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Posted by: dmuller Apr 14 2008, 01:30 AM

I am in the midst of programming a rather simple javascript to keep track of Phoenix's progress (and later EDL) together with a timeline of events. The current version is online at http://www.dmuller.net/phoenix, but if anybody has more details, I would greatly appreciate any input, in particular of upcoming events and their anticipated timing, as well as details during the atmospheric flight (altitude, speed, downrange). For all times, it would also be great to know their timezone and whether they are SCET or ERT. The "positions" information is calculated based on data downloaded from the SSD Horizons system, which is available right up to the Entry Interface.

Naturally, I also welcome any suggestions on what other information could be added to the script.

I can also provide an off-line version of the script (does not require php) e.g. for public display in a visitor center.

Please post any information / feedback / requests either here or send me an email through my public profile on this board. I may not respond for a couple of days as I will not have internet access.

Thanks a lot to everybody!

Phoenix Entry Interface in 41 days 22 hours. Distance to fly: 79.7 million km. Altitude above Mars: 9.6 million km

Posted by: Zvezdichko Apr 14 2008, 07:03 AM

Great work, I like it.

Posted by: djellison Apr 14 2008, 07:08 AM

Now that is very very cool.

I would say this is a reasonable starting point - http://www.mps.mpg.de/images/projekte/phoenix/phoenix08_xxl.jpg - it is very out of date I think - but the usual round of mission press con, and then science press con can not be too far away, and updated press pdf's will get released about then, and probably an updated landing time.

The attached is a bit more up to date.

Doug

Posted by: dmuller Apr 17 2008, 04:50 AM

Thanks Doug. That was the graph I was working from, though it has some shortcomings, such as the altitude referencing to MOLA and the touchdown being at altitude 0km even though the actual landing site is (as seen on the image) somewhere between 3 and 5 kms below MOLA. It also has a time elapsed of 470secs from entry interface to touchdown, which now seems to be 440 sec (+/- 30 secs).

On that note, the Canberra Deep Space Communication Complex visitor center told me at they have received information as of earlier this week that the nominal landing is on May 25, 23:53:52 UTC (+/- 30 secs) and atmospheric entry at 23:46:32 UTC (Earth Received Time). In Spacecraft Event Time, atmospheric entry is thus at 23:31:12 and landing at 23:38:32. (One-way light-time will be 920 secs)

I'll update the scripts in due course and will post a message here once that's done.

Edit: fixed error in SCET landing time

Posted by: Spirit Apr 21 2008, 12:33 PM

Does your script predict how many Gs will the spacecraft "feel" during the descent?

Posted by: dmuller Apr 21 2008, 01:49 PM

Unfortunately not (yet). The only information I have regarding this is the info that can be extracted from the charts above, with max deceleration being between 7 and 9 g's. I am trying to get more info from the Phoenix team / JPL, and will incorporate it into the script if I get good enough information to do so. Information on the atmospheric section of the flight (events, speed, altitude, downrange, deceleration etc) is pretty sparse at this time, and difficult to extrapolate from the little I have.

Posted by: dmuller May 4 2008, 01:48 AM

An update with 22 days and 5 million kilometers to go ...

First my thanks to Emily for mentioning the simulation on her Planetary Society blog. It attracted a large crowd (avg 100 visits/day) and by now I get a steady stream of visitors to the simulation from people who have bookmarked the site. Great!

As for the script, all functionality is now included, including DSN coverage, virtual commentary during landing and a bigger font for the numbers. At the moment, the script is in "Spacecraf Event Time", and "Earth Received Time" will be enabled shortly.

The challenge now is to fine-tune the data during the first part of the atmospheric flight, in particular from Entry Interface to Parachute deployment. Therefore, again, if anybody has information on the following, please share them with me ... pretty please ...

(1) Precise timing for TCMs 4, 5, 6 and 6X

(2) Anticipated nominal altitude as a function of time and speed as a function of time (time being from Entry Interface or landing). Trajectory reconstructions for Spirit, Opportunity or Beagle-2 would be welcomed too ... I saw references made to them on the net, but havent actually found one :-( I did, however, find a neat one for the Huygens landing on Titan

Piecing together the snippets of interviews found on youtube just doesnt give the whole picture.

Also, if you manage / work for / represent etc a spaceflight educational outreach position (and dont have internet access there), I can create an offline version of the script. At last count, it's already heading that way to 3 such organizations on 3 continents.

Posted by: Zvezdichko May 4 2008, 06:47 AM

I'm unable to open the web site ;(

Posted by: dmuller May 4 2008, 09:47 AM

Hmmm it works for me. Maybe you hit a busy spot? Try again at http://www.dmuller.net/phoenix

Posted by: jamescanvin May 4 2008, 03:07 PM

I've had no problems accessing the site from work but just tried it at home now and I get a "Failed to open page".

Posted by: dmuller May 4 2008, 03:28 PM

Looks like the host server has problems as I cant access the page now either and the host's own webpages are very slow. Better now than in 3 weeks. Anyway, I will arrange for a mirror site with a different host and advertise it here once it's up and running in a couple of days ... planned to do that anyway but not so early on.
Daniel

Posted by: kwan3217 May 15 2008, 06:31 PM

http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38898/1/05-2473.pdf "Landing on Mars" with a velocity vs altitude chart for all the past and current entry phase stuff. You could integrate it somehow to get downrange vs time, then the things you want.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080013471_2008012906.pdf "2007 Mars Phoenix EDL Simulation and Modeling Analysis" Another velocity vs altitude chart.

http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/30387/1/95-0980.pdf "Mars Pathfinder Atmospheric Entry Trajectory Design" includes an altitude and acceleration as function of time from entry interface. For Mars Pathfinder, so not particularly relevant.

All of these references say that Phoenix is similar to MER entry trajectory, which is very well documented (search ntrs.nasa.gov).

http://starbrite.jpl.nasa.gov/pds-explorer/dsidnode.jsp?nodename=ATMOS&datasetid=MER1/MER2-M-IMU-4-EDL-V1.0&volume=merimu_1001 Mars Exploration Rover EDL accelerometer record

I've seen acceleration and velocity vs time from entry interface charts, but I can't locate them again.

I'm working on a Phoenix model for Orbiter http://orbitersim.com and it looks like I have a valid aerodynamic and atmosphere model, since it is hitting exactly 9.2G peak on entry. I'll be able to get an extraordinarily complete log of my model's entry. I plan on publishing the model before the real thing does its entry.

Posted by: dmuller May 16 2008, 01:21 AM

Thanks Kwan for the links. Interesting reading, and please do make the orbitersim.com Phoenix model available for public use :-)

Meanwhile, the following animation has been put up at http://phoenix.lpl.arizona.edu/videos.php#edl_hud, very useful for my project, and impressive as is:

I will still use your references for the time from Entry Interface to plasma blackout.

Daniel

Posted by: dmuller May 21 2008, 12:03 PM

With 4 1/2 days to landing, and after 3,500 website visits (a lot for a website of mine) I can announce that the final version of the real-time simulation is now online at http://www.dmuller.net/phoenix. I do not intend to make further changes unless the entry interface and/or nominal landing times change "significantly". Such changes can be made as late as just after TCM 6. Some important information:

Download Speed: I would expect the simulation to take longer to load on May 25. At the moment, all position data is correct on an hourly basis and interpolated in between, but soon this will change to a minute-by-minute basis and requires more data to be loaded into the simulation. Starting from about 30 minutes before landing, all the remaining trajectory information will be loaded into the script when it does its auto-reload, or is accessed for the first time. This may take a while longer than usual, but avoids having to reload the script during the crucial EDL phase. Be patient :-)

Mirror Site: In case anything goes pear-shaped, the simulation is also running at http://www.dmuller.com/phoenix. You can use this site if the main page goes down or becomes too slow. I will not be able to attend to the script or server issues in the last 24 hours before landing as I wont be home, and the server sits in the US where there is a long weekend. On that note: could anybody record the NASA TV feed for me (preferably the one without commentary) ... I'll paypal for postage etc?

Beyond Phoenix: given the interest in the script and feedback I have received, I will create similar scripts in due course. However, I do need to catch up on my "proper", space-unrelated :-( work a bit before continuing (as a freelancer it's easy to 'scale back' work for other more interesting activities, but unfortunately the bank account starts to hurt a month later ...). Top of the list will be New Horizons (because I like that mission) and Messenger (for the upcoming Mercury flyby 2). Updates will be posted to where the Phoenix script sits at the moment. I will also look into creating a spaceflight (& related) outreach online library, so if anybody has any suggestions, you know where to find me.

8.5 million km to go. Good luck Phoenix, we're all waiting to hear from you from the surface of Mars.

Go, Phoenix!


Daniel

Posted by: tanjent May 21 2008, 03:47 PM

One question, dmuller. I have been watching your real time simulation for several weeks now and one feature that attracts my eye is the gravitational acceleration towards Mars. I have not really been writing down the values, but I will have to start doing so because it seems to be behaving in ways that I can't understand. The masses of Mars and Phoenix are not changing, so if the distance between the two bodies is getting monotonically closer, then the gravitational acceleration should never decrease, right? But on more than one occasion I believe I have seen it do so - most recently today compared to several days ago. The first couple times, I thought it was my imagination. Am I hallucinating, or maybe just counting the significant decimals wrong, or do we have a "Phoenix Anomaly"? My knowledge of physics is very weak, but I thought there were only those three mentioned variables involved, at least in the Newtonian world.

Posted by: dmuller May 21 2008, 04:05 PM

Hi Tanjent ... good spotting! no worries, it's all a display issue, but it got me scratching my head as well some time ago. Programming decimals in javascript is a bit of a headache and the way I do it causes the sixth decimal to be dropped if it happens to be a zero. Combine that with the right-side alignment and you have the following display problem:


_0.000038
_0.000039
__0.00004
_0.000041
_0.000042



The formula BTW is (acceleration) = (gravitational constant) x (mass of Mars) / (square of distance to center of Mars) and it is independent of the mass of Phoneix


Daniel

Posted by: djellison May 21 2008, 04:18 PM

FYI - this works beautifully on an iPhone/iPod Touch - I zoom in to the left hand side to get the bigger picture, or the right hand side for the details - it's perfect

Doug

Posted by: dmuller May 22 2008, 12:42 AM

Thanks for letting me know! I dont have such a device, but now I know anyway what column widths to use for any future scripts to make it work ... mmm call it iUMSF

Posted by: dmuller May 22 2008, 01:20 AM

Hello again Tanjent ... I had a nice strong cup of coffee and fixed the display issue

Posted by: kwan3217 May 22 2008, 05:50 AM

To anyone who was waiting for this, go get Phoenix v3.0 from avsim.com. Not by me. My model flies pretty well, but I am using the 3D models from this set and I have no right to re-publish them.

Posted by: BrianJ May 22 2008, 11:38 AM

Kwan, please feel free to repackage/republish my models. Although I have reworked the .dll's for a more accurate EDL profile and will be offering these as an upgrade shortly(see orbiter-forum.com)

I'll be running the sim in real-time on Sunday evening, and just for fun I thought I'd stream it live via Ustream at http://www.ustream.tv/channel/obc from 9.00pm BST (whilst checking dmuller's site for timings and Doug's Mars Live and NasaTV for info - my poor old PC will probably melt!)

dmuller - excellent site! I'm a daily visitor :-) Thanks.

Good luck Phoenix!

Regards,
Brian

Posted by: tanjent May 22 2008, 05:06 PM

OK then, I'm somewhat relieved although I figured it had to be something like that. Thank you for setting me straight on the formula. That's like Galileo dropping the different-sized cannonballs from the leaning tower of Pisa!

tanjent

Posted by: Skyrunner May 22 2008, 09:17 PM

Perhaps a bit late but are these of any help?

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080013471_2008012906.pdf [2MB]
http://www.4frontierscorp.com/dev/assets/Braun_Paper_on_Mars_EDL.pdf[3.5MB]

Posted by: dmuller May 24 2008, 06:07 AM

Announcement for those following the Phoenix Real-Time Simulation at http://www.dmuller.net/phoenix
Just in case anything goes wrong with the server, there is a backup / mirror site of the script at http://www.dmuller.com/phoenix
Enjoy watching the landing! Daniel


BTW thanks Skyrunner for the links. I have used the EDL HUD movie which is posted at the Phoenix website.

Daniel

Posted by: ugordan May 25 2008, 11:01 AM

Daniel, what does the mark event "Gravitational tug of Mars exceeds that of the Sun" mean physically?
As I write this, it's 41 minutes until that happens and the gravitational acceleration towards Mars is already greater than the Sun, 0.002248 m/s*s vs 0.002134 m/s*s.

Posted by: dmuller May 25 2008, 12:04 PM

Mmm yes I have seen that too. The timing of the event in the timelist is about 1 hour off. It's supposed to be where Fgrav(Sun)=Fgrav(Mars). I need to review what happened, off-hand I suspect I either got rounded numbers or picked the wrong solution of that quadratic equation.

Posted by: scalbers May 25 2008, 03:40 PM

Hello Dmuller,

Nice utility with the timeline. I wonder if it's worth adding things like NASA TV press briefings. As an example there should be one at 1900UTC today (Sunday).

Thanks,

Steve

Posted by: Stu May 25 2008, 04:10 PM

You mean they're REAL?!?!? People actually USE them?!?!?!?!? I thought they were just evil, fiendish things made up by maths teachers with no real application in the real world! Wow... The number of times I sat at my desk as a kid, trying to do those as part of my maths homework, and failed miserably.

Still, no big surprise, I kind of gave up on maths when we got past the "If I have two apples in one hand and one in the other, how many apples have I got?" stage. Not bragging about or proud of that, it's just with me it's always been words and not numbers that have inspired me, you know?

Posted by: DFinfrock May 25 2008, 06:35 PM

Stu:

Your words inspire us, too. I love the new poem on your web site.

David

Posted by: dmuller May 25 2008, 09:15 PM

The simulation is in design freeze now. But I'll add briefings for future missions


Uh yeah they're real. I was actually good in Maths in school ... wanted to study it, so I could study Physics and then Astronomy (so it makes my recent Maths blunders on UMSF even worse!). But I decided quickly that it would have been an overkill: 1st semester Maths: proove that there is only one number zero, then there is only one number one - the highlight of that semester would have been the definition of the sine. Nah, I switched to Economics. 20 years later I still wonder if that was a good thing to do

Daniel

Posted by: Stu May 25 2008, 09:52 PM

Daniel, your script looks great projected on my wall. Thanks for a FANTASTIC application which will give us all a greater appreciation of the landing, I'm sure.

Posted by: lyford May 25 2008, 09:55 PM

Just adding my thanks as well - looks great!

Posted by: dmuller May 26 2008, 09:49 AM

Thanks everybody for the kind words. I'm glad it was useful. I guess the statistics speak for the interest that spaceflight (still) generates. 17,000 site visits is not "bad"

Visits last 7 days (Sydney time)

Visits on landing day (Sydney time)

Posted by: Skyrunner May 26 2008, 09:59 AM

Is that 'unique visits' or hits?

Posted by: dmuller May 26 2008, 10:12 AM

it is 17,300 visits and 22,000 page views according to Sitemeter. The "visits" likely include the reloads. The Google analytics will give a better picture (especially new visits), but will take some time to analyze. There were 3,600 visits during the hour of landing (23:00-23:59 UTC), and the scripts should only have reloaded once in that period. So it was possibly running on 1,000 to 2,000 PC during landing.

I might just archive the script ... update it with actual flight event times and offer the last 10 minutes as a "history replay".

I have already been asked to develop similar scripts for other missions. Stay tuned, announcements will be made on UMSF. Anybody got any favorite missions to suggest?

EDIT: quick look at google analytics has 1,995 unique visits which includes the 300 or so on the "backup" site during or around landing

Posted by: Astro0 May 26 2008, 12:51 PM

Hi All,
I met Daniel today during this visit to the Canberra DSN to watch all the events unfold with Phoenix.
His script was invaluable to me during our outreach efforts today.
I was able to keep the audience informed as critical events occurred in both SCET and ERT, and it provided a clear timing for the excellent HUD EDL animation. We've also been running the various versions of the script over the past few weeks for our visitors, and it was a very useful tool to explain spacecraft events.

I'm glad that Daniel was able to share this script with all of us and I hope that he continues to develop other versions for future missions.

Thanks Daniel. Hope to see at the Canberra DSN again soon.

Astro0

Posted by: SpaceListener May 26 2008, 02:00 PM

First of all, I am very glad of your real time script which was a very valuable source of information as the reference of the sequence events. Keep up for others missions.

The second, I would want to let know that the Google analytic does not capture all hits since many Web Browser of FireFox forbides the use his URL in order to avoid the performance degradation.

Posted by: dmuller May 27 2008, 02:40 AM

Well, in whatever measure, it was a lot of visitors. Used up half of my monthly allowed bandwidth! And whatever may come from Phoenix in the future, for me the picture of the mission is and will always be this one:

Phoenix on its parachute as seen from MRO. Marvellous

Posted by: dmuller May 27 2008, 04:14 AM

Thanks Astro0, you did an excellent job keeping everybody there informed, dealing with the media and all. It was very impressive. It was also fascinating to look into the big dish as it pointed to MRO in the afternoon. No worries, I'm bound to head back to the DSN. My 4-year old LOVES it there with all the rockets etc. Last time we "only" went to Questacon, and after half an hour he was asking whether we can now go an see the place with the rockets.
Daniel

Posted by: dmuller May 31 2008, 01:01 AM

I started a new thread at http://www.unmannedspaceflight.com/index.php?showtopic=5197 about where to take this type of script for other missions. Please feel free to make suggestions there.
Daniel