Space Missions to Mars up to now have been small satellites where the entire mission was launched from Earth. The delta-V has been about 3.2 to 3.5 kilometers per second.
By refueling the SpaceX BFR in orbit and assembling a few stages in high orbit, a large chemically powered space mission can get up around 9.0 kilometer per second delta-V.
We will not need to wait decades for super-advanced space propulsion to be developed for less than 60-day trips to Mars. Elon Musk and SpaceX should have the BFR flying within 5 years.
Short 45-60 day or even 30-day trip using large multi-stage chemical rockets launched from high orbits after refueling will make large fast missions easy. The shorter times mean far less radiation and health issues for astronauts and passengers. The far larger ships means water and other material for radiation shielding.
Bigger and more powerful spaceship will be like cruise ship versus dingy
The Mars missions we have sent have been less than 1000 kilograms but putting a few BFR payloads together could send 1000-ton Mars missions.
SpaceX is bringing the next BIG future in space.
In World War 2, after D-Day there was 8,500 tons per day of cargo being sent to the beaches. Fifty SpaceX BFR would be able to regularly shuttle that amount of material to orbit. We will be able to invade space (moon, orbits, lagrange points, Mars) the way Europe was invaded by the allies.
Power starved up to now
The low power and delta-V budgets have forced space mission planners to use slower hohmann transfers. Those are the most economical but are long circular orbits that look more like orbits around the sun than targeting a flight to Mars.
Elliptical and parabolic orbits have less curve and are much shorter and much faster trips.
Earth-Moon Lagrange 2 or EML2 is one of 5 locations where earth’s gravity, moon’s gravity and centrifugal forces all cancel out. It lies beyond the far side of the moon at about 7/6 of a lunar distance from earth.
EML2 would make a great transportation hub. Not only for travel to destinations throughout the solar system but also within our own earth moon neighborhood.
The SpaceX BFR will be fully reusable and able to carry 150 tons for Earth to Low Earth Orbit but it could refly once to seven times per week. So a lot of refueling missions and taking large pieces of space stations and moving large payloads between low earth orbit, high orbits, moon and lagrange points will be easy.
Place Multiple Bigelow Hercules resupply depots at each Lagrange point, various Earth orbits, lunar orbit and Mars Orbits