NGIMS

NGIMS - CERTIFIED PDS4

Currently available data extend through May 14 2021 (Ls 45.1, MY 36) [ongoing]
(MAVEN Mars orbit insertion occurred Sep 21, 2014; Ls 340, MY 32)

The Neutral Gas and Ion Mass Spectrometer (NGIMS) is a quadrupole mass spectrometer with open and closed sources. The open ion source mode is used to measure reactive neutral gas species and to sample ambient thermal and suprathermal ions while the closed source samples non-reactive neutrals. The mass range is 2 - 150 Da.

Measurement Objectives

NGIMS will measure the neutral composition, isotopic ratios and scale height temperature of the major gas species (He, N, O, CO, N2, NO, O2, Ar, and CO2) in the upper atmosphere. It will:

Determine variation of the neutral composition with altitude, local solar time, longitude and season from the homopause to the exobase where neutral gas can escape.
Derive stable isotope ratios and variations.
Provide a basis for the study of thermospheric energetics, transport, circulation, and formation of the ionosphere.
Reveal the effects of lower atmosphere meteorological effects, such as dust storms, on the composition of the upper atmosphere and exobase.

Useful Mission Documents

Mission Description and Spacecraft Description Document
Mission Timeline (csv) This table is constructed from parameters derived from the MAVEN SPK file and The MAVEN events file. It contains information concerning mission activity that might affect the quality of the data as well as geometry at periapse and apoapse.
Software Interface Specification (SIS) - Description of the instrument and data structures
Calibration Document - See SIS
Calibration Files

Archive Bundle Contents

Documentation - Directory containing the document collection, which includes references to refereed journals using this instrument, and information about calibration and explanation of data structures.

NGIMS bundle

CAVEATS

Product Version Changes

Raw Data (l1a) - Directory containing the raw data files

Calibrated Data - Directory containing calibrated products.

Derived Data

Single species abundance vs. time, and vs altitude, or single species energy distribution vs. time, and vs altitude. Directory containing advanced products
Altitude resampled abundances and energy distributions. Directory containing advanced products. Note: there is no Altitude resampled abundance after Feb 2019 when the perhaps was raised.

Retrieving Data
The MAVEN/NGIMS data are in ACSII format with detached XML labels.

Selected data can be retrieved in 2 ways

1) Downloading an index, selecting components and uploading your selection.
Indices that tabulate information associated with each product are available. The associated geometry is given at the time of the midpoint of the observation. (Note – geometry at periapse is available from the NAIF SPK file.)

a. Select your index

Calibrated Data (csv)
Single species abundance (csv)
Altitude resampled abundances (csv) Note: there is no Altitude resampled abundance after Feb 2019 when the perhaps was raised.
Scale heights and temperatures (csv)
Winds (csv)

Note: The TID number (ie.urn:nasa:pds:maven_ngims:l3:mvn_ngi_l3_res-sht-14016_20141018t133538) can be used to track a specific observation through the data versions.

b. Sort and make your selection
c. Upload the URN values from your revised index (note the total uncompressed file size before requesting)
d. Retrieving housekeeping files
The calibrated data products include housekeeping files cal-hk, cal-mkr and cal-msg (See Systems Interface Specification Document – Table 6. NGIMS Data Products for explanation). To retrieve housekeeping files associated with specific URNs replace osnb or osion with cal-hk, cal-mkr or cal-msg and use the above approach. For larger number of products download the appropriate compressed file.

Example of retrieval of specific housekeeping products.
Science products
urn:nasa:pds:maven_ngims:l1b:mvn_ngi_l1b_osnb-24648_20170815t001953 urn:nasa:pds:maven_ngims:l1b:mvn_ngi_l1b_osion-24648_20170815t001953

Housekeeping
urn:nasa:pds:maven_ngims:l1b:mvn_ngi_l1b_ cal-hk-024648_20170815t001953
urn:nasa:pds:maven_ngims:l1b:mvn_ngi_l1b_ cal-mkr-024648_20170815t001953
urn:nasa:pds:maven_ngims:l1b:mvn_ngi_l1b_ cal-msg-024648_20170815t001953

2) Selecting specific parameters and requesting limited data files

Downloading annual collections of data
2014 calibrated (1 GB)            2014 abundances (76.3 MB)           2014 resampled abundances & Scale Heights (5.1 MB)
2015 calibrated (8.1 GB)         2015 abundances (694 MB)            2015 resampled abundances & Scale Heights (14.7 MB)
2016 calibrated (11.1 GB)       2016 abundances (813 MB)            2016 resampled abundances & Scale Heights (18.6 MB)
2017 calibrated (13 GB)          2017 abundances (806 MB)            2017 resampled abundances & Scale Heights (17.7 MB)
2018 calibrated (11 GB)          2018 abundances (1.6 GB)             2018 resampled abundances & Scale Heights (17.4 MB)
2019 calibrated (11.8 GB)       2019 abundances (2.6 GB)             2019 resampled abundances & Scale Heights (18.6 MB)
2020 calibrated (12.4 GB)       2020 abundances (3.1 GB)             2020 resampled abundances & Scale Heights (12.8 MB)
2021 calibrated (4.0 GB)         2021 abundances (387 MB)            2021 resampled abundances & Scale Heights (7.1 MB)

Raw Data is included in the complete bundle.

Citing Datasets for Publications

M. Benna, E. Lyness (2014), MAVEN Neutral Gas and Ion Mass Spectrometer Data, NASA Planetary Data System, https://doi.org/10.17189/1518931.

Other Useful Products for Interpreting the Data

References - A listing of team members to facilitate literature searches

SPICE - Archived MAVEN SPICE ancillary data providing observational geometry (positions, orientations, instrument pointing, time conversions, etc.) are available from the PDS NAIF Node.