Level 0D
Level 0D Science Data Description
Version 3.1.0
Description
This is the final stage of low-level data processing. It cleans up the MinXSS telemetry and adds ancillary data in preparation for processing to a usable science product at Level 1. The variety of MinXSS packet types (housekeeping, log, etc.) are not, in general, generated at the same time as the science packet, nor do we necessarily downlink the packets that were generated nearest in time to each other. However, some of that non-science telemetry is needed for the conversion to Level 1 and higher. We interpolate the non-science packet telemetry to the mid-point of the science integration periods, provided that the time step does not exceed a given threshold (presently 5 minutes for ADCS data and 1 minute for all other types). We also generate ancillary data such as the orbital position and the spacecraft’s relation to the sun based on our best estimate from an interpolated combination of the publically available two line elements. All of these data are merged into a single structure at each time interval, resulting in a single array of identically-defined structures. Level 0D will be released to the public soon, as well as the IDL code we use to process it to Level 1. That will enable users to e.g., change the threshold on time interpolation of telemetry.
Special note about Level 0D:
All spacecraft data is interpolated to the midpoint of the science packet times. This requires that data from those other packets (hk, adcs) be downlinked at sufficient cadence to result in a reliable interpolation between points. Level 0D will not do the interpolation if those points are further away than some threshold from the science packet time. In these cases the bad data flag is used for those telemetry items but the science data remains.
Externally derived data is also interpolated to the midpoint of the science packets, but this should be trivial since it can be generally be generated for arbitrary points in time.
What’s in Level 0D Data
minxsslevel0d is an array of anonymous structures (“anonymous structures” is IDL lingo that is the equivalent of dictionaries in other languages). Each element in the array is a point in time. The definition of the structure is provided in the table below.
Note: Bad data flag for bytes is 255 i.e. byte(-1). For strings it’s empty (‘’). For all other types it’s NAN.
Note: The primary science instrument is called the X123. The secondary science instruments are the SPS and XP. The attitude determination and control system (ADCS) is called XACT.
Level 0D structure definition
| Tag Name | Units | Description |
| flight_model | — | 1: MinXSS-1 in ISS orbit from 2016/05/16 – ??
2: MinXSS-2 in 550 km ? LTDN sun-sync orbit from 2017/??/?? – ?? |
| spacecraft_mode | — | 1: Phoenix (ADCS off, X123 off)
2: Safe (ADCS off) 4: Science (All on) |
| adcs_mode | — | 0: Coarse sun point
1: Fine sun point |
| eclipse | — | 0: when spacecraft in sunlight
1: when spacecraft in eclipse |
| radio_transmitted | bytes | Number of bytes transmitted by the flight radio |
| radio_received | bytes | Number of bytes received by the flight radio |
| eps_5v_cur | mA
(milliamps) |
Current draw on the 5V line, which only powers the X123 |
| eps_5v_volt | V
(volts) |
Voltage level of the 5V line, which only powers the X123 |
| sps_xps_pwr_3v | V
(volts) |
Measured voltage on the 3V line entering the SPS/XP |
| sps_xps_pwr_a5v | V
(volts) |
Measured analog voltage on the 5V line entering the SPS/XP |
| sps_xps_pwr_d5v | V
(volts) |
Measured digital voltage on the 5V line entering the SPS/XP |
| switch_sps | — | 0: SPS/XP is powered off
1: SPS/XP is powered on |
| switch_adcs | — | 0: Attitude Determination and Control System (ADCS) is powered off
1: ADCS is powered on |
| switch_battery_heater | — | 0: Battery heater is powered off
1: Battery heater is powered on |
| measured_attitude_valid | — | 0: ADCS attitude knowledge is invalid
1: ADCS attitude knowledge is valid |
| xact_wheel1_measured_speed | rad/s
(radians per second) |
Speed of the reaction wheels |
| xact_wheel2_measured_speed | ||
| xact_wheel3_measured_speed | ||
| attitude_quaternion1 | — | Defines rotation of spacecraft |
| attitude_quaternion2 | ||
| attitude_quaternion3 | ||
| attitude_quaternion4 | ||
| xact_measured_sun_body_vector_x | unit vector | ADCS measured relative vector to the sun |
| xact_measured_sun_body_vector_y | ||
| xact_measured_sun_body_vector_z | ||
| xact_sun_point_angle_error | º
(degrees) |
ADCS computed relative angle to sun |
| orbit_position_ECI1 | km
(kilometers) |
Earth Centered Inertial position in space |
| orbit_position_ECI2 | ||
| orbit_position_ECI3 | ||
| orbit_position_ECEF1 | km
(kilometers) |
Earth Centered Earth Fixed position in space |
| orbit_position_ECEF2 | ||
| orbit_position_ECEF3 | ||
| longitude | º
(degrees) |
Spacecraft location relative to Earth |
| latitude | ||
| altitude | km
(kilometers) |
Spacecraft height above the Earth’s surface |
| sun_right_ascension | º
(degrees) |
Relative angle to sun as determined from ground computation based on TLE |
| sun_declination | ||
| earth_sun_distance | AU
(astronomical units) |
Earth’s orbit is an ellipse so irradiance changes slightly due to the 1/r2 dispersion of light |
| spacecraft_in_saa | — | 0: Spacecraft is not in the South Atlantic Anomaly
1: Spacecraft is in South Atlantic Anomaly (possibility for more noise in science measurements) |
| sps_xps_temperature | ºC
(Celsius) |
Temperature measured on the power board of the secondary science instrument |
| sps_dark_data_hk | DN/s
(data numbers per second) |
Dark diode reading from the secondary science instrument as logged by the housekeeping system |
| sps_dark_data_sci | DN/integration
(data numbers per integration time) |
The total signal recorded in the dark diode during the science integration time |
| sps_sum_hk | fC/s
(femtocoulombs per second) |
The sum of the four fine sun sensor diodes with gain scaling to get physical units, as logged by the housekeeping system |
| sps_xps_count | counts/s
(counts per second) |
X-ray photometer (secondary science instrument) diode reading |
| sps_x_hk | — | Measured relative position of the sun in dimensionless units to be converted to degrees |
| sps_y_hk | ||
| sps_x_deg | º (degrees) | = (sps_x_hk/10,000)*3.0 |
| sps_y_deg | º (degrees) | = (sps_y_hk/10,000)*3.0 |
| sps_data_sci | DN/integration
(data numbers per integration time) |
The total signal recorded in the 4 fine sun sensor diodes during the science integration time (4 element array) |
| xps_fov_map | % deviation from the center | Percent deviation in response from the center (boresight – optical axis) |
| xps_data_hk | DN/s
(data numbers per second) |
Measurement from the XP as logged by the housekeeping system |
| xps_data_sci | DN / integration
(data numbers per integration period) |
Measurement from the XP over its integration time |
| x123_board_temperature | ºC
(Celsius) |
Temperature of the X123 electronics box |
| x123_detector_temperature | ºC
(Celsius) |
Temperature of the X123 detector |
| x123_accum_time | ms
(milliseconds) |
Integration period for the X123 |
| x123_live_time | ms
(milliseconds) |
Measured time that the slow counter of the X123 was not overrun with photons to count |
| x123_real_time | ms
(milliseconds) |
Another measurement of the time that the slow counter of the X123 was not overrun with photons to count |
| x123_cmp_info | — | Information from the X123 processor |
| x123_flags | — | Flags set by the X123 processor |
| x123_read_errors | — | Read errors detected by X123 processor |
| x123_write_errors | — | Write errors detected by the X123 processor |
| x123_gp_count | counts | X123 General Purpose Counter |
| x123_group_count | — | Count for the X123 Data: 0 = First |
| x123_high_voltage | V
(volts) |
Voltage applied across the X123 silicon drift detector |
| x123_radio_flag | — | 0: Flight radio was not transmitting during X123 integration period
1 or greater: Flight radio was transmitting “” |
| x123_spect_len | B (bytes) |
Length of the spectrum from the X123 |
| x123_fast_count | counts / integration | Total number of counts in the fast counter of the X123 during the integration period |
| x123_slow_count | counts / integration | Total number of counts in the slow counter of the X123 during the integration period |
| x123_spectrum | counts/s/ bin
(counts per second per bin) |
The 1024 bins of X123 data. Per intergration period per 0.03 keV bin |
| xps_fov_map | % deviation from the center | Percent deviation in response from the center (boresight – optical axis) |
| goes_xrs_1_8_A_flux | W/m2 | GOES 0.1 – 0.8 A flux |
| goes_xrs_05_4_A_flux | W/m2 | GOES 0.05 – 0.4 A flux |
| flare_flag | 1 or 0 | Boolean – 1 means flare and 0 means no flare |
Time (structure)
|
— | Time in a variety of formats
|
