Whooosh, boom!

This is what NASA does. They launch stuff to smash into asteroids, and I’m here for it. Here’s a video of the final seconds of the DART space probe, before it smashed into the asteroid moonlet Dimorphos (Dimorphos orbits a larger asteroid, Didymos). Wheee!

That video ends abruptly, as you’d expect. The probe launched a separate camera to record the collision, though, and that looks like this:


Why was this collision so strange? In 2022, to develop Earth-saving technology, NASA deliberately crashed the DART spacecraft into the asteroid moonlet Dimorphos. The hope was that this collision would alter the trajectory of Dimorphos around its parent asteroid Didymos and so demonstrate that similar collisions could, in theory, save the Earth from being hit by (other) hazardous asteroids. But analyses of new results show that the effects of the collision are different than expected — and we are trying to understand why. Featured here is the time lapse video taken by the ejected LICIACube camera LUKE showing about 250 seconds of the expanding debris field of Dimorphos after the collision, with un-impacted Didymos passing in the foreground. In 2026, Europe’s Hera mission will reach the asteroids and release three spacecraft to better study the matter.

Very pretty. All those rocks and dust streaming out of the moonlet…

It’s since been acting a bit weird, although more accurately, we ought to say that it acted unpredictably. The moonlet exhibited a slight slow deceleration for a prolonged period.

The DART team has since confirmed that Dimorphos did indeed continue slowing in its orbit up to a month after the impact — however, their calculations show an additional slowdown of 15 seconds, rather than a full minute. A month after the DART collision, the slowdown plateaued.

What caused Dimorphos to slow steadily for a month, before reaching equilibrium? A swarm of space rocks could be to blame: Recent observations of the asteroid have revealed a vast field of boulders — likely shaken loose from Dimorphos’ surface during the impact — strewn about the area. It’s possible that some of the larger boulders fell back onto Dimorphos within that first month, slowing its orbit further than anticipated, DART team member Harrison Agrusa told New Scientist.

I guess we have another reason to think the movie Armageddon was schlock. We can’t calculate the ultimate outcome of space collisions — there are just too many parameters.

Avi Loeb makes stuff up about another space rock

3I/ATLAS

Avi Loeb, the ridiculous Harvard astronomer who claimed that the interstellar object ʻOumuamua was a technological artifact, has battened on a different rock that was discovered in July called 3I/ATLAS as the object of his alien fantasies. He’s published his explanation in an in-house journal (which is not peer-reviewed) in a paper titled Is the Interstellar Object 3I/ATLAS Alien Technology?. The answer is “no”, but Avi really wants it to be “yes.” To give him a chance to make his argument, here’s the abstract.

At this early stage of its passage through our Solar System, 3I/ATLAS, the recently discovered interstellar interloper, has displayed various anomalous characteristics, determined from photometric and astrometric observations. As largely a pedagogical exercise, in this paper we present additional analysis into the astrodynamics of 3I/ATLAS, and hypothesize that this object could be technological, and possibly hostile as would be expected from the ’Dark Forest’ resolution to the ’Fermi Paradox’. We show that 3I/ATLAS approaches surprisingly close to Venus, Mars and Jupiter, with a probability of ≲ 0.005%. Furthermore the low retrograde tilt of 3I/ATLAS’s orbital plane to the ecliptic offers various benefits to an Extra-terrestrial Intelligence (ETI), since it allows the object access to our planet with relative impunity. The eclipse by the Sun from Earth of 3I/ATLAS at perihelion, would allow it to conduct a clandestine reverse Solar Oberth Manoeuvre, an optimal high-thrust strategy for interstellar spacecraft to brake and stay bound to the Sun. An optimal intercept of Earth would entail an arrival in late November/early December of 2025, and also, a non-gravitational acceleration of ∼ 5.9 × 10−5 au day−2, normalized at 1 au from the Sun, would indicate an intent to intercept the planet Jupiter, not far off its path, and a strategy to rendezvous with it after perihelion.

The paper is full of the technical details about the orbital mechanics of this object. It’s unpleasantly dry and boring, with occasional insertions of his wild speculations. Fortunately, he also has a blog post titled Is the Interstellar Object 3I/ATLAS Alien Technology? which is enriched for the Loeb lunacy, so I’ll mainly write about that.

Finding a big rock or comet of interstellar origin is not a revolutionary discovery — it’s interesting, but not something that is necessarily indicative that aliens are hitching a ride on it. His justification for suggesting that it’s an alien artifact are tenuous and based entirely on speculations about its trajectory. For instance, it’s approaching on roughly the ecliptic plane.

The retrograde orbital plane (defined by the orbital angular momentum vector) of 3I/ATLAS around the Sun lies within 5 degrees of that of Earth — the so-called ecliptic plane. The likelihood for that coincidence out of all random orientations is 0.2%.

So it’s unlikely that a rock flying through interstellar space would have the particular approach angle that this one has. But wouldn’t any specific trajectory be unlikely? So what?

Another coincidence is that it’s going to pass sorta close to Venus, Mars, and Jupiter.

For its orbital parameters, 3I/ATLAS is synchronized to approach unusually close to Venus (0.65au where 1au is the Earth-Sun separation), Mars (0.19au) and Jupiter (0.36au), with a cumulative probability of 0.005% relative to orbits with the same orbital parameters but a random arrival time.

Therefore it might be a probe that’s sent here to inspect the planets. It’s checking us out!

You might be thinking that zooming by Venus, Mars, and Jupiter is fine, but what about Earth? It’s not coming anywhere near us, which is evidence that it is a probe.

3I/ATLAS achieves perihelion on the opposite side of the Sun relative to Earth. This could be intentional to avoid detailed observations from Earth-based telescopes when the object is brightest or when gadgets are sent to Earth from that hidden vantage point.

So it’s checking us out, but specifically avoiding being detected by us. Convenient.

But the aliens must be fascinated by us! So he postulates that 3I/ATLAS will fire up its engines and change its trajectory out of our sight, on the other side of the sun, so it can intercept the Earth.

The near alignment of the retrograde trajectory of 3I/ATLAS with the ecliptic plane offers various benefits to an extraterrestrial intelligence, since it allows a spacecraft to access Earth with relative impunity. The eclipse of 3I/ATLAS by the Sun at perihelion for observers at Earth, would allow a spacecraft to conduct a clandestine reverse Solar Oberth maneuver, an optimal high-thrust strategy for interstellar spacecraft to brake and stay bound to the Sun. An optimal intercept of Earth would entail an arrival in late November or early December of 2025. Detection of a non-gravitational acceleration could also indicate an intent to intercept Jupiter, not far off the path of 3I/ATLAS, and a strategy to rendezvous with it after perihelion.

Note that this kind of maneuvering would suggest that 3I/ATLAS is an alien artifact, but it has not been observed. He can’t use a hypothetical motion that has not been seen as evidence that the object is capable of maneuvering. All of his evidence that 3I/ATLAS is an artifact is about remarkable changes in trajectory that have not been observed.

He has NOTHING to support his hypothesis that 3I/ATLAS is alien technology! The idea is that if it suddenly changes its path and approaches Earth, then it must be driven by some novel propulsive force. And, yeah, if a bunch of little green men pop out of it and use flying saucers to visit us, then at last Avi Loeb will be vindicated.

But of course, he does not predict that.

Our paper is contingent on a remarkable but testable hypothesis that 3I/ATLAS is a functioning technological artifact, to which I and my two co-authors do not necessarily ascribe.

So he does not predict that, but if it happens, he’s staking his claim on it. Very cheesy. He’s going to have a future as a television psychic, vague and making predictions so broad that they can cover all eventualities.

But there’s more! He wants us to prepare for the alien invasion!

1. The consequences, should the hypothesis turn out to be correct, could potentially be dire for humanity, and would possibly require defensive measures to be undertaken (though these might prove futile).

2. The hypothesis is an interesting exercise in its own right, and is fun to explore, irrespective of its likely validity.

He doesn’t actually believe 3I/ATLAS is an alien artifact, but we’d better start preparing defensive measures (what would those be, I wonder? Like maybe back in the 15th century someone should have suggested to the native Americans to prepare defensive measures.)

And no, it’s not an interesting exercise. He also admits that his speculation are a pedagogical exercise, and that it is probably just a comet.

Our paper is largely a pedagogical exercise, with interesting realizations worthy of a record in the scientific literature. By far, the most likely outcome will be that 3I/ATLAS is a completely natural interstellar object, probably a comet, and we await the astronomical data to support this likely origin.

He went ahead and spread his unfounded hyperbole, though. The story has made it to the NY Post, and you can guess what the headline was: ‘Possibly hostile’ alien threat detected in unknown interstellar object, a shocking new study claims.

I have to give some credit to the NY Post, though — they actually talked to real astronomers and got their opinion of Loeb’s hypothesis.

“All evidence points to this being an ordinary comet that was ejected from another solar system, just as countless billions of comets have been ejected from our own solar system,” added Samantha Lawler, an astronomer at the University of Regina in Canada who studies solar system dynamics, Live Science reported.

“Astronomers all around the world have been thrilled at the arrival of 3I/ATLAS, collaborating to use advanced telescopes to learn about this visitor,” Chris Lintott, an astronomer at the University of Oxford who helped simulate 3I/ATLAS’s galactic origins, told Live Science. “Any suggestion that it’s artificial is nonsense on stilts, and is an insult to the exciting work going on to understand this object.”

That ought to be the take-away on this story, that it’s “nonsense on stilts,” and it ought to diminish Avi Loeb’s already tattered reputation.

Microbial evolution…in spaaaace!

China has a space station named Tiangong that we don’t hear much about in US media, which is a shame. The station was launched in part because “Congress passed a law prohibiting NASA from collaborating with China aboard the ISS due to U.S. national security concerns.” More petty nationalism interfering with good science.

Anyway, they swabbed the crew quarters and discovered a novel bacterial species, Niallia tiangongensis. It is, of course, related to a common earth bacterium found in the soil, but it has evolved a few new adaptations.

Niallia tiangongensis exhibits structural and functional variations that mean it is well-adapted to existing in a space station. It possesses the ability to hydrolyze gelatin (break down this protein into smaller components) in a unique way, allowing the protein to be consumed for survival in nutrient-poor environments. In addition, these bacteria are able to form a protective biofilm, activate oxidative stress responses, and promote repair in the face of radiation damage. “This aids their survival in the space environment,” the paper explains.

In case you’re wondering if we’re creating a bacterium gap, have no fear: novel bacteria have also been found on the International Space Station. These 5 species are completely different from the Chinese species, unsurprisingly — these are new environments, and bacteria are rapidly diverging and adapting.

Five novel species of Gram-positive bacteria that were isolated from the ISS were analyzed. Their generic features and the results of other molecular analyses are presented. These bacteria were obtained from various flights, locations, and time periods, and are associated with different phylogenetic groups. The strain F6_3S_P_1C, which belongs to the Paenibacillus genus, has been identified as a spore-former, while the other four species were identified as non-spore-forming Actinobacteria. Through ANI and AAI analysis, we established closest Earth relatives. Additionally, we performed synteny analysis using all top ANI hits for each of the five organisms, but yielded no results (data not shown), thus indicating all ISS isolates are distinct species.

This is not a surprise. It’s what bacteria (and other living things) do — they adapt and evolve.

Not in the market right now, but I’d consider it

I drive a 2011 Honda Fit. It’s an ultra-reliable car, running without a hitch for 14 years now, not even a hiccup. The labels on some of the buttons on the dashboard are wearing off, but that’s the only flaw so far. I feel like this might well be the last car I ever own.

Except…the next generation of Hondas might tempt me to upgrade.

It’s a three hour drive from my house to Minneapolis, and maybe a ballistic trajectory would make the trip quicker.

Also, not exploding is an important safety feature to me.

Interesting planet, but not on my tourism itinerary

What a dramatic planet!

Astronomers have found a weird planet orbiting a very Sun-like star. Called K2-360b, the planet is 1.6 times Earth’s diameter, but 7.7 times its mass. That makes it dense: with an average density of 11 grams per cubic centimeter, it’s twice as dense as Earth! That’s literally as dense as lead. That mass and size makes its surface gravity three times Earth’s. If you could stand on it (which I would not recommend for many reasons, as you’ll see) you’d weigh three times what you do here.

…

Its size makes it a super-Earth, an exoplanet less than about twice Earth’s diameter. Why is it so dense? It likely started off life more like Neptune, with a thick atmosphere, but over time its ridiculously close orbit to the star meant its atmosphere got stripped away by the intense heat. What was left was the rocky-metallic core. The astronomers who did this research ran some models of what the interior is like, it’s likely to be about 50% core, which would explain the density; the cores of such planets are mostly metals. Fun place.

It’s close enough to its star to melt lead and iron, which immediately made me think of the phrase my brother and I would chant while capering about plotting mischief…”Molten metal! Molten metal!”.

I think we identified with Quasimodo in that old movie.

Soup in spaaaaace!

The country may be swirling down the drain, but at least we’ve got some interesting news from outer space…even if Nature chose a really misleading title for their article, Asteroid fragments upend theory of how life on Earth bloomed. Scientists are analyzing the samples returned from a probe sent to the asteroid Bennu. They’ve found all 5 nucleic acid bases, and 14 of our familiar 20 amino acids, which is not surprising. We’ve found those in meteorites here on Earth.

Furthermore, the molecules are found in roughly equal numbers of right- vs. left-handed enantiomers, which is also not surprising. It’s biological synthesis that favors one handedness over the other; this is exactly what we’d expect of molecules built via inorganic synthesis in a lifeless rock. We might have to upend a few theories if these molecules were found to have been assembled by living organisms that had been living on an ancient space rock. But they weren’t, so nobody is rewriting any biology textbooks.

I did not expect this, though:

In an accompanying paper published in Nature today, other researchers report that the material from Bennu is also rich in salts created billions of years ago, probably when watery ponds on Bennu’s parent asteroid evaporated and left behind a crust of minerals. Although no signs of life were spotted on Bennu, those salty ponds would have been a good environment to foster the chemistry that could lead to it.

Salty ponds? On space rocks? I’d like to know more about that, although note that there’s no evidence that life evolved in puddles on asteroids. It’s still cool to imagine briny ponds on distant moons and planetoids.