[X] My Assistant

[dmuller]

Upon request from someone here at UMSF I have created some quick and dirty Mars Clocks for MER-A,B,PHX at http://www.dmuller.net/mars Trying to verify my results, however, I found that virtually every Mars clock provided on the net gives a different time. So which one is correct?

As for the calculation, the way I understand it, all that is required is:

1. The Earth UTC time of midnight on the landing spot of the spacecraft (i.e. SOL 0, 00:00:00 - or SOL 1 00:00:00 for the MERs)
2. Calculating from that base using that 1 Mars second has 1027.49125 Earth milliseconds

I have not found any references to (1), so I trial&error until my results match one of the more official looking Mars clocks. But ... which one is the correct / appropriate one?

[HughFromAlice]

Thanks, I for one will find it useful in its current form!!

[Stu]

Upon request from someone here at UMSF I have created some quick and dirty Mars Clocks for MER-A,B,PHX at http://www.dmuller.net/mars

Thank you thank you thank you thank you thank you!

[djellison]

The someone was me It makes a great replacement for web-clip chunks of different websites I've taken to try and keep on top of things. Mars 24 is all-powerful BUT a resource hog ( seriously - the Mac version gets the fans on my MBP racing!! ).

Only problem is it's online only. If we can nail the local-time issues, package it up for offline use, I know a whole bunch of people who would find it useful

[dmuller]

Only problem is it's online only. If we can nail the local-time issues, package it up for offline use, I know a whole bunch of people who would find it useful

No problem, functionality has been built in the script all the time (I forgot to tell about it, though) ... just load it as http://www.dmuller.net/realtime/mars.php?offline=true (same url as for online viewing, just add ?...) and then in your browser choose "Save Page As ... web-page, complete ... and give it a .htm or .html suffix". Let me know if it causes issues, and visit the online version occasionally in case there are updates.

I made a minor change to the Mars Clocks, however, and they now update more frequently than at the previous 1 second interval.

The things with my scripts being based on server time (which requires more programming than having it on browser time) has a long history back to MEX MOI / Beagle2 EDL. I was in some sort of discussion with some ESA IT staff, and they said that their policy (then) was not to have javascripts because anything time based could go haywire if the user's browser time is off ... so I developed a small personal php script (I dont think ESA ever took it ) to deal with that, and it still lives on. Needless to say, at that time I did not know about UMSF and its predecessors!

EDIT: I probably should put the download instructions on the website itself, or provide another one-click solution. I'll try working on it tonite ...

[Tman]

Hi Daniel,

Looks like you've tried to copy the "Time on Mars" on the official MER website so far. This time display the so called Mission Time.
But this time doesn't display the real time and Local True Solar Time respectively. It's an artificial construction between Mars mean time units and the intent to have it roughly aligned with Local True Solar Time at the middle of the originally planned mission duration of 90 sols. It's described here.

Btw. the downloadable Mars24 Sunclock Java programm also display real time only when the computer's time and date, that runs it, is correctly set.

[Tman]

First of all, is there any doubt that the Mars24 time calculations display not the correct times on Mars?

I'm not really happy with the Flash applications on both the MER and Phoenix mission website, which are suggestive (IMHO) of being current local time for their landing sites, but in fact are different to the Local True Solar Time (LTST) that Mars24 calculates - Which displays actual planet-centered position of the sun in each sky and the actual time of the sunries, the noon and the sunset (for even horizon) respectively.

According to the Phoenix website their Flash clock displays "lander local time" as described here, but it's also still different to the Local Mean Solar Time (LMST) in comparison to the Mars24 display. Whereas the different of about one minute to LMST (on my computer) could be caused by different synchronized computer clocks. What differences do you get?
To mention yet is maybe that the difference between LTST and LMST, called Equation of Time (EOT), is for Mars between -51.1 and +39.9 minutes during a Mars year. That difference is based on the fact that LTST follows Mars's orbital eccentricity and obliquity in respect to the sun (causing the so called analemma figur on the sky at Mars during one year), that LMST does not.

What is the reason not to display the actual true local time and local true solar time respectively on the mission websites?

[djellison]

Using Mars 24 as a base..
For PHX - Dan's page is 5s ahead. The PHX Webpage is 2mins 30s behind.
For MERA - Dans page is 9 mins 6s behind. The MER flash icon is approx 8 minutes behind and MMB is just 2s behind.

Doug

[dmuller]

Yes Tman, you're absolutely right, I modeled it according to the marsrovers.jpl... website. I finally managed to download Mars24 (thus far I always ended up with a broken link) and have updated the script so that the times on the website match the Mars24 (give and take differences between server utc time and your local computer utc time). Unfortunately the web management part of my webhost seems to be down so I cannot upload it yet. Will advise when successful.

I ain't much of a Mars ground ops person, so I dont really know which time calculation method is either accurate or useful, so I let myself be guided by the folks who make use of the clocks "professionally" ... at the moment, well once I can upload it, the script on the website follows Mars24.

BTW Tman, always nice to chat with people from back home. I am originally Swiss, though I moved to Asia / Australia more than a decade ago.

EDIT: Updated version is now uploaded