I like space. I have 42 titles on my bookshelf with the word “space” on the cover. This probably triples if you include “Astronomy,” “Astrophysics,” “Stars,” “Planets,” “Universe,” “Cosmology,” etc. I’ve never really particularly cared about where “space,” begins, and that probably is because my dissertation work and many journal articles from there on dealt with objects that were sometimes billions of light years from Earth. To say they are located well past the starting “edge” of space (from Earth’s perspective) is an understatement. However, recently we’ve had some boasting from our favorite space fairing billionaires about which one was really going to “space” first. We may still dismiss this as irrelevant, but we can see why an agency with “Space” in its name, such as NASA, may have reason to define terms. Also, because there are international agreements on what can and can not be done in space, for legalistic reasons, we need to know what exactly has been agreed to and for that reason also, we might need to know what we mean by “space (though there is till no universally accepted legal definition!)”

As had been originally discussed by Karman, and then more recently by Jonathan McDowell and others, we can define a point in the atmosphere at which aerodynamic forces such as lift become weak as compared to dominate forces well above the atmosphere, such as centripetal forces related to gravity. Some have put this at about 50 miles and some have rounded to more like 60 miles (possibly because it works out to be close to 100 kilometers). The summer Virgin Galactic flight met the lower defined barrier and the Bezos flight met the larger estimate. Since this time, Space X has had one orbital flight consisting completely of civilian astronauts (space tourists). That flight was hundreds of miles above the surface of the Earth.

So now “The big three” competitors for space tourism have now gotten to space.

Does this have any real meaning? Perhaps it just means that getting to space is a bit cheaper and safer. I don’t think it really means we’re closer to colonizing Mars or anything like that (or at least not by much).

Also, I think its valid to consider whether this is the best use of our resources. True space exploration and deploying necessary satellites seem justified, but tourism?

Its an interesting turning point. When I was a kid I thought we’d be at this point before I became an adult (say, 1985). I thought in late adulthood, I’d probably be flying to the Moon regularly. Well, maybe I will be. Perhaps we’ve finally reached *that* future.

If you’d like to read more about such issues in science fiction, read The Physics and Astronomy of Science Fiction, by Steve Bloom (me) and available from Amazon, B&N, and the publisher, McFarland. Its is available in electronic and paperback.