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Unmanned Spaceflight.com _ InSight _ InSight Cruise Phase

Posted by: nprev May 8 2018, 05:35 AM

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).

Posted by: Tycho May 10 2018, 08:27 PM

Just to put it in my calendar: Is it possible to already determine at what time exactly the landing will happen? Does anybody know?

Posted by: Phil Stooke May 10 2018, 08:41 PM

hasty reply deleted!

Phil

Posted by: mcaplinger May 10 2018, 09:25 PM

Press kit says Nov. 26, 2018, about noon PST (3 p.m. EST; 20:00 UTC).

Posted by: nprev May 11 2018, 12:01 AM

Just out of curiosity <rimshot>, how much control over the landing date & time does InSight really have? Since it's a direct EDL I can't see the possible variance being more than a few minutes at most else it would miss the target area completely. Also, I'm sure that the amount of attitude control propellant on board is just enough to get that specific job done throughout cruise and entry with perhaps a small contingency reserve for leaks, etc.

Posted by: djellison May 11 2018, 12:25 AM

The TCMs between now and entry are not only designed to reach the appropriate target - but to do so at the exact right time. If you're targetting the landing ellipse at the wrong time, they your entry angle will be bad. If you target the right entry angle, but at the wrong time...you won't be landing in your ellipse...and so on and so on.


Timing is also crucial so that MRO will be in the right place to record UHF telemetry during EDL (MRO can only store and forward that data - no realtime bent-pipe)

Hopefully, if they make it, the MarCOs WALL-E and Eva will conduct bent pipe realtime UHF to XBand!

Posted by: nprev May 11 2018, 03:49 AM

Got it, and thanks for the great details, Doug. So, there is very little flex possible (none, really; it's all about error correction).

X-band...yes, please, and here's rooting for the MarCOs! A bit surprised that MRO doesn't have a bent pipe capability while MODY does, but I assume that's probably because a- MRO's primary mission payloads took up the mass budget and b- nobody seriously thought at the time that we'd have more than one operational surface asset AT a time for long enough to justify it.




Posted by: Explorer1 May 11 2018, 04:13 AM

There is a bit of margin in terms of inclement weather though, right? If I recall, was it Spirit's landing that was modified a bit in the exact timing of certain sequences due to dust storms? Or was that Curiosity?

Posted by: djellison May 11 2018, 05:06 AM

A shift in when to deploy the parachute.....but not a shift to the entry time and entry attitude. The landing time will remain unchanged to within a few seconds.


Posted by: djellison May 11 2018, 05:10 AM

QUOTE (nprev @ May 10 2018, 08:49 PM) *
A bit surprised that MRO doesn't have a bent pipe capability while MODY does,


So - as I understand it - MRO could, kind of, do a semi immediate store and forward approximating a bent pipe. It's not a mass problem. (TGO and MAVEN have basically the same UHF antenna and Electra radio system).

BUT - the choice has been made to record data in an open loop canister mode. Not immediately decoding the 1's and 0's - but recording all the Electra can hear. This entire data set will then be dumped back to Earth enabling a deeper analytical dive into the data if something goes wrong, and to throw computationally intensive analysis at it that MRO couldn't do in real time.

Back when MSL landed - MRO was doing the same thing, but Odyssey was also overhead doing the bent pipe. If you could only have one - you would take the recorded data because while it lacks immediacy of bent pipe....it makes up for it in potential to have more useful information after the fact.

The relevant facts start on page 28 - https://descanso.jpl.nasa.gov/DPSummary/MRO_092106.pdf

The MRO - MSL Mode is discussed on page 108 - https://descanso.jpl.nasa.gov/DPSummary/Descanso14_MSL_Telecom.pdf

"MRO cannot provide delay-free (bent-pipe) relay, as it first records the return-link relay data as it
is received from the descending spacecraft during the overflight and then sends the data to the
DSN. Both telemetry relay (specifically, unreliable bit-stream reception at MRO for EDL and the
Proximity 1 protocol [6F26] for normal relay) and open-loop recording (known as canister mode in
CE505 radio terminology) are being considered for the relay reception onboard MRO. The
current baseline is open-loop recording on MRO during EDL. However, open-loop recording
was successful during Phoenix EDL. MSL will choose either Prox-1 unreliable or open loop for
EDL in 2012 based on the predicted link signal level and variability.
"


This... https://ipnpr.jpl.nasa.gov/progress_report/42-197/197A.pdf appears to discuss it after the fact on page 6
"The UHF signal emitted by MSL was received by MROís Electra radio. The in-phase and
quadrature components of the signal were recorded on board MRO in open-loop fashion.
These signal data were relayed to a NASA DSN antenna on Earth over MROís DTE X-band
telemetry link. The spectra extracted from the open-loop data as a function of time were
examined and processed at different bandwidths to extract carrier-to-noise ratio (CNR) and
frequency estimates"

Posted by: nprev May 11 2018, 07:14 PM

Rocketcam video of launch and spacecraft separation:

https://spaceflightnow.com/2018/05/11/video-rocketcam-replay-of-insights-launch-to-mars/

Posted by: Explorer1 May 11 2018, 08:02 PM

QUOTE (nprev @ May 11 2018, 02:14 PM) *
Rocketcam video of launch and spacecraft separation:

https://spaceflightnow.com/2018/05/11/video-rocketcam-replay-of-insights-launch-to-mars/

Farewell InSight! Safe travels!

And not to be seen again by human eyes until the first good HiRise pass in November...

Posted by: Decepticon May 14 2018, 04:17 AM

QUOTE (nprev @ May 11 2018, 02:14 PM) *
Rocketcam video of launch and spacecraft separation:

https://spaceflightnow.com/2018/05/11/video-rocketcam-replay-of-insights-launch-to-mars/



Was this shown Live?

I don't remember seeing this!?

Posted by: Explorer1 May 14 2018, 02:09 PM

No, it was released a few days later.

Posted by: Explorer1 May 16 2018, 05:01 AM

First light from the cubesats: https://www.jpl.nasa.gov/news/news.php?release=2018-099&rn=news.xml&rst=7124

If all goes well in November, we might very well get a pale red dot too... getting larger and larger...

Posted by: propguy May 24 2018, 07:00 PM

TCM1 was completed 5/22 (yeah!). biggrin.gif Press release at: https://www.jpl.nasa.gov/news/news.php?feature=7138

Can't provide much more data than in the news release but the S/C performance was great and we hit the desired DV well within 1 sigma. Very healthy spacecraft and now we are on a path to Mars! Lots to do in the coming months, but so far a really smooth cruise!

Posted by: nprev May 25 2018, 12:42 AM

Music to our ears, Propguy; thank you!!! smile.gif

Posted by: MahFL May 25 2018, 12:53 AM

QUOTE (propguy @ May 24 2018, 08:00 PM) *
TCM1 was completed 5/22 (yeah!). biggrin.gif Press release at: https://www.jpl.nasa.gov/news/news.php?feature=7138

Can't provide much more data than in the news release but the S/C performance was great and we hit the desired DV well within 1 sigma. Very healthy spacecraft and now we are on a path to Mars! Lots to do in the coming months, but so far a really smooth cruise!



Good to hear.

Posted by: Explorer1 Jun 2 2018, 12:23 AM

The cubesats have done their TCMs as well ( https://www.jpl.nasa.gov/news/news.php?release=2018-123 )

Looks like B has a leaky valve, but it should be able to make it as well (showing how useful twin spacecraft are!)

Posted by: PaulH51 Aug 21 2018, 01:13 AM

InSight's Inner Sanctum Revealed (PIA22647): This long-exposure image (24 seconds) was taken by Instrument Context Camera (ICC) of NASA's InSight Mars lander. The image shows some of the interior features of the backshell that encapsulates the spacecraft. The backshell carries the parachute and several components used during later stages of entry, descent, and landing. Along with the heatshield, the backshell protects NASA's InSight Mars lander during its commute to and entry into the Martian atmosphere. The annotations in this image call out discernable components in the backshell -- the heatshield blanket, harness tie-downs, and cover bolts for the ICC. The heat shield blanket provides thermal protection from the hot and cold temperature swings encountered during cruise, and the high heat that will occur during Mars atmospheric entry. The tie-downs are used to secure harnesses (or other objects) so they do not move around inside the aeroshell while in flight. The ICC cover bolts secure a protective transparent window to the camera during cruise and entry, descent and landing. The cover is opened after landing and is not visible during surface operations. This image has been stretched to bring out details in the dimly lit scene. The illumination of the components on the inside of the backshell comes from sunlight entering around the edges of cutouts in the backshell to accommodate steering thrusters. https://photojournal.jpl.nasa.gov/catalog/PIA22647


EDIT: Not sure why I cant see the images in this post, they looked fine in the preview, but are not shown. I'm seeing them as downloads, but I cant download them. I removed and re uploaded them but the issue remains. You can get both images from the link to the Photojournal post.

Posted by: Phil Stooke Oct 24 2018, 02:00 AM

Do we know anything yet about the image release policy for Insight? I would hope we will see all images released quickly, as we have come to expect from NASA Mars missions. Hopeful cartographers need to know!

Phil

Posted by: MahFL Oct 26 2018, 12:09 AM

Any news on Insight being updated on Eyes, so we can watch the approach and landing ?

Posted by: Hungry4info Oct 26 2018, 01:10 AM

QUOTE (Phil Stooke @ Oct 23 2018, 08:00 PM) *
Hopeful cartographers need to know!


I'm certainly looking forward to your routemaps laugh.gif

Posted by: djellison Oct 28 2018, 03:02 PM

QUOTE (MahFL @ Oct 25 2018, 04:09 PM) *
Any news on Insight being updated on Eyes, so we can watch the approach and landing ?


Not going to happen Iím afraid - there just arenít the resources to pull it off.

Posted by: mcmcmc Oct 29 2018, 02:49 PM

QUOTE (MahFL @ Oct 26 2018, 01:09 AM) *
Any news on Insight being updated on Eyes, so we can watch the approach and landing ?

I don't know where he gets the data, anyway here they are:
http://www.whereisroadster.com/insight/

I'll see if I can turn them into something more graphical like I did for https://programmi.000webhostapp.com/hayabusa2/simulator/simulator3.html and https://programmi.000webhostapp.com/osiris/osiris-counter.html.

Posted by: Explorer1 Oct 31 2018, 06:07 PM

InSight press conference on now, everything with the spacecraft remains nominal. Newest thing is confirming MRO will try to image the landing (and I can update my avatar at last)!

Posted by: mcmcmc Nov 7 2018, 07:07 PM

Insight will have same EDL profile of Phoenix, so while we wait for november 26th we can imagine how it will be: this video mixes real mission control audio+video with video simulation to show what happened 10 years ago and what will happen 3 weeks from now:
https://www.youtube.com/watch?v=hH5pNFROlYU


Note: for some reasons, the "freefall phase" after parachute jettisoning is not called like that for Insight, but instead called "gravity turn"; then engines are started ("Powered descent phase"), and after 3 seconds of freefall+deceleration Insight will enter the "Constant velocity phase"; once Insight slows down to 30 km/h (around 50m from ground) it turns on ground contact sensors on legs; at 8 km/h engines are turned off, to prevent too much regolite from being blown around, and a final free-fall (few centimeters) starts, and we are on Mars.

This document analyses actual Phoenix EDL recorded data:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080034645.pdf

Reconstructed Insight timeline (from multiple inconsistent sources):



Text version:

CODE
n    t    alt m    v m/s    v mph    v kmh    Event
1    -420                    cruise stage detachment
2    -390                    Entry turn starts
3    -300                    Entry turns end
4    0     128000      75301      13000      17017     atmosphere entry
5    100                    7.4g
6    223     12000     415    928    1494    Parachute
7    238     10300     132    295    475.2    heat shield jettisoned
8    248.0                    leg1
9    248.5                    leg2
10    249.0                    leg3
11    249.5                    legs ready
12    300     5500                 Radar on
13    333     2300                 Radar acquires ground
14    351     1100     61    136    220    Parachute/Lander separation
15    354     900                 Gravity turn start (free fall)
16    378     51     8    17    28    Constant velocity start (powered descent)
17    393.75        2.2    5    8    Engine off
18    394    0    0    0    0    Touchdown


Status monitor:
http://win98.altervista.org/space/exploration/



Phoenix EDL analysis:



Sources:
https://www.seis-insight.eu/en/public-2/the-insight-mission/landing
https://mars.nasa.gov/insight/timeline/landing/entry-descent-landing/
https://www.jpl.nasa.gov/news/press_kits/insight/assets/images/mission/Layer-2.jpg

Posted by: propguy Nov 9 2018, 09:11 PM

QUOTE (mcmcmc @ Nov 7 2018, 01:07 PM) *
Note: for some reasons, the "freefall phase" after parachute jettisoning is not called like that for Insight, but instead called "gravity turn"; then engines are started ("Powered descent phase"), and after 3 seconds of freefall+deceleration Insight will enter the "Constant velocity phase"; once Insight slows down to 30 km/h (around 50m from ground) it turns on ground contact sensors on legs; at 8 km/h engines are turned off, to prevent too much regolite from being blown around, and a final free-fall (few centimeters) starts, and we are on Mars.


Actually gravity turn is not a freefall. There is a very short freefall once we separate from the backshell and parachute (~0.5 second) and then we begin the tip-up portion of powered descent. That lasts ~2.5 seconds (the tip-up is the align the lander with the velocity vector, which should still have some appreciable horizontal velocity, whereas when we drop out of the backshell we will mostly be dropping down). Then we begin gravity turn which is the main portion of powered descent where we are eliminating the horizontal velocity and reducing vertical velocity down to 2.5 m/sec or so. After we hit that vertical velocity limit we enter the final phase of powered descent called constant velocity. Constant velocity is where we descend at the 2.5 m/sec rate until one of the three legs achieves contact with the surface and the descent engines are then turned off. This is one of the keys to powered descent. The main goal is to achieve constant velocity not too close to the surface (or you risk hitting at too high a speed) or too high (or you end up using too much fuel since you have a very long time at this slow descent rate). As shown in the above Phoenix diagram we spend a third of powered descent in constant velocity while only descending the last 50 meters or so (luckily also at a lower thrust since at this point we only have to thrust at a value equal to the Mars gravity of the lander, so fuel usage is lower). So to summarize, the freefall begins at separation from the backshell and parachute, followed by tip-up, then gravity turn, and then constant velocity, and then landing (Whoohoo!).

Here is a little InSight summary too (without providing any true details, which I am not allowed to provide, that must come from official sources). We are as you know nearing Mars. S/C is performing beautifully. We have 3 potential maneuvers left (TCM4, 5, and 6) set on the next 3 Sundays (11/11, 18, and 25). These are only required to fine tune the entry location and time (i.e. TCM3 pointed us at the correct location, these are used to adjust for errors in final arrival location). This is the same plan that Phoenix had and they only performed the middle one (TCM5). If I were to guess I think that may be or path to entry too, but that is simply a guess. Also today I am reviewing the final EDL sequence for upload (one of the many reviewers who have to approve) and that should go up in the next week (same sequence we have had for a while, we just rerun one final time with the latest vehicle state and entry parameters for timing). Starting to get very real and will be quite busy in 2 weeks as we get ready for entry.

P.S. My company has put out a website about InSight EDL and it has lots of facts plus a podcast I am in with one of our system engineers. You can even see what I look like (I am the guy in the dark shirt on the right in the photo). I hope you find the website interesting.

Go InSight and Go Marco! (so hopefully we get real time EDL data just like we did on Phoenix).

https://www.lockheedmartin.com/en-us/news/features/2018/returning-to-mars.html


Posted by: mcmcmc Nov 13 2018, 01:16 PM

QUOTE (propguy @ Nov 9 2018, 10:11 PM) *
so hopefully we get real time EDL data just like we did on Phoenix

Thanks, very interesting. NASA site has a lot of pictures but very few science/engineering data!

I really would like to setup a simulator for Insight http://programmi.000webhostapp.com/osiris/osiris-counter.html, but specifically for Insight EDL, with multiple countdowns for each phase. I was thinking about synching it with youtube animation of EDL. Synching it also to realtime telemetries would be great! I don't know if it is feasible in just 12 days, but I want to try.

Planned development phases:
1) Setup multicounter page - quick & easy once I have the timeline... which I posted above.
2) Synch to youtube - I need to study youtube API and find the most suitable video/animation of Insight; looks quite feasible in time.
3) Synch to realtime telemetries - Possible only if:
a) fast network available
B) official json data available
c) anonymous CORS access to data allowed
d) only main events shown (at least 10 seconds one from the other)

Do you think you could setup in such a short time a json URL with realtime telemetries?

Posted by: mcaplinger Nov 13 2018, 03:22 PM

QUOTE (mcmcmc @ Nov 13 2018, 05:16 AM) *
Do you think you could setup in such a short time a json URL with realtime telemetries?

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.

Posted by: mcmcmc Nov 13 2018, 03:40 PM

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 :-( )

Posted by: mcaplinger Nov 13 2018, 04:03 PM

QUOTE (mcmcmc @ Nov 13 2018, 07:40 AM) *
...like publishing realtime telemetries. Did it happen for Phenix?

No.

Posted by: propguy Nov 13 2018, 04:22 PM

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!

Posted by: mcmcmc Nov 14 2018, 05:42 PM

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:


Posted by: mcmcmc Nov 16 2018, 01:24 PM

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

Posted by: mcmcmc Nov 16 2018, 02:42 PM

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/archive/data/phx-m-ase-5-edl-rdr-v10/phxase_0002/DATA/

Posted by: mcaplinger Nov 16 2018, 04:09 PM

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_1.1.0.0/ASE_Bundle_1100/data/ but it's quite difficult to do anything with the raw data.

Posted by: mcmcmc Nov 17 2018, 09:59 AM

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_1.1.0.0/ASE_Bundle_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 becausehttps://pds-atmospheres.nmsu.edu/pdsd/archive/data/phx-m-ase-5-edl-rdr-v10/phxase_0002/DATA/PHXPROFILES.TAB, 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 https://pds-atmospheres.nmsu.edu/pdsd/archive/data/phx-m-ase-5-edl-rdr-v10/phxase_0002/DATA/PHXPROFILES.LBL
*2316 seconds elapsed since reference time "2008-05-25T23:00:00.000" (defined in https://pds-atmospheres.nmsu.edu/pdsd/archive/data/phx-m-ase-5-edl-rdr-v10/phxase_0002/CATALOG/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: https://pds-atmospheres.nmsu.edu/pdsd/archive/data/phx-m-ase-5-edl-rdr-v10/phxase_0002/CATALOG/DATASET.CAT)

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 https://descanso.jpl.nasa.gov/DPSummary/PhxArticle_--RC100915ADocX_COMPRESSED_amf_26.pdf says (of course) a different story: 0.1 m/s horizontal speed, but I can't find it in the data.

https://pds-atmospheres.nmsu.edu/pdsd/archive/data/phx-m-ase-5-edl-rdr-v10/phxase_0002/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

Posted by: mcmcmc Nov 17 2018, 10:37 AM

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/archive/data/phx-m-ase-5-edl-rdr-v10/phxase_0002/CATALOG/DATASET.CAT

Posted by: mcaplinger Nov 17 2018, 10:34 PM

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.


Posted by: mcaplinger Nov 18 2018, 12:24 AM

Attached is a text file with 1-minute sampling from the SPK file https://naif.jpl.nasa.gov/pub/naif/INSIGHT/kernels/spk/insight_nom_2016e09o_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.)

 edl.txt ( 34.22K ) : 0

Posted by: mcmcmc Nov 18 2018, 07:36 PM

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 https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&MAKE_EPHEM=%27YES%27&TABLE_TYPE=%27VECTORS%27&OUT_UNITS=%27KM-S%27&REFTemplateANE=%27ECLIPTIC%27&REF_SYSTEM=%27J2000%27&VECT_CORR=%27NONE%27&VEC_LABELS=%27YES%27&VEC_DELTA_T=%27NO%27&CSV_FORMAT=%27YES%27&OBJ_DATA=%27YES%27&VEC_TABLE=%276%27&START_TIME=%272018-11-26%2019:00%27&STOP_TIME=%272018-11-26%2020:38%27&STEP_SIZE=%271%20m%27&COMMAND=%27-189%27&CENTER=%27@499%27

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.



Posted by: mcaplinger Nov 18 2018, 08:06 PM

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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