Revelling in things that are non-quantifiably, hard-to-explain, valuable for their own sake is one of the great features of being human. For me, one of these things is an interest in space. Rockets, stars, impossible questions about infinity — you name it, I’m a sucker for it. Sure, there are great practical reasons to learn about all this. But space is also just, well, exciting and wonderful and frightening and beautiful — all of those slightly embarrassing, overly emotional words — in itself. One of my favourite childhood memories is looking at the stars with my dad; I rarely do so these days without thinking about and missing him. He loved the idea and reality of space even more than me.

Like most of us, though, I don’t make enough time for my less pragmatic interests. I’m never going to be an astronaut or an astronomer, so I don’t prioritise reading or thinking about their domain. Having disbanded my usual priorities over the Christmas break, however, I read the Canadian astronaut Chris Hadfield’s excellent 2013 book about his three missions in space and what he’s learnt from them. It convinced me that space exploration can be used as an exemplar point for many standard arguments within the realm of politics and policy. (Or, yes, maybe I just want to prolong the holidays and think about this stuff some more.)

Hadfield spends a great deal of the book — both explicitly and implicitly — justifying the existence of the Canadian space programme. Its enterprises are, unsurprisingly, vastly costly to the taxpayer. He does a great job: emphasising the educational benefits, defence and geopolitical gains, advances brought to medical science thanks to astronauts’ experimentation, and so much more. The man is a (space)walking example of why space travel is important. But that doesn’t necessarily mean that taxpayers should fund it, does it? At the least, it doesn’t tell us anything about the extent to which they should.

This leads to a crucial yet overlooked problem. We don’t spend enough time truly justifying taxpayer expense. Governments don’t. Policy-thinkers don’t. Sure, people do sums, and make clever arguments. But, too often, we’re left dependent on idealised aggregate answers, such as estimates of the welfare-maximising level of government spending as a proportion of GDP, and the like. The personal tax burden here is at its highest for decades, yet we rarely hear an acceptance of that truth, never mind concerns about it. And without that acceptance and those concerns, we can’t get down to the important work of determining what should indeed be paid for by the taxpayer — and how this changes over time.

There are two main reasons why things might genuinely need to be funded in this way. The first is that they are essential — or justifiably desirable — yet might not otherwise come about. This is usually termed along the lines of a ‘public good’ argument: we won’t each voluntarily choose to pay for a proper nationwide road system, so the state had better tax people and set it up for them, and so on. It’s probably the case that too many things are lumped into this reasoning, but it surely stands regarding some necessities. The second reason is that these are things that the state (read taxpayer) ’should’ fund, for other reasons aside from (or on top of) necessity of provision, often on the grounds of principle. These are much trickier, and include examples ranging from “education is tainted by the profit motive”, to “we can’t trust our national security to a motley band of foreign mercenaries”.

Space travel is almost always funded by the taxpayer — certainly outside of America — and the usual ‘argument’ given is that it has to be: that it wouldn’t happen otherwise. This argument depends on two assumptions: that space travel has to (or should) happen, and that there is no other solution than state funding. For now, let’s give the first assumption the benefit of the doubt. Hadfield et al make a convincing case, not least in terms of the twenty first-century space-race context. If a drone can stop an airport, just imagine what an enemy country could do with modern space power. The proponents of ’space diplomacy’ are currently seeking to counter the rise of ‘space militarism’ — this is not a battle we can realistically ignore.

But to what extent should this be funded through general taxation? Space X and Virgin Galactic are becoming household names, and many other private space companies are making leaps and bounds. These leaps are nowhere near Neil Armstrong’s yet, however. Sure, the private sector is driving the UK’s capacities in this area: Gabriel Elefteriu, a space-policy expert, points out that the UK’s ‘domestic space champions include Inmarsat, one the of world’s largest satellite operators, and Surrey Satellite Technology Ltd (SSTL), the world’s leading small-satellite manufacturer’. But the truth is that nobody’s getting to the moon without vast amounts of state support, and even the most successful private space companies tend to depend on state grants, and have the incentive of big (American) government contracts. The recent Lunar X Prize competition proved quite how expensive participating in the field is — this neat MIT article explains that the un-won $20 million prize was ‘actually relatively little money: to have any chance at winning, teams found, they needed much more’.

Yes, as private companies succeed, more investors will come to join the brave early adopters. Yes, we should thank the rich people who advance science for all of us by blowing their money on their far-off dreams of joining Branson or Musk in space. Yes, competition will drive up standards and push down costs. But, for now, it’s hard not to accept that space travel is dependent on the Government committing our hard-earned cash.

The best arguments for this emphasise our need to be protected through advances in defence capabilities, ranging from military to medical technology. But they also respond to that fundamental interest — that human need and desire — to know more about the universe, to engage with it, to play our part and explore and achieve. To value knowledge in itself, and our world for what it is. If we agree to take part in organised society, and therefore recognise that the state has a role to play in our lives, then it seems as if space exploration is a good that the state can enable, for the benefit of all mankind. Of course, the level of spending on this still needs to be justified, and we must continue to keep assessing its relative importance. But there’s something about space that just won’t go away.

This article first appeared on Conservative Home.