PDS: The Planetary Atmospheres Node
- Wind Sensor, WS (two detectors, WS1 and WS2, placed on two booms)
- Air Temperature Sensor, ATS (five detectors: three of them placed on the RSM, and two more at the front of the rover body)
- Thermal Infra-Red Sensor, TIRS
- Relative Humidity Sensor, HS
- Radiation and Dust Sensor, RDS (it also includes the SkyCam imager, not covered in this SIS)
- Pressure Sensor, PS (inside the Instrument Control Unit, ICU)
July X, 2021 (Ls X MY X) to [ongoing]
Location of MEDA Sensors onboard the Mars2020 rover Credit NASA/JPL-Caltech
The principal goal of this sensor suite is to provide continuous measurements that characterize the diurnal to seasonal cycles of the local environmental dust properties (opacity, size distribution, and phase function) and their temporal response to meteorology, and the local near-surface environment (pressure, air and surface temperature, relative humidity, wind, and solar radiative forcing in the UV-visible-IR parts of the spectrum).
The MEDA instrument consists of a suite of sensors and a control unit, packaged in eleven enclosures:
The wind sensors are housed in two small Booms structures mounted orthogonal to the Remote Sensing Mast (RSM) of the Rover. Each Boom provides 6 wind sensor transducer boards on the head of the main boom cylinder. Booms include front-end mixed ASICs to condition and acquire the data from the wind sensors and to communicate serially with the Instrument Control Unit (ICU).
The Thermal-Infrared Radiation Sensor (TIRS) is also mounted on the RSM and it is composed of 5 thermopiles pointing upward and downward to measure different ground and atmosphere temperatures in different infrared bands and the solar radiation reflected on the ground (albedo).
The Humidity Sensor (HS) is directly mounted to the RMS as well. It contains up to three capacitive sensor heads sensitive to the ambient relative humidity.
The Radiation and Dust sensor (RDS) is mounted on the rover top deck and comprises of eight upward viewing UV photodetectors (8 photodiodes), 8 lateral viewing UV photodiodes (every photodiode looking 45º apart from the previous to cover the full 360º around the unit), a reference dark-current photodiode and an upward looking camera. The signals coming from these photodiodes and thermopiles will be routed to the ICU to be conditioned and digitized inside the ICU. The ICU will also control the camera through its power and data interfaces.
The instrument control unit, the ICU, is mounted upside-down to the Rover Avionics Mounting Panel (RAMP), inside the rover chassis just under the top deck. It plans and controls the sensors’ data acquisition, communicating with Rover Computer Element (RCE) and temporarily storing science and housekeeping data.
The pressure sensor (PS) is located with the ICU analog module but additionally uses a small tube to reach the Martian environment outside the rover. This tube passes through the ICU base plate, the RAMP, and into a cavity in the rover top deck. The opening is protected from dust and for planetary protection reasons by a cover that attaches to the rover top deck
The instrument will regularly make measurements throughout the Martian day and night, over the lifetime of the Mars 2020 mission. To achieve these measurements, MEDA is designed primarily to operate from an autonomous, low-power “sleep” mode, which can be powered even while the RCE is off. An internal timer wakes MEDA to take observations according to a pre-determined schedule, saves the data internally, and goes back to sleep. Instrument housekeeping tasks can also be performed to a schedule.
Farley, K.A., Williford, K.H., Stack, K.M. et al. Mars 2020 Mission Overview. Space Sci Rev 216, 142 (2020). https://doi.org/10.1007/s11214-020-00762-y
Balaram, J., Aung, M. & Golombek, M.P. The Ingenuity Helicopter on the Perseverance Rover. Space Sci Rev 217, 56 (2021). https://doi.org/10.1007/s11214-021-00815-w
Software Interface Specification SIS for Raw Data (EDRs)
Software Interface Specification SIS for processed, calibrated and derived data (RDR)
Each MEDA Science Data Product consists of an ASCII data file and an XML label and contains science and engineering calibrated data, as processed from the raw data included in MEDA EDRs.
Each MEDA RDR contains one SOL of data. The size of each MEDA RDR data file will depend on the type of data, the measurement strategies and if all data were received, or if only partial data are available. If there are updates to the source raw data or to the calibration processes, the file will be updated and its version number will be incremented. The version number will be indicated in the filename. The latest version of the file should always be used, with previous versions kept only for historical purposes.
Each row within each data product is accompanied by three clock references fields: SCLK (as approximated by MEDA internal clock, without partition and including decimal thousandths of a second), LMST and LTST
Raw Data
MEDA data comes down in Science Data Frames (SDF) which contain a number of Science Data Products (SDP). These are converted inti EDRs which are processed, using NAIF, calibration data and any other ancillary information needed, will generate the RDR processed data products.
Partially Processed Data
These data products contain data from processing at an intermediate step between the raw digital numbers obtained from sensors and the generation of physical environmental magnitudes. The magnitudes provided in these files are mainly voltages, intensities and resistances. Their main purpose is to facilitate engineering evaluation of the sensors’ health and trends.
Pressure
Relative Humidity
TIRS
ATS
Wind
RDS
Calibrated Data
The least processed data products at which science environmental magnitudes are provided include pressure, humidity, wind, temperatures and radiation. When a sensor subsystem has multiple detectors, the data provided are per individual detector. The processing applied to get the data for these data products is based exclusively on pre-landing calibration and post-landing adjustments (based on observed trends). Little or no assumptions of external conditions or models are made.
In addition to science data from the sensor, there is also the calibrated engineering data product. The magnitudes contained within this data product have two purposes: to be used in the generation of calibrated data and to help evaluate the health of MEDA from an engineering point-of-view.
Some data products have some additional “flag” fields noting additional factors that could have an impact on the reliability of the measurements, such as shadows, noise sources or blocking objects. When those fields exist, a general convention is used in which a value of “1” represents a good condition (e. g. the possible source of noise is off), and “0” represents a bad condition
Pressure
Relative Humidity
TIRS
ATS
Wind
RDS
Engineering
Derived Data
Derived data are what most users wanting to work MEDA’s data will want, when available for a particular sensor..
Derived data products are processed from calibrated data products using assumptions or models. For some sensors, this is necessary to provide a unique magnitude when there are several detectors involved (e. g. pressure or wind). For other sensors, such as TIRS, there are further assumptions on external conditions not used in calibrated data products. Not all sensors have derived data products.
In addition to science derived data, there is also a special data product, called ancillary data, that contains geometry information that may have an impact in the sensors’ measurements, such as the position of the sun, RSM head or rover speed. This information is calculated using the NAIF SPICE tool kit. It is provided as part of the MEDA dataset for convenience.
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.
a. Select your index
b. Sort and make your selection
c. Upload the URN values from your revised index (note the total uncompressed file size before requesting)
2) Selecting specific parameters and requesting limited data files
Downloading annual collections of data
The Instrument Package
The MEDA instrument consists of a suite of sensors and a control unit, packaged in eleven enclosures:
The wind sensors are housed in two small Booms structures mounted orthogonal to the Remote Sensing Mast (RSM) of the Rover. Each Boom provides 6 wind sensor transducer boards on the head of the main boom cylinder. Booms include front-end mixed ASICs to condition and acquire the data from the wind sensors and to communicate serially with the Instrument Control Unit (ICU).
The Thermal-Infrared Radiation Sensor (TIRS) is also mounted on the RSM and it is composed of 5 thermopiles pointing upward and downward to measure different ground and atmosphere temperatures in different infrared bands and the solar radiation reflected on the ground (albedo).
The Humidity Sensor (HS) is directly mounted to the RMS as well. It contains up to three capacitive sensor heads sensitive to the ambient relative humidity.
The Radiation and Dust sensor (RDS) is mounted on the rover top deck and comprises of eight upward viewing UV photodetectors (8 photodiodes), 8 lateral viewing UV photodiodes (every photodiode looking 45º apart from the previous to cover the full 360º around the unit), a reference dark-current photodiode and an upward looking camera. The signals coming from these photodiodes and thermopiles will be routed to the ICU to be conditioned and digitized inside the ICU. The ICU will also control the camera through its power and data interfaces.
The instrument control unit, the ICU, is mounted upside-down to the Rover Avionics Mounting Panel (RAMP), inside the rover chassis just under the top deck. It plans and controls the sensors’ data acquisition, communicating with Rover Computer Element (RCE) and temporarily storing science and housekeeping data.
The pressure sensor (PS) is located with the ICU analog module but additionally uses a small tube to reach the Martian environment outside the rover. This tube passes through the ICU base plate, the RAMP, and into a cavity in the rover top deck. The opening is protected from dust and for planetary protection reasons by a cover that attaches to the rover top deck
The instrument will regularly make measurements throughout the Martian day and night, over the lifetime of the Mars 2020 mission. To achieve these measurements, MEDA is designed primarily to operate from an autonomous, low-power “sleep” mode, which can be powered even while the RCE is off. An internal timer wakes MEDA to take observations according to a pre-determined schedule, saves the data internally, and goes back to sleep. Instrument housekeeping tasks can also be performed to a schedule.
Useful Publications
Farley, K.A., Williford, K.H., Stack, K.M. et al. Mars 2020 Mission Overview. Space Sci Rev 216, 142 (2020). https://doi.org/10.1007/s11214-020-00762-y
Balaram, J., Aung, M. & Golombek, M.P. The Ingenuity Helicopter on the Perseverance Rover. Space Sci Rev 217, 56 (2021). https://doi.org/10.1007/s11214-021-00815-w
MEDA Documents
The Mars Environmental Dynamics Analyzer, MEDA. A Suite of Environmental Sensors for the Mars 2020 Mission.
Software Interface Specification SIS for Raw Data (EDRs)
Software Interface Specification SIS for processed, calibrated and derived data (RDR)
Archive Products
Each MEDA Science Data Product consists of an ASCII data file and an XML label and contains science and engineering calibrated data, as processed from the raw data included in MEDA EDRs.
Each MEDA RDR contains one SOL of data. The size of each MEDA RDR data file will depend on the type of data, the measurement strategies and if all data were received, or if only partial data are available. If there are updates to the source raw data or to the calibration processes, the file will be updated and its version number will be incremented. The version number will be indicated in the filename. The latest version of the file should always be used, with previous versions kept only for historical purposes.
Each row within each data product is accompanied by three clock references fields: SCLK (as approximated by MEDA internal clock, without partition and including decimal thousandths of a second), LMST and LTST
Raw Data
MEDA data comes down in Science Data Frames (SDF) which contain a number of Science Data Products (SDP). These are converted inti EDRs which are processed, using NAIF, calibration data and any other ancillary information needed, will generate the RDR processed data products.
Partially Processed Data
These data products contain data from processing at an intermediate step between the raw digital numbers obtained from sensors and the generation of physical environmental magnitudes. The magnitudes provided in these files are mainly voltages, intensities and resistances. Their main purpose is to facilitate engineering evaluation of the sensors’ health and trends.
Pressure
Relative Humidity
TIRS
ATS
Wind
RDS
The least processed data products at which science environmental magnitudes are provided include pressure, humidity, wind, temperatures and radiation. When a sensor subsystem has multiple detectors, the data provided are per individual detector. The processing applied to get the data for these data products is based exclusively on pre-landing calibration and post-landing adjustments (based on observed trends). Little or no assumptions of external conditions or models are made.
In addition to science data from the sensor, there is also the calibrated engineering data product. The magnitudes contained within this data product have two purposes: to be used in the generation of calibrated data and to help evaluate the health of MEDA from an engineering point-of-view.
Some data products have some additional “flag” fields noting additional factors that could have an impact on the reliability of the measurements, such as shadows, noise sources or blocking objects. When those fields exist, a general convention is used in which a value of “1” represents a good condition (e. g. the possible source of noise is off), and “0” represents a bad condition
Pressure
Relative Humidity
TIRS
ATS
Wind
RDS
Engineering
Derived data are what most users wanting to work MEDA’s data will want, when available for a particular sensor..
Derived data products are processed from calibrated data products using assumptions or models. For some sensors, this is necessary to provide a unique magnitude when there are several detectors involved (e. g. pressure or wind). For other sensors, such as TIRS, there are further assumptions on external conditions not used in calibrated data products. Not all sensors have derived data products.
In addition to science derived data, there is also a special data product, called ancillary data, that contains geometry information that may have an impact in the sensors’ measurements, such as the position of the sun, RSM head or rover speed. This information is calculated using the NAIF SPICE tool kit. It is provided as part of the MEDA dataset for convenience.
Pressure
Relative Humidity
TIRS
Wind
Ancillary
Relative Humidity
TIRS
Wind
Ancillary
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.
a. Select your index
b. Sort and make your selection
c. Upload the URN values from your revised index (note the total uncompressed file size before requesting)
2) Selecting specific parameters and requesting limited data files
Downloading annual collections of data
Privacy / Copyright
Freedom of Information Act
Curator: Lyle Huber
NASA Official: Nancy Chanover
Last updated;
