This page should help with the question of whether or not they have some sort of FTL drive! 
Speaking of science fiction, have we all read Ancillary Justice by Ann Leckie? I know it swept all the major genre awards, but this novel only came to my attention about a month ago. And now I understand why it won all the awards! It’s one of those stories you want everyone else to read too, just so you have someone you can have a deep discussion with about it. I picked it up with nothing more than a solid recommendation, and having read neither reviews or even the back cover blurb, I plunged in. This is my favourite way to read books, but I suspect this approach might be why it took me longer than usual to wrap my poor brain around what was going on. No lie, some of the ideas presented are quite challenging to imagine, not least of which is the main character. But wow, what a great book. I’ve read the sequel now as well, and I anxiously await the third coming later this year. If you’re looking for an amazing summer read, here you go!
Maybe they ought to patch up the main drive, and make an exploration trip out of it, if it’s going to take that long. Would probably be easier than fixing that silly Jump Engine…
To be honest, I got the impression the Jump Engine’s perfectly fine. It’s everything else that went wrong, for whatever reason.
How would they even locate the resuply points that far out?
Or maybe they just run into some psycic butterflies
Ohhh boy. Like calculating they’re 21 parsecs away from home isn’t anxiety enough…
I also love going right in a book without reading the back cover. Either I know and trust the author, or I give confidence that it’s well-structured due to recommendations. At least, for fiction books.
Now Fusella can of course calculate the time needed to reach Earth from the top of her head. She’s just asking for dramatic effect. Clearly just divide the distance by the interstellar speed limit (we don’t want to get a ticket, do we?)…. s = 21.5 pc = 21.5 * 3.1*10^16 m = 6.6 * 10 ^ 17 m. Also 7 months is approx t = 7 * 30 * 24 * 3600 s = 18 144 000 s Since spaceships are like cars, v = s / t, i.e. v = 6.6 * 10 ^ 17 m / (18.1 * 10 ^ 6 s) = 36.4 * 10 ^ 9 m/s. So the Galaxion’s top speed is 36.4 billion metres per second (which is about 130 billion kph or about 80 billion mph). No, spaceships are not like cars. Assuming that first half of the journey the spaceship undergoes constant acceleration, then constant deceleration. 0.5s = s’ = 0.5 at^2, so a = s / (t^2). That gives us a = 6.6 * 10 ^ 17 m / (18.1 * 10 ^ 6 s)^2 = 2000 m/s^2 =~ 200 g. So Galaxion’s top acceleration is some 2 000 m/s^2. I’m sure glad it has an artifical gravity/intertial damper system, lest the crew would find travelling while being squashed to the back wall (or front wall in the second half of the journey) by acceleration of mere 200 Gees somewhat uncomfortable
Not unless the speed of light in Fusella’s universe is a LOT higher than it is in our universe, and she has some sort of magic no-fuel “vacuum energy” drive so she can accelerate `forever’.
In our universe, even with a magic no-fuel “vacuum energy” drive that allows acceleration at a constant 1 gee (plus hellaciously good shields against interstellar gas and dust, which from the ship’s POV will hit as hard radiation at 0.999+ cee), it will take a minimum of ~72 years Earth time, ~8.4 years ship time to get back in “normal space” — see http://www.convertalot.com/relativistic_star_ship_calculator.html. Needing to “stop twice to resupply” raises that to ~76 years Earth time, ~19 years ship time.
Accelerating at a constant 200 gees doesn’t help the Earth time much, but it helps the ship time a LOT: ~70.11 years Earth time, ~34 days ship time nonstop, or ~70.14 years Earth time, ~90 days ship time with two stops for resupply — which would make it pointless to “stop for resupply”; they will get home faster and use fewer consumables if they don’t stop!
Of course in reality, acceleration takes fuel, and fuel has mass, so even with the most efficient possible drive (photon drive using 100% conversion of mass to energy) and the maximum practical ship’s mass-ratio (fuel mass = ~10x ship’s dry mass), Fusella can accelerate to a maximum cruising speed of no more than about ~0.83 cee no matter what acceleration she uses, which only gives a time dilation factor of ~1.8. Earth time for the return trip will be ~85 years nonstop, ship time about ~49 years. Stopping twice to resupply will add roughly 4 years to the Earth time, and more than 3 years to the ship time.
Bottom line is: Unless the Galaxion’s “regular” drive is FTL, the crew is not getting home before they are close to retirement age, and they’d be better off looking for a planet to colonize…
I just assume that the regular drive is FTL, and that “power” means how fast they can travel rather then fuel. If so a 70% cut in power can mean 30% of max speed or it can mean 30% of acceleration or 30% “warp”. In short the fysics of an interstellar civilization is magic to us, nuclear power vs flint and steel.
It’s interesting how different people interpret this scene differently. My mind followed this path of reasoning:
21.5 parsecs x 3.26 light-years/parsec = 70.09 light-years x 12 light-months/light-year = 841.08 light-months.
841.08 light-months/7 months = effective speed of 120 c (or 120 times the speed of light). Definitely a FTL drive!
My assumption was that the Galaxion’s main drive functions like Star Trek’s warp-drive or the Star Wars hyper-space drive.in that it gets around the light-speed barrier by going outside of normal space. Also, as with those other drives, there is no significant time needed for acceleration or deceleration. Are these assumptions wrong? I ask because I don’t remember any stories which actually describe how this universe’s normal FTL drive functions.
There’s something else I’m wondering about. Back on page 365, Scavina told Fusella, “The understanding was, once we completed the jump home, command of the Galaxion would return to you.” My question is, did Scavina mean “home” as in their home universe or “home” as in back at Earth (or even inside the Colonial Sphere)? Depending on what exactly that understanding was, Scavina could still be in command of the Galaxion, right?
Back on page 26, Scavina pointed out she was still in command because “The experiment is not yet over”. If they still need to use the Jump Drive, then I think that means Scavina is still in command, because she’s in charge of figuring out how the Jump Drive works.
I think comparisons with Star Trek’s warp drive might be right on track. I suspect issues of acceleration haven’t come up because they really aren’t plot points (so far).
As for “Who’s in Command”… during Scavina’s discussion on Page 365 (and subsequent pages), I got the impression that Scavina considered the experiment over once the second jump was complete – she was, after all, apologizing for overstepping her authority, and she said she would announce the reversion of command back to Fusella once the immediate repair crisis had calmed down a bit. I think Scavina would honor that decision even in the face of this new data, though she would probably be a big part of any decisions to be made going forward. Fusella might also be more open to asking Scavina for advice as well.
I’m still a little worried about Col. Anderson, though… I’ve noted before his attitude towards TerSA officers in general and the Galaxion’s crew in particular is cold. How he might react to Fusella’s resumption of command duties, I shrink to imagine.
Tara discussed the issue of travel speeds and the Terran Sphere of Influence back in 2008 in this blog post. She compared the current FTL engines with the Jump engine as being analogous to sea travel vs air travel on Earth — for example, it takes six weeks to sail halfway round the world but only 24 hours in an airplane.
Thanks, Fred! I’d forgotten all about that post.
Good to be reminded!