Starship will change everything. And I mean everything. Everything you know about spaceflight going back to Sputnik will be wrong.
The old paradigm is that you launch something to the place it’s going to need to be, on a rocket that you throw away. You accept the payload penalty of going to that place that is suboptimal, in terms of
inclination or altitude, relative to its nominal due-east performance
from its launch site. You also have to accept launch windows, and the
risk of missing them due to weather, or technical issues, which can be a real problem for a grand tour of the solar system that you only get one shot at in a decade or five, because that’s just the way it is, and the way it’s been forever.
That is about to change.
The easiest orbit to get to from the planet’s surface is equatorial. You get maximum advantage of earth’s rotation by launching due east at the equator. There are no launch windows to get there; you can launch any time of the day, every day, and you will be in the equatorial orbit plane. There is also little weather risk; hurricanes at the equator are almost unheard of (there’s too little coriolis there to spin things up).
So if you want a steady pipeline of stuff going into space (and coming
back) at minimal cost, it can be done from some number of spaceports on the equator.
There is another advantage to equatorial orbit, from a space
sustainability standpoint. If everything we had in space was in a single orbit plane, it would be much easier to do space traffic control because it is reduced to a two-dimensional problem, at low relative velocities, without all of the high-velocity conjunctions that occur in multiple orbit planes.
Finally, having a single orbit plane to deal with vastly simplifies
mission planning for beyond-LEO flights, whether to the moon or beyond cislunar space. This is where my harbor analogy comes in. Everything leaving the vicinity of the earth or returning to it, will do so via that orbit plane.
So why don’t we do that?
For two reasons: 1) You can’t get to an equatorial orbit from a
non-zero-latitude launch site without severe payload penalties (if you can get there at all), and all sovereign launch sites to date are non equatorial; and 2) Many satellites want to have inclinations greater than zero (e.g., remote sensing, and communications and navigation constellations), and the velocity cost of getting to those inclination in LEO from an equatorial orbit can be higher than the cost of getting into orbit in the first place. For example, if you wanted to do a plane change of sixty degrees in LEO of a payload that had been delivered there by a Falcon Heavy, you’d have to start by putting another Falcon Heavy in orbit to do it.
There are solutions to both of these problems, and they’re happening now.
The first problem is solved by building equatorial spaceports out of
which SH/Starship (or its I hope inevitable competitors) can operate to provide regularly scheduled service to and from ELEO. The idea would be to do everything that doesn’t require a different
inclination/altitude (e.g., weightless research and manufacturing, or
space tourism that accepts that only the equatorial region will be seen from orbit) in the equatorial plane.
The second is solved by moving things that do require different orbit planes and altitudes there by alternate means to chemical propulsion (e.g., electric thrusters). This can take a long time, but if there’s no rush, that’s not a problem; we’re already doing it with GEO comsats. But for those things that do require higher inclinations/altitudes and are in a hurry and can afford it (e.g., space tourists who want to see a lot more of the planet from above), this will continue to provide some business for existing launch sites.
But here is the key point. I am not proposing this for existing markets; it will require vast new ones. The goal is not to reduce the amount of stuff going into space via the old paradigm (though that will happen to a significant degree), but to dwarf that amount of activity with new activities enabled by the new one, with its vastly reduced costs of getting things into and out of orbit. I’ll quit here for now, and let people discuss in comments just what those things might be.