On changing trajectories
Discover more from Not Not Rocket Science
On changing trajectories
From interstellar orbits to the names of telescopes, changes in knowledge demand a shift in motion
In this issue:
The Overview: We Might Not Be Alone In the Universe
Scientific American: NASA Needs to Rename the James Webb Space Telescope
Aliens, As Usual
Recently I had the pleasure of being interviewed for Peacock's The Overview, a news show hosted by Gadi Schwartz. As you may have guessed, it was about aliens— I do love to talk about aliens— but specifically, Gadi wanted to talk about the idea of astronomical anomalies, weird objects or events that seem to defy the usual astrophysical explanations.
For the past several years, I've worked on the very fun problem of trying to find what you're not looking for. When I worked on the Kepler mission, I was struck by how many cool new discoveries beyond its haul of exoplanets happened by chance— because Kepler's goal was to find planets around other stars (which it was very good at doing!), all the mission's software was designed to do exactly that. That's not a flaw, but rather part of designing space missions: astronomers work backwards from carefully crafted scientific questions to build both hardware (the telescope) and software (the algorithms) geared towards answering the mission's questions. If other discoveries get made along the way, then great, but they're often side quests in the larger journey. As a result, other curious stuff in the data was often spotted by a person looking at it by eye (rather than by any kind of automated program, like the ones used to find planets), and I often wondered what would become of those discoveries if no one happened to look.
At the time, I had also started working on The Vera Rubin Observatory, a massive telescope project (currently under construction in Chile) that will image the night sky every few nights for ten years, creating something like a giant stop-motion movie of the universe. The Rubin Observatory (then called the less-catchy "Large Synoptic Survey Telescope", or LSST) would be collecting so much data, it wouldn't be possible for someone to look at all the data— it might not even be possible for MANY someones to look at it all, leaving us reliant on careful software mining. But how would we find anomalies— the weird things, the FUN things, the things you don't even know you're looking for?
How to find something when you don't know what to look for is one of my favorite questions, because it is the most central problem in the Search for Extraterrestrial Intelligence (SETI). We human beings do a lot of thinking about what kinds of signals might indicate that we've intercepted signs of life from beyond our planet, but as my colleague at NASA Ames Jeff Scargle once put it, we're really just "psychoanalyzing E.T.". Our efforts to make informed guesses about what signals to look for aren't bad— in fact, I think they're great— but also, we really don't know anything about what alien life might be like. We design experiments with the hope that some of our informed guesses will be correct… or perhaps with the hope that, if the universe produces a plethora of life, maybe some of it will be enough like us that our guess would be close. And we might be right! But also, we might be wrong.
I often think about an incident that happened with my cats a few years back: I had a very fluffy gray cat named Fermi, who in his senior citizen years was not always great at keeping up with his abundance of fur, and so who I would occasionally take to the groomer for trims. Behold, proof of fluff:
One time, the groomer doused him in an eye-watering amount of what I suppose I'll call cat perfume; he smelled like a chemical spill at a baby powder factory. I brought him home, figuring it would wear off, and plopped him down in the living room. My other cat O-Ren, who usually adored him and had seen him a mere few hours earlier, arched her back, hissing and snarling. I couldn't figure out why, and then I realized: to me, he was the same Fermi, he just smelled awful. To her, he was unrecognizable— because as much as we anthropomorphize animals, they are not human, and therefore relate to each other and the world completely differently than we do. Cats don't think of smell as a superficial quality that can be changed— they don't apply perfume, or lotion, or use soap. A cat that doesn't smell like himself may as well be a different cat.
I think about that moment because it's rare to get such a direct view into how differently another intelligence— in this case, a cat— views the world. In SETI, people study animal communication (particularly among whales) to get hints into how other species interact and share information. And yet, we are only slightly closer to speaking to whales than we are to speaking with some unknown form of alien life.
So, I do the opposite of what most SETI searches do: I use software to just look for everything that's unusual in these big piles of data we now collect (and are hoping to harvest more of soon). In recent years, most of that work has been done by my colleague and former graduate student, the newly-minted Dr. Daniel Giles, who is now a postdoc at the SETI Institute working with Dr. Ann Marie Cody on looking for anomalies in the data from the Transiting Exoplanet Survey Satellite, or TESS. Unlike traditional SETI searches (which are very much complementary to my approach, and worthwhile in their own right), it's hard to find a so-called smoking gun using this method— there are often weird things in large datasets, and usually those weird things are pretty boring (data glitches and the like). But, it does open you up to finding what you never knew to look for in the first place, and that's exciting!
Anomalies have been in the news again recently because of Prof. Avi Loeb, an astronomer at Harvard, and scientifically-speaking, what Charlie Murphy might call a "habitual line-stepper". Prof. Loeb works on a wide variety of topics, and is in particular known for his more fanciful ideas. Of these ideas, the one that's back in the news is his assertion that 'Oumuamua, the interstellar object discovered back in 2017, is a remnant of an alien spacecraft (spoiler alert, in case you stop reading here: it is almost certainly not an alien spacecraft).
I have previous written about his work on 'Oumuamua in the context of whether imaginative hyperbole actually pushes boundaries in science (which you can read here)— the short version is that if you are a tenured Ivy League professor (and a cishet man, and white), your reputation as a scientist has essentially been bulletproofed against all but the most outlandish claims. As a result, making provocative claims might work well for you, but doesn't actually push boundaries by making it easier for other scientists to do so— scientists who don't have job security, or assumptive authority conferred by identity, are still vulnerable in all the ways they were before... it's just that now, in addition to whatever else they were doing, they also have to answer questions about whether 'Oumuamua is a spaceship.
So, I know you want to ask: IS 'OUMUAMUA A SPACESHIP??? OK, let's recap. As mentioned in The Overview, the image you've perhaps seen of 'Oumuamua, where it looks like a long rocky cigar, is an artist's conception. That illustration is informed by the data itself— in 'Oumuamua's case, changes in brightness that indicated that it had to be elongated and tumbling, end over end— but it's intended to express the scientific imagination, and isn't a photograph. 'Oumuamua came plunging into our solar system on what's called a hyperbolic orbit, meaning that it swung by the Sun and then slingshotted back out, never to be seen again. No doubt, this is very cool! It's the first thing we've ever seen passing through that isn't something from within our own solar system, so it's a momentous discovery.
One of the things that had many people puzzling over 'Oumuamua is that it seemed to yeet itself out of the solar system at a slightly faster rate than we would have expected, a tiny little extra kick of acceleration. In every day human experience, we think of acceleration as something people do— most often to their cars— but lots of other things can offer space objects a little extra go. Bizarrely, one of these factors is actually light from the sun— yes, light— which in some cases can create a subtle but significant change in how objects in space move. We see acceleration from the light of the sun in comets all the time: as they get close to the sun, comets warm up and begin releasing gas, which can act like a little extra propellant (and even in non-comets, solar radiation itself also creates a bit of pressure that can change how things move too). But, whether that could plausibly be responsible for 'Oumuamua's change in velocity depends on a lot of things: what it's made of, how much light it absorbs or reflects, its shape, etc— all things we don't know very well, because while we wish we had a detailed photograph, we instead have a speck of light and an artistic illustration.
The whole "'Oumuamua might be a spaceship" thing started because of a paper by Bialy and Loeb, where they suggested that solar radiation pressure COULD explain this little extra kick IF 'Oumuamua was pancake-shaped and made of an extremely thin sheet of material. Believe it or not, human beings have actually been thinking about sending thin films of material, known as light sails, into space— and it's not surprising that the idea would appeal to Loeb and his colleagues, because he is an advisor for the Breakthrough Starshot project, which hopes to do exactly that. But at the same time, human beings have not yet figured out how to send a light sail to other planetary systems— there are a lot of ideas, but thus far, nothing particularly feasible. And meanwhile, we already know that the universe makes a metric shit ton of more ordinary things, like comets.
So was 'Oumuamua a comet? If it was, that would also explain its additional acceleration. That's hard to answer— there was no data to suggest that it had a comet-like tail, but because its very nature means that it exited the solar system before we could study it further, we don't really know if that means it isn't a comet, or our data was just limited in what it could tell us. Science is annoying like that sometimes— sometimes, the universe does not cooperate when you wish it would.
However, we may get our answers soon enough: one of the promising things to come from 'Oumuamua's discovery is that while it may be the first interstellar object we've spied in our solar system, there actually might be many others like that we've previously missed. In the intervening years, another interstellar object— this one definitively a comet, known as 2I/Borisov, was discovered. When the Rubin Observatory opens its grand eye on the universe, discoveries of "anomalies" like 'Oumuamua or 2I/Borisov might become commonplace. Only time will tell, but the best news of all is you won't have to wait long: the Rubin Observatory begins observations in the next few years.
Speaking of changes of trajectory: did you notice that earlier, I mentioned that The Rubin Observatory was previously called "LSST", or the Large Synoptic Survey Telescope? It was, up until just a few years ago. The name was a placeholder— telescope naming is a mysterious alchemical practice, usually devoted to honoring people who have changed our world for the better, and sometimes for people who have invested a lot of money (Lick Observatory, which serves as a kind of astronomical tomb for the late James Lick, is a good example of the latter). A few years ago, Congresswoman Eddie Bernice Johnson sponsored a bill that called for the renaming of the LSST in honor of Dr. Vera Rubin, an accomplished astronomer who discovered dark matter, and whose work and memory is an inspiration to many astronomers working today. (Inspiration aside, this renaming was also a relief, because seemingly no astronomer knew what "synoptic" actually meant— as a grad student I had heard it used for years in the context of "having something to do with time", and later learned it just meant "affording a general view of the whole", which is definitely not how people were using it in talks.)
Readers of this newsletter will perhaps have seen that lately, the name of another telescope has been in the news: NASA's next flagship successor to the Hubble Space Telescope, the James Webb Space Telescope (or JWST). JWST is named for James Webb, who served as the NASA administrator during the Apollo missions— and whose prior role at the Department of State included complicity with the purge of queer people from government service. In a new op-ed for Scientific American, my colleagues Chanda Prescod-Weinstein, Sarah Tuttle, Brian Nord, and I propose that NASA should rename the mission the Harriet Tubman Space Telescope, in honor of Tubman's incredible accomplishments (which include using the stars to navigate herself and others to freedom).