Manned Spaceflight Versus Wilderness Refueling

[Spacescifi]

The safest option would be for manned spaceflight to rely on propellant depots already in existence.

It seems illogical for manned spaceflight to ever bother with wilderness refueling themselves rather than relying on a pre-made propellant depot.

 

Why do I say this? Because processing propellant by the ton takes time... could be weeks or days depending on how much you need.

During that whole time ideally the manned vessel is spinning 100 meters away from a rotating axis point... likely another vessel, while a third vessel is unmanned and gathering and processing chemicals/gases for propellant.

 

Otherwise crew would suffer from having no gravity.

 

The safer alternative to this is to simply send unmanned propellant depot fleets ahead of manned missions, set up and fill the depots, and THEN send manned flights.

 

Kind of like paving a road for cars to drive upon.

 

What I am particularly at odds with is the Star Trek way... boldly going where no man has gone before without even bothering to send an unmanned propellant depot ahead of them first.

 

I know with Trek refueling at sublight is really never an issue... only warp requires refueling.

But a somewhat more realistic scifi setting would indeed send propellant depots ahead of any manned missions always.

Because imagine if you drove your car, was low on fuel, but no gas station was around and you already knew that?

So you do what any unusual person would do... you grab your tools and machines out your car trunk and begin digging for oil... since you were at least wise enough to drive around where natural oil deposits exist.

It takes you a whole month, but eventually you process your fuel and drive back home.

 

Quite the ordeal... and space wilderness refueling is so much worse from a difficulty and dangerous enviroment POV.

 

I know in video game space sims like Elite Dangerous and others you can refuel easily but realistically such is a process of steps and a lot of waiting.

Edited July 23, 2022 by Spacescifi

[SunlitZelkova]

23 minutes ago, Spacescifi said:

Because imagine if you drove your car, was low on fuel, but no gas station was around and you already knew that?

This is not how “all-up” missions work. They just take all of the fuel they need.

25 minutes ago, Spacescifi said:

The safer alternative to this is to simply send unmanned propellant depot fleets ahead of manned missions, set up and fill the depots, and THEN send manned flights.

 

Kind of like paving a road for cars to drive upon.

 

What I am particularly at odds with is the Star Trek way... boldly going where no man has gone before without even bothering to send an unmanned propellant depot ahead of them first.

 

I know with Trek refueling at sublight is really never an issue... only warp requires refueling.

But a somewhat more realistic scifi setting would indeed send propellant depots ahead of any manned missions always.

It depends on the mission type. For scientific expeditions, I don’t think you really need depots. Early Mars mission proposals had all-up missions, the idea of sending ISRU equipment or fuel itself ahead only got developed because it was thought to be cheaper, not any particular mission requirement.

For sustained transport though, whether that be a base or some sort of early colony, refueling at a depot or using ISRU makes more sense.

29 minutes ago, Spacescifi said:

Quite the ordeal... and space wilderness refueling is so much worse from a difficulty and dangerous enviroment POV.

ISRU would never be done without a good sense of what is going to happen on the ground.

Basically every single real life spaceflight concept does not work in such a manner anyways. It’s not like ships where you can veer off course, find an island, and then go about doing whatever you need there- you go to one place period. Everything is planned for that place so there is no particular major danger.

With soft sci-fi engines, it can really just be adjusted as needed for the plot. I may be wrong but I don’t think any of these “acts like a car trying to get from Portland to Chicago” type engines exist in real life, even as far future concepts. They either can’t get there at all, are just right to get where they need to go with residuals for an emergency, or don’t get there at all.

I.e., every single engine is constrained by orbital mechanics to a certain extent so it just goes where it was intended to or doesn’t at all (fails), while the only “point and click go there” type concept- the Alcubierre drive- is so powerful it would likely never run into such a situation.

No “my (sea) ship got blown off course and now I’m faced with this dangerous unknown environment” type things. With 99% of real life concepts, you would require so much energy to end up in such a situation that you would have to be trying to veer off course for it to occur.

Star Trek/Star Wars/soft sci-fi in general type engines that do have such adventures can really just be adjusted for the plot as needed, without real life rhyme or reason, because they aren’t realistic in the first place.

[Spacescifi]

11 minutes ago, SunlitZelkova said:

This is not how “all-up” missions work. They just take all of the fuel they need.

It depends on the mission type. For scientific expeditions, I don’t think you really need depots. Early Mars mission proposals had all-up missions, the idea of sending ISRU equipment or fuel itself ahead only got developed because it was thought to be cheaper, not any particular mission requirement.

For sustained transport though, whether that be a base or some sort of early colony, refueling at a depot or using ISRU makes more sense.

ISRU would never be done without a good sense of what is going to happen on the ground.

Basically every single real life spaceflight concept does not work in such a manner anyways. It’s not like ships where you can veer off course, find an island, and then go about doing whatever you need there- you go to one place period. Everything is planned for that place so there is no particular major danger.

With soft sci-fi engines, it can really just be adjusted as needed for the plot. I may be wrong but I don’t think any of these “acts like a car trying to get from Portland to Chicago” type engines exist in real life, even as far future concepts. They either can’t get there at all, are just right to get where they need to go with residuals for an emergency, or don’t get there at all.

I.e., every single engine is constrained by orbital mechanics to a certain extent so it just goes where it was intended to or doesn’t at all (fails), while the only “point and click go there” type concept- the Alcubierre drive- is so powerful it would likely never run into such a situation.

No “my (sea) ship got blown off course and now I’m faced with this dangerous unknown environment” type things. With 99% of real life concepts, you would require so much energy to end up in such a situation that you would have to be trying to veer off course for it to occur.

Star Trek/Star Wars/soft sci-fi in general type engines that do have such adventures can really just be adjusted for the plot as needed, without real life rhyme or reason, because they aren’t realistic in the first place.

Kind of like spaceship rendezvous... meeting in space up close generally must be agreed upon by both parties otherwise it won't happen.

[StrandedonEarth]

The plan was never to wait around for fuel to be generated;  send the ISRU plant on ahead and launch the crew from Earth when the ISRU tanks are full

2 hours ago, Spacescifi said:

Because imagine if you drove your car, was low on fuel, but no gas station was around and you already knew that?

Gas stations, how quaint. Sailing ships didn't need fuel; just wind. Crew supplies was another matter; (some citrus would be nice). But for a car, the modern plan for driving into the unknown would be an electric vehicle towing a PV panel trailer, or perhaps a water turbine or self-erecting wind turbine. The annoying thing about spacecraft is the need for reaction mass for propulsion, since there is plenty of sunlight in the inner solar system for power. Of course, anything would do for reaction mass if you have a mass driver and are willing to sling hypervelocity sand around the solar system...

 

1 hour ago, SunlitZelkova said:

that you would have to be trying to veer off course for it to occur.

Astrogation error. Don't tell me you never started a burn only to realize later than sooner that the control point was set to that side docking port, and you're thrusting 90deg from your intended vector.

Edited July 23, 2022 by StrandedonEarth

[kerbiloid]

8 hours ago, SunlitZelkova said:

ISRU would never be done without a good sense of what is going to happen on the ground.

Basically every single real life spaceflight concept does not work in such a manner anyways.

Tell it to Musk and Zubrin, with the Martian methane plant for backflight.

***

The refuelong makes sense only at the planet with industrial base on it, and a flight schedule.