When will the next space disaster strike? Riding the unicorn of reusability
After the retirement of the space shuttle in 2011, Nasa has used Commercial Crew Launch Vehicles to ferry astronauts and supplies between the International Space Station (ISS) and Earth. It was marketed as turning over space to the private sector. As the legendary founder and director of Flight Control Christopher Kraft (RIP) pointed out, the money comes from public funds, and the companies (SpaceX and Boeing, and to a lesser degree Amazon) build the craft, so it’s open to debate how private the new venture is, but that’s another discussion. Don’t get me even started on touchscreens.
I hate touchscreens.
There was not a single fatal disaster since Columbia accident in 2006, involving a now retired spacecraft. Taking Crew Dragon of SpaceX as the milestone, crewed missions continue from 2020. In four years, there was not a single fatal event, and SpaceX and NASA deserve applause for that. Comparing with the space shuttle, which made its maiden flight in 1981, there would be 5 full years of safe flight. However, a problem was brewing, and as it turned out, it took 5 years to come to the fore. Without elaboration, O-rings on the solid rocket boosters (SBRs) were so damaged that even with a redundancy they failed to hold super-heated gas from penetrating the SRB’s surface and cauing the explosion of the vehicle.
Reusability is a popular concept from software programming to mechanical engineering. The gist is that reusable components reduce cost. SRBs were reusable components. They would fall into the sea, then recovered, checked for damage and refitted for the next flight. The idea, originating in the conception of the shuttle, was that reusability would decrease cost as was canonically preached. Financially, it was proved to be wrong. Any part of equipment must be made to a higher standard, and so is more expensive that a one-time use one. Especially in a field as safety-critical as human space flight, a reusable component actually increased costs. The shuttle turned into a white elephant sucking more funds. But money is irrelevant compared to human lives. Not only did reusability fail to lower cost, it also made failure more likely after consecutive flights. Even though reusability is limited to 4 or 5 times, it makes failure more likely.
Not only did reusability fail to lower cost, it also made failure more likely after consecutive flights.
Timing is the critical concept here. As in the shuttle, metal parts show wear in a few years. As time goes on, metal fatigue and other factors start to emerge. And in the extreme heat and cold of space, these effects are amplified. The early period of successful space flight should not make us complacent about possible failures that can manifest themselves only in a few years. Reusable components should only be considered for non-critical cargo missions, and banned for human and nuclear missions. The time to raise the alarm and check the books is now. Before it strikes.
The early period of successful space flight should not make us complacent about possible failures… Reusable components should only be considered for non-critical cargo missions, and banned for human and nuclear missions.
