Humanity's expansion into the Solar System seems to be a recurrent theme around here. We dedicated a podcast to The Expanse and reviewed the book Beyond Earth, which imagines humanity colonizing Saturn's moon Titan. Recently, we got a chance to look at a different take on humanity's travels to other worlds, one that goes a step beyond political drama and existential threats.

Instead, it's all about planetary tourism. Set up like a travel guide, with chapters for each planet and Pluto, Vacation Guide to the Solar System imagines a future in which people spend a couple of decades to do a round-trip to Saturn and don't want to miss any of the major sights when they get there. And, while Vacation Guide is anything but a hard science book, you'll probably end up smarter for having read it. Which is the entire point.

Guerillas in space

The book's authors, Olivia Koski and Jana Grcevich, belong to a group called Guerilla Science, which uses art, installations, performances, and more to try to insert a little science into the lives of people who weren't necessarily looking for it. The group started the Intergalactic Travel Bureau as a bit of a performance—members of Guerilla Science would act as travel planners and ask people what they were interested in before suggesting a planet that would suit those tastes. Eventually, the made-up bureau morphed into an actual storefront in Manhattan.

Now, the Intergalactic Travel Bureau has released a book, one that adopts most of the tropes of a typical tourist guide. So, for each planet, there's a page of basic statistics on the destination, like how Venus goes around the Sun at 78,000 miles an hour. Or how its runaway greenhouse means that the high, low, and median temperatures are all the same. Or how its slow rotation means a day drags on for over 2,800 hours.

Vacation Guide to the Solar System has sections on when to go to each world (Pluto's highly elliptical orbit makes getting there while it's close key) and a detailed discussion of travel times, as well as how to travel around the planet once you get there. For those planets where the surface is accessible and not made of metallic hydrogen, there's a discussion of precautions you need to take to survive seeing the sights.

Thanks to the ESA, NASA, and the Soviet space program, we have a remarkably good idea of what those sights are. So each chapter has a long list of craters, cloud formations, and other strange terrain that no space tourist should miss. Even if the planet doesn't have a surface, it's guaranteed to have moons that do. Koski and Grcevich imagine all sorts of mountain-climbing challenges, along with some truly sci-fi pastimes, like low-gravity baseball or bungee jumping through the depths of Saturn's atmosphere from one of its floating cities.

The authors do cut the verisimilitude ever so slightly short, though. Unlike in a real travel guide, Vacation has no tips on where to stay or eat. There is, however, a long discussion of the unpleasantries of space travel, making it unclear why anyone would want to spend more than a decade to get to Pluto. Though the authors helpfully note that a lot of tourists make this their final journey, since the round trip is nearly half a lifetime.

Does it travel well?

Let's be clear: the authors' dedication to staying in travel-guide mode is admirable and definitely the biggest charm of the book. That said, most people don't read a travel guide cover-to-cover, because it can get more than a bit repetitive. For this topic, the risk of repetition is enhanced by the fact that most of the striking features NASA has identified off-world are variations on craters, chasms, and cliffs. Comparisons to Everest and the Grand Canyon abound.

That said, Vacation is not a book that suffers if you put it down for a bit and come back to it. There's no plot, so forgetting details of an earlier chapter is irrelevant.

And those details are definitely in keeping with the overall goal of sneaking science in to what's partly a work of science fiction. Jana Grcevich is an astronomer, and the material in the book was vetted by multiple other astronomers. The basic information is all solid.

Where Vacation really shines, however, is that Koski and Grcevich have thought through the consequences of those facts carefully. Like noting there's a moon (one of Mars', I think) that's small enough that someone with reasonable arm strength can throw a baseball into orbit. But the attention to detail goes much deeper than that.

For example, they note that we can't build anything that would survive conditions anywhere close to Saturn's surface, which means lighter-than-air ships are essential. But Saturn has a low-density atmosphere that's mostly hydrogen. So, for a dirigible to work on Saturn, its entire interior would have to be a vacuum. In contrast, Pluto's low gravity and frigid nitrogen ices make transport a snap. Simply pump a bit of waste heat under your hovercraft, and it'll explosively evaporate the surface, allowing you to speed across the dwarf planet.

Vacation has plenty of other examples, and I'm having a hard time avoiding spoiling the best of them (I've deleted at least three sentences with others). To see more, you'll have to pick up the book. If you do, it's a fun, new way to look at our Solar System. But, if you're like me, that'll mix with a wistfulness about how you'll never actually see it all.