[tz] Sol 5000 for Opportunity

Today, 16 February 2018, at 01:26:20.092 UTC, it is 01:01:06 Coordinated Mars Time on Mars Sol Date 51235, which corresponds to midnight HLST (hybrid local solar time) at the beginning of mission sol 5000 for the Opportunity (MER-B) rover at its mission reference longitude. The sol will last, of course, for 24 hours 39 minutes 35.244 seconds, ending on 17 February 2018 at 02:05:55.336 UTC. Curiosity will observe its mission sol 2000 next month, reckoned in mean solar time at its landing site, from 2018-03-22 13:24:49.020 UTC to 2018-03-23 14:04:24.264 UTC. -- Tim Parenti