There has been heaps of activity in space lately—all sorts of countries and insane rich people are putting all sorts of stuff into Earth orbit. I think there’s a temptation to look at this trend and think “hey, humans will probably settle other planets soon.”

However, I do not think that this necessarily follows. The above reasoning masks a few hidden assumptions, which I do not think are valid. Specifically, I believe:

  1. There is a large qualitative distinction, in terms of financial cost and technical challenges, between putting something into Earth orbit and leaving Earth orbit.
  2. There is a large qualitative distinction between an unmanned spacecraft leaving Earth orbit and a human leaving Earth orbit.
  3. There is a large qualitative distinction between leaving Earth orbit and landing on the Moon.
  4. There is a large qualitative distinction between landing on the Moon and landing on Mars, even for unmanned spacecraft.
  5. There is a large qualitative distinction (likewise in engineering and cost, but here also in the very long time-frames) between getting to Mars and getting to the more distant planets, moons, or asteroids in the solar system.

And so on…

To illustrate, ~17,000 satellites have been launched into Earth orbit since 1957 (Wikipedia). About ~200 spacecraft have left Earth orbit since 1960, and a similar number have left Earth orbit and also gone onto either visit or land on the Moon ([(Wikipedia)[https://en.wikipedia.org/wiki/List_of_Solar_System_probes], (Wikipedia)[https://en.wikipedia.org/wiki/List_of_lunar_probes]]).

Now, to date there have been exactly 12 humans who have landed on the Moon (Wikipedia), and to this you could add a few astronauts who orbited the Moon but did not land (space.com).

Nobody has yet been to Mars. The engineering and financial challenges are serious (industry folk talk of a “Mars curse”).

A mere 9 spacecraft have been launched to visit the outer planets (Wikipedia). 2 probes have left the Solar System (Wikipedia) but these aren’t the sort of spacecraft that you’d like to live on.

Note the massive drop-off in numbers: 17,000 satellites, ~400 spacecraft leaving Earth orbit and/or visiting the Moon, a dozen astronauts visiting the Moon, precious few spacecraft that have visited the outer planets or beyond, and 0 humans visiting anything more distant than the Moon.

Clearly there is a bottleneck between launching heaps of satellites and each subsequent step!

An analogy: a child wading in a rock pool and using a magnifying glass to look at all the animals and plants vs touching the bottom of the Mariana trench. Sure, these are both activities involving the ocean, but doing the former does not necessarily mean you can do the latter and using the former as a proxy for the ability to do the latter would be misleading. There are major engineering challenges and costs involved in the latter that are simply not present in the former.

So being capable of putting something into orbit, while certainly a very impressive and meaningful accomplishment—and one that can do much good in terms of improving people’s lives here on Earth as well as bringing us very cool science—does not mean that an actor has overcome any of the major bottlenecks to even getting to the Moon, let alone Mars, let alone Europa, let alone outside the solar system…
so sure, never say never, but it would be misleading to use success in one as a proxy for the ability to do the other

Certainly, human technology is astonishing and can advance quickly. I’m typing this blog post on a computer, rather than chiselling it into a cave wall. Never say never! But there are major hurdles remaining in terms of technology, costs, and time frames.

(For an excellent and mostly up-to-date general overview of human activity in space, see the book The New Frontiers of Space: Economic Implications, Security Issues and Evolving Scenarios by Stefania Paladini.)

(There is also a major debate about whether humanity should colonise other celestial bodies in the sense of having permanent human settlements. Having considered this issue in detail, I’m firmly in the “no” camp. Even the language used in this debate makes me deeply uncomfortable. A good summary of this debate can be found in the book and podcast episode here. Note that I think space colonisation and putting satellites into space are also very different ethical questions—to me, the latter seems far more justifiable than the former.)