Fortress Sol by Stephen Baxter: Review by Alexandra Pierce

Fortress Sol, Stephen Baxter (Gollancz 978-1-39961-461-0, £25.00, 480pp, hc). October 2024.

Fortress Sol is classic Stephen Baxter. It’s driven by big ideas: Humanity’s response to a perceived existential threat includes both dispersing to the stars and mind-boggling engineering projects. Like 2021’s Galaxias, the focus is not so much on the alien threat as on humanity’s response. There’s a relatively small cast of characters, who are engag­ing enough but may not be sufficient to keep a reader attached if they’re bored by the science and engineering. And some pressing contemporary questions are addressed through the various crises.

In the year 2198, humans are mining the clouds of Neptune. The crew of the James Watt encounter and name the ‘‘lumes’’ (for ‘‘luminous menaces’’) – small objects which appear from outside of the solar system, fall into Neptune, and release an unexpectedly large amount of energy. There is no communication from them, no indication of intent, and no explanation of what they’re doing. Humanity basically panics. Some people end up fleeing – constructing generation ships to take them, hopefully, to safety. Others stay behind and construct a fortress.

Flash forward to 3207. Earth’s solar system is now hidden in two ways: there’s the System Mask, an envelope for which the word ‘‘big’’ is laughably inadequate: It encloses the solar system from Uranus on in, and anyone approaching from outside will be shown a destroyed (and therefore unattractive) solar system. And then there’s the Solar Wrap, which hides the sun both physically and gravitationally. Inside the Mask, the planets and human society are connected by the Frame, a solar-systemwide highway. And all of this is only possible because, while still fearing the intent of the lumes, humans have learned to harness the lumes for power and light.

Baxter focuses on the consequences for human­ity of constructing this fortress, with the narrative almost entirely set within the solar system. He does so through both those who live within its bounds and through outsiders. On the inside, the key character is Rab, a young man whose mother was so determined that he would not end up being sent to the Mercury mines that, when he was two years old, she tried to run away from her assigned living space – and when that failed, she cut his hand off. Now an engineer, Rab works on the Mask, coincidentally under the former law enforcement officer who caught his mother trying to run. Rab is working on the section of the Mask that identifies the first ever ship outside of the Mask. It turns out to be a generation ship from a colony established many centuries ago, returning to see how Earth is faring. One of those onboard is 19-year-old Muree, whose main job on the starship Lightbird is working on the lume tank, and whose friendship with Rab is the core of the story. Together, they find themselves questioning everything Rab has ever known – especially the purpose of the Mask and the Wrap, and the way the solar system society works.

Urgent questions are addressed in Fortress Sol: In particular, what do humans do when faced with an existential threat – do we run or do we hide? (Or, the third way which is hinted at but not ad­dressed – try to understand it.) And then how do we assess when that threat might be over, or might not actually be the threat we thought it was? Espe­cially when the people in power have little reason to want to change the way things have been for a long, long time. Population control, for example, has been a powerful issue for both those who fled and those who remained, both in terms of birth rate but also in deciding what jobs need to be filled and how to make sure that (for instance) there are enough workers to do the hard, dangerous mining required to keep the society functioning. In this and other issues, conservatism – this is the way it always has been and the way it must continue to be – has reigned supreme; any challenge must be dealt with swiftly. Which is, of course, the grit that becomes the pearl here. This questioning of the status quo was a deeply satisfying part of the novel.

There are aspects of the story that don’t entirely work. In particular, I found it hard to accept that humans who have been separate for a thousand years could assimilate quite so quickly: Imagining myself talking to someone from, say, Cnut’s Eng­land seems unimaginable. Of course we have had phenomenal technological change in that time – but even for someone from (what we call) England in 1024 talking to someone from England in 2024, the differences would be enormous. Baxter does address this issue briefly, mentioning ‘‘translation circuits’’ and essentially suggesting the deliberate conservatism of both cultures has prevented too much change; but it did feel awkwardly hand-wave-y. Another heavy-handed aspect is when Rab and Muree’s adventures become a grand tour of the solar system, and Muree learns all about how the Frame and the Mask work. The novel becomes overly didactic – especially because it was inspired by classical, pre-Copernican conceptions of the solar system, which then need to be explained also.

Fortress Sol is an enjoyable, standalone, hard-science fiction novel; it’s evidence, if it were needed, that big engineering ideas can still become excellent stories.

Interested in this title? Your purchase through the links below brings us a small amount of affiliate income and helps us keep doing all the reviews you love to read!

This review and more like it in the December 2024 issue of Locus.

While you are here, please take a moment to support Locus with a one-time or recurring donation. We rely on reader donations to keep the magazine and site going, and would like to keep the site paywall free, but WE NEED YOUR FINANCIAL SUPPORT to continue quality coverage of the science fiction and fantasy field.

©Locus Magazine. Copyrighted material may not be republished without permission of LSFF.