SpaceX took a big step towards full reusability of space launchers on 13 October, a step towards a transformation in accessing space far more cheaply, frequently and with big payloads.

The remarkably successful fifth test flight of the Starship launcher on that day saw a spectacular recovery of the rocket’s 300-ton first stage, Super Heavy, into the arms of the launch pad gantry. The second stage, also called Starship, meanwhile climbed and accelerated to almost orbital velocity and splashed down precisely in the targeted Indian Ocean location off Western Australia. This took the company closer to landing second stages for re-use.

The full reusability of Starship will dramatically reduce launch costs. That means it’s possible to consider new types of activity in space that simply were not viable technologically or were too expensive with past launch architecture.

Most of the envisaged applications are civilian, but possible military applications include launching surveillance and other satellites far more cheaply, and therefore in greater numbers, and even urgent delivery of large payloads across Earth with suborbital flights.

Once SpaceX achieves the capability for one Starship to take fuel from others in orbit, a single mission will be able to deliver up to 100 metric tons or 100 people to the Moon, to Mars and potentially beyond.

The cost of launch matters. Only the first stage of SpaceX’s existing Falcon launcher returns for re-use, yet that rocket has driven launch costs down to U.S.$2720 per kilogram from the U.S.$25,000 per kg that users paid for NASA Space Shuttle flights. The total cost of a Falcon launch is about U.S.$67 million.

Because no hardware will be lost on a Starship flight, the only costs will be fuel, maintenance and use of the pad: U.S.$10 million or less per launch for a future Starship version and, according to SpaceX CEO Elon Musk, eventually U.S.$2 million to U.S.$3 million. That suggests a launch cost of U.S.$100 to U.S.$200 per kg.

Compare this with NASA’s Space Launch System (SLS) rockets, which will be fully expended on each mission, except for their Orion crew capsules. They will initially cost U.S.$4 billion per launch and may end up around U.S.$2.5 billion. NASA will launch only one SLS per year, at best.

Starship’s capacity means it will be able to launch large numbers of satellites on each mission, further reducing cost and rapidly deploying mega constellations, such as Starlink. Alternatively, it will be able to carry very large payloads into orbit—as much as 200 metric tons in a future version of Starship.

At its Boca Chica launch site in Texas, SpaceX is establishing what it calls the Starfactory, an assembly line that will be able to build a Starship a week, up from three a year now. With two more launch sites at Cape Canaveral, there is a suggestion of up to 44 flights a year from this location. Add in the launch facilities at Boca Chica, and the launch rate can exceed that of Falcon 9, currently one every 2.7 days.

Low cost, high payload to orbit and a fast launch cadence open up new opportunities for radically different purposes, particularly when in-orbit refueling is proven.

The most important role for Starship is supporting NASA’s Artemis program to get humans back to the Moon in preparation for human missions to Mars. SpaceX is developing a special lunar-landing version of Starship. Musk has suggested flying uncrewed Starships to Mars by 2026, and potentially crewed missions there by 2028, with his goal being the establishment of a permanent human presence on the planet’s surface.

Low-cost launches by Starship could also support a permanent human presence on the Moon that could then establish an in-space economy and manufacturing capability based on the use of lunar resources. All indications are that the Moon has substantial ice deposits in its regolith around the south pole, where humans will land first. If the water can be used for a base and in making rocket fuel for Starship launches from weak lunar gravity, the Moon will become a launch pad for exploration and resource exploitation across the inner solar system. That’s more important than Mars colonisation in coming decades.