Hello, SFIA audio listeners. In this month's Nebula exclusive, big alien theory,

we're asking the reason alien civilizations might be rare is because most aliens are huge.

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Whether it's real spaceships or those in science fiction, it seems like they are always

breaking down and barely being held together by duct tape.

So what do we do if our ship breaks down a trillion miles from home?

No! down a trillion miles from home. Whether it's crashing a flying saucer into Roswell or Hans Solo, trying to jumpstart the Millennium Falcon, broken ships are something of a staple of space travel speculation and a regular plot point in science fiction,

but they're a very real concern in science and engineering. Spaceships do break a lot,

even for all the top-notch engineering we put into them, because they

are for extreme conditions, and in many ways nearly every single flight is a test flight

or a prototype of something.

We don't have thousands of routine missions to field test some new widget or feature until

it is ultra-reliable.

The flip side of that is that we would expect that in the future,

and so it's surprising how often things break on spaceships in sci-fi, or get sabotaged,

or have a backup that's also broken. A quote that comes to mind is for my favorite Starfleet

engineer, Chief Myers O'Brien, when he's explaining why he had to replace

a component with a lower capacity one to make room for a secondary backup.

Well, in order to bring the system up to Starfleet code, I had to take out the couplings

to make room for a secondary backup.

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