John Glenn was the first American to orbit the Earth, in 1962. It was the start of the adventure that led to the lunar landing in 1969; only seven years later. It was an age of enthusiasm and of great expectations; a time that, today, looks remote. The conquest of space may have been made possible by the high energy yield of fossil fuels that made us rich. But it is a wealth that we don't have anymore; the depletion of the high yield fossil resources is making us unable to afford the kind of extravagances that were possible decades ago. So, the death of John Glenn may signal the end of the cycle of human spaceflight.
On this occasion, I thought I could reproduce a post that I published on Cassandra's Legacy in 2015. It may not be unrelated to the general decline of the concept of human spaceflight that the Italian astronaut Samantha Cristoforetti was criticized in Italy on the basis of the idea that women should stay home and have children. And also because she is probably a witch.
The last astronaut: the cycle of human spaceflight is coming to an end (Feb 9, 2015)
Smart, dedicated, competent, polyglot, and more; Samantha Cristoforetti seems to have been invented for a "Star Trek" episode. She is shown here at the International Space Station, where she is staying at the moment of publication of this post. Cristoforetti may not be the last astronaut to orbit the earth, but it is possible that the end of what was once called "the space age" will not be far away in the future. (image credit: ESA/NASA)
As you see, the number of people sent to space peaked in the 1990s, following a cycle that can be fitted reasonably well using a bell-shaped curve (a Gaussian, in this case). We have not yet arrived at the end of space travel, but the number of people traveling to space is going down. With the international space station set to be retired in 2020, it may be that the "space age" is destined to come to an end in a non-remote future.
The shape of the cycle can be seen as a "Hubbert curve." This curve typically describes the exploitation of a non-renewable resource; fossil fuels in particular, but it also describes how economic activities are affected by a diminishing availability of resources. In this case, the shape of the curve suggests that we are gradually running out of the surplus resources needed to send humans into space. In a sense, the economics of human spaceflight are like those of the great pyramids of Egypt. These pyramids were expensive and required considerable surplus resources to be built. When the surplus disappeared, no more were built. The shape of the pyramid building curve was, again, Hubbert-like.
This result is not surprising, considering that we are reaching the planetary limits to growth. In part, we are reacting to the diminishing availability of resources by replacing humans with less expensive robots, but sending robots to space is not the same as the "conquest of space" was once conceived. Besides, the decline of space exploration is evident also from other data, see for instance this plot showing the budget available to NASA (from "Starts with a Bang").Note how the peak in human spaceflights coincides with the peak in the resources destined to space exploration.
If space exploration is directly related to the availability of resources, it is also true that, from the beginning, it was not meant to be just a resource drain. The idea of the conquest of space involved overcoming the limits of the earth's ecosphere and accessing the resources of the whole solar system. Some of the concepts developed in this area were thought explicitly as ways to avoid the dire scenarios laid out in the 1972 study, "The Limits to Growth." Proposals involved placing giant habitats at the Lagrange libration points, where no energy was necessary to keep them there. The idea gained some traction in the 1970s and, in the figure, you see an impression of one of those habitats - the "Bernal Sphere."(image credit: NASA)
Today, we can't look at these old drawings without shaking our heads and wondering how anyone could take them seriously. Yet, these ideas were not impossible in themselves and, in the 1970s, we still had sufficient resources to make it possible some kind of human expansion into space, even though not on the grand scale that some people were proposing. But we missed that occasion and we much preferred to invest our surplus in military toys. Today, we can't even dream of colonizing space anymore.
The space age is not completely over, yet, but it is becoming more and more difficult to sustain the costs of it. Right now, the Russians are still willing to launch to orbit West European astronauts. But how long will they continue to do so while Western Europe is enacting sanctions devised to cripple the Russian economy? Samantha Cristoforetti, brave and competent Italian astronaut, may well be a member of the last patrol of humans orbiting around the earth for a long time to come.