InSight Cruise Phase, Events during Mars transit prior to EDL |
InSight Cruise Phase, Events during Mars transit prior to EDL |
May 8 2018, 05:35 AM
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#1
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Merciless Robot Group: Admin Posts: 8785 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Hey again, everyone. This thread will be for discussion of anything that happens between now & landing day, currently 26 Nov US Pacific time (UTC-8 hrs during that part of the year).
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Guest_mcmcmc_* |
Nov 21 2018, 02:46 PM
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#2
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Guests |
Can anybody help? I found this description:
QUOTE The Level 2 data files in the RDR_DATA subdirectory contain the following data: Spacecraft Clock count: Units = seconds Relative time from a defined entry state: Units = seconds The altitude of the spacecraft above the landing site: Units = seconds Planetocentric latitude of the spacecraft at the time of sample acquisition: Units = degrees Planetocentric east longitude of the spacecraft at the time of sample acquisition: Units = degrees Speed of the Phoenix entry probe at the given location: Units = m/s But I can't find this RDR_DATA folder it refers to. Apart from the wrong unit of measure, the highlighted data could be possibly more precise than radial distance from Mars center I'm currently using for the simulator. |
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Nov 21 2018, 05:18 PM
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#3
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
...But I can't find this RDR_DATA folder it refers to... Maybe this document, and the according server and directories could be a better point to start from. See also this LBL file together with this table. |
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Guest_mcmcmc_* |
Nov 22 2018, 07:59 AM
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#4
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Guests |
Maybe this document, and the according server and directories could be a better point to start from. See also this LBL file together with this table. Yes, that table (and PHXPROFILES) is all I was able to find, but I think they do not match with that description. In this file you find the list of all fields: QUOTE PHXPROFILE.TAB contains the following items. Time (relative to reference time, seconds) UTC_TIME Radial distance (m) RADIAL_DISTANCE Areocentric latitude (degrees north) LATITUDE Areocentric longitude (degrees east) LONGITUDE X-component of position (m) X_POSITION Y-component of position (m) Y_POSITION Z-component of position (m) Z_POSITION Element 0 of quaternion (dimensionless) Q0 Element 1 of quaternion (dimensionless) Q1 Element 2 of quaternion (dimensionless) Q2 Element 3 of quaternion (dimensionless) Q3 X-component of velocity (m/s) X_VELOCITY Y-component of velocity (m/s) Y_VELOCITY Z-component of velocity (m/s) Z_VELOCITY Speed of spacecraft relative to atmosphere (m/s) VREL X-component of acceleration (m s^(-2)) X_ACCELERATION Y-component of acceleration (m s^(-2)) Y_ACCELERATION Z-component of acceleration (m s^(-2)) Z_ACCELERATION Angle of attack (degrees) ALPHA Axial force coefficient, CA (dimensionless) CA Normal force coefficient, CN (dimensionless) CN Mach number (dimensionless) MA Knudsen number (dimensionless) KN Density (kg m^(-3)) RHO Pressure (Pa) PRESS Temperature (K) TEMP QUOTE PHXCOMPACT.TAB contains the following items. Radial distance (m) MRADIAL_DISTANCE Altitude (km) MALTITUDE Density (kg m^(-3)) MRHO Pressure (Pa) MPRESS Temperature (K) MTEMP The description in my previous post says: QUOTE Spacecraft Clock count: Units = seconds Relative time from a defined entry state: Units = seconds The altitude of the spacecraft above the landing site: Units = seconds Planetocentric latitude of the spacecraft at the time of sample acquisition: Units = degrees Planetocentric east longitude of the spacecraft at the time of sample acquisition: Units = degrees Speed of the Phoenix entry probe at the given location: Units = m/s So I think they are different datasets. ------------------------- I got weird results while turning "angle of attack" data into something graphical, i.e. an image of the lander rotating as per AoA data, so then I analysed visually last seconds of the data and also plotted them, and they're weird: how can AoA become greater than 90°? (AoA is column 2x19=38 in PHXPROFILES.TAB). It also remaines greater than 90° after landing. Definition: QUOTE The angle of attack, namely the angle between the spacecraft symmetry axis and the vector velocity of the atmosphere relative to the spacecraft, was also determined using the assumption that the atmosphere rotates with the solid body of the planet. Translation: angle w.r.t ground. In the animation I obtained by rotating the image of spacecraft in realtime according to AoA (animation not yet online) it's clearly visible the effect of the engines being turned on (vibration of the lander), so one can assume that AoA>90° is due to backshell avoidance maneuver, but I expected AoA to become again 90° at landing, but it last value is 132°. |
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