Back in 1848, John Stuart Mill made a classic argument that money was insignificant to the essential nature of an economy, because it was only a facilitator for what really matters--the actual transactions. Mill wrote (Principles of Political Economy, Book III, Ch. VII):
A century ago, John F. Carter wrote an essay about “These Wild Young People’ by One of Them,” in the Atlantic Monthly (September 1920, pp. 301-304, an excerpt is here, although as far as I know the entire essay isn't freely available online). It offers a useful reminder that complaints from young adults about the terrible world they are inheriting, so much worse than any previous generation ever inherited, are nothing new. Enjoy the 100 year-old version of the classic young-to-old intergenerational rant:
Tyler Cowen has conducted one of his thought-provoking and entertaining interviews in "Abhijit Banerjee on Theory, Practice, and India" (Medium.com, December 30, 2019, both podcast and transcript available). Among his other accomplishments, Banerjee was of course most recently a co-winner of the Nobel prize in economics last fall. The interview is worth consuming in full. As it says in the overview:
Ben S. Bernanke delivered his Presidential Address to the American Economic Association last weekend on the topic, "The New Tools of Monetary Policy" (January 4, 2020, here's a weblink to watch the lecture, and here's a written-out version of the paper on which the lecture was based). To set the stage, he started the talk with a figure similar to this one showing the "federal funds" interest rate--the key interest rate on which Fed policy focuses.
The results of the UK elections have shown something that I have commented on several occasions: The widely spread narrative that British citizens had regretted having voted for Brexit was simply incorrect.
William McChesney Martin chaired the Federal Reserve for 19 years and during the terms of five different presidents, from April 1951 to January 1970. He became chair of the Federal Reserve at the time of the Treasury-Fed Accord of 1951, when the modern Federal Reserve invented itself by declaring that it was no longer going to view its job as keeping interest rates low to facilitate government borrowing--as it had during World War II--but instead was going to focus on how monetary policy affected the economy as a whole. Martin became so synonymous with monetary policy that John F. Kennedy once told an adviser that, before he became president, he could only remember the difference between fiscal and monetary policy by reminding himself that "m" was the first letter of both "monetary" and "Martin." He's the one who publicized the phrase that the job of the Federal Reserve was like a chaperone who needs to take away the punch bowl just when the party is warming up.
The short answer for an estimate of the size of the space economy is: "Probably around $400 billion."