headings)
In Open source product: Ar, CO2, He, N2, CO (CS & OS**), O2, O, NO
Reactive products (containing oxygen etc) need open source mode in order to be distinguished from non-reactive (CO2 from CO, O2 from O etc).
Features (both)
t_unix, t_sclk, t_tid, tid, orbit, focusmode, alt, mass, species, cps_dt_bkgd, abundance, precision, quality

10. Level 2: Ions
Open Source Ion v04_r01 alternates with closed source neutral
t_unix, t_sclk, t_tid, tid, orbit, focusmode, alt, mass, cps_dt, abundance, sensitivity, precision, quality
If NAN—indicates cps saturated detector and no correction available. Mass note: m16, 32 and 28 might roll over and has a correction with m182, m166, and m178 for certain orbits (included in L2)
However, with m16 background increasing we will continue to monitor m16 for rollover and use attenuation channel 156 when necessary.
Sensitivity calibrated from LPW electron densities. O+, O2+ compared with STATIC as dominant ions.
No background in ion mode
Precision: error physical units; quality: P(preliminary)/D(definitive)

11. Level 3—resampled (SHT/DEN)
Scale Height Temperature (SHT) v01_r02
t_unix, t_sclk, t_tid, tid, orbit, focus_mode, mid_alt, mass, species, scale_height, temperature
Inbound temperature and scale height fits between km
No scale heights for He, difficult to reasonably fit.
Scale height for all other species
Density (DEN)
Same heading as L2, averaged density over 10km steps
Scale Height Fits
Ar Temp fit

12. Some Results OS/ION
Neutral OSNB orbit 1166 (TID 15832)
Ion OSION orbit 1165 (TID 15830)

13. NGIMS m19 Contamination
In late Dec 2014, NGIMS experienced contamination on m19 channel likely from Fl.