What Scifi Planet Hopping Via Scifi Spaceships Would Really Be Like
Posted: Sat Nov 27, 2021 2:17 am
In both Star Wars and Star Trek, spaceships are huge and have the required power to launch into orbit without any first stage drop off. They are all SSTO.
Also apparently the exhaust in either setting is non-radioactive and relativeky safe, otherwise the spaceships would not be landing near or flying low around heavily populated areas.
And both settings have vessels tgat can accelerate for days on end without refueling.... with a very high specific impulse and TWR when it comes to the relatively small amount of fuel/propellant tanks tanks they actually use.
So in such a setting, what is the safest way to transport goods to planets?
Not the way Star Wars does it. Just think, if any ship can just fly through and into a planet from hyperspace, then safety is impossible,
Part of the problem is that in SW nukes apparently don't exist or are never used. So it either takes fleets to pound away at a planet for a prolonged period or megastructures like the deathstar which can one-shot planets as easily as tiny fighter craft can one-shot it.
The safest way: Hover above an earth-like planet, do not orbit, just slow until you can use engines to hover above the planet in space. Why? You have delta v and thrust in excess anyway, and it won't take long for a planet launched ship to reach you... less then ten min if you hover over the right spot. A large Transport vessel would hover with you, let crew and cargo onboard, while your vessel on auto-pilot lights it's engines for orbit to save fuel. The transport would then fall back down to the planet.
Planetary transport vessels would be called Transports and they would be massive. Why? They would trade the really high maximum speed a long traveling space vessel needs for much higher thrust at the cost of a lower max speed. Higher thrust is needed to get as much payload off a planet and back as possible.
Top speeds for scifi vessel engines are more or less arbitrary, so lets say the massive Transporter has about 6 hours of thrust at 3g, but will last longer if it lowers thrust. For example it could last 1g for 20 hours, but 1g is only good for space, not for getting off Earth.
Meanwhile spaceships would actually be smaller or at least weigh less than Transporters. Why? Because they trade lower thrust for higher max speeds.
Example? A spaceship could travel 1000 hours at 1g before running out of fuel, but it's engines could never haul as much mass as a transporter does. Yet unlike a Transporter a spaceship could do 3g for over 300 hours.
Arbitrary? Partially but partially not.
IRL we can only dream of such high perfomance, but also it is a known fact with rocket engines you often must trade high max speeds for lower thrust (ion engines) or low max speeds for high thrust (chemical rockets).
In scifi you can just.... amplify everything.
Main lesson I learned is the great irony that vessels whose sole job is to shuttle between hovering ships in space and the planet below would and probably should easily be the biggest ships in the scifi setting.
How else do you think all that orbital infrastructure and large spacestation building material gets into space so fast?
Also apparently the exhaust in either setting is non-radioactive and relativeky safe, otherwise the spaceships would not be landing near or flying low around heavily populated areas.
And both settings have vessels tgat can accelerate for days on end without refueling.... with a very high specific impulse and TWR when it comes to the relatively small amount of fuel/propellant tanks tanks they actually use.
So in such a setting, what is the safest way to transport goods to planets?
Not the way Star Wars does it. Just think, if any ship can just fly through and into a planet from hyperspace, then safety is impossible,
Part of the problem is that in SW nukes apparently don't exist or are never used. So it either takes fleets to pound away at a planet for a prolonged period or megastructures like the deathstar which can one-shot planets as easily as tiny fighter craft can one-shot it.
The safest way: Hover above an earth-like planet, do not orbit, just slow until you can use engines to hover above the planet in space. Why? You have delta v and thrust in excess anyway, and it won't take long for a planet launched ship to reach you... less then ten min if you hover over the right spot. A large Transport vessel would hover with you, let crew and cargo onboard, while your vessel on auto-pilot lights it's engines for orbit to save fuel. The transport would then fall back down to the planet.
Planetary transport vessels would be called Transports and they would be massive. Why? They would trade the really high maximum speed a long traveling space vessel needs for much higher thrust at the cost of a lower max speed. Higher thrust is needed to get as much payload off a planet and back as possible.
Top speeds for scifi vessel engines are more or less arbitrary, so lets say the massive Transporter has about 6 hours of thrust at 3g, but will last longer if it lowers thrust. For example it could last 1g for 20 hours, but 1g is only good for space, not for getting off Earth.
Meanwhile spaceships would actually be smaller or at least weigh less than Transporters. Why? Because they trade lower thrust for higher max speeds.
Example? A spaceship could travel 1000 hours at 1g before running out of fuel, but it's engines could never haul as much mass as a transporter does. Yet unlike a Transporter a spaceship could do 3g for over 300 hours.
Arbitrary? Partially but partially not.
IRL we can only dream of such high perfomance, but also it is a known fact with rocket engines you often must trade high max speeds for lower thrust (ion engines) or low max speeds for high thrust (chemical rockets).
In scifi you can just.... amplify everything.
Main lesson I learned is the great irony that vessels whose sole job is to shuttle between hovering ships in space and the planet below would and probably should easily be the biggest ships in the scifi setting.
How else do you think all that orbital infrastructure and large spacestation building material gets into space so fast?