Slight Spoilers of A Call to Duty below, so caveat lector.

2

1

The HMS Mars figures in the early part of the book.

When the Guardian reaches Marienbad, the ships there are parked in a set of mid-distant orbital lanes, which to me suggests sub-Marienbad-stationary orbits, and this seem indeed to be the case based on events later on.

Now we receive no data on the size or mass of Marienbad, but that absence could be taken to suggest we are talking about an Earth-like world, or at least can use Earth as a reasonably accurate model for it.

So ...

When the Wanderer clears the obstruction of Marienbad, i.e. peeks just over the horizon, the range to target is “forty-five thousand kilometers”.

Assuming both the Wanderer and the closely-grouped threesome of ships she can see are at the same (approximate) orbital altitude, and that Marienbad’s diameter is (exactly) the same as Earth’s; a double-horizon length of 44,982.6 km works out to an orbital altitude of 17,000 km, respectively 45,000 km to a 17.008,4 km orbit. That is, the 45kkm/17kkm pairing is accurate to within a margin of 0.05%.

Now 17.000 km is the (rounded value for the) Areosynchronous orbital altitude … so the question is now, does this bit of math “just so happens” to work out, or is this an combination Easter Egg & Bon Voyage salute to the Mars?