Translated from the German original. Read the original in German.
In my previous posts I showed where the current limits of what is achievable lie: interstellar space for probes and lunar orbit for humans. To become an interplanetary species, we must make journeys possible between Earth, the outer planets and their moons. That requires reusable launch vehicles and spacecraft.
The first reusable space transportation system was the US Space Shuttle, which flew a total of 135 missions between 1981 and 2011. The programme was designed for maximum reusability – only the external main tank was jettisoned after each launch, and the solid rocket boosters could only partly be reused.
Developed in the 1970s, the Shuttle was a technical masterpiece, yet it fell far short of expectations. Originally 40 to 50 launches a year were planned; in practice there were only four or five. Maintaining the reusable components proved enormously laborious and costly – above all the thermal protection system with its roughly 24,000 heat-shield tiles.
Moreover, much of it was based on 1970s technology, and the risk of total loss was high. Tragically, there were two disasters: Challenger (1986) and Columbia (2003).
In total, 14 astronauts lost their lives.
Financially, too, the Shuttle programme was a disaster. Instead of the originally planned US$200–300 per kilogram of payload to low Earth orbit, actual costs ultimately reached as much as US$60,000 per kilogram.
Nevertheless, the Shuttle marked the beginning of the era of reusability. Many of the necessary foundations were developed by NASA.
The decisive breakthrough, however, came from SpaceX: only six years after the end of the Shuttle programme, on 30 March 2017, it succeeded in relaunching the first stage of a Falcon 9 – another historic milestone in spaceflight. Since then, boosters have been successfully reused on around 90% of all Falcon 9 launches.
Today, reusability really does deliver significant cost savings. The current cost of transporting one kilogram of payload to low Earth orbit (LEO) is now only around US$2,000 to 3,000.
