How To Ecological and Unexpensive technological approach for launch vehicles

Nov 1, 2021
Hello everyone,
We all know how difficult is to make rockets to fly to space. The most important is what fuel pair is chosen. Each has its own probs:
1. Oxygen-Kerosene : the most common, but requires a huge and expensive cryogenic infrastructure and Oxygen mini-plant near.
2. Hydrgen-Oxygen: same expensive cryogenic inftrastructure + huge issue with Hydrogen itself - it leaks thru almost everything as the atom is the smallest :)
3. Other storable propelats (Acids, Hydrazines etc): super-toxic, super unstable, require a huge safaty infrastructure and storage.
4. Solid propellants: safety first :) no smoking :), and very poor possiblity to do something when it is started :)

But thinking about this, do you have any ideas about someting in-between. Is there any propllants that can be less expensive, less harmful for life? Of course, not to compomise a lot with achieving of good specific impulse :)
And how to make the overal cost of launch reduced as much as possible, using the modern technics, materials and engineering.
I think such discussion can be pretty interesting.
Jul 27, 2021
For sure, the leaders of space flight are working daily to make propellants less expensive, less harmful with all the lore and cutting-edge technologies, tests, applications, having all the variety of engines.
'In-between' might be not exact term to be used. 'Trade off' - is what matters everywhere.
You might put the time into the equation.Time of tests and mission aims.