Blargh

Been reading N. M. Browne's Warriors of Alavna and Warriors of Camlann. I've read a small snippet of how the third book might open in rasfc, and I'm now terrified of reaching the end of Camlann.

In other news:

I have figured the ship out. It's a nearly 500 meters high cylinder with a radius of seven meters. Most of the middle of the ship contains relatively small water containers, too many to count. In total, at launch, the water masses at nearly 11 million kilograms.

The ship contains an unobtainium drive that converts water to energy (in the Einsteinian E=mc² sense) at 50 % efficiency (the other half is emitted in netrinos). The drive manages, in some fey fashion, to direct that energy as electromagnetic radiation mostly in one direction, providing thrust. The drive provides a sustainable (ship-observed) acceleration of 9,81 m/s², and there is enough fuel (water) to sustain that acceleration for two years. Thus, the ship accelerates for one ship-year, reaching the peak speed of 0.77c (that is, 77 hundreths of the speed of light), coasts for decades and then takes another ship-year to decelerate back to rest near the destination. The acceleration creates an Earth-like gravity with "down" being toward the engines. While coasting, the ship rotates in such a way that up and down are (roughly) perpendicular to the height of the ship, with "down" being either toward or away from the enines, depending on where on the ship one is located. In the exact middle, there would be a zero-gravity zone, while at both ends of the ship, gravity would be the familar one gee.

I still need to figure out what happened on Earth between today and the 2050's. Obviously, someone invented that unobtainium drive, but I need details.

(And no, I'm not asking people to supply possibilities.)

I wrote a small vignette about the ship. Probably can't use it. It's still the only narrative verbiage I've produced.

Ah! It is good of you to have come!

This star here is relatively cool and relatively dim, as stars go, although I agree with you that it is plenty hot and plenty bright, as biologics measure such things.

Never mind the planets that are orbiting that star. We'll get to them eventually, but they're not what is interesting about this star at this particular time. Zoom in on this particular point, billions of kilometers away from the star. See that small stick hurtling toward the star? Good. It's actually not that small, as you'll notice if you zoom in much further. It is actually almost half a kilometer long... what?

Ah, you notice it is a nearly perfect cylinder in shape? Do you think it is artificial? Good, you have a sharp wit. What do you think it is? A spaceship? A good guess, and accurate. Notice how it is slowly turning? I've measured it, it's turning a full circle in one minute. There must be quite a gravity in both ends of the ship, thanks to the rotation.

I feel like crap. I think I need to get out more.

Tentative data on the moon

On request. Feel free to rip to shreds (and hopefully suggest ways to make it work), I'm not yet wedded to these numbers.

My model for the star and planet is HD 69830 d as it is currently known, but I'm not using it verbatim and I'm not going to say that the story is set in that system. My source on the physics is Stephen L. Gillett's World-Building. I'm no expert :)

The star has spectral class K5 (absolute magnitude 7,4, bolometric correction -0,8), which puts the habitable zone at roughly 67 million kilometers. A planet at that distance will have an orbital period of 134 standard days.

Assuming a Saturn-like planet, we have a rough density of 1600 kg/m³ and radius of 4 Earths, yielding a mass of 19 Earths. According to my numbers, the star-induced tidal forces on the planet are about 7 times as large as that of the Sun on Earth, which I'm hoping is small enough for avoiding tidal lock.

I've given the planet one Earth-like moon: radius 80 % of Earth giving a mass of 50 % of Earth and about 80 % surface gravity. I've currently assigned the moon a 24-hour orbital period, putting the moon at 0,1 million kilometers from the planet (center to center). The moon is well out of the Roche limit. The tidal force is enormous, and so the moon will be tidally locked to the planet.

Something I'm not sure about (in terms of feasibility) but would consider very cool is if the moon's axial tilt was nearly 90 degrees. This would mean that the moon's orbit would have a similar inclination relative to the plane of the planet's orbit. Please tell me it is feasible :)

I probably forgot some crucial parameters I have in my spreadsheet. Ask and I'll tell :)