Add long-term ephemeris predictions as pseudo-msids

[aarvai]

I am envisioning three new content types (e.g. orbitephem_lt, lunarephem_lt, solarephem_lt?), where the objects are Chandra/Moon/Sun and the type is Predictive – 25 year. The ephemeris itself (position and velocity) would have to be generated by the FOT using STK and provided in a text file. We were thinking that it would be something only updated once every few years. (Perhaps just by replacing the ingest files?) Obviously the fidelity would decrease with time, but it’s not practical to require daily STK runs, and this level of fidelity should be acceptable for most uses.

Perhaps then the other derived ephemeris params (e.g. DIST_SATEARTH) could use the 25 year predictions when other data isn’t available? If I remember correctly, it already prioritizes which ephemeris to use based on what’s available, so this one could be added to the bottom of the list.

[taldcroft]

@aarvai - what would be the sampling rate for such ephemeris data coming from STK? 5 minutes or daily or ?? I'm thinking of generalized "quasi-static" content types where any sort of time series data can be put through a one-time (or infrequent) ingest process and coerced into the eng archive data structure. It's slightly easier if I don't need to generate the "5min" and "daily" stats, although that's not a huge deal either.

Are there other quasi-static data that would be useful to drop into the eng archive?

[aarvai]

I'm picturing 5min data, like the existing ephemeris, which comes down every 300 sec. They also have 5-min stats (every 328 sec), although it's not particularly relevant. However, it would still probably be preferable to generate the 5min stats for the new ephemeris to keep it consistent with the existing ephemeris.