In Sputnik’s Orbit

A few thoughts to tide you over…

 

What is an orbit, anyway?

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What is an orbit, anyway? And what do we mean by freefall, microgravity, and weightlessness?

To answer these questions, first understand the difference between mass and weight. Mass is a property of all (ordinary) matter, and can loosely be thought of as the amount of stuff in that matter. A bucket full of iron nails has a lot more mass than the same bucket full of wooden pegs because there are a lot more electrons, protons and neutrons in every atom of iron than there are in the carbon and other atoms in wood.

All (ordinary) matter has its own gravity, which is just its attraction to all other matter. A bucket of nails weighs more than a bucket of pegs because the earth pulls harder on it–because it has more mass crammed into the same space, and mass is what gravity pulls on.

Crate up the bucket and launch it into space and it still has the same mass, so why does it float around and get nails into everything? It’s still being attracted to the earth, isn’t it? So where did all its weight go?

To understand this, you need to understand inertia. Ever play air hockey ? Or ice hockey? Or knurling? Set the puck flying and it keeps going until it hits something. Give it a tap, and it creeps along until you reach out and hit it again, or till it strikes something, or till the slight friction against the table (or ice or lane) brings it to a stop. And once it stops, it’ll sit there till the cows tip over unless you go get it. Why? Because matter is lazy, that’s why.

No, I don’t mean matter is living in it’s mother’s basement playing video games all night. I mean it likes to keep doing what it’s already doing until something makes it change. If it’s still, it will remain still until pushed. If it’s moving, it will remain moving in a straight line until acted upon. This property of lazyness is called inertia, and it totally makes sense if you think about it. After all, if a bit of rock is hurling through space smoking weed at 82,000 kilometers per second, it’s not just going to stop, put on a tie, and go out for interviews at Starbucks. Why should it?

Any change in an object’s motion — whether speeding up, slowing down, or changing in direction — is called “acceleration.” We sometimes say “deceleration” to mean a reduction in speed, but in terms of physics, it’s just a type of acceleration–a change in the speed or direction of motion.

Inertia makes perfect sense–after all, why would an object speed up or change direction on its own? Except in everyday life, we don’t live in a hockey rink or in space. If we roll a ball through the garden, it rubs against the carrots and slows down pretty fast, so we think that’s normal. And it is, in the garden. But toss a cat out an airlock from the International Space Station, and it will go hurtling off in a straight line in whatever direction you tossed it (you sorry, cat-hating heathen). Except it won’t…because Earth is pulling on it…which brings us to orbits.

Sir Isaac Newton probably never got hit in the head with an Apple, but he was a pretty smart fellow. Three hundred years ago, he understood gravity and inertia and proposed this thought experiment: Say you climb up to the top of Mount Everest with a shiny new cannon. After negotiating the tip with your sherpa, you fire the cannon flat and level toward the horizon. What will happen?

Nothing, right? You fire the ball, it falls and hits some mountaineer on the head, lawyers are called, the usual. But if you pack more powder into the cannon, you can fire the ball further. Fire it far enough, and you can hit base camp. The faster the ball leaves the cannon, the further it will go, until eventually, the curvature of the earth starts to carry the ground away beneath the falling cannon ball.

What if you traded your magic beans for elfin gunpowder that lets you fire the cannon as hard as you like and send your projectile flying without any resistance from the air? Eventually, it would fly so far that the ground was carried perpetually away and the ball would circle the globe–forever.This is what we call an orbit, and we can actually do it in space where the air is so thin it takes months, years, or centuries to slow down our cannon balls, er satellites.

Objects in orbit still have the same mass they do on earth. The earth’s gravity still pulls on them (though not quite as hard, because gravity diminishes with distance). In fact, if you stepped on a bathroom scale while standing atop a tower as high as the International Space Station, you would weigh almost 90% of your normal weight on the ground. And so would all the steel and concrete in the tower, which is why it would collapse, so don’t do that.

But if you jumped off the tower, you would instantly be in free fall (which sounds a lot nicer than “screaming, oh crap! I stepped off the tower”). You would have no weight because the scale that measures weight would be falling along with you and would have nothing to push against but the chewing gum sticking it to your feet. You would not burn up (like a reentering spacecraft). You would fall through the near vacuum, speeding up due to gravity all the time and would eventually exceed the speed of sound before slowing down again in the thickening air. You brought a pressure suit and a parachute, right?

But why would you jump off the tower? It’s not like the ISS is about to crash into your bathroom. Crap! The ISS is about to crash into your bathroom! At 17,500 miles per hour. That’s gonna leave a mark!

Why so fast? Because the ISS is in freefall too. At 88.9% of normal surface gravity, it’s in what NASA likes to call, “microgravity.” It’s falling towards the earth all the time, and to keep from smacking into Disneyland, it’s been set moving in a straight line at 17,500 miles per hour. If the earth weren’t here, it would fly off in a straight line at that speed forever (ignoring a few dozen details that aren’t relevant here). But the earth IS here, and at 17,500 mile per hour, the ISS is flying away in a straight line at precisely the same rate it’s falling toward the earth. Freefalling. Weightless, but still with a lot of mass (the official mass of the ISS is 3.217 crap-tons).

The moon orbits the earth in the same way. The earth orbits the sun, the sun orbits the center of mass of the galaxy, and the galaxy orbits the disembodied mass of Donald Trump’s ego. It’s all the same.

So there you go. Did I leave anything out? Let me know and I’ll try to clear it up. Or jump over to my homepage and request some free scifi and I’ll send you, you know, some free scifi.

 

 

 

 

The Chicken Or The Egg

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This is a repost of a piece I wrote for Informed By Nature a while back:

Which came first, the chicken or the egg? This seeming paradox actually has a clear, specific answer, and that answer reveals as much about how we know what we know as it does about where our breakfast comes from.

To ancient philosophers, the question evoked the deepest mysteries of existence and creation. In popular culture, it’s used to imply the futility of hard reasoning. Both views are wrong—utterly wrong—and it’s easy to see why, even if the actual solution takes a little more effort. The chicken or egg question is an infinite regress, and like division by zero or answers containing infinities, this is usually a sign not of some profound truth but of a poorly framed question.

One famous example is Zeno’s argument that motion is impossible because to move any distance one must first move half way, and before that, half again, and so on. The fact that Zeno—living in ancient Greece—lacked the nineteenth-century mathematics necessary to sum infinite series and calculate geometric limits did not prevent his moving outside to address his neighbors. Another example is Anselm’s attempt to prove the existence of God. He first defined God as the greatest being imaginable, then argued such a being would be greater still if it were real and thus concluded that the greatest imaginable being must therefore necessarily be real. Among the more egregious problems with this argument are that it fails to explain why the whole of reality should be bound by the thoughts of one medieval monk and that it argues with equal force for the abominable snowman.

Clearly, asking the right question is very important.

The correct question here is, how did egg-laying chickens come to exist? To ask “Which came first” implies a false dichotomy—a one or the other choice that isn’t real. It implies that all chickens are the same, that all eggs are the same, and that at some point in the past, one or the other must have popped into existence exactly in its present form. This isn’t true.

The category of birds we call “chickens” is a population of animals that, while very similar to one another, is every one unique. Each chicken is a blend of features from the previous generation, each egg of features from its parent hen. Over time, certain traits may be selected for across the population so that it tends as a whole to drift, from Belgian bantams, say, to Bearded Antwerps. Go back 8,000 years, and you would find red and gray jungle fowl drifting into something recognizable as modern domesticated chickens.

Chickens, like all living things, change along a messy continuum. Any particular chicken came from slightly different parents which in turn arose from even more different ancestors, and so on and so on until at some point in the past, we humans arbitrarily declare the ancestor not to be a chicken at all.

The thing is, there is no such thing—in nature—as species. This is a concept we invented to help categorize and study life. We divide modern chickens into distinct species and breeds, though no genetic barrier prevents their interbreeding. On the other hand, chickens can’t breed with dozens of other kinds of birds in nine modern orders, though countless genetic markers tell us they all descend from a common ancestral population.

The “tree of life” we all learned in elementary school is a useful metaphor, but it’s only a rudimentary approximation of how life actually changes over time. Put aside the nice, flat diagram from the biology book and picture instead a tree that branches in three dimensions and is very, very, blurry—as if viewed through an out of focus camera.

Blurred trees

Blurred tree of life

Zoom in, and distinctions break down between branches. At each fork, blurriness causes overlap between the offshoots. The blurriness represents the variation among individuals. The overlap is the ability of neighboring populations to interbreed. If two branches continue to diverge, the gap between them  grows too wide—they lose the ability to interbreed.

This—more or less—is how species arise. There’s no set line between one species and its neighbor. Polar Bears can breed with Brown bears if we provide the accommodations. Hybrids even occur between more distant branches, such as between jackals and wolves. How is this possible? Because every population is varied—every branch is blurry.

There was never a day when the first chicken appeared. There was only a population that gradually acquired more and more “chicken like” characteristics. The “species” of modern chickens and jungle fowl all overlap. Trace them up the tree and they join up with nine larger branches that once overlapped, but no longer do because they’ve continued to diverge. Far enough, and the branch holding the Rhode Island Red eventually blurs into what once led to certain dinosaurs.

It’s a messy, elegant progression. It never leads from one distinct type to another. It leads instead through diverging groups until time and survival raise a new species from the shadows of its origins. So now when someone asks which came first, the chicken or the egg, you know the correct answer: “Neither. Both come from an evolving population.”

Yes Virginia, We Really Did Land On The Moon

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For those genuinely in doubt as to whether we sent twelve men to walk on the moon, some facts.

220px-alsep_as15-85-114681. We left retroreflectors on the moon, just like bicycle reflectors only bigger and not as pretty. Visit the McDonald Observatory or any other with the proper laser range-finding equipment and you can see for yourself that the laser energy returns when the telescope is pointed at the designated landing sites and does not return elsewhere.
2. Two recent survey missions have photographed the landing sites. The LRO has dipped low enough to resolve not just shadows and disturbed soil, but the descent stages and rovers we left behind. No word yet on the poop bags, but they’re here somewhere.584640main_apollo17-right-670

3. We have films of much of the research and testing, and if you know enough about science and engineering to know what you are looking at, it’s all clearly the real thing.

4. We still have much of the hardware. For example, F5 engines from the Saturn-V are currently being disassembled and in some cases fired as part of an effort to develop a cheaper follow-on engine. They clearly are what they claim to be. I’ve personally seen the Saturn-V stack on display in Houston, and it is clearly authentic. Among other things, a  prop would not be made of the same materials, and it would either have phony components or all off the shelf 1960’s hardware. But much of the Apollo hardware was custom developed at great expense, and if you know what you’re looking at, you can see it’s for real. A prop or fake would not have details that only an engineer (or nerd who’s studied the blueprints) would notice.

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Workmen at JSC in Houston inside the SLA (the adapter where the LM sat during launch), looking up at the heat shield of a real Service Module without an SPS engine installed. The hole at top (behind the strut) is an access port for fueling, venting, and testing the SPS propellants.

5. We have thousands of pictures taken on the moon, which clearly are what they claim to be. All alleged problems with these materials only demonstrate the ignorance of the conspiracy nuts alleging the problems.

For example: Many conspirators complain that the lander didn’t kick up a lunar dust cloud. Of course it didn’t. Billowing dust can only occur in an atmosphere. In vacuum, each particle—no matter how small–flies off in a straight parabolic arc never to be seen again.

For another example: Motions of the flag claimed to be caused by air currents are—in every case—clearly inertial movements or static electric attraction caused by astronaut movement. The very movements the nutters complain about prove the landings were real. (For many other such examples, visit Bad Astronomy)

6. We have hundreds of pounds of moon rocks. Granted, you need access to them and you need to be a geologist with the right credentials to evaluate them, but at least some, such at the helium-3 impregnated rocks from by Apollo 17, could not have been produced on earth.

7. The Soviets were watching everything we did. They would have ratted us out. They would have LOVED to rat us out.

8. Thousands of people saw it. Not just the spectacular launches and the sailors on the recovery ships, either. Thousands in Hawaii, for example witnessed the Trans-Lunar-Injection burns.

http://pages.astronomy.ua.edu/keel/space/a8_saomaui.jpg

 Others around the world watched the spacecraft on its way to the moon:

Hatfield photo of Apollo 8 fuel dump

http://pages.astronomy.ua.edu/keel/space/a11young1.jpg

Apollo 11 was observed by thousands in British Columbia, and the streak in this photo from Table Mountain South Africa shows the spacecraft in time exposure, midway through the lunar coast phase.

 

NASA telescopic photo of Apollo 13 and gas cloud

9. We have documentation in the form of operations manuals for the command and service modules, the LEM, the suits, the rover and much more–all completely authentic and sprinkled across the world including depository libraries like the one at Louisiana Tech where I read them before the conspiracy nuttery had gotten any legs.

10. This guy:

I’ll be posting in more detail soon about specific conspiracy claims and how what they really prove is the ignorance of those making them.

We went to the moon. It was expensive, but like Frosty the Snowman, we’ll be back again some day.

Goodbye To The Goblin King

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David Bowie passed away sunday after 69 decidedly not boring years. My daughter, who knows him as the Goblin King for his role in The Labyrinth, came in after hearing the news and said, “Did you know? He had two different colored eyes.”fe608c1bb4bd3590117f95a7e7889c24

No, actually, he didn’t. Both of his eyes were the same color, but the left was permanently dilated, a condition called anisocoria. In his case, it stemmed from a fistfight with a friend over a girl when he was 15 years old.

The girl forgotten, Bowie remained friends with his mate, George Underwood, who he credited for helping build his mistique.

It’s a Miracle

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“It’s a miracle!”

We hear it all the time, often from newscasters who want to maximize the emotional impact of some story of survival—the cat in the well, the baby in the twister, the passengers who walk away from an air crash. These are all miraculous—except they aren’t really, and using this hyperbolic term may actually put people at risk.

Consider the humble air crash. Big plane hits the ground, thousands of gallons of Jet-A. Go through a crash and you’re screwed right? You definitely need a miracle.

You might be surprised.

Plane crashes are spectacle—fire, wreckage, flashy lights—it’s easy to expect the worst. But according to an NTSB study of 568 crashes between 1983 and 2000, only five percent of passengers were killed. The remaining 95 percent escaped unharmed or without life-threatening injuries. In another study of more serious crashes, the odds were better than 50/50 that passengers got out alive. And crashes that occur on the ground often have very high survival rates.

This is not a string of miracles. It’s the result of science, engineering, and training. Attributing these survivals to divine intervention ignores nearly a century of NTSB investigation, hard fought regulation, and the bravery, skill, and experience of flight and ground crews across the country.

Maybe there are miracles, but fortune favors the prepared.

Fire in the Deep?

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In researching a new story, I learned that Deepsea Challenger, the deep sea submersible James Cameron used to visit the Challenger Deep, was recently damaged by a vehicle fire while being moved by truck.

famous-submarine-fire

This is quite a shame. The context of my research was possible exploration of Venus, where surface pressures are around 90 Earth atmospheres.

That’s pretty extreme, but you know how much pressure this baby could take? 1,099 atmospheres! With people inside! And with a window!

The Transcontinental Airway System

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Ever see one of these?

Directional marker of the US Transcontinental Airway System

In the 1920s, the US government built a coast-to-coast system of navigational aides to help airplanes deliver airmail day and night, in good weather and bad, across a vast, sparsely inhabited interior without benefit of radio or radar.

The system would have been immediately understood by any engineer in ancient Rome: Some 1,500 concrete arrows pointing the way, generator shacks and fifty-foot towers by which rotating beacon lights helped pilots find the markers, and flashing lights identified each marker by number using Morse code.

It’s the kind of system that calls into doubt the sort of prognostication we often attempt in scifi. It seems absurd today, given than radio navigation beacons were less than a decade away–but they didn’t know what at the time. Nor were they willing to wait. So they did what they could with what they had, and by all reports, it was deemed highly successful by the standards of the day.

But imagine if you will, flying alone in a twine engine biplane, searching for one of these across the barren plains of Nevada, or among the treacherous passes through the Rockies. Oh the stories these forgotten slabs have seen transpire.

Women in Space

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I thought I’d post about something most people don’t seem to know about, that I’ve run across in my research.

In the early days of spaceflight, NASA made the not-unreasonable decision that astronauts would be drawn from the ranks of high-performance test pilots. At that time, mostly due to long-time stereotypes and discriminatory norms, all such test pilots were white males.

Ergo, all crews for Mercury, Gemini, and Apollo, in addition to the Air Forces MOL program, were made up of males and all but a couple of the MOL astronauts were white.
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In 1961, Randy Lovelace, whose Albequeque medical research clinic had been tasked by NASA to test Mercury astronaut candidates for fitness, invited female aviator Jerrie Cobb to take the test. She did as well as or better than several of the qualifying male astronauts. When Randy reported this to his friend, the world-famous female pilot and record breaker, Jackie Cochran, she agreed to pay to have a couple of dozen more women tested.

Most of the women were drawn from the ranks of Jackie’s organization of lady flyers, “The Ninety-Nines.” Many washed out, unsurprisingly given the small sample size (Lovelace had tested something like 400 men for Mercury), but 13 had performance comparable to the best of the men.

This intrigued Lovelace, who observed that women weigh less, eat less, burn less oxygen, and need less water, all important considerations in sending astronauts into space. He made arrangements to send “The Mercury 13” on to the second of three phases of testing, but this depended on a handshake agreement with a contact in the Navy. About this time, the media got wind, the flags of controversy flew, and the military pulled out, and that was that.

Jerrie Cobb felt she had been lied to. This seems unlikely, as not only Randy Lovelace but the other ladies have stated that he made it clear from the beginning that this was a science project unaffiliated with NASA. Nevertheless, Jerrie and Jane Hart went to complain to LBJ, who was then Vice President, that women should be given a shot. LBJ may or may not have said encouraging things to Jerrie. If he did, he was lying. When his aide drafted an innocuous letter to NASA director James Webb indicting that, while of course the idea was absurd, NASA should still look into the idea for appearances, LBJ wrote across the top, “Let’s stop this now!”

So Jerrie pressed on until she got a congressional hearing, where none other than the first American to orbit the earth, Mercury Astronaut John Glenn testified that men do the flying and women stay home “because that is our social order.” Wow.

Then Jackie Cochran submitted a letter to the hearing in which she undercut the “astronettes” saying the effort to beat the Russians in space would be compromised if NASA diverted resources to train women for spaceflight.

To modern eyes, this all seems hard to fathom. However, it really would have been absurd for NASA to include women in these early efforts, which really did call for the calm nerves of experienced high-performance test pilots. The real issue is that woman had not been welcomed into the engineering and test pilot ranks after WWII. If they had been, then some of them would doubtless have been ready and able to fly in these early space efforts.

As it was, Russia flew a woman (whose only qualification was her skydiving hobby) and then on the basis of her having supposedly performed less than perfectly, didn’t fly another for 17 years until the US was about to.
But this all has a neat finish. When Eileen Collins commanded Space Shuttle Columbia in 1995 she invited the surviving members of The Mercury 13 to watch the launch as her guests. Candidate Wally Funk went on to become the first women air crash investigator. Jerrie Cobb went on to get a nomination for the Nobel Peace Prize for her work using air service to deliver aid in the developing world.

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So you see, these women may not have had the credentials NASA wanted for the first tentative steps into space, but they definitely had the right stuff.

Since When Is Life Fair?

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Damn you Eric flint, for writing this excellent essay and distracting me when I’m supposed to be writing! (Not really, Eric, you’re awesome and your cap is awesome).

In this excellent essay, Eric demonstrates that the fundamental charge underlying the recent Hugo kerfuffle is valid, that the nominations in recent decades have diverged from the tastes of the broader market. He goes on to argue persuasively that this is an inevitable phenomenon for any award, and not the dark ideological conspiracy imagined by the puppies campaigners.

To which my reply is, so what if it was?

Why would anyone think the Hugos SHOULD reflect the mass market in the first place? As I told Brad Torgersen early last year before attempting to bow out of the ensuing train wreck, it’s the WSFS’s show. They make the rules, and if the puppies or anyone else doesn’t like them they are free to create and fund their own award. I’ve seen awards that are explicitly only open to women or minorities or people who reside in Alabama. So what? Other awards are only looking for stories with certain outlooks or themes. So what? Clarkesworld, Analog, Asimov’s, and the editors at Tor and Daw and Baen all have their own interests and tastes, their own slice of the market they believe they can serve, and so that’s what you send them. Sometimes they tell you what they are looking for. Usually you take a stab. Often, what they tell you turns out to be wrong. So what?

Is it really such a shock or disgrace if the group funding the award honors their own collective tastes–just like every professor teaching in every MFA program anywhere on Earth? So what? The market already rewards the crowd pleasers, and if the problem is that some up-and-comer thinks he needs a Hugo for the publicity boost–well, the Hugo doesn’t exist to promote up-and-comers, it exists to sell tickets to WorldCon, to pay omage to Hugo Gernsback, and to do whatever the heck else those who put up the purse and throw the shindig want it to.

Those who don’t like it are free to complain. They are also free to write whatever they think will win a Hugo, or to promote WSFS memberships among their fans and friends, and so add diversity if they see it lacking, without stooping to petty games and mudslinging.

That’s it. That’s all I’ve got. I have word count targets to meet.