Lunar Time

I read an article in Nature today about the difficulties of establishing a lunar standard time. Riveting! There are a few pieces of this that I think are interesting to consider:

Lunar Time Zones

The first question would be to decide whether or not to use lunar time zones. Depending on the number of lunar bases, and how far apart they are, it might make sense just to have one single lunar standard time. Similarly to how the entirety of China is one timezone — this is certainly the quickest solution for establishing ground truth.

Determining Precise Time

If we do decide to go with time zones, however, then we have the challenge of determining a person’s longitude on the moon, in order to determine which zone to place them in. There have been a number of delightful books about establishing earth’s UTC (1, 2) but in our modern age this is solved by using GPS satellites. On the moon, however, we don’t have enough satellites to guarantee accurate triangulation for all locations!

Extraplanetary Timekeeping

To date, we don’t have a standard way of tracking “the time” on other planets, because we don’t have other humans living on planets. On Mars, for example, each rover has its own epoch time, starting from the moment the spacecraft landed on the planet. So we have highly relative calendars on a per-machine basis. It would be tempting to define lunar time by a similar metric, i.e. the first human to set up shop for a bit gets to define 00:00 on the 0th day. We’re going to have multiple countries sending missions to the moon, however, and given how well humans have got along with each other historically… it will be interesting to see how they will converge on a shared calendar system.

Just keep it in Earthtime

For the beginning, this will be the simplest solution. A lunar day lasts 24 hours and 50 minutes, which is definitely off-kilter enough to drive people crazy if they tried to stay on earth time. Martian days are 37 minutes longer than earth days — when the MSL rover was first landing on Mars, JPL operators lived on Martian time to maximize the available window of sunlight and data processing on the rover. It drove people crazyyyyy to be shifting out of sync with the rest of their loved ones, 37 minutes at a time!