What if?

One of the problems with space travel is the need for matter where there is little and the need for energy, which exists in abundance, but not in a convenient form.

Obviously, you don't want to carry matter with you which imposes a mass penalty during the escape from the deep gravity well of the Earth.  So, the trick is to get the matter you need up there and use it over and over again.

Moreover, the propulsion necessary for travel will have to come from an energy source of some kind and a matter source for reaction mass.  Since the matter you need is scarce- since it is after all, outer space- which is empty, you will need a way to get matter for propulsion without having to go deep into a gravity well.

So, here is the proposition:  Make a solar panel large enough to provide energy for propulsion and it will also be powerful enough to recycle matter an endless number of times.

Such a large panel require a large structure, and there may be a way to accommodate that.

If you are going to be in space, you will need some type of artificial gravity.  In order to have an artificial gravity of 1g, it will entail a structure that is 1000 meters in diameter.  Such a structure could provide also for a large solar panel to be installed on top of it.  Once spun up, it will provide the gravity, plus all the energy that you can possibly use and then some.

The sun provides about 1300 watts per square meter.  Given the size of the structure, the amount of electricity that could be generated would be about 1 gigawatt at 30% percent efficiency.  One gigawatt is more than enough electricity to power a VASIMR towards Mars on a fast trajectory.

Solar panels need not weigh that much, thus the mass of the panels would not be too prohibitive.  Matter might be obtained from asteroids and an occasional foray onto the Moon or Mars.  Perhaps a LOXLEO design could be implemented which could be powered from the solar panels from Earth orbit and collect gases from the upper atmosphere.

Getting the structure up into space could be the bigger challenge, since it is not clear at this time how that may be done.  If it is to be done at all, it must be modular in design and be lifted and constructed piecewise until the structure is complete.  It should be obvious that this would require a lot of launches and missions.

Therefore, a cost effective way of getting out of the deep gravity well of the Earth must be found first.

This may be possible if a launch system like Stratolaunch is successful.  If not Stratolaunch, some other way may be found.