Reynard said:
Hard science? Hmm. Power plants are fission at best. Engines are reaction drives. No FTL, maybe a Starfire wormhole network though I'm not sure that counts as hard science. No inertial compensators, grav plates or grav thrust. No screens. Lasers, rail guns, particle accelerators, missiles and Sandcasters seem possible from the trials today. Laser pistols and rifles with bulky power packs seem reasonable. Thank goodness Traveller deems slug throwers and swords as viable. No man portable BFGs. Maybe gauss rifles and pistols again with very bulky power packs. Low berths... maybe. Drones are possible and robots should be at higher technologies.
It's getting to sound more like 2300.
There are a few things that are hard science, that you have not included. What you listed here is low tech hard science, that is tech level 8 basically, you could have higher tech levels of hard science.
For instance from this thread Slower than Light tech levels:
http://forum.mongoosepublishing.com/viewtopic.php?f=89&t=116920
Slower than light tech levels -----c = 299792458 m/sec
Tech Level Speed -----% of speed of light -----γ
0 -------0.000625 km/sec 0.00% -----1
1 -------0.0025 km/sec 0.00% -----1
2 -------0.01 km/sec ------0.00% -----1
3 -------0.04 km/sec ------0.00% -----1
4 -------0.16 km/sec ------0.00% -----1
5 -------0.64 km/sec ------0.00% -----1
6 -------2.56 km/sec ------0.00% -----1
7 -------10.24 km/sec ----0.00% -----1.000000001
8 -------40.96 km/sec ----0.01% -----1.000000009
9 -------163.84 km/sec ----0.05% -----1.000000149
10 -------655.36 km/sec ----0.22% -----1.000002389
11 -------2,621.36 km/sec ----0.87% -----1.00003823
12 -------10,480.63 km/sec ----3.50% -----1.000611648
13 -------41,618.07 km/sec ----13.88% -----1.009777455
14 -------149,774.30 km/sec ----49.96% -----1.154387706
15 -------285,737.82 km/sec ----95.31% -----3.304731592
16 -------299,752.39 km/sec ----99.99% -----61.16588226
You can pretty much ignore the tech levels 7 and lower, what interests me are the tech levels 8 and higher on this table. Instead of making faster than light travel possible at tech level 9 and higher, I'm just allowing starships to get closer to the speed of light, while not quite reaching it or exceeding it. For example at tech level 8 the cruising velocity of a starship is 0.01% of the speed of light, the power plant used to power the reaction engine is a fission power plant, the reaction mass required to reach this velocity is 10% of the hull displacement in dtons, if you want to slow down, then you will need an additional 40% of the ship's hull in fuel for a total of 50% of the ship's hull and 50% of the ship's mass the actual velocity is 40.96 km/sec.
TYPICAL DISTANCES Tech Level 8. Primary Power Source (Fission)
World Surface to Orbit 10,000 km 4 minutes
Satellite 400,000 2.71 hours
Close Neighbor World 45,000,000 km 12.72 days
Far Neighbor World 255,000,000 km 72 days
Close Gas Giant 600,000,000 km 169.5 days
Far Gas Giant 900,000,000 km 254.3 days
TYPICAL DISTANCES Tech Level 9. Primary Power Source (Fusion)
World Surface to Orbit 10,000 km 4 minutes
Satellite 400,000 40 minutes
Close Neighbor World 45,000,000 km 3.18 days
Far Neighbor World 255,000,000 km 18.01 days
Close Gas Giant 600,000,000 km 42.39 days
Far Gas Giant 900,000,000 km 63.6 days
TYPICAL DISTANCES Tech Level 10. Primary Power Source (Fusion)
World Surface to Orbit 10,000 km 4 minutes
Satellite 400,000 40 minutes
Close Neighbor World 45,000,000 km 3.18 days
Far Neighbor World 255,000,000 km 4.5 days
Close Gas Giant 600,000,000 km 10.6 days
Far Gas Giant 900,000,000 km 15.9 days
At tech level 11 it takes 505.75 years to travel to our nearest neighbor 4.4 light years away. Primary Power Source (Fusion).
At tech level 12 it takes 125.71 years to travel to that same star. Primary Power Source (Fusion).
At tech level 13 it takes 31.7 years to travel to that star. Primary Power Source (Antimatter).
At Tech Level 14 it takes 8.8 years to travel to Alpha Centauri. Primary Power Source (Antimatter).
At Tech Level 15 it takes 104.92 years to travel 100 light years, although to the crew, it seems like 31.8 years due to time dialation, the primary power source is either antimatter or an interstellar fusion ramjet.
At tech level 16 it takes 1000 years to travel 1000 light years, although to the crew, it seems like 16.35 years due to time dialation, the primary power source is the interstellar fusion ramjet.
All is this is hard science, as no laws of physics as we know them are violated. Antimatter exists. I eschew Giant lasers and laser sails and other such projected propulsion methods in favor of self-contained starships. A laser sail could reach a higher velocity at a lower tech than could a self-contained starship doing the same thing. An interstellar ramjet picks up its fuel from interstellar space ahead of it, there are some technical challenges to overcome, mostly having to do with interstellar drag, but at tech level 15 this is figured out, and ramjets exceed the abilities of antimatter rockets, at tech level 16, antimatter rockets just can't compete with fusion ramjets because most of the mass of the antimatter starship would have to be the matter/antimatter fuel, one can use staged rockets, but then the starship would not be self-contained. Ramjets take over at tech level 16 for self-contained starships that player characters prefer!