Inkblot Extraterrestrials
Aliens are in the news.
It's not surprising. A little less than half of the electorate of the US has decided that conspiracy theory as a form of government is just fine with them, so why not? It's all fun to laugh at, until it isn't.
But I think the thing with aliens is really interesting. Whether or not you believe that there are aliens out there right now buzzing through our skies says a lot about you as a person. There are some obvious things – a lack of trust in the government, disbelief that non-Europeans could have built big things, not understanding technology so it must have been reverse-engineered – that sort of stuff.
But a belief that aliens exist and are among us is also a weird kind of optimism.
"But where is everybody?" is (allegedly) how Fermi put it. If the universe is big, and life can arise in other places like it did here, and Earth isn't the first place to develop life, then someone should be out there. Little green men aren't walking around downtown, so their absence sort of demands an explanation. Maybe we're early in the life-bearing era of the universe. Maybe every intelligent species eventually nukes themselves into non-existance. Maybe they all develop giga-computers and stop caring about the universe as they plug into the Matrix. Maybe FTL isn't possible. Maybe it's hard to do space travel and also feed everyone on your planet. Or maybe we are unique, and the professor at my college was right, and his dubious math showing life couldn't actually arise anywhere did prove it had to be intelligent design, and the people who didn't get good grades because they disagreed were wrong. But I digress.
If there's other life in the universe, but there are no alien visitors to Earth, it's bad news for humans. That means somehow every species has gotten stranded on their homeworld, and it's probably for reasons that are kind of a bummer. So, to me, the people who advocate that yes actually the aliens are out there are profoundly hopeful. We can get through the Great Filter, because someone else already did. We'll eventually solve hunger, because how would you go out into the universe if you haven't solved scarcity? We'll eventually figure out how to avoid nuclear armageddon, because check it out, they did. FTL is possible – see, they're here. We won't all just lock ourselves into a VR-island-of-lotus-eaters, becuase they managed not to.
I don't think the aliens are here.
And besides the fact that we have no credible evidence for them, I just don't think anyone can get through that Great Filter. In 1945 the whole world figured out how easy it would be to fail that test, but really, you don't need nukes for that. The World Wars kind of stopped because of nukes, and without them, we'd probably have had another one in the 50s or 60s. A culling like that every twenty years would keep us firmly planted on this planet. But with nukes, we have to worry about The Last War, where those of us who aren't radioactive vapor get to pay for bullets with bottle caps and try not to get eaten by radroaches.
Maybe nukes aren't the Great Filter. It could be something else. It wouldn't have taken that many base pairs to be different and the 2020s could have been like the 1350s. As long as the aforementioned conspiracy theorists keep getting elected, I'm not sure that won't be a problem going forward. That'll definitely keep us focused on continuing to breathe, not going to alpha centauri.
I mentioned the whole voluntary-extinction-through-Matrix thing because that's less overtly horrible than the rest of them, and (given it would be possible) I can totally imagine us doing that. Surveillance Capitalism is a lot easier when your whole mind has cookie tracking on it. Or maybe it's boring, and we just exhaust the resources of the earth as we create a lot of value for shareholders. Not every Great Filter has to be violent.
My guess? We'll eventually get caught in a Great Filter, just like everyone else, and that's why there are no aliens, and it's probably because of a thing we don't even know about yet. It's pessimistic, I know. I'd like to be proven wrong. But the types of folks that just insist that they exist don't give me a lot of confidence.
An Ode to Delta IV Heavy
The final Delta IV Heavy launch from Vandenburg just happened, and it kind of makes me sad to see it wind down – especially when comparing it to SLS. There are plenty of things to complain about relating to SLS, but two stand out when comparing to Delta IV Heavy: the engines and the boosters.
Its main RS-68 engines are derived from the Space Shuttle's main engines, but are intended for a single use, and are simpler and less expensive as a result. The heavy variant has three nearly-identical cores in the first stage, with the outer two serving as boosters. The RS-68 sheds much of the complexity of the RS-25's by cooling the nozzle ablatively, which you can do when you only need to use it once.
Compare that to SLS. If it ever gets off the ground, it will result in four flight-proven, re-usable RS-25 SSME's being thrown into the ocean as garbage. An earlier iteration of the Shuttle-derived booster concept did use a few upgraded RS-68's, but they decided the engineering required to manage the interactions of the RS-68's ablative nozzles with the solid boosters was too difficult to overcome.
And yeah, the boosters. SLS uses Shuttle-derived solid rocket boosters. I think this is really bad for everyone that doesn't work for Northrop-Grumman. Humans should never fly on a rocket that uses solids as part of its primary propulsion. Obviously, there's Challenger. That failure was predicted and ignored by managers suffering from go-fever. But in the leadup to SLS's predecessor program, the Air Force determined that in some phases of flight, a solid rocket failing would have a 100 percent chance of killing the crew due to the escaping capsule's flight through a shower of burning fuel. Watching a capsule full of crew successfully escape a failing rocket only to lose its parachutes to burning debris would be heartbreaking.
Delta IV Heavy doesn't use solids for primary propulsion. A failing side- or core booster would be really bad, of course. But it would probably result in an explosion that isn't followed by a persistent fire. By the time an escaping crew came back down through the altitude where the failure happened, the propellant would already be done burning.
Okay, so how about the upper stages? I'd compare them, but SLS uses Delta IV's second stage in an almost unchanged state. Of course there are plans to upgrade SLS's upper stages in the future. But that requires it to fly more than once or twice. We'll see.
Crew-rating the Delta IV Heavy would take some effort. NASA did a study (pdf) early in the Constellation days and said it could be done. It would require some new software, avionics, and process changes in manufacturing. The biggest change would be to modify the second stage. Here's the thing – that modified second stage could be done, because that's what the SLS second stage is. Although I'm not sure how I feel about Boeing's ability to safely implement hardware and software changes without cutting corners.
In the end, I'd feel a lot better about a crew-rated Delta IV Heavy than SLS. Sure, it's expensive, something like $250 million a pop. But SLS is like eight times that. And you have the solid failure debris problem, and the bad feeling of throwing SSME's into the ocean. And while I think the safest crew-rated rocket on the planet right now is Falcon 9, I'd much rather climb onto a Delta IV Heavy than SLS.