**NSSDCA ID:** PSPA-00522

**Availability:** Archived at NSSDC, accessible from elsewhere

This description was generated automatically using input from the Planetary Data System.

Data Set Overview ================= All level zero accelerometer data are packaged by periapsis number for each aerobraking orbit. Each orbit is identified by a folder with name Pyyy where 'yyy' is the three digit periapsis number. Level 0 y-axis accelerometer data are provided every 1.0 seconds during an interval of time that generally assures that the initial and final data points are taken at least 250 km above the surface of Mars.

For each orbit, Level 0 data consist of four arrays in four files in folder Pyyy. The array in 'ACCEL.TAB' is n-by-2 in size, where n is the number of seconds of data received during the aerobraking pass. Column 1 contains the time in UTC and follows the PDS format YYYY-DDDTHH:MM:SS.SSSZ where YYYY = four digit year, DDD = day of year, HH = hour, MM = minute, and SS.SSS = seconds. T is a separator for date and time and the Z is the UTC Z. Column 2 contains the 1.0 second y-acceleration for the second beginning at the time stamp. The array in 'RATEQUAT.TAB' is n-by-8 in size. Column 1 is the time corresponding to the filtered rates and quaternions in the same UTC format as described for the acceleration above. Columns 2-4 contain the angular rates about the x, y and z axes respectively. Columns 5-8 contain the quaternions. The third file, 'THRUSTER.TAB', is a k-by-9 array. The first column is time as described above. The next 8 columns are the cumulative reading of how long each thruster has been fired during the mission. Column two corresponds to thruster number one, column 3 with thruster 2, and so on. Column 9 corresponds with thruster 8. The fourth file, 'ORBELEM.TAB', is a 1-by-6 array of osculating elements at periapsis in the order semi-major axis (km), eccentricity, inclination (radians), longitude of the ascending node (radians), argument of periapsis (radians), and universal time of periapsis (seconds past J2000).

Acceleration and rates are given in the MRO body system with the y-axis along the centerline of the bus, positive z on the same side of the bus as the high gain antenna and x completing the right hand system, ref. MROGNC2005. The quaternions define the orientation of the body axes with respect to the IAU Mars Centered Mars Equatorial at Time of Jan 1, 2000 12:00. Orbital elements are given relative to the IAU system.

Timing ====== The times in the data sets are UTC. For orbit calculations, ephemeris time ws converted to UTC using the current ET-UTC conversion. No attempt was made during operations to synchronize the data types.

Data Set Overview ================= All PROFILE data are packaged by periapsis number for each aerobraking orbit. PROFILE data are provided at one second resolution in a table labeled Pyyy.tab where 'yyy' is the three digit periapsis number. For each orbit, PROFILE data consist of an n-by-11 array in the file Pyyy, where n is the number of seconds of data received during the aerobraking pass. Column 1 contains the time from periapsis. Columns 2 through 11 contain Latitude, Longitude, Local Solar Time, Solar Zenith Angle, Altitude for 1 Second Density, 1 Second Density, Sigma for 1 Second Density, Altitude for 39 Second Density, 39 sec. Density and Sigma for 39 Second Density. Processing ========== Accelerometer data were processed in the PROFILE stage through several steps and the entire process with examples is given in [TOLSONETAL2007] First, traditional Euler terms were removed body angular rates. During operations,no attempt was made to synchronize data or to remove the effects of thruster firings. Because of the considerable wave structure in the density data, which do not represent the 'mean' thermosphere, a second data set is also archived. A 39 point running mean of the 1 second density is the final data product. Data are included for only those times following the final negative 1 sec. density inbound, and prior to the first negative density value outbound. These negative densities values arise due to the offsets and biases of the system at small accelerations. Coordinate System ================= Latitude and longitude are in the IAU Mars Centered Mars Equatorial System. Altitude is above the IAU reference ellipsoid, with a=3396.19 km and f=0.005886.

Data Set Overview ================= All ALTITUDE data are packaged by periapsis number for each aerobraking orbit. ALTITUDE data are provided in a table labeled Pyyy.tab where 'yyy' is the three digit periapsis number.

For each orbit, ALTITUDE data consist of an 15 by 10 array in the file folder Pyyy. Each row gives atmospheric characteristics at a constant altitude. When applicable, inbound and outbound legs are in separate rows. The altitude levels going from row 1 to row 11 are: periapsis, 1.26 nbar inbound, 1.26 nbar outbound, 100 km inbound, 100 km outbound, 110 km inbound, 110 km outbound, and so on to 150 km inbound, 150 km outbound. The columns from one to ten are separated as follows: altitude, latitude, longitude, local solar time, longitude of the sun, solar zenith angle, density, sigma density, scale height, and sigma scale height. Processing ========== Density and density scale heights are provided at reference altitudes of periapsis, 1.26 nbar, 100, 110, 120, 130, 140 and 150 km. Except for periapsis, these are obtained by a least squares fit to the 39 point running mean data sets that span 5 km on either side of a reference altitude for both the inbound and outbound portions of the orbit. The values at periapsis are obtained by a similar fit to all data within 10km of the periapsis altitude. See [TOLSONETAL2007]. Coordinate System ================= Latitude and longitude are in the IAU Mars Centered Mars Equatorial System. Altitude is above the IAU reference ellipsoid with a=3396.19 km and f=0.005886.

These data are available on-line from the Planetary Data System (PDS) at: http://pds-atmospheres.nmsu.edu/PDS/data/MROA_0001/

- MRO ALTITUDE DATA RECORDS V1.0 (PDS)
- MRO PROFILE DATA RECORDS V1.0 (PDS)
- MRO-M-ACCEL-2-ACCELDATA-V1.0
- MRO-M-ACCEL-5-ALTITUDE-V1.0
- MRO-M-ACCEL-5-PROFILE-V1.0

- Planetary Science: Atmospheres

Questions and comments about this data collection can be directed to: Dr. David R. Williams

Name | Role | Original Affiliation | |
---|---|---|---|

Dr. Gerald M. Keating | Data Provider | NASA Langley Research Center | |

Dr. Robert H. Tolson | General Contact | George Washington University | tolson@gwu.edu |