Ice to See You
The last place in the solar system you’d expect to find ice (except maybe on the Sun, duh) is Mercury. Rocky, barren, airless, and very, very hot, Mercury doesn’t sound like the ideal location for storing vast quantities of frozen water.
But in the 1990s evidence started coming in that perhaps Mercury was holding a surprise. At its north pole are deep craters, and because of their high latitude, the low Sun never reaches the crater floors. They’re permanently dark, and because of that they’re very cold. Cold enough to hold on to any water that might have found its way there (presumably through water-bearing asteroid and comet impacts).
The first evidence was from radar observations; those craters were found to be very radar-reflective, which suggested ice, though other materials were possible. But over the years more clues arrived, and when the MESSENGER spacecraft began orbiting the tiny world, the idea of polar water got kick-started. Neutrons were reflected from the crater floors, which indicated the presence of hydrogen (water molecules have two hydrogen atoms each and are very good at reflecting incoming neutrons). MESSENGER has an infrared laser altimeter on board (it uses timing of pulses of light to measure its height off the surface and get topological data), and the craters were again found to be very reflective, which is consistent with ice.
And now we have further, very striking data: Pictures taken of the floor of the crater Prokofiev* show that some of the surface itself is a bit brighter, a bit shinier, than surrounding material. Not only that, but the brighter regions correspond extremely well with what has been found before.
The picture here shows the data. The upper left (A) is from radar observations; the blue circle is the crater rim, the red region is where it’s permanently shadowed—the Sun never shines there—and the yellow is where the radar reflections were brighter than normal. The bottom left (B) shows where the laser altimeter found unusually bright material. On the right (C and D) are the images taken by MESSENGER’s visible light camera. They are the same area and have the same orientation but were taken when the Sun was shining from different directions. The brighter landscape there is clearly visible on the right, and as you can see matches the other observations right on the nose.
The scientists found similar results in other craters even farther north on Mercury (Prokofiev is about 5° south of the north pole, and is 112 kilometers, or 70 miles, across). The amount of ice estimated to be trapped in the floors of these craters is 10 billion to one trillion tons—a huge amount. As the paper points out, that’s about the volume of Lake Ontario.
Personally, I find this to be pretty convincing. It's not a 100 percent lock, but the evidence is getting to be pretty hard to deny.
The ice is likely to be young, too. Impacts, ultraviolet light breaking down the molecules, and other weathering could darken, bury, or eradicate the ice on a timescale of tens or hundreds of millions of years, so it’s likely this deposit hasn’t been around since the early solar system (astronomers define "young" differently than normal humans).
In practical terms, I have a hard time seeing us sending folks to Mercury, setting up a base at its poles, and taking long hot baths using native water any time soon. But this shows that even now, with our huge telescopes, advanced hardware, and robot probes peeking and poking into every corner of the solar system, there’s still a lot to learn about our neighborhood, and a whole lot of surprises waiting to be unwrapped.
We also have similar evidence of water at the Moon’s poles, too, buried under and mixed into the rock at the floors of eternally darkened craters. I don’t have a hard time seeing us going there at all. There could be enough water on the Moon to support a colony for quite some time. That is something I would very dearly love to know more about.
*Craters on Mercury are named after artists: composers, painters, writers, and so on. Sergei Prokofiev was a Russian romantic composer, and one of my favorites; his Fifth Symphony is an astonishing work. It pleases me that such an important discovery has been found in his namesake.
To Pluto … AND BEYOND!
In July of 2015, the New Horizons space probe will whiz past Pluto, traveling at 40,000 kilometers per hour. For several weeks before and after the close flyby—it’ll pass within 10,000 km above the tiny world’s surface—it will examine Pluto, its moons, and the environment around it.
But this is not an orbiter, or a lander. Pluto is 5 billion kilometers from Earth, and the only way to get a probe there in any decent amount of time was to strip it down as light as possible and fling it as hard as possible, getting it moving so rapidly it could traverse the yawning chasm between us and Pluto as quickly as possible (with a boost from Jupiter along the way).
This is a fast flyby, with no slowing down. Once New Horizons is gone, it’s gone.
Except the solar system hardly ends at Pluto. There’s a vast collection of objects out there in the dark: cold, icy worldlets called Kuiper Belt objects. There are millions of them, relics from the formation of the solar system itself, and largely unchanged for billions of years. Getting a look at one up close is a very tempting goal.
The New Horizons team started a search in 2011 using large ground-based telescopes, and while they found dozens of these KBOs, none was near enough to the probe’s trajectory to investigate. Remember, space is vast and empty—that’s why we call it “space”—and while there may be millions of KBOs, they’re still spread pretty thin out there.
So they turned to Hubble. Narrowing the search but able to detect fainter objects, Hubble was the last hope … and it paid off. They found three potential targets, each over a billion kilometers farther out than Pluto. One, called (for now) PT1 (guess why) should be easy to reach given New Horizons’ present path and fuel supply. Its size is not clear, but based on its brightness and likely surface reflectivity it’s probably more than 30 km (20 miles) in diameter. New Horizons would fly past it in January 2019.
Not that this is a given. Ostensibly, the probe’s mission is over once it flies past Pluto. The team will have to ask NASA for an extension, and those aren’t given out lightly. However, I think this is a very worthy goal. We’ve never seen a pristine KBO up close, just moons we think used to be KBOs but were captured by planets, like Neptune’s Triton and Saturn’s Phoebe. These are likely to have changed over time since they became enthralled to their parent planets, so finding a KBO in its natural habitat is a very exciting idea.
Also, politically, I think it’s a feather in NASA’s cap to be able to retool a space mission to do something more than it was originally designed to do. If things go well at Pluto, and we expect they will, the public will be pretty excited about the mission; folks seem to have a special place in their hearts for the little ice ball. Leveraging that would be pretty smart on NASA’s part.
For details on the search and how they planned this flyby of a KBO, go read Emily Lakdawalla’s write-up. She has (as usual) an excellent and very thorough article about it.
I’m excited about this. I’ve been interested in KBOs since my own days with Hubble; I spent a little bit of time looking into using Hubble to search for objects very far from the Sun, and unfortunately given the logistics at the time (back in the late 1990s) it wouldn’t have really worked. But the cameras are better now, our techniques have improved, and it’s really gratifying to see this getting done. And if PT1 does rate a flyby, we’ll see that little blip in the Hubble image turn into a place, a small but perfect example of what our solar system is like, in the far reaches of nearly—but not quite—empty space.
Evidence for Evolution, Stated Clearly
Here at BA Central, we’re* big supporters of evidence-based reality and using science as a way to collect and weigh that evidence.
The problem is that a lot of science isn’t well understood by the public for a large number of reasons; some folks blame the education system, which certainly has issues, though perhaps a much larger and more endemic problem is ideology, which gets into your brain and acts like a bouncer at a bar, only letting through ideas that are on a preconceived checklist.
Evolution is an obvious example. Despite being one of the fundamental bases for all of modern biology (along with things like molecular biology, genetics, and so on), it is routinely and falsely attacked by many. A lot of scientists and science communicators scratch their heads over that; what’s hard for us on this side of reality to understand is how anyone can ignore the vast mountains of evidence supporting evolution.
My friend Zach Weiner put his finger right on it, in my opinion, when he wrote this:
The more I read from creationists, the more I think they're not anti-evolution. They're anti-some crazy version of it their pastor taught.— Sexy Z. Weinersmith (@ZachWeiner) April 4, 2012
I think that’s it; the folks who don’t “believe” in evolution are the ones disseminating a weird, wrong, strawman version of it.
While there’s not a huge amount I can do about that, what I can do is try to make correct, easy-to-understand information about evolution available. I’ve done it before and it seemed to work out well.
So I’m pleased to send y’all to a great website called “Stated Clearly,” where artist and science communicator Jon Perry has created a series of wonderful videos where information about and evidence for evolution is, well, stated clearly.
The video “What Is the Evidence for Evolution?” is fantastic. It’s simple without being oversimplified, and it gives clear examples that can be followed easily even if you’re not all that familiar with the science.
That last part is critical, because, as Zach pointed out, the ones fighting tooth and nail against evolution are almost assuredly not that familiar with it. If they were, we wouldn’t be spending our time defending evolution. We’d be spending more money investigating it.
Perry has assembled quite a team to create these videos (including, I was pleased to see, Rosemary Mosco, a field naturalist, science communicator, and friend-of-a-friend). There are articles there as well expounding further on some of the themes.
The evidence video was sponsored wholly through Kickstarter, which is great, since it costs a fair bit to put together something like this. If you have any extra filthy lucre lying around, you should consider throwing it their way. They’ll have merchandise soon, and I’ll be keeping an eye out for that. I want a shirt of Darwin riding an Archaeopteryx.
Tip o’ the telomere to Raw Story.
I Got Shot in the Asteroid
Once again this year I have talked the talk and walked the walk: I got my annual flu shot.
I was hoping you’d see more of my asteroid tattoo in this picture, but what the heck. It gets the job done. As usual, the shot was painless, inexpensive, and should help my immune system do what it’s meant to do.
Flu shots are important. Everybody’s freaking out about Ebola right now, but every year the flu kills far more people! By getting my shot, I’m doing two things: teaching my immune system how to fight off the influenza virus likely to be common this season, and also keeping me from becoming an unwitting host to the virus, able to infect others.
That’s critical. For me personally, if I get the flu the odds are I’ll be miserable for a few days and more whiny than usual. But my wife is immunocompromised, and if she gets a full-blown infection, the complications could be very serious. That’s why we get our immunizations every year. It helps build herd immunity, and that protects people who cannot get the shot and could get critically ill from the flu.
Sure, Ebola is scary, but it’s made far scarier by the media in this country that have their priorities grossly out of whack. Given how communicable influenza is, and how dangerous it is, they’re spending way too much telling you about the wrong virus.
And that’s not even including measles, pertussis, and more diseases that are making strong comebacks due largely to the anti-vaccination movement. But I’ve already been pretty clear how I feel about that.
Go talk to your board-certified provider and find out what’s best for you. And if they recommend it, go get yourself vaccinated.
And before you ask about the T-shirt I was wearing ... did you see yesterday's post?
Self-Portrait 10 Miles From a Comet
Holy Periodic Comet Photos! Check. This. Out!
That is a self-portrait taken by the Philae landing craft onboard the Rosetta space probe, when they were just 16 kilometers (10 miles) from the comet 67P/Churyumov–Gerasimenko. You can see the side of Rosetta on the left and the solar panel that’s keeping it powered on the right.
And at the top is the comet itself, magnificent and moody in this high-contrast grayscale composite (two images were combined so that both the spacecraft and comet were exposed well). You can even see a jet emanating from the comet, a stream of gas blown out as ice is hit and warmed by sunlight. Stunning.
Rosetta is nosing closer to the comet, and will release the Philae lander in a few weeks. On Nov. 12, the probe will touch down on the surface of the comet, a milestone in our exploration of space. Judging from the quality of this picture, what we will see on that day will be jaw-dropping.
Why Yes, It Is Exactly Rocket Science!
A little while back I posted an amazing Vine video taken by an astronaut on the International Space Station. It shows the release of the Cygnus cargo resupply ship Janice Voss, which had finished its mission bringing supplies up to the ISS. It was filled with trash, unberthed using the robotic CANADARM 2, then put into an orbit that would drop it into Earth’s atmosphere to burn up over the Pacific Ocean.
In the video, the Voss looks like it goes up, into a higher orbit than the ISS, which I thought might be due to the use of a wide-angle fisheye lens. I also supposed it might be due to the orbit of the ship. Watch the video:
So, what’s going on? I got an email from someone who knows orbital mechanics (but prefers to remain anonymous), and he confirmed my suspicions. To explain, I need to give you a brief intro to orbital mechanics. It’s not like the movies … and let me note that I’m no expert in orbital mechanics, so if I make an error here it’s mine, and not my source’s. I’m also going to leave out some details that are a bit hairy, but if you like, you can read up on how orbital mechanics works. It’s pretty cool.
When an object is in orbit around the Earth, its velocity is dependent on how far it is from the center of the Earth (the orbital radius) and the shape of its orbit. For a circular orbit, the orbital radius doesn’t change, so the velocity is constant. If you increase the radius (its distance from Earth) the velocity slows down, so a circular orbit with a larger size means the spacecraft orbits more slowly.
If you want to get to a higher orbital radius, you point your spacecraft into the direction it’s heading and ignite the rocket. The thrust adds velocity to spacecraft for a short time. But that doesn’t put it in a bigger circular orbit; the added energy stretches out the orbit, making it elliptical. The highest point of this new orbit (called apogee) is above the old circular orbit, and the lowest point (perigee) just meets the old one (the old-fashioned term for this is “osculating,” which means “kissing,” a delightful use of the word).
So what does this mean for the ISS and Voss? They start off moving at the same speed, because they’re connected. Voss faces forward, disconnects, and ignites its thruster. The added energy puts it on an elliptical orbit, and it immediately goes up into a higher orbit than ISS; that’s what we see in the video, and why Voss appears to move away from Earth. That’s because it does move away!
Now, if that’s all there was to it, one orbit later Voss and ISS would meet up once again when Voss reaches perigee. But we don’t want that! The whole point is get the spacecraft away from the ISS. So how did they do that?
Watch the video again. Just before the burn, Voss dips its nose a little bit, pointing it slightly down toward the Earth. So it wasn’t thrusting exactly tangent to its orbit; the rocket pushed it down a bit. That maneuver also affects the shape of the elliptical orbit, changing where Voss will reach perigee, and also dropping perigee a bit lower. One orbit later, when Voss reaches perigee, it will be ahead of and lower than ISS. That prevents any chance of collision, even if the spacecraft loses power; the orbits no longer cross.
That would be the situation forever if nothing changed. However, the endgame here is to drop Voss into Earth’s atmosphere. So, a couple of days later, after engineers made sure everything was kosher, they made a final maneuver. They turn Voss around, so now it’s facing backwards in its orbit (tail first). The rocket is fired again, which drops the apogee of the orbit to inside that of ISS, again preventing a collision. The perigee also drops, and the burn lasts long enough so that at perigee the Voss is inside Earth’s atmosphere.
Half an orbit later Voss reaches perigee, and Earth’s air now has a large drag effect. It steals energy from the orbit, dropping the spacecraft even lower. At that point, atmospheric drag really takes over, and you get the spectacular fireball as the ship hypersonically rams the air in front of it, compressing it, and heating it up hugely. The ship becomes a human-made meteor, and falls into the ocean (where, I suppose, it becomes a human-made meteorite).
I find orbital mechanics fascinating, because it all works following (relatively simple) rules that only seem counterintuitive (I had the devil’s own time understanding this video until I realized the Voss was on an elliptical orbit; the mechanics suddenly became way easier to understand). That’s OK, as long as you don’t fret over the instincts humans have developed over millions of years living on the ground.
Flying into space we put centuries of math to the test … and it works. It works. That to me is one of the most amazing things about science that there is: The Universe obeys a set of rules, and we can figure them out. And in many cases, we truly have.
Britain’s “Best Loved Psychic” and the Very Definition of Irony
File this under “Too Ironic to Describe Without Making Your Head Asplode”:
Briefly, Sally Morgan is a self-proclaimed “psychic” who says she can to talk to the dead, and so on. However, reports on her readings make me extremely skeptical of them, as they sound an awful lot like cold reading. She sells out theaters, charging a fairly healthy sum for tickets (as well as for telephone readings).
Recently, a British skeptic named Mark Tilbrook handed out fliers outside some of Morgan’s shows, simply asking people to think about her methods critically. He never says she’s a faker, fraud, scammer, or anything like that; the wording is polite and matter-of-fact.
After doing this at a few shows, Tilbrook was accosted by Morgan’s husband and son. They threatened Tilbrook physically, made death threats, and used homophobic slurs in their confrontation. There’s video of the whole thing.
Since that went public over the weekend, Morgan has had to go on the defensive (and the offensive, claiming Tilbrook has "targeted" her, though by his own account his actions have not been pushy). She’s made a public statement on her site, saying she has “sacked” her husband and son, who no longer will hold the positions of personal manager and tour manager, respectively. In the statement she apparently doesn't perceive any self-imposed irony, saying:
I have come from a family background that has always been very accepting, many of my friends are gay and I have always felt happy that I am often referred to as a gay icon through my work. I am utterly ashamed and devastated at the behaviour of my husband John and Son in Law Daren and neither of them will have anything to do with my work, my business and right now I honestly have no idea what is going to happen to my marriage.
If she really doesn’t know what the future holds for her, maybe she should consult a psychic.
Last Week’s Lunar Eclipse Seen … From Another Planet
… but none quite like this: The eclipse was observed by the MESSENGER space probe, all the way from Mercury! Normally MESSENGER looks straight down on the tiny world, mapping the terrain that slides underneath it. But engineers saw an opportunity for something neat, so they pointed the camera toward Earth and took 31 images, each two minutes apart, to capture the dance of light:
It’s not often something makes me laugh in delight, but that grainy, lumpy video did. You can see the Earth on the left, all of five pixels wide in the original images (the entire video has been expanded by a factor of two), and the Moon on the right, just barely bigger than a single pixel. The motion of the Moon is too small to detect, but as it passes into Earth’s shadow it dims considerably, disappearing.
Even then, the brightness of the Moon has been multiplied by 25 to make the change more obvious. On Oct. 8, during the eclipse, Mercury was nearly between the Earth and Sun, so to MESSENGER, the Earth and Moon were close to full. But the Earth is bigger and more reflective than the Moon, and would look 50 or so times brighter. I’m not surprised they had to enhance the Moon’s brightness.
MESSENGER was 107 million kilometers (66 million miles) from Earth when it took these images. I think that may be a world universal record for the most distant (terrestrial) lunar eclipse ever seen.
Tip o’ the umbra to Emily Lakdawalla.
What Does 200 Billion Stars Really Mean?
The sheer scale of space is overwhelming. Oh, sure, we have words to make it more palatable, like “light-years”—as if a distance of 10 trillion kilometers is graspable by our puny simian brains.
And when I think about our galaxy, the Milky Way, I know that it’s 100,000 light years across, but that’s just a number, the reality too huge to truly hold in my mind.
But what really gets to me is how many stars are in the galaxy. Astronomers, including me, offhandedly say it has something like 200 billion stars comprising its bulk. Two hundred billion. Written out, that’s
And I look at that, and my brain parses it, dissects it, counts the zeroes, makes analogies, uses scientific notation … all in an attempt to grasp the ungraspable.
So how many stars is that, really?
I have been known, over the course of the past few years, to post pictures of the odd cloud or two. And I do mean odd. Sometimes they’re photos I’ve taken myself (and some of which have been very difficult to identify), sometimes they’re from machines in space, and sometimes from humans in space.
Still, I’m not a cloud chaser per se; you won’t see me hopping in my car and driving hundreds of kilometers to spy a weird cloud formation someone tweeted about, for example. On the other hand, if someone were to tell me they saw something like this nearby, well, I’d think pretty hard about getting my car keys and going for a look-see.
Those are undulatus asperatus (agitated or turbulent wave) clouds, a type of cloud that is starting to get consideration as a wholly new category. From what I can tell, they are formed when there’s rising air that creates wide-spread cloud cover, together with wind shear that blows across the rising air. This can set up gravity waves, where air moves up and down as buoyancy and gravity battle it out, creating long rippling waves that carry the clouds up and down.
You can find out more about this on Slate’s Atlas Obscura blog. I urge everyone to bookmark that blog; it is always a fascinating tour of the weirder and wonderfuller places on our planet.
And let me leave you with this simply jaw-dropping video of undulatus asperatus in action. Make it high-def and full screen, because seriously: Holy wow.