InSight Cruise Phase, Events during Mars transit prior to EDL Options

[nprev]

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).

[Tycho]

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

[Phil Stooke]

hasty reply deleted!

Phil

[mcaplinger]

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

[nprev]

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.

[djellison]

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!

[nprev]

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.

[Explorer1]

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?

[djellison]

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.

[djellison]

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/Des...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 MRO’s 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 MRO’s 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"

[nprev]

Rocketcam video of launch and spacecraft separation:

https://spaceflightnow.com/2018/05/11/video...launch-to-mars/

[Explorer1]

Rocketcam video of launch and spacecraft separation:

https://spaceflightnow.com/2018/05/11/video...launch-to-mars/

Farewell InSight! Safe travels!

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

[Decepticon]

Rocketcam video of launch and spacecraft separation:

https://spaceflightnow.com/2018/05/11/video...launch-to-mars/

Was this shown Live?

I don't remember seeing this!?

[Explorer1]

No, it was released a few days later.

[Explorer1]

First light from the cubesats: https://www.jpl.nasa.gov/news/news.php?rele...ml&rst=7124

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

[propguy]

TCM1 was completed 5/22 (yeah!). 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!

[nprev]

Music to our ears, Propguy; thank you!!!

[MahFL]

TCM1 was completed 5/22 (yeah!). 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.

[Explorer1]

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!)

[PaulH51]

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. link

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.

[Phil Stooke]

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

[MahFL]

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

[Hungry4info]

Hopeful cartographers need to know!

I'm certainly looking forward to your routemaps

[djellison]

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

Not going to happen I’m afraid - there just aren’t the resources to pull it off.

[Guest_mcmcmc_*]

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 Hayabusa 2 and OSIRIS-Rex.

[Explorer1]

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)!

[Guest_mcmcmc_*]

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.ntr...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...mission/landing
https://mars.nasa.gov/insight/timeline/land...escent-landing/
https://www.jpl.nasa.gov/news/press_kits/in...ion/Layer-2.jpg

[propguy]

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/f...ng-to-mars.html

[Guest_mcmcmc_*]

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 like I did for OSIRIS-Rex, 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?

[mcaplinger]

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.

[Guest_mcmcmc_*]

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 :-( )

[mcaplinger]

...like publishing realtime telemetries. Did it happen for Phenix?

No.

[propguy]

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!

[Guest_mcmcmc_*]

Not exactly "realtime telemetries", but a good approximation! ;-)

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:

[Guest_mcmcmc_*]

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

[Guest_mcmcmc_*]

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/

[mcaplinger]

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.

[Guest_mcmcmc_*]

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

[Guest_mcmcmc_*]

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???

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

[mcaplinger]

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.

[mcaplinger]

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.)

 edl.txt ( 34.22K ) Number of downloads: 812

[Guest_mcmcmc_*]

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.

[mcaplinger]

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.

[Guest_mcmcmc_*]

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.

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.

[mcaplinger]

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.

[Guest_mcmcmc_*]

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.

Download is not working for me neither.

[Guest_mcmcmc_*]

(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

this remembers me of something...

how do Phoenix and Insight prevent Schiaparelli final event from happening?
And by the way, recorded data on Phoenix show and incredibly wrong modelization of Pitch, Roll and Yaw for Phoenix:
https://ntrs.nasa.gov/archive/nasa/casi.ntr...20080034645.pdf

(fig. 6, 7, 8).

By the way, is anything similar to Phoenix raw data available for unfortunate Schiaparelli mission? Or was it supposed to upload them once landed?

[mcaplinger]

And by the way, recorded data on Phoenix show and incredibly wrong modelization of Pitch, Roll and Yaw for Phoenix:
By the way, is anything similar to Phoenix raw data available for unfortunate Schiaparelli mission? Or was it supposed to upload them once landed?

Has it occurred to you that maybe the problem is your interpretation of the data, not that they are "incredibly wrong"?

There was some realtime downlink of Schiaparelli data, I think it's described in the failure report. I'd be very surprised if it was online in raw form.

Here's the Insight dump with 1-second intervals.

 edl.zip ( 2.37MB ) Number of downloads: 347

[Guest_mcmcmc_*]

Has it occurred to you that maybe the problem is your interpretation of the data, not that they are "incredibly wrong"?

Suggestions?
I just see two heavily different curves named "predicted" amd "reconstructed".

Here's the Insight dump with 1-second intervals.

 edl.zip ( 2.37MB ) Number of downloads: 347

No way to download this file, still gives an error, anyway never mind, I tried setting up the simulator with data I have:
http://win98.altervista.org/space/explorat...-simulator.html

It has yet to be cleaned up and I'll try to also add some fancy graphical instrument like I did here, if I have time, but time is short, only one week remains.

[propguy]

Latest status. We did TCM5 yesterday (could not mention until official announcement came out Official InSight Twitter Page). So far looks like very good maneuver (well than 1 sigma error) and just waiting for Nav results to see if we are setup for entry as expected. Hoping to skip TCM6 this weekend, but ready if we have to do it. Things looking good for EDL.

On a side note, I have been trying to come up with a good EDL song to play that day on the way into work. For launches there are lots of ones that work, but none that seem to cover landing. Best I could think of was Helter Skelter "Coming down fast from miles above you". Good line but the rest of the song does not fit my hopes for that day. Any good ideas?

[nprev]

Thanks for the insight (rimshot!) as always, Propguy.

EDL songs...hmm...Rock Lobster? (down, down, down!)

[mcaplinger]

Any good ideas?

"Eight Miles High" by the Byrds?

[RoverDriver]

Going Down, Jeff Beck

"Well I'm going down
Down, down, down, down, down
I'm going down
Down, down, down, down, down
I've got my head out the window
And my big feet on the ground"

It's even 7 minutes long. And play it LOUD!!!

Paolo

[akuo]

The Rasmus - F-F-F-Falling

"I need a flame, I need a spark
Don't be afraid to open my heart
I need a game, I need a shock
Don't be afraid my heart is unlocked
Made up my mind 'bout the music
Made up my mind 'bout the style
I know that I'm stable and able
To settle down
F-f-falling"

[Guest_mcmcmc_*]

Latest status. We did TCM5 yesterday

Good to hear that.
I just found out a weird thing I did not know: during travel toward Mars, probes are not oriented as we see in all videos, but in such a way that solar panels are correctly oriented toward sun, then the "tip turn" (which I would call "Entry Attitude Setup Maneuver") is performed.
I also read that only a short time before Phoenix arrival at atmosphere interface somebody thought that there was a possibility of recontact between cruise stage (or parts of it) and lander after lander deployment, as they're both on same ballistic trajectory, and cruise module is only slightly slowed down by the pyro devices during lander deployment: it was calculated a minimum distance of 6 meters between lander and cruise module during EDL!
So, if I understand correctly, now the lander deployment is performed before EASM, so cruise module is not just slowed down by lander deployment, but it is also put on a different trajectory due to the transverse force impressed by pyro devices; is this interpretation correct?
But if this "Cruise Module Avoidance Maneuver" was introduced only with Phoenix... how did it go for Pathfinder and MERs?
And I wonder if cruise stage falling parts could have messed up Schiaparelli descent.

During Phoenix EDL they also figured out through simulation that thrusters in the backshell can't be used as designed (i.e. during hypersonic phase), because simulations showed that due to "werid" aerodynamic effects and interactions at high speed they could result in a force being applied to the lander in the OPPOSITE direction w.r.t. what the thrusters were supposed to do! So they were not used at all during descent, unless an "emergency situation" was encountered.

These are all interesting manuevers and "rocket science things" which I've never seen in any video, but they would look much more interesting in a video than in a PDF!

[Guest_mcmcmc_*]

There was some realtime downlink of Schiaparelli data, I think it's described in the failure report. I'd be very surprised if it was online in raw form.

I found this PDF which led me to this page which I will have to investigate a lot!

[Guest_mcmcmc_*]

Found another interesting page, which makes more simple to use SPICE (I don't know anything about SPICE but I was able to gather some data):
https://wgc.jpl.nasa.gov:8443/webgeocalc/#StateVector

Unfortunately I can't find data for Insight and Phoenix.
Phoenix is "-84" and Insight is "-189".

[propguy]

Good to hear that.
I just found out a weird thing I did not know: during travel toward Mars, probes are not oriented as we see in all videos, but in such a way that solar panels are correctly oriented toward sun, then the "tip turn" (which I would call "Entry Attitude Setup Maneuver") is performed.
I also read that only a short time before Phoenix arrival at atmosphere interface somebody thought that there was a possibility of recontact between cruise stage (or parts of it) and lander after lander deployment, as they're both on same ballistic trajectory, and cruise module is only slightly slowed down by the pyro devices during lander deployment: it was calculated a minimum distance of 6 meters between lander and cruise module during EDL!
So, if I understand correctly, now the lander deployment is performed before EASM, so cruise module is not just slowed down by lander deployment, but it is also put on a different trajectory due to the transverse force impressed by pyro devices; is this interpretation correct?
But if this "Cruise Module Avoidance Maneuver" was introduced only with Phoenix... how did it go for Pathfinder and MERs?
And I wonder if cruise stage falling parts could have messed up Schiaparelli descent.

During Phoenix EDL they also figured out through simulation that thrusters in the backshell can't be used as designed (i.e. during hypersonic phase), because simulations showed that due to "werid" aerodynamic effects and interactions at high speed they could result in a force being applied to the lander in the OPPOSITE direction w.r.t. what the thrusters were supposed to do! So they were not used at all during descent, unless an "emergency situation" was encountered.

These are all interesting maneuvers and "rocket science things" which I've never seen in any video, but they would look much more interesting in a video than in a PDF!

We do jettison the cruise stage prior to the slew to entry attitude (what you call EASM). That event occurs roughly 30 seconds before the slew begins, which is about 6-7 minutes prior to the start of entry. I am not allowed by ITAR to discuss the why or how come we decided to do that (sorry). I can say that all the EDL monte carlo sims also look for cruise stage contract and flag those runs, so it is not something we have missed or have forgotten. From the limited info I know about the Schiaparelli failure this is an unrelated topic (the publicly available report EXOMARS 2016 - Schiaparelli Anomaly Inquiry shows their failure was due to high rates on the parachute swamping some fault protection values for rates and thus the IMU data was ignored and they miss estimated altitude and shut off the descent engines too early). I doubt any rate that could come from contact with the cruise stage prior to entry could result in rates that created an issue at parachute deployment while still allowing for a successful entry portion (where angles of attack are very narrow for survival).

Regarding the roll reversal issue on the RCS thruster in hypersonic. That was a predict on Phoenix that came out of some a CFD analysis (see page 12 of this paper Analysis of effectiveness of phoenix entry reaction ... - NTRS - NASA). No one is sure if that is accurate or not, but to be safe Phoenix (and InSight) inhibit thruster usage after a certain time in the entry portion to avoid any potential issue. The only thing the RCS would be doing a that time anyway is roll control and as opposed to MSL we do not have a tight roll control requirement on entry (just don't spin up like a top).

[Guest_mcmcmc_*]

From the limited info I know about the Schiaparelli failure this is an unrelated topic (the publicly available report EXOMARS 2016 - Schiaparelli Anomaly Inquiry shows their failure was due to high rates on the parachute swamping some fault protection values[...]

I imagine debris from cruise stage falling over the open parachute amd causing a mess.

Anyway, in the meantime I slightly updated my simulator, now you can see something moving eventually! :-)

http://win98.altervista.org/space/explorat...-simulator.html
Unfortunately data at low altitude are quite low in precision.

It's a pity I have no time to further study and process telemetry data to get a yaw/pitch/roll graphical representation, maybe I'll do on real Insight data once available; for now I can try adding acceleration, and possibly atmosphere data (temp, pressure and density), all contained in same PHXPROFILES.TAB file.
I also see "attack angle" in PHXPROFILES.TAB, I wonder if I can turn it into an image of Phoenix/Insight rotating while going down in these remaining 4 days.

[djellison]

I imagine debris from cruise stage falling over the open parachute amd causing a mess.

Not a statistically likely event. For InSight, the cruise stage separates before the turn to entry - it's not directly following InSight into the atmosphere.

Anyway, in the meantime I slightly updated my simulator, now you can see something moving eventually! :-)

http://win98.altervista.org/space/explorat...-simulator.html

Both the image and the URL are missing...

The requested URL /space/exploration/insight/screenshot1.png was not found on this server.

The requested URL /space/exploration/insight/insight-edl-simulator.html was not found on this server.

[PaulH51]

Does anyone know what happens to MarCO-A & MarCO-B after they complete the communications relay of the InSight EDL data?

Is there any more science planned? Or do they simply head away from Mars basically following the cruise stage?

[ElkGroveDan]

On a side note, I have been trying to come up with a good EDL song to play that day on the way into work.

Bruce Springsteen
I'M GOIN' DOWN

We sit in the car outside your house, I can feel the heat coming 'round
I go to put my arm around you and you give me a look like I'm way out of bounds
Well, you let out one of your bored sighs, well lately when I look into your eyes
I'm going down, down, down, down
I'm going down, down, down, down
I'm going down, down, down, down
I'm going down, down, down, down

https://www.youtube.com/watch?v=3fdZWbIsrFk

[Paolo]

Or do they simply head away from Mars basically following the cruise stage?

I think the cruise stage re-enters with the lander

[MahFL]

Does anyone know what happens to MarCO-A & MarCO-B after they complete the communications relay of the InSight EDL data?

Is there any more science planned? Or do they simply head away from Mars basically following the cruise stage?

They are in the orbit of the upper stage, not the cruise stage.

[dmuller]

Hello again ... those who have been here a decade ago(!) for Phoenix may remember my realtime simulations. They've been running since, however I was too busy at work to further develop them, but I am once again sacrificing sleep trying for a new home for them and managed to get one up for InSight (fingers crossed bug-free):

https://spaceoutreach.com/spaceflight/insight/

Note times are SCET (I dont have time to do ERT) and Entry Interface is inferred from the published trajectory data. Also, my main interest is in the astrodynamics of it all, i.e. until we hit entry interface, so EDL data may not make it into the sim in time for landing.

Re cruise stage, it separates too close to Mars to deflect it, so it will trail (I presume) InSight and burn up in the atmosphere. If the separation speed is 1m/s (I think it's more in reality), it will be almost 500 meters behind InSight, and has lots more drag so even if something isnt burning up it will not match the downrange of Insight itself.

Dont forget to buy peanuts.

[PaulH51]

They are in the orbit of the upper stage, not the cruise stage.

I'm not sure how much they adjusted that trajectory, but they both completed at least one trajectory-correction maneuver after they separated from the upper stage, see this (Link)

The reports I have read, state that their mission will end shortly after the Insight EDL communication link is completed, I was just curious if there were any other science activities planned before their mission ends. For example, could they use any of the remaining thruster propellants to point their camera at Mars as they pass by? Be great outreach if they could do that

[Guest_mcmcmc_*]

Not a statistically likely event. For InSight, the cruise stage separates before the turn to entry - it's not directly following InSight into the atmosphere.

For Phoenix it was calculated a minimum distance of 6 meters between cruise stage (or its debris) and the lander during EDL, before they uploaded the corrective maneuver.

Both the image and the URL are missing...

The requested URL /space/exploration/insight/screenshot1.png was not found on this server.

The requested URL /space/exploration/insight/insight-edl-simulator.html was not found on this server.

of course! I forgot the server name...
http://win98.altervista.org/space/explorat...-simulator.html

[Guest_mcmcmc_*]

my main interest is in the astrodynamics of it all, i.e. until we hit entry interface, so EDL data may not make it into the sim in time for landing.

Good because I wasn't able to find any data for pre-entry phase!

[Explorer1]

For example, could they use any of the remaining thruster propellants to point their camera at Mars as they pass by? Be great outreach if they could do that

They already took images of Earth after departure, and there was one of Mars approach as well back at the start of October ( https://www.jpl.nasa.gov/news/news.php?feature=7263 ). It would be nice to see just one more, though since their main mission is data relay, it's hard to say if we can get an 'approach movie' that doesn't interrupt that.

[Guest_mcmcmc_*]

Can anybody help? I found this description:

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.

[Guest_mcmcmc_*]

For example, could they use any of the remaining thruster propellants to point their camera at Mars as they pass by? Be great outreach if they could do that

BTW, will MRO be in good position for this EDL?

[Explorer1]

Yes, 3 minutes before touchdown an image will be attempted (see Emily's excellent write-up): http://www.planetary.org/blogs/emily-lakda...ng-preview.html

[djellison]

Does anyone know what happens to MarCO-A & MarCO-B after they complete the communications relay of the InSight EDL data?

Is there any more science planned? Or do they simply head away from Mars basically following the cruise stage?

The cruise stage enters Mars and burns up (maybe a few pieces will survive to impact)

MarCO A and B each get a little gravity assist that changes their trajectory - so they start getting further and further apart from one another.

From an engineering perspective, I believe the intent is to keep in contact with them for as long as they hold up. At some point their prop systems will be exhausted and they'll no longer be able to maintain pointing for solar power and comms - and they'll go silent.

(InSight, MarCO A and B are all in Eyes on the Solar System......there just isn't a landing module for InSight like there was for Curiosity)

They have cameras. They'll be flying by Mars. Fingers crossed...there will be pics.

[Guest_mcmcmc_*]

Yes, 3 minutes before touchdown an image will be attempted (see Emily's excellent write-up): http://www.planetary.org/blogs/emily-lakda...ng-preview.html

Who better than you can know? (nice avatar)

[Gerald]

...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.

[PaulH51]

They have cameras. They'll be flying by Mars. Fingers crossed...there will be pics.

Fingers and Toes crossed Thanks for the info Doug

[djellison]

Fingers and Toes crossed

And then some...... Spoiler alert - I'm helping with planning and processing of pics from their tiny camera. Trying our best to estimate reasonable exposure times in the next 48hrs before committing on Sat AM.

[PaulH51]

...before committing on Sat AM.

Excellent news indeed

[Guest_mcmcmc_*]

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:

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

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:

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:

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°.

[Guest_mcmcmc_*]

These links provide raw numerical data for MARCO-A (code "-65") and MARCO-B (code "-66") as per NASA Horizons site.

Position & speed are expressed w.r.t. Mars center.

[ElkGroveDan]

And then some...... Spoiler alert - I'm helping with planning and processing of pics from their tiny camera.

Just make sure you don't get your thumb or the camera strap in the images and you should be OK.

[Guest_mcmcmc_*]

And then some...... Spoiler alert - I'm helping with planning and processing of pics from their tiny camera. Trying our best to estimate reasonable exposure times in the next 48hrs before committing on Sat AM.

Don't forget the switch to turn the images upside-down (somebody said on july 20th, 1969...) ;-)

[nprev]

Forum note: The EDL thread will go live at 0800 PST (1600 GMT) this Monday, 26 Nov, and discussion concerning that will happen there. Will post a link to it then.

[Guest_mcmcmc_*]

Added manometers for deceleration and attack angle.
http://win98.altervista.org/space/explorat...-simulator.html

It's cool to see even parachute oscillations and legs deployment in the "amplified" accelerometer! (first gauge)
Paper says attack angle is unreliable after chute deployment, I don't know why.

[Guest_mcmcmc_*]

Paper says attack angle is unreliable after chute deployment, I don't know why.

from official papers it results that even NASA does not why attack angle data are totally unreliable after parachute deployment, but i can't find any further update after 2010.

There are 3 different issues on attack angle reconstruction:
1) discrepancies between predicted and re-constructed angles of attack addressed by Desai et al.(2008).
2) discrepancies (+/- 2° , which could be "explained" by a 300 m/s wind) between results from direct reconstruction from gyros and indirect reconstruction from accelerometers - "Results from the Phoenix Atmospheric Structure Experiment" Paul Withers and David Catling - 2010
3) nonsense values of angle attack at parachute deployment (46°) and after (up to 132°) - "Production of Reduced Data Records for the Phoenix Atmospheric Structure Experiment" - Paul Withers, D. C. Catlingb -

From data it also appears that Phoenix touched ground... 1.2 km above ground ("Results from the Phoenix Atmospheric Structure Experiment" Paul Withers and David Catling - 2010). I'm not sure if they are talking about "above MOLA level" or "above ground level".


MSL EDL data just stop at 12 km above surface.
I've yet to examine EDL data for MPF, MER, and Schiaparelli, anyway last part of EDLs looks quite "mysterious" yet. Still a lot of work to do till safe manned capsule landing on Mars!

Now I am very curious about what Insight EDL data will show.

----------------

I also found another interesting paper about an unexpected issue on Phoenix mission: descent radar locking on jettisoned heatshield and thus providing false values for altitude!
"Phoenix Landing Radar Heatshield Anomaly" - J. Eric Belz, Curtis Chen, and Ben Cichy

Together with high possibility of Phoenix cruise stage recontact with Phoenix lander during EDL, it's an issue I was totally unaware of till a week ago.

[Guest_mcmcmc_*]

Just to better know what Insight is about to face:
Overview of the Phoenix Entry, Descent, and Landing System Architecture - Myron R. Grover III, Benjamin D. Cichy

[nogal]

For the Google Mars community, here is a KMZ file with InSight's landing ellipse.

Unfortunately, Google Mars does not have any CTX registered for this area, so I suggest going to GE's left panel and in the Layers section, select under Global Maps the Daytime Infrared. This is the base map appearing, for instance, in landing ellipse image contained in the press kit.

To install the file, download it to your favorite location and double click it. This should startup Google Earth, if not already opened, and initiate a switch to Google Mars (a pop-up will display). The globe should automatically rotate and position itself over the ellipse area. Acknowledgements, credits, and a short explanation are available on the file's help panel. To get to the panel select the file's name on GE's Places panel.

The ellipse is approximated by a 180-sided polygon. I'd welcome information on any errors that may exist.
Fernando
 InSight.kmz ( 4.74K ) Number of downloads: 248

[Guest_mcmcmc_*]

For the Google Mars community

Damn!
If just you'd remebered me before about existence of Google Earth, I could have set up something better than this....
I totally forgot that I can create animations in google earth!
This is the Phoenix EDL:
http://win98.altervista.org/space/explorat...Phoenix-EDL.kmz

It's even possibile to make the marker shape change depending on altitude, and shift whole trajectory to Insight site (just for fun, it's a simulator)... but I think it would require more time than remaining time to the event. :-(

In case anybody has time/wish to help, this is the source code which converts EDL data into KML format:
http://win98.altervista.org/space/explorat...t/crea-EDL.html

Data are here:
http://win98.altervista.org/space/explorat...ht/js/coords.js

Taken as usual from PHXPROFILES.TAB .

This line gets one sample every 200 to make things faster; change "200" to "1" for a realtime animation:

CODE

    for (index = 0; index <= latLonAlt.length-1; index += 200) {

[nprev]

I believe that angle of attack information after chute deployment is irrelevant. The aeroshell is no longer providing any significant lift; it's all about the inflated chute at that point, which had better be normal to the flight path.

[Guest_mcmcmc_*]

I believe that angle of attack information after chute deployment is irrelevant.

Irrelevant for what?

[djellison]

It doesn't actually matter. The s/c will be swinging backwards and forwards under the parachute. It's 'angle of attack' isn't really a thing any more. The s/c uses the IMU at this point to interpret RADAR data, but the actual angle really doesn't matter.

[nprev]

Another way to put it: The angle of attack of the parachute with respect to prevailing airflow should be 90 deg.

[nogal]

Damn!
If just you'd remebered me before about existence of Google Earth, I could have set up something better than this....
I totally forgot that I can create animations in google earth!

Here it is, quick and dirty, using Phoenix's EDL data (rotated and re-centered). You have to play with the slider controls to see the full path. Maybe I'll polish it latter but right now it is way past my shuteye time. Cheers

Fernando

 InSight_EDL_Sim.kmz ( 11.12K ) Number of downloads: 303

[Guest_mcmcmc_*]

Here it is, quick and dirty, using Phoenix's EDL data (rotated and re-centered). You have to play with the slider controls to see the full path. Maybe I'll polish it latter but right now it is way past my shuteye time. Cheers

Fernando

 InSight_EDL_Sim.kmz ( 11.12K ) Number of downloads: 303

Cool.
We should also find a method to:
- make a real time video (Google Earth settings do not allow a speed lower than "10 seconds per second")
- make markers representing different phases of the landing (I have the images, I have tocleanup them and see if I can make their background transparent)
- add camera orientation to each point to create kind of a movie centered on lander

In the meantime, I have to finish the other simulator.

All in around 55h.

It doesn't actually matter. The s/c will be swinging backwards and forwards under the parachute. It's 'angle of attack' isn't really a thing any more. The s/c uses the IMU at this point to interpret RADAR data, but the actual angle really doesn't matter.

The point is: if you are going to land on Mars (not "generic you", but you nprev or djellison), wouldn't you like to know in advance how your spaceship/spacecraft/aircraft/whatelse will be oriented during final descent? I would. All this EDLs have to be (also) interpreted as test for future manned landings, but we currently don't know anything about lander attitude between parachute deployment and landing.
Additionally, an error in merging and crossprocessing radar data and IMU data by GNC caused fatal failure of Exomars 2016, so design needs a little improvement for this phase, IMHO.

[Guest_mcmcmc_*]

NASA horizons data about Insight usually stopped after 2018-11-26 20:40, and they did not implement at all the landing.
Now they say that landing will happen on november 25th?!?

2458448.318055556, A.D. 2018-Nov-25 19:38:00.0000, 9.125119431869558E-01, 2.735641984023738E+05, -3.024901901551133E+00,
2458448.318750000, A.D. 2018-Nov-25 19:39:00.0000, 9.119065406414170E-01, 2.733827032851672E+05, -3.024935345862831E+00,
2458448.319444444, A.D. 2018-Nov-25 19:40:00.0000, 1.131818709765760E-02, 3.393107130110657E+03, 4.196530165013691E-14,
2458448.320138889, A.D. 2018-Nov-25 19:41:00.0000, 1.131818656712531E-02, 3.393106971061080E+03, -5.212723928404643E-06,

4th datum is distance in km from Mars center; Phoenix landing site in Phoenix EDL data is stated as to be 3376.3 km distant from Mars center, so 3rd line here above appears to describe a landing happening at right time but in wrong date.

[Guest_mcmcmc_*]

Declared sources for Horizons data:

CODE

Trajectory files                           Start (TDB)           End (TDB)
  --------------------------------------  -----------------   -----------------
  od002_v1.V0.1                           2018-May-05 12:39   2018-May-05 21:00
  od037_v1_delTCAL.V0.1                   2018-May-05 21:00   2018-Jun-08 00:00
  od092_v1.V0.1                           2018-Jun-08 00:00   2018-Jul-29 00:01
  od102_v1.V0.1                           2018-Jul-29 00:01   2018-Nov-25 19:40
  4day_landed.V0.1                        2018-Nov-25 19:40   2018-Nov-29 19:40

are we missing something?!?

[Guest_mcmcmc_*]

Simulator is eventually finished: I cleaned it up, added official Twitter feed, NASA live video and descriptions for all phases.
http://win98.altervista.org/space/explorat...-simulator.html

Attached thumbnail(s)

 

[djellison]

wouldn't you like to know in advance how your spaceship/spacecraft/aircraft/whatelse will be oriented during final descent? I would.

What point are you trying to make?

That we should be able to invent some impossible simulation technology in advance of EDL in complete defiance of chaos theory?

Or that a spacecraft swinging under a parachute should expend fuel unnecessarily to control it's attitude?

The vehicle knows it's attitude at the time, and conducts an appropriate heading change during the powered decent stage so it lands at the correct orientation. Phoenix executed the same EDL method well. I'd suggest reading several of the post landing reconstruction analysis papers such as this one http://citeseerx.ist.psu.edu/viewdoc/downl...p1&type=pdf

This landing system has no common heritage with ExoMars.

[mcaplinger]

The point is: if you are going to land on Mars (not "generic you", but you nprev or djellison), wouldn't you like to know in advance how your spaceship/spacecraft/aircraft/whatelse will be oriented during final descent?

You need to calm down a little.

Certainly for previous landings there have been a lot of simulations of what the attitude on chute was, and we used them to calculate exposure times, photometric angles, etc, but at best they were measures of what could have happened. Nobody expected them to look much like reality, and they didn't. For example, the MSL descent was much less oscillatory than some of the simulations.

[Guest_mcmcmc_*]

I'd suggest reading several of the post landing reconstruction analysis papers such

Thanks, I've already read 6 of them: all complain about unexpainable terribly wrong data about attack angle after parachute deployment, and some of them presume that wind could be a possible cause, and the authors presume that radar could help fixing the data, but I was not able to find any EDL analysis report taking into account radar data.


Note that they don't say that this is a critical point; they just say that "nothing is known about spacecraft attitude between parachute jettisoning and landing, but it's evident that it is good as spacecrafts usually land safely" (this sounds a little scary to me, being an engineer).

This is why I think that the parachute-to-landing phase design needs some improvements (currently it sounds like "hey, let's hope all goes fine, we can't do anything better here"). Instead, all other phases look very precisely designed against any possible Murphy attack.