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InSight Cruise Phase, Events during Mars transit prior to EDL
Guest_mcmcmc_*
post Nov 13 2018, 03:40 PM
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QUOTE (mcaplinger @ Nov 13 2018, 04:22 PM) *
Not to rain on your parade, but this is extremely unlikely to happen. For past missions the EDL data were released to PDS years after the landing. Even the MSL landing simulation on Eyes wasn't based on realtime data AFAIK.


He said "so hopefully we get real time EDL data just like we did on Phoenix"; assuming that people officially involved in the uploading EDL firmware will receive realtime telemetry by sure, I deduced he was talking abouth something like publishing realtime telemetries. Did it happen for Phenix?
Anyway, telemetries of "just" surface operations like initially happened for Philae would be good too. :-) (I followed in realtime the depletion of the battery... until DLR cut the feed :-( )
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mcaplinger
post Nov 13 2018, 04:03 PM
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QUOTE (mcmcmc @ Nov 13 2018, 07:40 AM) *
...like publishing realtime telemetries. Did it happen for Phenix?

No.


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propguy
post Nov 13 2018, 04:22 PM
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QUOTE (mcmcmc @ Nov 13 2018, 08:40 AM) *
He said "so hopefully we get real time EDL data just like we did on Phoenix"; assuming that people officially involved in the uploading EDL firmware will receive realtime telemetry by sure, I deduced he was talking abouth something like publishing realtime telemetries. Did it happen for Phenix?
Anyway, telemetries of "just" surface operations like initially happened for Philae would be good too. :-) (I followed in realtime the depletion of the battery... until DLR cut the feed :-( )



Sorry to create confusion. By real time telemetry I mean that we on the ops team would see real time UHF telemetered EDL data through the Marco small sats. On Phoenix we got a real time link through Odyssey (it was very cool to see the real time data, I remember thinking, wow I'm seeing data from a spacecraft on a parachute over Mars!). If the Marco links do not work we will still get the open loop recording of the UHF data stream from MRO (the program decided to record the open loop stream, then if there were any issues the full transmitted stream would be available for data extraction). That will downlink later in the day for review by the ops team. Of course with a successful landing we will also get the playback of the data in the first Odyssey pass about 5 1/2 hours after landing, so the MRO data is primarily for anomaly review.

Of course the real time data is not something that will be available outside of the project. When and how they will publish that data is not something I know anything about. Sorry to provide a false hope of seeing this data on NASA TV or other sources. Any animation you see of EDL will be purely open loop with estimated timelines from prior to EDL. Assuming we do get the UHF data in real time there should still be a running status of the EDL progress over NASA TV (as you are used to with Phoneix and MSL). If we do not get the link from Marco we get a few blips on the UHF direct to Earth transmit (too low a signal to see data, just get the open loop signal strength) in EDL that provide progress such as on the parachute and landing. Certainly critical data, but not the same as receiving real time data.

Things looking good less than 2 weeks to EDL!
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Guest_mcmcmc_*
post Nov 14 2018, 05:42 PM
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Not exactly "realtime telemetries", but a good approximation! ;-)
QUOTE
Monday, Nov. 26: Landing Day
11 a.m. to 12:30 p.m. PST (2 p.m. to 3:30 p.m. EST) - Live landing commentary on the NASA TV Public Channel and online. In addition, an uninterrupted, clean feed of cameras from inside JPL mission control, with mission audio only, will be available at the same time on the NASA TV Media Channel, at www.nasa.gov/ntv and at https://www.youtube.com/user/JPLraw/live.

https://www.jpl.nasa.gov/news/news.php?feature=7279


My extended/international version of the schedule:

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Guest_mcmcmc_*
post Nov 16 2018, 01:24 PM
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Any chance that data used to plot charts in this document are available in numerical format somewhere? (XLS, CSV, whatelese...)

https://arc.aiaa.org/doi/pdf/10.2514/1.48239
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Guest_mcmcmc_*
post Nov 16 2018, 02:42 PM
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Well I eventually found something. They're only altitude and speed data, which will be enough for my Insight EDL 2D simulator, but in the future it would be interesting to also find pitch, roll and yaw data to create even a 3d simulator using Sketchfab API or Clara.io APIs (in this dataset I can only find accelerometer data, not gyro data, which are instead used for charts in above document)

https://pds-atmospheres.nmsu.edu/pdsd/archi...xase_0002/DATA/
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mcaplinger
post Nov 16 2018, 04:09 PM
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There are SPICE predict files at https://naif.jpl.nasa.gov/pub/naif/INSIGHT/kernels/ but I don't know how well they model the final descent.

The raw IMU data from Phoenix including angles and rates is at https://atmos.nmsu.edu/pub/PDS4/Version_1.1...ndle_1100/data/ but it's quite difficult to do anything with the raw data.


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Guest_mcmcmc_*
post Nov 17 2018, 09:59 AM
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QUOTE (mcaplinger @ Nov 16 2018, 05:09 PM) *
The raw IMU data from Phoenix including angles and rates is at https://atmos.nmsu.edu/pub/PDS4/Version_1.1...ndle_1100/data/ but it's quite difficult to do anything with the raw data.

Thanks, they're the same data I found. In theory they are clearly explained in .LBL files, but actually I am a little in trouble because PHXPROFILES.TAB (54 MB), which should contain whole EDL data, ends with:
2316.9030 0.0000 3.3774E+06 1.4861E+03 ( ....) 8.1841E+01 3.6288E+00 -4.4009E+01 3.5347E+00 3.1595E+00 5.2946E+00

Which should mean, by its LBL file:
*2316 seconds elapsed since reference time "2008-05-25T23:00:00.000" (defined in DATASET.CAT)
*Radial distance from Mars center of mass: 3377.4 km, sigma 1.486m
*SpeedX = 81 m/s, sigma 4.6 m/s
*SpeedY = -44 m/s, sigma 3.5 m/s
*SpeedZ = 3 m/s, sigma 5.2 m/s
(distance of landing site from Mars center: 3376.3 km)

Ok for altidue and SpeedZ... but 81 m/s horizontal speed at landing???
Last line has a timestamp = 2316.9030, which is 459 seconds after first timestamp (1857,733), and 459 seconds are a duration compatible with EDL duration... but why those nonsens X and Y speeds?

Figure 1-7 in this study says (of course) a different story: 0.1 m/s horizontal speed, but I can't find it in the data.

PHXCOMPACT.TAB has no speed data, only altitude and atmospheric data at 1km interval:
Radial distance (m) MRADIAL_DISTANCE
sigma
Altitude (km) MALTITUDE
sigma
Density (kg m^(-3)) MRHO
sigma
Pressure (Pa) MPRESS
sigma
Temperature (K) MTEMP
sigma
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Guest_mcmcmc_*
post Nov 17 2018, 10:37 AM
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Damn... How do I calculate/find SpeedX, SpeedY and SpeedZ of landing site w.r.t. Mars center in each moment of the EDL sequence???

QUOTE
Position and velocity (X_POSITION, Y_POSITION, Z_POSITION and
associated uncertainties; X_VELOCITY, Y_VELOCITY, Z_VELOCITY and
associated uncertainties) are given in an XYZ cartesian frame
whose origin is at the center of mass of Mars. The +Z axis
passes through the north pole and the +X axis passes through the
equator at zero degrees east areocentric longitude at a specified
time. The +Y axis completes a right-handed set.

https://pds-atmospheres.nmsu.edu/pdsd/archi...LOG/DATASET.CAT
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mcaplinger
post Nov 17 2018, 10:34 PM
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Presumably you are still seeing the rotation rate of Mars in the Phoenix data.

However, I'm not sure what the point of doing anything with the Phoenix data is anyway unless you are going to pretend that the Insight trajectory is exactly the same, which of course it won't be.

One could write a very simple program to extract position from the Insight SPK files using the SPICELIB spkezr function, but I don't know how accurately those files try to model EDL.



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mcaplinger
post Nov 18 2018, 12:24 AM
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Attached is a text file with 1-minute sampling from the SPK file https://naif.jpl.nasa.gov/pub/naif/INSIGHT/...e09o_edl_v1.bsp -- items are J2000 time, distance from Mars center in km, and XYZ position and velocity in km from Mars center and km/sec, both in Mars body-fixed (iau_mars) reference frame.

Most of the SPK files on NAIF don't appear to have the landing portion modeled in them, they fly past Mars (atmosphere unmodeled, maybe.)

Attached File  edl.txt ( 34.22K ) Number of downloads: 114


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Guest_mcmcmc_*
post Nov 18 2018, 07:36 PM
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QUOTE (mcaplinger @ Nov 18 2018, 01:24 AM) *
Most of the SPK files on NAIF don't appear to have the landing portion modeled in them, they fly past Mars (atmosphere unmodeled, maybe.)

Too many variables and randoms factor to predict anything during EDL: each major event (parachute, heatshield, backshield) spans in a range of 20 seconds, i.e. "who knows when it will happen"?
No luck also with Horizons data.

Anyway what I am actually trying to build is a Phoenix simulator... which can be used, with a little of imagination and manually starting/restarting each event when NASA announces it has been confirmed, to "visualize" what is (approximately) happening in Mars sky during those 6 minutes of terror on 26/11. :-)
And it will also be useful to analyze actual data after landing.


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mcaplinger
post Nov 18 2018, 08:06 PM
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QUOTE (mcmcmc @ Nov 18 2018, 11:36 AM) *
Too many variables and randoms factor to predict anything during EDL: each major event (parachute, heatshield, backshield) spans in a range of 20 seconds, i.e. "who knows when it will happen"?

Well, the way this works for the team (and I was pretty involved in this for MPL, PHX, and MSL) is that hundreds of Monte Carlo runs are done and the probability distribution of when major events could happen is calculated. Some parts of the descent are pretty locked down (for example, powered descent duration can't vary by much because you run out of fuel if it goes too long and you crash if it goes too short) whereas some parts are highly variable (time spent on parachute, for example).

BTW, I can't download the attachment from my last message and maybe you can't either (some forum issue?), but I guess you're not interested anyway.


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Guest_mcmcmc_*
post Nov 18 2018, 09:52 PM
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QUOTE (mcaplinger @ Nov 18 2018, 09:06 PM) *
BTW, I can't download the attachment from my last message and maybe you can't either (some forum issue?), but I guess you're not interested anyway.

you said it does not cover EDL part, so I didn't even try downloading it. Thanks for the attempt anyway.

QUOTE
Presumably you are still seeing the rotation rate of Mars in the Phoenix data.

I don't think so, altitude, position and speed are given w.r.t Mars center.

Anyway I just figured out that vertical speed w.r.t. landing site can be calculated as Vz/cos(90-Latitude), being Vz speed along Z axis of Mars w.r.t. Mars center. Vx and Vy are way too complex... but who cares? :-) I don't need them... and anyway I have latitude and longitude of Phoenix every 0.005 seconds, which I could use to determine Vx and Vx w.r.t landing site. (it drew a strange "U" curve above surface .... was it due to the wind?!?)

Acceleration data are given w.r.t spacecraft axes, not Mars axes, and I get a 9.2g value along X axis of spacecraft, w.r.t foreseen 9.2g and recorded 8.5g (?) in this paper.
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mcaplinger
post Nov 18 2018, 10:55 PM
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QUOTE (mcmcmc @ Nov 18 2018, 01:52 PM) *
you said it does not cover EDL part, so I didn't even try downloading it.

I said most of the kernels on the NAIF site don't model the landing. The one I extracted the data from does at least at some level, otherwise I wouldn't have bothered with it.


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