ORBITAL SERVICE STATION

If rockets could be refuelled in space, it could open up interplanetary travel

Following SpaceX’s first successful landing of its Starship test vehicle and the award of a NASA contract for a lunar lander based on Starship, it’s looking increasingly likely that a Starship will reach orbit in 2021. When launched on its booster stage ‘Super Heavy’, it will become the largest launch vehicle yet, capable of placing up to 150 tonnes into orbit. But once it has done that it will have exhausted its propellants, and the driving purpose of Starship, and indeed SpaceX itself, is to provide cost-effective transport to Mars.

The first challenge was to dramatically reduce the cost of reaching space, and SpaceX set about this by developing reusable rockets – initially the Falcon 9, and now Starship. As Musk has commented, if a jet airliner was used for a single transatlantic flight before being thrown away, flights would be impractically expensive. Recovering the expensive stages and using them again was the key to getting into space cheaply enough to ship a lot of cargo and passengers to Mars. Starship will make that cheaper still, but the next challenge is to refill craft in space so they can actually go somewhere else.