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?

Sciency Words: Heartbeat Tone

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

HEARTBEAT TONE

Last week, I watched NASA’s live coverage of the Perseverance rover landing on Mars.  Naturally, I had a notepad ready, and I picked up quite a few new scientific terms.  My absolute favorite—the one that brought the biggest smile to my face—was “heartbeat tone.”  I love the idea that Perseverance (a.k.a. Percy, the Mars Rover) has a heartbeat.

As this article from Planetary News describes it, Percy’s heartbeat tone is “similar to a telephone dial tone.”  It’s an ongoing signal just telling us that everything’s okay.  Nothing’s gone wrong, and everything’s still working the way it’s supposed to.

Of course, other NASA spacecraft use heartbeat tones as well.  According to two separate articles from Popular Mechanics, the Curiosity rover on Mars and the Juno space probe orbiting Jupiter also send heartbeat tones back to Earth.  And that article about Juno offers us a little bit of detail about what Juno’s heartbeat actually sounds like: a series of ten-second-long beeps, sort of like very long dashes in Morse code.

Based on my research, it seems like the earliest NASA spacecraft to use heartbeat tones (or rather, the earliest spacecraft to have this heartbeat terminology applied to it) was the New Horizons mission to Pluto, which launched in 2005.  As this article from Spaceflight 101 explains it, New Horizons’ onboard computers monitor for “heartbeat pulses” that are supposed to occur once per second.  If these pulses stop for three minutes or more, backup systems kick in, take over control of the spacecraft, and send an emergency message back to Earth.

So, I could be wrong about this, but I think this “heartbeat pulse” or “heartbeat tone” terminology started with New Horizons.  To be clear: I’m sure spacecraft were sending “all systems normal” signals back to Earth long before the New Horizons mission.  I just think the idea of using “heartbeat” as a conceptual metaphor started with New Horizons.  But again, I could be wrong about that, and if anyone has an example of the term being used prior to New Horizons, I would love to hear about it in the comments below!

P.S.: I recently wrote a post about whether or not planets have genders.  With that in mind, I was amused to note in NASA’s live coverage that everyone kept referring to Perseverance using she/her pronouns.  However, the rover has stated a preference for they/them on Twitter.  So going forward, I will respect the rover’s preferred pronouns.

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!

Sciency Words: Orthofabric

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we explore the definitions and etymologies of scientific terms.  Today on Sciency Words, we’re talking about:

ORTHOFABRIC

If you’re planning to spend any amount of time floating around in outer space, you need to dress appropriately.  You’ll need protection against solar and cosmic radiation.  You’ll need protection against extreme temperatures, both extreme cold and extreme heat (direct sunlight in the vacuum of space can make things super hot super quick).  Oh, and there are lots of tiny micrometeoroids whizzing about up there.  You’ll need protection against those too.

Around the same time that the space shuttle program got going, NASA started using a new fabric for the outermost layer of their spacesuits.  That fabric is still used today for spacesuits aboard the International Space Station.  It’s called Orthofabric (sometimes spelled with a hyphen: Ortho-fabric).

Orthofabric is made by a company called Fabric Development Inc., based in Quakertown, PA.  Orthofabric is made using three different synthetic fibers: Gore-Tex, Nomex, and Kevlar.  As reported in several research papers (like this one or this one), Orthofabric consistently holds up well against the harsh conditions found in space.  That’s why NASA keeps using it.

For these Sciency Words posts, I think it’s important to say something about the etymology of the word we’re talking about, but I had an extremely hard time finding any sort of etymology for this one.

The prefix “ortho-” comes from a Greek word meaning righteous, virtuous, or pure (hence the word orthodox).  “Ortho-” can also mean upright or straight (hence the word orthopedic).  But what do either of those meanings have to do with Orthofabric?  The prefix “ortho-” also has a specialized meaning in chemistry, but based on my research, the chemistry sense of “ortho-” didn’t seem relevant to Orthofabric either.

So finally, I picked up the phone, called Fabric Development Inc., and asked.  I was told the name Orthofabric was chosen after some back and forth consultation with NASA.  The name doesn’t mean anything in particular.  It’s just a name.  I guess somebody thought it sounded good.  End of story.

P.S.: NASA’s new Perseverance rover will be searching for life on Mars, but as a little side experiment Perseverance is also carrying a small sample of Orthofabric, along with samples of other commonly used spacesuit materials.  NASA wants to see how well these spacesuit materials hold up in the windy and dusty Martian environment.

Sciency Words: Perseverance

Hello, friends!  Welcome back to Sciency Words, an ongoing series here on Planet Pailly where we talk about science or science-related terms.  Today on Sciency Words, we’re talking about:

PERSEVERANCE

Mars rovers are among the most advanced pieces of technology we humans have ever produced.  And by a longstanding tradition dating back to the Sojourner rover in 1997, the official names for NASA’s Mars rovers are chosen by school children.

The Perseverance rover, currently on route to Mars, was named by 7th grader Alex Mather.  He won an essay contest.  Here’s a video of Mather reading his essay, followed by a quick Q and A session with some NASA officials.

You know, after listening to Mather’s essay, I have to agree.  Perseverance is the right name for our newest Mars rover.  It’s even more right of a name now than it was back in March, when the name was announced.

Things are scary here on Earth.  So many people are suffering.  So many people are struggling.  So many lives are being needlessly lost.  But I do believe, as Mather says in his essay, that perseverance is our most important quality as a species.  In the end, humanity will persevere.

Orbiting the Blogosphere: Aliens, NASA Missions, and Flat Earthers

Hello, friends!

Today, I thought we’d take a quick look around the blogosphere and see what other space/science enthusiasts have been writing about.

First up, why is science fiction so obsessed with alien life?  Steven Lyle Jordan explores that question in an article for Medium.  Click here to check out that article, or click here to visit Steven’s blog.

Next, NASA has announced the finalists for the next Discovery-class mission, and one of those finalists involves a return to Neptune (frickin’ finally, am I right?).  Specifically, this would be a mission to explore Triton, Neptune’s largest moon.  Jay Cole from Digestible Space can tell you more.  Click here!

Meanwhile, NASA’s InSight mission has been gathering a surprising amount of data about earthquakes on Mars (a.k.a. marsquakes).  Maybe Mars isn’t as geologically dead as we thought?  Blaine Henry from Gimme Space can tell you more.  Click here for that!

And lastly, but not leastly, Fran from My Hubble Abode pays tribute to a prominent Flat Earther who recently passed away.  Fran has done many great posts debunking Flat Earth nonsense and other conspiracy theories.  But still, everyone deserves some compassion and respect.  Fran has set a wonderful example of how to disagree with someone without being disrespectful.  Click here.

That’s all for now.  If you read and enjoyed any of these posts, please be sure to let the author know with a comment.  It’s important that we all keep sharing and spreading our love for space and for science!

Next time on Planet Pailly: this might sound like an odd question, but which way is time going?

Learning More About NASA’s New Spacesuits

Following my recent Sciency Words post on “bunny hopping,” I got a lot of questions about NASA’s new spacesuit design.  I wasn’t really able to answer those questions, so today I’d like to share a video from someone who’s a little better qualified to talk about this stuff.

Scott Manly is an astrophysicist and YouTuber.  On his channel, he plays a lot of space-themed video games and talks about scientific accuracies (or inaccuracies) in said video games.  I started watching Mr. Manly back when I was obsessed with Kerbal Space Program.

I think the big takeaway from this video is that NASA’s new spacesuit is not quite finished yet.  It’s still a work in progress.  That might explain some of the confusion over what the new spacesuit is supposed to do for astronauts once they’re on the Moon.

One thing I’m still wondering about: the new space boots.  Several articles I looked at (like this one) describe the new boots as “hiking-style boots with flexible soles.”  That doesn’t really satisfy my curiosity about these boots, so I’ll have to do more research on that.

Sciency Words: Bunny Hopping

Sciency Words: (proper noun) a special series here on Planet Pailly focusing on the definitions and etymologies of science or science-related terms.  Today’s Sciency Word is:

BUNNY HOPPING

So yesterday I was reading up on the latest spacesuit design from NASA, and I came across a term that I don’t remember ever seeing or hearing before.  In this article from Space Daily, NASA Administrator Jim Bridenstine is quoted as saying: “If we remember the Apollo generation, we remember Neil Armstrong and Buzz Aldrin, they bunny hopped on the surface of the Moon.”

This left me wondering: do people really use the term “bunny hopping” to describe how Apollo astronauts moved about on the Moon?  I tried really hard to trace the etymology of this term.  I didn’t find much, but honestly, when you see clips like this one, it’s easy to figure out where the term came from.

In my previous research on this topic, I’ve seen this method of locomotion referred to as “loping-mode” or “skipping-mode.”  But sure, we can call it “bunny hopping” too.  So why did astronauts do this?

Well, there’s something about walking that most of us, in our daily lives, don’t realize: Earth’s gravity does some of the work for us.  When you take a step, first you lift your foot off the ground, then you extend your leg, and then… well, try to stop yourself at this point.  With your leg extended forward like that, you’ll find that your center of gravity has shifted, and you can feel the force of gravity trying to pull you through the remainder of your walk cycle.

So walking feels like a natural and efficient way for us humans to get around because Earth’s gravity helps us.  Take Earth’s gravity away, and walking suddenly feels awkward and cumbersome.  In lunar gravity, which is approximately ⅙ of Earth’s gravity, the Apollo astronauts found other methods of locomotion to be more comfortable, more natural.  In this clip, we hear audio chatter of astronauts disagreeing about whether “hopping” or “loping” is a better way to get around.

Personal preference seems to be important here, both in how astronauts “walked” on the Moon and in how they described the experience of this new kind of “walking.”

Getting back to the new spacesuits from NASA, the new design features a dramatically improved range of motion.  The next astronauts on the Moon will have a much easier time getting around, and according to Administrator Bridenstine there will be no need for bunny hopping.  “Now we’re going to be able to walk on the surface of the Moon, which is very different from the suits of the past.”

And that’s got me confused.  I’m really not sure what Bridenstine means by that statement because, as I just explained, it was the Moon’s gravity—more so than the spacesuits—that made Apollo era astronauts feel the need to “bunny hop” on the Moon.  The new spacesuits, with their improved range of motion, should help astronauts in the new Artemis program avoid gaffs like these…

But without altering the Moon’s gravity, I don’t see any way to avoid “bunny hopping.”

Sciency Words: Entomopters

Sciency Words: (proper noun) a special series here on Planet Pailly focusing on the definitions and etymologies of science or science-related terms.  Today’s Sciency Word is:

ENTOMOPTERS

It is aerodynamically impossible for insects to fly, or so French entomologist Antoine Magnan famously claimed in 1934.  And it’s true.  If aerodynamics means the scientific principles governing the flight of airplanes, then you will have a very hard time explaining how insects fly using aerodynamics alone.

Do you know what else is aerodynamically impossible, or at least aerodynamically very, very difficult?  Flying on Mars.  The atmosphere is too thin for fixed-wing aircraft.  But perhaps where traditional aerodynamics fails, insect aerodynamics might succeed!

At least that was the thought behind the entomopter, a project proposed by Robert Michelson and colleagues at the Georgia Tech Research Institute back in the early 2000’s.  The term entomopter comes from two Greek words—entoma, meaning insect, and pteron, meaning wing.  So an entomopter is a flying machine that mimics the “aerodynamically impossibly” flight of insects.

As Michelson explains in this article:

Aerodynamic analyses of [insect] flight consistently revealed that their wings must produce 2-3 times more lift than conventional wings, and in some cases up to 6-7 times.  The extra load-lifting capacity this would offer Entomopters is highly significant, and indicates that a novel design based on flapping insect flight would outperform a more traditional aerodynamic approach.

The prototype entomopter built by Michelson and his research team was modeled after the hawk moth (scientific name Manduca sexta).  With a ten-centimeter wingspan, the hawk moth is an unusually large insect, which makes it easier to observe and study the movements of its wings. And I have to admit in this concept video from NASA, there is something distinctly moth-y about the way the entomopter flies.

I first learned about the entomopter while researching last week’s post on NASA’s NIAC program.  The entomopter was one of those so-crazy-it-might-work proposals that won grant money through NIAC.

You may have heard about the Mars Helicopter Scout (a.k.a. Marscopter), which will be accompanying NASA’s next Mars rover.  You may have also heard about Dragonfly, the robotic quadcopter that NASA plans to send to Titan sometime in the 2030’s. Neither of these spacecraft qualify as entomopters, and I’m really not sure how much thanks either Marscopter or Dragonfly owe to the entomopter project.  But I strongly suspect there is some sort of connection there.