# NASASpaceFlight.com Forum

## Robotic Spacecraft (Astronomy, Planetary, Earth, Solar/Heliophysics) => Mars Science Laboratory (MSL) and Mars 2020 Rover Section => Topic started by: Yeknom-Ecaps on 07/30/2018 06:47 pm

Title: Curiosity Sol to Earth Date Conversion
Post by: Yeknom-Ecaps on 07/30/2018 06:47 pm
Have looked but haven't found a site that converts Curiosity Sol to corresponding Earth date and vice versa. Anyone know of one? Thanks.
Title: Re: Curiosity Sol to Earth Date Conversion
Post by: ccdengr on 07/31/2018 01:52 am
http://jtauber.github.io/mars-clock/

If you can run a Java app locally, https://www.giss.nasa.gov/tools/mars24/
Title: Re: Curiosity Sol to Earth Date Conversion
Post by: Yeknom-Ecaps on 07/31/2018 03:59 am
Thanks ccdengr ......

this gives current date/sol ..... this is helpful but not exactly what I am looking for .... here is an example of what I want to be able to do .....

given Sol 15 return August 20, 2012
or
given June 3, 2018 return Sol 2070
Title: Re: Curiosity Sol to Earth Date Conversion
Post by: eeergo on 07/31/2018 09:37 am
You can do this with a simple formula yourself:

- Curiosity landed (Sol 0, 3 p.m. at Martian local time) on August 6th, 2012, 05:17 UTC. Therefore, Sol 0 started approximately 15h before the rover touched down, or August 5th, 2012, at approximately noon UTC.

- A Martian day (Sol) is 24 h 37 m 22.663 s, that is, approximately 1.0275 Terrestrial days.

Therefore, the Sol and time for Curiosity as a function of UTC is:

T(Curiosity) = 20120806(05:17) + ( T(Earth) / 1.0275 )

More conveniently, you can consider the landing time in UTC as 0, and just count the number of seconds/minutes/hours/days (depending on the precision you want) from that moment onwards, and divide by the length of a Martian day in the appropriate units (88,642.663 seconds, 1477.38 minutes or 24.623 h).

For example: today 20180731 is Sol 2127.

Or you can use this table ;) https://an.rsl.wustl.edu/msl/mslbrowser/tab.aspx?t=MS (http://msl-curiosity.requio.com/)
Title: Re: Curiosity Sol to Earth Date Conversion
Post by: ccdengr on 07/31/2018 05:19 pm

- A Martian day (Sol) is 24 h 37 m 22.663 s, that is, approximately 1.0275 Terrestrial days.

Actually, that's a martian sidereal day.  A martian solar day (sol) is 24 h 39 m 35.244147 s (88,775.244147 seconds) and I think that's the value you need to use.
Title: Re: Curiosity Sol to Earth Date Conversion
Post by: eeergo on 08/01/2018 10:36 am

- A Martian day (Sol) is 24 h 37 m 22.663 s, that is, approximately 1.0275 Terrestrial days.

Actually, that's a martian sidereal day.  A martian solar day (sol) is 24 h 39 m 35.244147 s (88,775.244147 seconds) and I think that's the value you need to use.

You would be right, that's the value that actually gives the correct day-to-sol conversion, otherwise you would get an offset of almost 3 days for today's MET. Thanks for the precision.