NASA’s DART Mission: Rest in Peace

Hello, friends!

As you probably know, NASA’s DART spacecraft deliberately rammed itself into an asteroid on Monday.  This was a test.  It was only a test.  The asteroid in question (named Dimorphos) was never a threat to us.  Someday, though, another asteroid may come along… an asteroid that does threaten us… an asteroid that could end life as we know it.  The DART Mission was intended to test out ability to defend ourselves, should a large and genuinely threatening asteroid ever show up on our doorstep.

I spent Monday night watching NASA TV’s livestream of the DART Mission.  Those final images from DART’s navigational camera were amazing!  I never really thought about what it would look like to crash into the surface of an asteroid.  Now I know exactly what that would look like.

Anyway, today I thought I’d share a few things that I learned—things that I did not know before—while watching NASA’s livestream, as well as the press conference that was held after the mission was over.

The Space Force: So I knew DART launched almost a year ago, but I didn’t know it had launched from Vandenberg Space Force Base (I also didn’t know Vandenberg Air Force Base had been renamed).  I still think the whole Space Force thing is cringy, but at least the Space Force did help do something to actually defend our planet.  So that’s cool!
DART’s Solar Panels: In addition to testing our planetary defense capabilities, the DART spacecraft also tested a few new space technologies.  Most notably, DART was using a new, experimental solar panel design.  DART launched with its solar panels rolled up into cylinders, then the solar panels unrolled once the spacecraft was in space.  The new design apparently weighs a lot less than traditional solar panels, and anything we can do to lower the weight of a spacecraft helps make spaceflight less expensive.
Dimorphos’s Shape: This one really surprised me.  Apparently nobody knew what Dimorphos looked like until those last few minutes before impact.  The most high-res images we had were still not high-res enough to reveal the asteroid’s shape or any useful details about its appearance.  As a result, DART had to be programmed with some sort of machine learning algorithm to help it figure out what it was supposed to be aiming for.

While the DART Mission was a success, it’ll still be a while before we know exactly how effective it was at moving the orbit of an asteroid.  Telescopes up in space and down here on the ground will continue monitoring Dimorphos as the dust settles (both figuratively and literally).  Still, as a citizen of Planet Earth, I do feel a little bit safer living on this planet.  I mean, we still have a lot of challenges we need to overcome, but that asteroid problem?  I think we’ve got that one covered now.

So did you watch NASA’s livestream on Monday?  Did you learn anything new, either from the livestream or from other news sources covering the DART Mission?

P.S.: If you missed the livestream, click here to watch it on YouTube.  Or you can click here to watch the press conference that was held afterward.

NASA’s DART Mission: Brace for Impact!!!

Hello, friends!

We are only a few days away from what is, in my opinion, the #1 most important space story of the year.  No, I’m not talking about the launch of Artemis 1.  And no, this has nothing to do with the Webb Telescope either.  I’m talking about NASA’s DART Mission.

For eons now, asteroids have been zipping and zooming past our planet.  Every once in a while, one of those asteroids will hit our planet, causing anywhere from minor to major to global mass extinction event levels of damage.  But on Monday, September 27, 2022, humanity will perform our first ever experiment to see if it’s possible to smack an incoming asteroid away.

The asteroid in question is named Dimorphos.  Dimorphos is not actually a threat to us, but if we’re going to perform an experiment like this, Dimorphos is a rather convenient target for target practice.  That’s because Dimorphos is not just an asteroid; it’s also a moon (or should I call it a moonlet?) orbiting a larger asteroid named Didymos.

When the DART spacecraft crashes into Dimorphos, the force of the impact will change Dimorphos’s orbit around Didymos.  It should be fairly easy for astronomers to measure this change, and thus it should be fairly easy to judge how effective DART was—and just how effective DART would have been against an asteroid that was actually threatening us.

Oh, and just in case anyone’s concerned that DART might accidentally knock Dimorphos out of its original orbit entirely and send it hurtling our way, thus ironically causing the very disaster this mission was meant to help prevent—don’t worry.  Didymos’s gravitational hold on Dimorphos is strong.  No matter what happens on this mission, Didymos is not going to let her little moonlet go (another reason why Dimorphos was selected as the target for this experiment).

So on Monday, September 27, 2022, there will be a head-on collision between an asteroid/moonlet and a NASA spacecraft.

An Italian-built spacecraft named LICIACube will be positioned nearby to observe the experiment.  A multitude of Earth-based telescopes will also be watching.  The European Space Agency also plans to send a follow-up mission (named Hera) in 2026, to check up on Dimorphos after its post-impact orbit has had some time to settle down.

Life on Earth has never been able to defend itself from incoming asteroids before.  Life on Earth has never had the ability to even try, until now [citation needed].  Obviously asteroids are not the only threat to life on our planet.  Obviously this is not the only challenge we need to overcome.  But the DART Mission is a huge first step.  A true giant leap.  No, DART probably won’t get the same kind of love and attention as Webb or Artemis 1, but still I’d say this is the #1 most important space story of the year.  This may be one of the most important science experiments in all of Earth history.

WANT TO LEARN MORE?

P.S.: I said life on Earth has never before had the ability to defend itself from incoming asteroids.  Technically speaking, we cannot be 100% sure that’s true.  Click here to read my post on the Silurian Hypothesis.

October Is Europa Month Here on Planet Pailly!

Hello, friends!  Let’s talk about aliens!

If we want to find alien life, where should we look?  Well, if money were no object, I’d say we should look anywhere and everywhere we can.  Phosphorous on Venus?  Could be aliens.  Let’s check it out.  Melty zones beneath the surface of Pluto?  Let’s check that out too.  Ariel?  Dione?  Ceres?  Let’s check them all for signs of alien life!

But money is an object.  We simply don’t have the resources to explore all of these places.  Space exploration is expensive.  Space exploration will always be expensive so long as we’re stuck using rocket-based propulsion.  The Tsiolkovsky rocket equation makes it so.

Whenever you’re working within a restrictive budget, you need to think strategically.  With that in mind, astrobiologists (scientists who specialize in the search for alien organisms) have focused their efforts on four worlds within our Solar System.  Their names are Mars, Europa (moon of Jupiter), Enceladus (moon of Saturn), and Titan (another moon of Saturn).

This month, I’m going to take you on a deep dive (no pun intended) into Europa.  In my opinion, of the four worlds I just listed, Europa is the #1 most likely place for alien life to be found.  I don’t mean to denigrate Mars, Enceladus, or Titan.  There are good reasons to think we might find life in those places, too.  But there are also good reasons to think we might not.

  • Mars: Life may have existed on Mars once, long ago.  But then the Martian oceans dried up.  We’re unlikely to find anything there now except, perhaps, fossils.
  • Enceladus: Enceladus’s age is disputed.  She may be only a few hundred million years old, in which case she may be too young to have developed life.
  • Titan: If you want to believe in life on Titan, you have to get a little imaginative about how Titanian biochemistry would work.

Europa doesn’t have those issues.  Unlike Mars, Europa has an ocean of liquid water right now, in modern times.  Unlike Enceladus, Europa’s age is not disputed; she’s definitely old enough for life.  And unlike Titan, Europa doesn’t require us to get imaginative about biochemistry.  The same carbon-based/water-based biochemistry we use here on Earth would work just as well for the Europans.

There are still good reasons to search for aliens on Mars, Enceladus, and Titan.  Finding fossils on Mars would be super exciting!  Enceladus’s age is, as I said, in dispute, with some estimates suggesting she’s very young, but others telling us she’s plenty old.  And while life on Titan would be very different than life on Earth, scientists don’t have to imagine too hard to find plausible ways for Titanian biochemistry to work.

But if I were a gambler, I’d put my money on Europa.  And if I were in charge of NASA’s budget, I’d invest heavily in Europa research and Europa missions.  Europa just seems like the safest bet to me, if we want to find alien life. And in the coming month, I plan to go into more detail about why I feel that way.

WANT TO LEARN MORE?

If you’re interested in learning more about the Tsiolkovsky Rocket Equation, you may enjoy this article from NASA called “The Tyranny of the Rocket Equation” (because NASA is the American space agency, and anything Americans don’t like is tyranny).

As for astrobiology, I highly recommend All These Worlds Are Yours: The Scientific Search for Alien Life, by Jon Willis.  Willis frames the search for alien life just as I did in this post: alien life could be anywhere, but you only have a limited budget to use to find it.  So how would you spend that money?

Oops! I Learned Something Wrong About Io

Hello, friends!

As you may remember from a previous post, Io is my favorite moon in the Solar System.  He may not be the prettiest moon, and he certainly isn’t the most habitable.  I, for one, would never, ever, ever want to live there.  You see, Io is the most volcanically active object in the Solar System.  He is constantly—and I do mean constantly!—spewing up this mixture of molten hot sulfur compounds.  It gets everywhere, and it is totally gross.

But it’s also super fascinating—fascinating enough that Io ended up becoming my #1 favorite moon in the whole Solar System.  I’ve read a lot about Io over the years.  I thought I understood Io pretty well.  But I was wrong.  One of the facts in my personal collection of Io-related facts was based on a fundamental misunderstanding of how Io’s volcanism works.  Let me explain:

Io is caught in this gravitational tug of war between his planet (Jupiter) and his fellow Galilean moons (Europa, Ganymede, and Callisto).  Jupiter’s gravity pulls one way; the moons pull another; Io is caught in the middle, feeling understandably queasy.  I always thought this gravitational tug-of-war was directly responsible for Io’s volcanic activity.  But it’s not.  Recently, while reading a book called Alien Oceans: The Search for Life in the Depths of Space, I realized that I had some unlearning to do.

The gravitational tug-of-war has forced Io into a highly elliptical (non-circular) orbit.  This means there are times when Io gets very close to Jupiter, and times when Io is much farther away.  When Io’s orbit brings him close to Jupiter, Jupiter’s gravity compresses Io’s crust.  And when Io moves father away, his crust gets a chance to relax.  This cycle of compressing and relaxing—of squeezing and unsqueezing—causes Io’s interior to get hot, which, in turn, keeps Io’s volcanoes erupting.

This squeezing and unsqueezing action wouldn’t happen if not for Io’s highly elliptical orbit, so the gravitational tug-of-war with Jupiter’s other moons is still partially responsible for Io’s volcanism.  But the tug-of-war is not the direct cause of Io’s volcanism, as I always assumed it to be.

I wanted to share all this with you today because some of you may have had the same misunderstanding about Io that I did.  Hopefully I’ve cleared that up for you!  But also, I think this is a good example of how the process of lifelong learning works.  If you’re a lifelong learner (as I am), you may have favorite topics that you think you know an awful lot about.  But there’s always more to learn, and sometimes learning more means unlearning a few things that you thought you already knew.

WANT TO LEARN MORE?

If you’re an Io fanatic like me, I highly recommend Alien Oceans: The Search for Life in the Depths of Space by Kevin Peter Hand.  The book is mainly about Europa and the other icy/watery moons of the outer Solar System, but there’s a surprising amount of information in there about Io, too.  Apparently, if it turns out that Europa really is home to alien life (as many suspect her to be), then Io may have played a crucial role in making that alien life possible.

Abyssal Gigantism on Europa?

Hello, friends!

So the first time I heard about the subsurface ocean on Europa (one of Jupiter’s moons), my imagination ran wild.  Or should I say it swam wild?  I imagined all sorts of wonderful and terrifying sea creatures: krakens with lots of horrible tentacles and teeth; crab-like creatures scuttling around on the ocean floor; and perhaps even extraterrestrial merfolk with a rich and complex civilization of their own.

As I’ve learned more about space and science, though, I’ve scaled back my expectations for what we might find on Europa.  Or on Enceladus, or Dione, or Titan, or Ariel, or Pluto… there’s a growing list of planetoids in the outer Solar System where subsurface oceans of liquid water are suspected and/or confirmed to exist.

Any or all of those worlds might support alien life.  But not giant sea monsters.  When astrobiologists talk about alien life, they’re usually talking about microorganisms.  For Europa, rather than civilized merfolk and tentacle-flailing leviathans, we should imagine prokaryotic microbes clustered around hydrothermal vents, feeding on sulfur compounds and other mineral nutrients.  If we ever find evidence that these Europan microbes exists, it will come in the form of a weird amino acid residue, or something like that.

That’s the most exciting discovery we can hope for, realistically speaking.  Unless…

On Monday, I introduced you to the term “abyssal gigantism,” also known as “deep-sea gigantism.”  Abyssal gigantism refers to the tendency of deep-sea organisms to grow larger (sometimes much larger) than their shallow-water cousins.  As an example, see the giant squid.  Or if you really want to give yourself nightmares, look up the Japanese spider crab.

The more I read about abyssal gigantism, the more my thoughts turn to Europa (and Enceladus, and all the rest).  The environment beneath Europa’s icy crust shouldn’t be so different from the deepest parts of Earth’s oceans.  So shouldn’t what happens in the deepest parts of Earth’s oceans also happen on Europa?

According to this article from Hakai Magazine, yes.  Yes, it should.  The same evolutionary pressures that cause abyssal gigantism here on Earth should cause a similar kind of gigantism on Europa.  In fact, it would be strange if that didn’t happen.  One marine biologist is quoted in that article saying: “You would have to come up with a rationale why [abyssal gigantism on Europa] couldn’t happen, and I can’t do that.”

Before you or I let our imaginations swim wild, I should note that that article from Hakai Magazine was the one and only source I could find on this specific combination of topics: abyssal gigantism and life on Europa.  So maybe take all of this with a grain of salt (preferably a grain of Europan sea salt).  But… well, I’ll put it to you this way: if someone were to write a story about a NASA submarine being attacked by sea monsters, that story would seem plausible to me.

Sciency Words: FarFarOut

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we take a closer look at new and interesting scientific terms so we can expand our scientific vocabularies together!  Today’s Sciency Word is:

FARFAROUT

You know, I recently spent a couple days trapped at home due to a snow storm. Don’t worry, I don’t live in Texas—I wasn’t trapped in that snow storm.  Anyway, after reading a little about Dr. Scott Sheppard, I feel as though I seriously misused those snowed-in days.

Dr. Sheppard is one of the key players in the ongoing search for Planet X, also known as Planet Nine or (as I like to call it) New Pluto.  Together with fellow astronomer Chad Trejillo, Sheppard has discovered more than sixty objects of various sizes out beyond the orbits of Neptune and Pluto.

Among those sixty-plus objects Sheppard and Trejillo discovered is a possible dwarf planet nicknamed “FarOut” (official designation 2018 VG18).  FarOut is—or rather was, very briefly—the most distant natural object known to exist in our Solar System.  Hence the nickname.

But in early 2019, Sheppard was reviewing his data and happened to notice another object even farther out than FarOut.  As Scientific American tells the story, this happened while Sheppard was “snowed in during a blizzard.”  (I spent my recent snowed-in days watching cartoons on my phone.)  The new object Sheppard found in his data has the official designation 2018 AG37, but Sheppard nicknamed it “FarFarOut,” for obvious reasons.

According to this article from Carnegie Science, FarFarOut has a highly eccentric (non-circular) orbit, with an orbital period of approximately one thousand years!  Seriously, a thousand years!!!  A portion of that highly eccentric orbit is actually not that far away at all; at its closest approach to the Sun, FarFarOut’s orbital path actually crosses within the orbit of Neptune.

I do have to take issue with some of the news articles and social media posts I’ve seen about FarFarOut.  Strictly speaking, FarFarOut is not the most distant known object in the Solar System.  We should probably call it the most distant natural object, or the most distant non-articifical object, that we currently know about, because there is one known object that’s even fartherer out than FarFarOut.

Do Planets Have Genders?

Hello, friends!

So a while back, I got some unsolicited feedback from a person I know in real life.  This person had seen one of the illustrations I’d drawn for this blog, and she was incensed—absolutely incensed—that I would depict the planet Saturn as female.  You see, Saturn is a very masculine planet.  That’s a fact, apparently.

A lot of my thinking about planets—including my thinking on the gender identities of planets—was shaped by a book called Venus Revealed, by David Grinspoon.  That book was my first serious introduction to planetary science.  In a section titled “Men are from Venus, Women are from Mars,” Grinspoon has this to say:

At first I tried being completely gender-neutral in my writing, but this was unsatisfying because, to me, Venus is not just a “thing.”  Venus is not, in my mind, inanimate, and so “Cousin It” will never do to describe him… or her.

In that same section, Grinspoon does a little cross-cultural analysis and finds that Venus has been “a real gender bender” across human cultures and human history.  Sometimes she’s male; other times he’s female, depending on which mythological tradition you’re looking at.  And some cultures have apparently assigned different genders to the Morning Star and Evening Star, thus effectively making Venus genderfluid.

So do planet’s have genders?  No, of course not.  But much like David Grinspoon, I can’t see the planets as purely inanimate objects.  Planets have too much personality for that.  And since I think of the planets as having personalities, then, for better or worse, I also think of them as having genders.

For purely arbitrary reasons, I tend to think of Saturn as female.  But if you’d prefer to think of Saturn as male, or as something else entirely, that’s okay.  I’m not going to fight you over it.  I can love Saturn (and all the other planets, too) just the same, no matter what gender identities we pretend they have.

P.S.: While doing research for this post, I ended up reading a lot about how astrology assigns genders to planets (and also to numbers, elements, constellations, etc). I don’t want to dive too far down that particular rabbit hole, but I thought I should at least share this article on the subject. I used to think astrology was just silly. Now I think it’s problematic for reasons that go beyond mere pseudoscience.

Sciency Words: Chromophore

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we take a closer look at those weird words scientists use.  Today’s Sciency Word is:

CHROMOPHORE

Recently, just for fun, I was watching an old interview with Carl Sagan (the same interview I cited in Wednesday’s post, by the way).  Around 25 minutes into that interview, Sagan talks a little about Jupiter, and he mentions that Jupiter’s distinctive coloration is caused by something called “chromophores.”

Sagan then goes on to say, flippantly, that we call it a chromophore because “we don’t know what it is.”  But the word chromophore is not quite a meaningless placeholder term for a thing we don’t understand (like dark matter).

Definition: A chromophore is a group of atoms within a larger molecule that are responsible for giving that molecule its color.  So, for example, chlorophyll molecules have chromophores in them that soak up red and blue light, thus giving chlorophyll its characteristically green appearance.

Etymology: Chromophore comes from two Greek words meaning “color” and “bearing.”  According to the Oxford English Dictionary, the earliest recorded usage of the word is in this 1879 dictionary of chemistry.  The word appears in a section about the chemical reactions used to make dyes.

Fun fact: just like the planet Jupiter, the oil pastels I used to draw this picture of Jupiter contain “chromophores.”

To say that Jupiter’s coloration is caused by chromophores is absolutely correct, but somewhat unhelpful.  It’s like asking “what caused that sound?” and being told “vibrations of the air.”  But, at least for now, it seems we don’t have a better answer.  To the best of my knowledge, we still don’t know which chemicals, specifically, are responsible for giving Jupiter his distinctive coloring (though Jupiter researchers have a lot of plausible-sounding guesses).

But whatever those chemicals are, they must contain chromophores.  Almost by definition, that must be true.

Shameless Self Promotion Time: Looking for Jupiter T-shirts, Jupiter notebooks, or other Jupiter-themed stuff?  Click here to check out all the Jupiter-related products available in the Planet Pailly store on Redbubble!

Is There Life on Earth?

Hello, friends!

Let’s imagine some space aliens are cruising by our Solar System.  They turn their scanners on our planet and see… what?

Among other things, they’d notice that Earth’s landmasses are partially covered with a strange, green-colored substance.  Of course, you and I know what that green substance is.  It’s chlorophyll.  But would those extraterrestrial observers, who have no prior knowledge of our planet, be able to figure that out?  Even if they did, would they realize what chlorophyll is used for?  Maybe.  Probably not, though.

Which brings me to my all-time favorite scientific paper: “A search for life on Earth from the Galileo spacecraft,” by Carl Sagan et al.  I love this paper in part because it’s so clearly and concisely written, with jargon kept to a minimum.  Sagan was, after all, a talented science communicator.  But I also love this paper because its conclusions are so shocking, so eye-opening.

In 1990, NASA’s Galileo spacecraft turned all its high-tech instruments toward Earth and detected… not much, actually.  Galileo did pick up radio broadcasts emanating from the planet’s surface.  Aside from that, though, Galileo’s data offered highly suggestive (but also highly circumstantial) evidence on Earthly life.  The lesson: finding life on other planets is hard.  Even using our very best equipment, it was hard for NASA to detect signs of life right here on Earth!

At least that’s what I got out of reading Sagan’s Galileo experiment paper.  And based on various commentaries I’ve read or heard about this paper, that seems to be the lesson other people got out of it too.  So I was surprised to hear Sagan himself, approximately seven-and-a-half minutes into this interview, saying the exact opposite.

We’ve flown by some sixty worlds.  We claim that we haven’t found life anywhere, and that that is a significant result.  That is, that we would have found life had it been there.  But this has never been calibrated.  We’ve never flown by the Earth with a modern interplanetary spacecraft, all instruments on, and detected life here.  And so Galileo, because of this peculiar gravity assist VEEGA trajectory, permits us to do that.  And as I’ll describe tomorrow, we find life five or six different ways, including intelligent life.  And this then means that the negative results that we find elsewhere are, in fact, significant.

I’ve been puzzled by this for a while now, but I think I’ve finally figured out why Sagan would say this.  It’s politics.

On the one hand, scientists need to understand the challenges they’ll face (including the limitations of their own equipment) in searching for life on other worlds.  That really is, I think, the purpose of the Galileo experiment paper.  On the other hand, it would not do to say on public television, to cantankerous taxpayers and the listening ears of Congress, that NASA spends millions of dollars on space probes that are not even capable of detecting life right here on Earth.

Space exploration is expensive.  And like all expensive types of research, sooner or later the researchers involved have to learn how to play politics.

Sciency Words: Safety Ellipse

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we talk about those wild and crazy words scientists use.  Today’s Sciency Word is:

SAFETY ELLIPSE

I don’t know about you, but when I’m trying to dock my shuttle pod with another spaceship, I like to take a few long, leisurely loops around that other spaceship first.  You know, like this:

Spaceships are pretty!  Who wouldn’t want to get a good look at them from every conceivable angle before completing docking maneuvers?  But it turns out that circling round and round a spaceship like this is not just for admiring the view.  It’s also for safety!  As explained in this paper:

A “safety ellipse” is an out-of-plane elliptical periodic relative motion trajectory around the primary spacecraft such that the trajectory never crosses the velocity of the primary.

That clear things up?  No?  Okay, how about a quote from this paper instead:

This paper defines a safe trajectory as an approach path that guarantees collision avoidance in the presence of a class of anomalous system behaviors.

Still confused?  Here’s a short video demonstrating what a safety ellipse (a.k.a. a safe trajectory) looks like:

Basically, if your shuttle pod experiences engine failure or any other major malfunction, flying in a safety ellipse ensures that you will not collide with the ship you were trying to dock with.  At least not for a good, long while.

I first heard about this term the other day while watching the livestream of the SpaceX Dragon capsule approaching and docking with the International Space Station.  Several times, the livestream commentators mentioned that Dragon was utilizing a “24 hour safety ellipse” or “24 hour safe trajectory,” meaning that if anything went wrong, mission control would have at least 24 hours to fix it before Dragon and the I.S.S. collided.

So remember, friends: the next time you’re going to dock with another spacecraft, do that out-of-plane elliptical periodic relative motion thing.  In other words, circle around the other ship a few times before making your final approach to dock.  It’s for safety reasons.

P.S.: It’s also for enjoying the view.  Spaceships are pretty!