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October 28 2013

Ep. 318: Escape Velocity

Sometimes you’ve just got to get away from it all. From your planet, your Solar System and your galaxy. If you’re looking to escape, you’ll need to know just what velocity it’ll take to break the surly bonds of gravity and punch the sky.

Show Notes

May 25 2013

Ep. 299: Space Stations, Part 4 — Future Space Stations

Sometimes a trilogy needs four parts. We’ve looked at the history and modern era of space stations but now it’s time to peer into the future at some space station concepts still in the works. Most of these will never fly, but the ideas are important. We can’t call ourselves a true spacefaring civilization until humans live permanently outside the Earth.

Show Notes

Reposted bycheg00 cheg00

Ep. 300: What We’ve Learned in Almost 7 Years

We created Astronomy Cast to be timeless, a listening experience that’s as educational in the future as it was when we started recording. But obviously, things have changed in almost 7 years and 300 episodes. Today we’ll give you an update on some of the big topics in space and astronomy. What did we know back then, and what additional stuff do we know now?

Show Notes

Ep. 298: Space Stations, Part 3 — International Space Station

And now we reach the third part in our trilogy on space stations, with the largest vehicle ever assembled in space: the International Space Station. Launched in 1998, it now consists of 450 metric tonnes of modules, power systems and spacecraft and is regular host to a handful of astronauts from many countries.

Show Notes

Ep. 297: Space Stations, Part 2 — Mir

Last week we introduced the history of space stations and focused on the US and Soviet stations that were launched. This week we look at one of the longest running missions ever launched: Mir. From its launch and construction to its fiery finale, Mir helped both the Russians and the Americans extend their understanding of what it actually takes to live in space.

May 19 2013

Ep. 296: Space Stations, Part 1 — Salyut and Skylab

It’s one thing to fly into space, and another thing entirely to live in space. And to understand the stresses and strains this puts on a human body, you’re going to need a space station. In this three-part series, we explore the past, present and future of stations in space, starting with the American Skylab and Russian Salyut stations.

Show Notes

December 06 2012

Ep. 278: Animals in Space

We always think about humans in space, but the cold hard reality is that animals have always been first in space. First to fly, first to orbit, and sadly, first to die. Let’s learn about how our animal companions have been our trusty partners in space exploration, and let’s recognize their noble sacrifices over decades of experiments.

Transcript: Animals in Space

Download the transcript

Fraser: Welcome to Astronomy Cast, our weekly facts-based journey through the Cosmos, where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain; I’m the publisher of Universe Today, and with me is Dr. Pamela Gay, a professor at Southern Illinois University – Edwardsville. Hi Pamela, how are you doing?

Pamela: I’m doing well. How are you doing, Fraser?

Fraser: Good. So as we are recording this right now, Hurricane Sandy is chewing up the Eastern seaboard of the United States, so we want to send our warm wishes and hopes for safety for everyone involved there. Please keep your head down! And we were just noting this before the show: if it doesn’t out cut your power, enjoy this opportunity to see the Milky Way for the first time.

Pamela: Except how are they going to hear us if they cut their power? Never mind.

Fraser: Never mind.

Pamela: Yeah, metaphysics…

Fraser: They’re going to watch it on YouTube through their cell phones and then look up and notice that there’s a cloud of stars in the sky.

Pamela: It’s a great use of battery life during emergency circumstances.

Fraser: Yeah, exactly. I also wanted to…I put a quick post into Astronomy Cast a couple of days ago sort of mentioning our super awesome “phases of the moon” app, which we’ve just updated, and now it works on Android, it works on IOS, and I’m holding it up to the screen, but the people, I guess, watching the podcast won’t be able to see it, but it’s really cool. You can just kind of drag the Moon, drag the terminator back and forth, and see the phases change and lots of cool stuff. We actually just submitted the iPad app, so you can find that on either iTunes (just search for “phases of the Moon”), Universe Today, or search for it on the Google play store (“phases of the Moon-Universe Today”), and you’ll be able to find it. It’s only .99 cents and it helps us feed out children, so…

Pamela: And what I love about it is you actually got the librations correct, so…

Fraser: Yeah, well, we actually based it on NASA imagery, so NASA released a whole pile of really highly detailed animations of the Moon, and we incorporated it into this app, so you can actually see the shadows changing over the Moon, you can see how the Moon wobbles back and forth… It’s very cool and I hope you people find it very helpful for seeing when the next moon phases are, and also just hand it off to a kid and let them drag the Moon back and forth to see how it works.

Pamela: On more thing: during our last hour of recording, which was last week, for those of you listening to this on the podcast, we put out a plea for people to donate for to help pay for our server costs, and I love our listeners, Domfromderby– I may not be able to pronounce our listeners – Domfromderby tweeted, “I’m 31 tomorrow in case anyone wants to get me anything just click on the donate button to help make more shows – ta.” And I love the idea that someone’s asking to have his birthday gifts help get more science out, help us keep our servers turned on, and communicate out to the world, so I just wanted to share that piece of awesome human goodness, and during the last hour while we were recording we actually got two donations, so if any more of you want to help, it’s “” If you go to, that goes to pay for our audio editing, if you go to that helps pay for the servers for the forums, and for a lot of other things.

Fraser: All of the other science outreach that we’re doing. Cool!


Fraser: So we always think about humans in space, but the cold hard reality is that animals have always been first in space: first to fly, first to orbit, and sadly first to die. Let’s learn about how our animal companions have been our trusty partners in space exploration, and let’s recognize their noble sacrifices over decades of experiments. Yeah, we were…we’ve not been very nice to our animal companions as it relates to their sacrifice in space exploration, so I think this is kind of a morbid episode, but I think it’s important to recognize just how important animals have been in helping out with space exploration.

Pamela: But it is a good episode as we head into Halloween because it is an episode filled with the creepy-crawlies.

Fraser: That’s true — scary episode! Now you actually dug up a really great piece of history for the sort of first animal explorers who have been pushing the boundaries of not really space exploration, but perhaps air exploration? So tell us the story.

Pamela: One of the places that when I’m researching for the show I go as a starting point is Wikipedia because it links to everything off of that and it usually is full of random, esoteric information that I wouldn’t know to Google, and I came across this sentence that is awesome. It simply reads, “Animals had been used in aeronautic exploration since 1783 when the Montgolfier brothers sent a sheep, a duck, and a rooster aloft in a hot air balloon, the duck serving as the experimental control.” There’s some joke waiting to be told. I don’t know what it is, but a sheep, a duck, and a rooster…

Fraser: Yeah, but the duck was the control.

Pamela: And the rooster wasn’t. I’m not sure what that says about rooster.

Fraser: Well, the duck flies, right?

Pamela: Roosters pretend to fly. They don’t do it so well.

Fraser: Yeah, but a duck can actually fly and go to high altitude, while a rooster was never meant to, or has long evolved out of the ability to fly, so I think that was the point was, if the duck is normally able to fly, what would happen to a rooster that doesn’t fly. So what was the outcome?

Pamela: It doesn’t say. I’m assuming they came back fine. It’s not like hot air balloons go very high.

Fraser: With the tenor of this episode, I’m going to assume they crashed somewhere and were forgotten.

Pamela: I think it would have been listed though. That would have been listed, so I’m thinking it was all good for those three critters.

Fraser: Alright, so that’s…but then that was the beginning of I guess airline, air travel exploration, but let’s talk about actual space exploration. So when did animals first join the quest to explore the final frontier?

Pamela: The 1940s. Once we had recovered, conquered, stolen – I’m not sure what word we want to go for here…

Fraser: Liberated?

Pamela: …V2 rockets from Germany during World War II, both America, both the United States, and the Soviet Union had their retinue of stolen German rocket scientists, and began to fling things into space, and what’s interesting is the differences in what got flung by the two nations. Here in the United States we started simple with fruit flies, went on to rodents, went on to monkeys, the Soviets went to dogs instead. I’m not sure why; I’m not sure what that says, but the Soviets had a long history of sending well, “muttniks” was the derogatory term used here in the United States.

Fraser: Muttniks?! I’ve never heard that before!

Pamela: Yeah, Muttnik to go with Sputnik.

Fraser: I’ve never heard that. That’s awesome!

Pamela: And we sent up monkeys and mice and fruit flies.

Fraser: So what was the first…what were they doing here? They were testing these out on V2 rockets?

Pamela: Right, so it started out with fruit flies just trying to figure out how bad is the radiation because we had no information as to what happens when you go up, so start with fruit flies, start with something that…well, they’re going to die if you radiate them.

Fraser: Yeah, they’re fragile.

Pamela: Yeah.

Fraser: Although you would think how hard it is to get rid of fruit flies from your house, but they are actually kind of fragile.

Pamela: Yeah, radiating them will kill them — unlike cockroaches, but that…we’re going to get there. So it started with fruit flies, mice, went on to Rhesus monkeys… yeah. One of the interesting things with the fruit flies is they also were launching moss, and I’m not quite sure what was being looked at. We look back on these experiments and it’s just sort of like, “What were they thinking?” But at the same time, they had no information.

Fraser: Well, they didn’t even know if you could eat in space. They weren’t sure if that you could swallow, that somehow gravity was required to get food from your mouth down to your stomach.

Pamela: Well, what gets me is why didn’t they ask a fourth-grade girl hanging upside down eating her snack at recess because, really, we all did it because we were told not to? So yeah, the 1940s were the years of the fruit flies and the monkeys, and one of the disturbing things was these poor critters, they…medical technology wasn’t that advanced either, so it wasn’t like today where you go in and they tape electrodes all over you and they just have to shave your head if they want to do fancy brainwave analysis, and even then they don’t have to do much shaving nowadays, but back then, not quite there yet so there was a lot of embedding electrodes, there was no taping monitors to the body and to the back, it was into the body, so that was a little bit disturbing.

Fraser: Yeah, but then these animals weren’t expected to survive for very long anyway.

Pamela: No. No.

Fraser: It’s a sad episode if you like animals. Right. OK.

Pamela: Yeah, but they did put them under anesthesia for launch because they didn’t want to scare the bejesus out of them, although I don’t know why they thought launch was scarier than zero gravity.

Fraser: Or having electrodes implanted in your head.

Pamela: Well, yeah.

Fraser: Well, yeah OK, so then what is sort of like the first real important animal experiment that was done?

Pamela: I think the first big one that people pay attention to might be Laika? It was the Soviet dog that orbited all the way around the planet. A lot of people also look back and remember the monkeys, Able and Baker. Miss Baker, she actually lived at the Huntsville Space and Rocket Center until 1984, and lots of people got to see her in the public while she was on display there.

Fraser: Right. So that’s a successful return to Earth. That’s a monkey that was treated with…

Pamela: And Laika was not a successful return. Laika orbited…

Fraser: OK, so let’s start with Laika, then. Can you talk about the Laika mission and sort of what happened?

Pamela: So Laika was the second-ever orbiting spacecraft, and they carried the first animal into orbit, and this was a Soviet spacecraft, November 3, 1957. Laika was just a happy pooch with pointy ears, easy to draw cartoon characters of, stamps made after Laika, and Laika died during flight because they didn’t know how to bring Laika back, so this was one of those points in history where we had the technology to launch things, had the technology to orbit things, did not have the technology to bring things back. So Laika went up, Laika orbited, Laika proved that it’s safe to orbit, Laika was put to sleep.

Fraser: Right. And so Laika sort of crashed…or I mean, could Laika actually survive in orbit?

Pamela: Laika survived in orbit, yeah. How long are you going to keep a dog alive in space? Well, they figured that one out later, but…yeah.

Fraser: And so this was like the first mission right after Sputnik, right?

Pamela: Not right after, but yeah.

Fraser: But you said the next orbit, right? So Sputnik was the first orbit.

Pamela: So this was Sputnik II.

Fraser: Right, and so it carried a little dog inside, and Laika was a little…almost like a Jack Russell terrier, like a little dog, right?

Pamela: Right, a little pointy-eared cute dog, lots of cartoons, so this was followed in 1958 by a squirrel monkey (Gordo) getting launched from here in the United States, and then we had Miss Baker and Able that went up in 1959, so the 1950s were the years of the dogs and monkeys. Also, of note were several frogs, lots of mice, small critters. Along the way the basic idea was to try and get a sense of: how does weightlessness affect biological processes? They launched eggs. Can the eggs be hatched once you bring them back down to Earth? All sorts of different things, but mostly they were worried about will things survive. Now, the first critters to be brought back from orbit were — cause Able and Baker didn’t orbit, they just went up – in the 1960s sputnik V went up with Belka and Strelka, so this was the first one to orbit animals, bring the animals back, and what’s kind of neat is one of the puppies of Strelka was given to Caroline Kennedy by Nikita Khrushchev, and one of the side effects of this is there’s now long lines of space puppies.

Fraser: I want a space dog!

Pamela: Isn’t that kind of awesome?

Fraser: Yes! I didn’t know! Now I totally want a space dog!

Pamela: So yeah, these are the things that we have done. We have sent dogs to space, we have returned dogs from space, we have bred the dogs that went into space, we have turned them into political pets from space.

Fraser: Right. Well, I really want one. That’s awesome! Right, OK, but the point here is these dogs were returned safely to Earth and able to breed afterward, and I mean, this is part of the experiment, right? This is like: we send a dog to orbit, bring it back, can it breed? And because they didn’t know, right? They didn’t know any of this stuff.

Pamela: And so then the next big breakthrough was figuring out if you send something into space, can it think? Can it maintain the ability to do activities?

Fraser: Right, so like is your brain going to work? Will the glucose move around properly?

Pamela: Do you become dumb like you do at altitude because there is all sorts of stories from people who build telescopes at the tops of mountains, climbing high peaks where they simply lose reality. It’s the “no matter how long I keep cutting it it’s still too short” – it’s problems like that, and this is where Han the Chimp came in. This is the first chimp sent into space, he was a friendly little soul, and he actually went into space and he pulled levers, and the good and the bad of this is he was trained to pull the levers in order to get banana treats, but if he didn’t, he’d get shocked. It was one of these where they did both the shocking and the treating and…yeah. It was the 1960s, so yeah.

Fraser: I believe that would be an animal rights violation right there.

Pamela: I’m not sure – that’s the part that bothers me. I’m pretty sure that’s legal.

Fraser: Right, so I guess the point here is they knew if you were at high altitude your brain didn’t work right, and I’m sure to a certain extent they knew this was caused by the low air pressure and the lack of oxygen getting to your brain, but could there be something else just about being far away from mother earth that would affect you in orbit. They didn’t know, so they taught this chimp a whole pile of cool tricks and sent him to space and see if he could perform these tricks in the same way.

Pamela: And this was kind of the last test before they let human chimps go into space because one of the complaints of the early astronauts was they were being treated like trained monkeys — they weren’t given their own buttons to escape out, they weren’t given very many controls. It was they wanted to fully automate the rockets, and so Ham was the trained monkey — that preluded the astronauts who felt they were trained monkeys, and Ham successfully proved that you could do it. He came back happily able to interact with his trainers. Yeah. It was all good.

Fraser: I would think he wouldn’t have liked those trainers after they shocked him, but…anyway, continue.

Pamela: [laughing] So, as time progressed and more and more nations began to get into the launching mammals into space act, with France flying rats in the 1960s. France did have a space program at one point. We had China in the 1960s launching rodents. The Russians continued to launch their dogs, and this was one that when I tried to research it I wish I could have found more information because in the 1960s at the beginning of Voskhod program, they launched two dogs for over twenty days. I’m trying to figure out…I can figure out how they fed them, I can figure out how they watered them, but were they like floating in a capsule filled with, well, processed food and water? It’s not like you can catheter a dog that…did they catheter the dog?

Fraser: Probably had some kind of fancy diaper on him. And then they had some kind of feeding tube…

Pamela: For 22 days?

Fraser: Whatever. They’re dogs. They’re cruel to animals. Send them into space, let them poop in their diapers and eat from tubes, you know, they probably kept them constrained in some kind of harness…

Pamela: Used airflow? I’m hoping they used airflow because…

Fraser: I don’t think they cared.

Pamela: Yeah, that’s what bugs me, and the other part that bugs me is here I am 38 years old and what’s the first question I have? What happened to the canine poo and pee? But yeah, that’s exactly where my brain went.

Fraser: Yeah, they just didn’t care. But they sent…it was later on the Gemini mission, they had a couple of astronauts up there for the better part of two weeks. It was pretty complicated. They had a lot of that kind of thing going on. Read some of the…

Pamela: You have to have no privacy concerns if you’re an astronaut. Everything’s hanging out.

Fraser: If you watch like from the Earth to the Moon and you see what they were in, how small that capsule was… It’s just astounding how they lived through it. I mean, Apollo was like a luxury hotel compared to the Gemini missions. OK, so we’ve got some dogs up there for twenty days, which is a fantastic feat, and it shows that a living creature can survive in space for twenty days.

Pamela: So we’re now entering the period of time where the Americans and the Soviets were successfully launching humans. We’re seeing other nations work to launch rodents, and looking through this history, you find all these nations that I wasn’t aware had their own space programs. Argentina launched a rat, and so there’s just all these people thinking, “We’re going to be next,” and no, it was America and the Soviet Union that kept going, but over time, we began launching more and more different critters, trying to understand the effects of 0-G. One of my favorite stories is during Skylab in 1973, they started doing student programs, where they allowed students to suggest various projects that can be done in space and one of the suggested projects was to launch spiders and see what would happen. And the reality is spiders do not like 0-G; they will not leave their little test tubes unless forced. They will cling to their test tubes. When you force them out of their test tubes, they attempt to swim through 0-G, but once you get them going, they will build webs that aren’t quite up to snuff compared to what you see on the planet Earth, but over time they increased their ability. What was kind of awesome with this particular experiment is the first web that got built was a somewhat drunken looking web, but it was recognizable that this is a spider web with a spider sitting in the spider web, and because the spiders can go a long time without eating, they fed the spiders prior to launch and figured they’d kill the spiders before they needed to eat again, but the astronauts were so thrilled with the results of the initial experiment that they were like feeding the spiders pieces of rare meat to keep them going.

Fraser: Wow! That’s amazing.

Pamela: Unfortunately, the spiders eventually died of dehydration. They were provided water, but apparently, 0-G, water, sponge…spiders just didn’t get the whole notion real well.

Fraser: Right, but they didn’t plan for the possibility that the astronauts would want to take care of the spiders and continue watching them and seeing how they learned over time, but I mean, other experiments later on came along, I know, and started to take multiple generations into account. A lot of these long duration space flights went into that.

Pamela: And right now on the International Space Station – just to jump forward, we have with the International Space Station, they just finished installing on the Japanese Experiment Module a really neat fish tank, and I’m a big fan of fish tanks. And this is like the best fish tank ever. No cleaning of the fish tank is required, and their goal is to figure out what happens to multiple generations of fish born in space, and it never really occurred to me that fish suffer the same bone degeneration that astronauts suffer because, but you’re weightless in water, but you’re not actually weightless in water; you’re suspended in the water, but there’s still all the gravitational effects on your biology, and in space you don’t have that, so they have this really neat fish tank with neat little fish in it and they’re planning to go through multiple generations of the fish to see what ends up happening. Is there a higher mutation rate? There’s so many different questions to be asked, and we have found examples of space change in biology – salmonella becomes much, much more virulent in space, and I can imagine food poisoning actually turns you into a rocket in space, so really those two shouldn’t be mixed.

Fraser: Waterbears become more adorable.

Pamela: They’re just adorable anyway.

Fraser: Yeah. Right, and the Soyuz just docked like a week ago with these fish, which is great. OK, so when last we saw our heroes we were looking at the spiders on the Soyuz capsule – oh sorry, on the Spacelab.

Pamela: Spacelab, yeah.

Fraser: I mean, then there was years and years of the space shuttle missions, and you need an actual space station. I mean, there was a ton more experiments done with plants, with animals…it went on and on.

Pamela: It wasn’t just with those. There were also the tomato seeds in space in the early 80s, which then got brought back and given to schools all across America to grow to see if the tomato seeds would continue to grow. There have been a ton of spiders sent into space, a ton of mice sent into space, mice born in space, and what’s interesting is it’s actually challenging to find results from these stories because results, other than the salmonella becoming much more virulent, there hasn’t been anything so Earth-shattering that it’s made the cover of “Science” or “Nature,” so biology seems to be pretty happy to go in space, and there’s just a lot of brain…uh, bone degeneration (not brain degeneration) bone degeneration going on.

Fraser: Now there’s one tragic story about an animal in space. I don’t know if you know about this one. There were some nematode worms on…

Pamela: Oh yeah, this one actually isn’t a tragedy I don’t think.

Fraser: On Columbia, right?

Pamela: The Columbia was a tragedy, so the last mission of the Columbia, the first space flying space shuttle, and it unfortunately blew up in 2003. It was doing an experiment with worms called nematodes, and they were in a special container that somehow they managed to survive the explosion of the Columbia during re-entry, survive the high heat, survive impact and this was one of those moments of…well, we know that when big enough asteroids hit the Earth, it sent debris and dinosaurs into space, and we now know that the nematodes could survive re-entry, so ideas behind Panspermia become much more realistic, and it’s also a little bit terrifying how hard it is to kill a nematode.

Fraser: Yeah. So there were generations and generations of these nematodes that have been, I know, passed around. Researchers were able to get their hands on them and do experiments on them and continue on the lines of them, and yeah they kind of survived, which is back to that concept of…

Pamela: Not kind of – they did survive.

Fraser: They did survive! And it’s like the waterbears. The waterbears can withstand almost anything and go to space. They really truly will be our future space travelers. So where do we stand now? Fish? We just sent some fish to the space station. Do you think we’ll ever see more permanent – like pets in space? Things like a dog in space, or a monkey in space?

Pamela: One of the things Bigelow’s doing, and I’m not sure if they’re intending this to be pets or not (I don’t think they’re intending it for it to be pet), but I know folks that own Madasgascar hissing cockroaches as pets because they’re giant cockroaches seven inches long sometimes, and they like to hiss, and for a variety of different reasons, including the fact that these suckers can survive in near-vacuum, Bigelow has launched them, and scorpions, and other creepy-crawlies into space in their Genesis I and Genesis II inflatable modules, and they’re basically looking at what are the effects on 0-G on these biologicals, and it’s kind of extraordinarily gross, but this is what Bigelow is doing. They haven’t launched any bedbugs yet, so I think their hotel business is still in line, be doing just fine.

Fraser: Wouldn’t it be a nightmare if the Bigelow hotel gets infested with bedbugs? How would you get rid of them?

Pamela: You don’t. You just give up.

Fraser: What a disaster! You give up. De-orbit. De-orbit. That’s it. Cool. Alright, well I think we’re good for animals in space, so thank you once again. And again, I hope everyone on the East coast stays safe with Hurricane Sandy, and we will see everybody next week.

Pamela: Sounds great, Fraser. I’ll talk to you later.

This transcript is not an exact match to the audio file. It has been edited for clarity.

November 26 2012

Ep. 277: Orbit

When an object is orbiting the Earth, it’s really falling. The trick, described in the Hitchhiker’s Guide to the Galaxy, is how to throw yourself at the ground and miss. There are several different kinds of orbits, and they are good for different reasons. From suborbital jumps to geostationary orbit, time to learn everything there is to know about going around and around and around.

Show Note

Transcript: Orbit

Download the transcript

Fraser: Welcome to Astronomy Cast, our weekly facts-based journey through the Cosmos, where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain; I’m the publisher of Universe Today, and with me is Dr. Pamela Gay, a professor at Southern Illinois University – Edwardsville. Hey, Pamela, how are you doing?

Pamela: I’m doing well. How are you doing, Fraser?

Fraser: Good. So a bunch of people asked me if I had gotten hit by this recent earthquake that happened off the coast of Prince Rupert, and totally fine, didn’t even feel it, no tsunami was generated, so I don’t think there were any injuries, no damage; it was a pretty tame 7.7 magnitude earthquake, which is quite surprising.

Pamela: It’s always good when they’re in largely unpopulated areas – like Canada.

Fraser: Like Canada, which is largely unpopulated… Now you had a couple of things that you wanted to mention and kind of shamelessly promote?

Pamela: Well, I did! So Christmas season is fast approaching, according to my local department stores, which are all terrifyingly filled with Christmas stuff. We would like to remind all of you that one of the ways that we pay our bills is we sell t-shirts, and if you can please, please, please buy our t-shirts, this will help us pay all our server bills. We’re actually running short on funding for our server bills right now, so and if you want to donate specifically for server bills, don’t donate to Astronomy Cast, go to Astrosphere because Astrosphere pays for the servers, so buy t-shirts, donate to, and we will hopefully keep our servers turned on, and that’s always a good goal.

Fraser: That is the umbrella organization that holds Astronomy Cast and 365 Days of Astronomy, Cosmoquest, and all the fun stuff we do.

Pamela: So Astronomy Cast is a joint production of Astrosphere New Media, Southern Illinois University-Edwardsville, and Universe Today, and when you donate to Astronomy Cast that goes through Southern Illinois University –Edwardsville. That goes to help pay for our show notes, it goes to help pay for Preston to do all of our editing, that does not pay for the servers. Astrosphere pays for the servers, so if you want to donate for the servers, donate to Astrosphere — and we really need money for that!

Fraser: OK. Alright, well let’s get rolling then.


Fraser: So when an object is orbiting the Earth, it is really falling. The trick — as described in The Hitchhiker’s Guide to the Galaxy, the trick is how to throw yourself at the ground and miss. There are several different kinds of orbits, and they’re good for different reasons — from suborbital jumps to geostationary orbit. Time to learn everything there is to know about going around and around and around.

Pamela: [laughing] So I never get to see your intros before we start, and I love the quote from Hitchhiker’s.

Fraser: I know, I know. It’s a great… I sort of stole it, right, because it’s this quote about flying. The trick to flying is to just fall at the ground but miss, and the lead character in the books at one point finally figures out how to do this and flies around, but that’s really what orbit is, right? Orbit is falling and missing the ground.

Pamela: It is! It helps to start from a large altitude.

Fraser: So, you know what, I want to go back a bit. We did a bunch of shows on Newton, and I don’t think we gave Newton…Newton’s thoughts on orbit kind of short-shrift, so can we have a quick conversation about how Newton figured out what orbit is and piece together what the Moon is doing with cannon balls, and…right?

Pamela: It wasn’t so much Newton that figured out orbits as Kepler, and then Newton figured out the “why” of orbit. So what Kepler figured out was orbital periods, that orbits are ellipses, and then Newton figured out that there’s this crazy force, called gravity, that causes keys to fall to the ground and causes moons to fall towards the Earth and miss, and the trick is if you simply drop a set of keys straight down, applying no force on them, just releasing them, they’re going to fall straight toward the center of mass of the Earth. The center of mass of the keys is attracted toward the center of mass of the planet. Now if you instead toss the keys, they’re going to move with a certain amount of horizontal velocity, and ignoring air resistance, ignoring friction, things like that, they’re going to maintain a constant horizontal velocity while falling toward the center of the Earth vertically. Now, the catch is if you throw those keys hard enough, they’re going to keep going further and further and further, getting further around our curved planet.

Fraser: You can imagine like shooting those keys out of some kind of gun that shoots keys.

Pamela: Yes. Exactly.

Fraser: A key gun, yeah.

Pamela: Which, in some ways seems more dangerous than cannonballs, but if you get enough velocity on those keys, they’re going to come all the way around and hit you I the back of the head, and so the catch is they’re falling at the same rate that the Earth is curving, and if you get the velocity horizontally just right, they’re going to keep falling all the way around the planet and come back to where they started.

Fraser: Right, and I was actually just going to go into that exact question, which is if you don’t add quite enough force, they’re going to spiral inward, but if you add more force, that perfect balance, then they spiral outward, right?

Pamela: Exactly. So you have…this is the difference between a ballistic trajectory, which is one that hits the planet again somewhere else, orbital velocity, which is one where you end up with anything from a circular to an elliptical orbit, to an escape orbit, which is kind of like Voyager, or any other of those interplanetary space probes that got away from the Earth and kept going.

Fraser: Right, right, and of course these are all…all of these are different kinds of orbits that scientists are…they have use for — for different reasons. So we’ll talk about some of those. So let’s go back to the beginning. So what was the big leap, maybe, that Newton made about the Moon and gravity?

Pamela: Well, Newton’s big leap was: “The Moon is falling around the planet.” Up until then we knew things orbited, we had no clue why they orbited, we had no clue what held the planets around the Sun, no clue what held the Moon around the Earth. This was all highly mysterious, and it was Newton coming along and saying, “Whoa! Gravity!” and putting this idea of forces together, and every action is due to a force, for every action there is an equal and opposite reaction, putting all those pieces together — that was what Newton’s big breakthrough was.

Fraser: Right, right, and so you’ve got the situation where the Moon is falling toward the Earth, and at the same time, it’s falling around the Earth, and it’s this perfect balance: it’s always continuously missing, but it’s not spiraling inward, and it’s not…I guess it’s slowly spiraling outward.

Pamela: It’s slowly spiraling outward.

Fraser: Yeah, yeah, but that’s a different force that’s going on. OK, great! So let’s talk about the kinds of orbits that maybe we’ll use, and let’s get Low to Earth first. And I think something that’s actually not an orbit at all is the kind of flight that, for example, Felix Baumgartner just did, right? He didn’t orbit at all, but he, you know, travelled to the edge of space (I am holding up my air quotes). So what’s that?

Pamela: So basically, there’s a certain point where you get high enough above the atmosphere, or high enough into the atmosphere (depending on how you want to mince your atmospheric levels)…

Fraser: I thought you were going to say mince your astronauts!

Pamela: [laughing] Let’s not mince astronauts! No, mince our atmospheres! So as you get higher and higher into the atmosphere, the density of the atmosphere drops. This is something you start to experience just by going to the city of Denver. It gets worse as you do things like climb Mt. Everest. As you keep going up you begin to run out of air, and one of the side effects of running out of air is you run out of stuff to scatter the sunlight and create the pretty blue sky above you. So as you get sufficiently high up at weather balloon altitudes – 50 km and higher, basically — you start to reach the point where you can see where the blue sky ends and the blackness of space begins, and you aren’t actually necessarily in space at the point that you can see that transition. That’s one of the funky things is how do you define what space is? And it’s not defined by where you go from pretty blue sky above you to stars above you; it’s actually defined based on energies because that’s much more mathematical. So when we first start talking about where does space begin, we start with thinking about, well, where do we start to see the starry blackness of space? And that’s once you start getting to weather balloon, or crazy-dude-jumping-out-of-capsule altitudes, which is roughly 50 km or higher.

Fraser: So you can see…I don’t know if anyone actually had a chance to watch this live or see what happened, but he tumbled out of a capsule and was totally out of control for the first, probably, minute or so.

Pamela: That was terrifying!

Fraser: I know! It was really scary! And then you could see he was able to sort of get some air or wind resistance, and he was able to get under control until he was in this nicely controlled flight, and you could really see where he had no atmosphere, and then he had enough atmosphere to start to orient himself and that spin, but yeah…it sounds like it really scared the pants off him! OK, so that’s your first situation. The next one is you’ve got Spaceship 1, and the upcoming Spaceship 2, which is again…

Pamela: Well, there’s actually many more layers to go through before you start getting that complicated.

Fraser: What do you mean?

Pamela: So Spaceship 1 and Spaceship 2 — that’s just suborbital flight, but then you have to look at (and I’m going to mispronounce this because, really, there has to be at least one mispronounced word per show) — it’s the Kármán line? It’s at an altitude of 100 km above sea level, and this is another one of those places where we start defining “what is spaceflight?” And in this case, it’s where we’re looking at a lot of energy boundaries. We’re starting to look at: so how do you travel? Do you travel using the lift generated by your wings? Do you travel using thrusters and orbital velocities? And it’s at this line that the atmosphere gets sufficiently thin that you are now a rocket and not an airplane.

Fraser: Right, and but I think that’s really important for people to understand is that like with Spaceship 1, they just go up to this line (the 100 km line), and then come back down, and that is…it requires a lot of energy, but it still uses a fraction of the energy to actually go into orbit. I mean is that really suborbital?

Pamela: Well, suborbital is any time you hit the international boundary for space, which is 100 km.

Fraser: OK, yeah.

Pamela: So by definition, since they hit the 100 km, since they get past the altitude at which you are no longer travelling as a plane…

Fraser: Yes.

Pamela: They do count as suborbital, and the reason that the “sub” word is there is because there’s no orbiting involved. There’s simply the going up and the coming back down part. It’s ballistic.

Fraser: Right – ballistic, and it’s using a fraction of the energy. Now, what would scientists…I know scientists like to use, they’ll use like sounding rockets and things like that. There’s some value in going into a suborbital flight. Even like straight up and down, right?

Pamela: Right, so there’s lots of different advantages for when you need just quick data. You can do things to measure radiation levels, you can do things to measure thicknesses of the atmosphere at different altitudes, you can take quick x-ray measurements, so instead of having to launch an orbiting x-ray satellite, you can get basic x-ray, you can also get basic microwave data by launching yourself up into the atmosphere. Now, instead of using sounding rockets, another cheaper way to go is to actually use the equivalent of weather balloons — just swap out the sensor package, get high enough up and float around, and whereas you have a few minutes with a sounding rocket, you can get many hours out of a weather balloon.

Fraser: Right…until your balloon pops.

Pamela: Well, yes, that is a problem.

Fraser: Yeah. OK, cool. So that’s straight up and down, and it’s really important for people to understand this distinction that the energies required to go up and then come back down are a fraction of the energy to actually go into orbit. So let’s talk about some more ballistic flight now. I think a great example was the first American man in space, Alan Shepherd. He went on a ballistic trajectory.

Pamela: Right, and in fact, he and many animals that we’ll be talking about in the next show…so the what they did is they basically went up, went up high enough that they could experience zero-G, that they wouldn’t be up there long enough that they had to worry about food and water because they didn’t know people could eat in space initially, and then just bring them straight back down. And this is what we’re looking at for Spaceship 2; this is what we’re looking at for a lot of the X-Prize commercial stuff. Many of these different tourist flights are going to be these suborbital flights that go up just long enough that you can see the starry night, that you can experience zero-G, that you can make some distance across the ground (luckily the planet’s also rotating beneath you), but you don’t have to get all the way up and all the way around the planet as you do with orbit.

Fraser: Right, and then I think you can take that concept even further. I mean, you’ve got the horrible intercontinental ballistic missiles, or futuristic…

Pamela: You see, you say “horrible,” and I’m looking forward to the day that we have, I don’t know, Spaceship 3, and we can fly to Australia suborbital. I want to be ballistic to Australia!

Fraser: Of course! Of course! And that’s the whole point. Let’s remove the nuclear payload, and let’s replace that with a nice scramjet or ramjet.

Pamela: And decrease the velocity of re-entry.

Fraser: Yes. Yes. So, you know, I mean, in these situations, like, what kind of trajectory will an ICBM take? If you want to destroy Russia, which we don’t want to destroy Russia, but let’s say the Americans did plan to do that…

Pamela: Yeah, let’s say…I don’t know…let’s not destroy anything. Let’s say that we uh…

Fraser: Let’s send flowers to Russia on a missile.

Pamela: No! I want to send, like, news reporters overnight to Australia! This is what I want to do!

Fraser: Sure.

Pamela: No. You pick the…it’s not so much an orbit at this point as throwing a football. You have three different things that you need to take into consideration, and each of them plays a different role. At the most simplistic level, you’re trying to pitch it so that it goes up and then comes back down, and time up is roughly equal to time down — it’s that whole football arc. There’s usually two different angles that you can pick to get to the same location, so you can go really high and have this nice gentle arc, up and over. You can go low and you have to get much more horizontal velocity to be able to get there before you crash into the ground if you take the lower angle. Both of these are fairly straightforward to calculate. It’s one of those things we torture freshman physics students with. The second thing you have to take into consideration as you’re calculating these trajectories is our planet is rotating. So the point you’re aiming at now is not going to be there later, so you have to figure out where the point you’re aiming at is going to be as the planet rotates, and in the process of figuring this out, the third thing that you have to take into consideration is that you’re moving as well, so as your rocket is getting taken off from the ground, the ground is moving, giving you initial velocity. This is part of why we like to launch from places like French New Guinea, from Cape Canaveral, from near-equatorial regions is because those parts of the planet are rotating about the center of mass of the Earth the fastest. If you were aiming from Cape Canaveral, or New Mexico, and you’re trying to land in South Africa, well, South Africa is going around at a different rate, and you have to take all of these things into consideration in trying to figure out how to get from here to there, and Coriolis forces end up playing a role in all of this because of those differences in rotation rates.

Fraser: Well, and this really is the “big frontier.” If people are working on these different kinds of technologies – scramjets and ramjets, you know, if they can come up with something that can go Mach 20 or so, and be able to handle the atmospheric re-entry, then we will be able to do flights from, say, you know…from Los Angeles to Sidney, Australia in just a couple of hours. It will be a dramatic change.

Pamela: Well, the things with the scramjets and stuff is they’re still doing those at fairly low altitudes compared to the suborbital flights, so I think the suborbital flights, in some ways, have a much easier way to go. The only trick is if you want to get from America to Australia…

Fraser: Landing…

Pamela: Well, that and trying to get from America to Australia, the planet’s rotating in the opposite direction that you want it to be for that particular journey, so you can almost imagine a future where it’s easier to go from New Mexico to South Africa to Australia, or…that’s probably bad…from new Mexico to Morocco to Australia.

Fraser: Right, break up the velocity changes a bit.

Pamela: And you’re going in the correct direction around the planet when you do it that way. As long as everyone’s going in the same direction it becomes a lot energetically easy.

Fraser: Alright, so we’re going to kick things up to the next level then and actually go into orbit. So you know now we’ve got a rocket. I think what’s really important here is that it’s not about velocity upwards it’s about velocity sideways.

Pamela: Yes. And this is the tricky part, so you have to get high enough up that well Low Earth orbit, you’re traveling at about 8000 meters/second, so that’s… compare to an airplane that goes maybe 1500, 2000 meters/second for the fastest ones we build, so you’re looking at four times faster than our fastest airplanes in order to orbit. That’s…it’s harder than you would think to double your speed twice.

Fraser: Right, and so you’re looking at, I mean, yeah, what — 20,000, 25,000 km/hour to get into orbit.

Pamela: It’s about 30,000 km/hour, about 20,000 mph.

Fraser: Yeah, and that’s as you say many…almost an order of magnitude more than just to try and just go up and come back down. It’s a phenomenal amount of energy, so really only rockets have the energy output to be able to do this and in many cases a rocket is all fuel, so it burns up all its mass, all its fuel, to get into that velocity.

Pamela: And this is one of those things we’re trying to figure out. What is the most energy efficient way to launch things? It’s such a difficult challenge without a space elevator. You have people who are trying to use magnetic cannons, where essentially you use magnetic fields to accelerate things along rails, you have people who are considering various slingshotting things, although really this is best expressed in “Moon is a Harsh Mistress,” rather than in science reality. You then have all the different rockets.

Fraser: You’ve got tethers…

Pamela: Tethers isn’t so much a good way to get off the surface of a planet. Space elevators…

Fraser: Yeah, space elevators, boost your orbit.

Pamela: Yeah, and then there’s matter of do you start from the ground, or do you start from an airplane? So there’s all different ways to look at doing this and when you look at our early suborbital testing, it was drop something off the bottom of an aircraft that is 2/3 fuel and pretends to be an airplane, and see how high it can go.

Fraser: Yeah, so then what are the different kinds of orbit? I mean, what’s… I guess the first one was the Low Earth orbit.

Pamela: So here you’re looking at a few 100 miles up, orbiting the Earth every hour-and-a-half or so, and in these Low Earth orbits, one of the things you have to worry about is you’re still in the thick enough part of the atmosphere (you’re still in the thermosphere up until you get to about 700 km up) that you have to not constantly, but on a regular basis boost yourself back up because there’s sufficient drag from this very, very thin diffuse part of the atmosphere that it’s still pushing on you enough to slow down your orbit, and will eventually, like it did with Skylab, pull you out of space, and that’s a bad thing when you’re trying to stay in space.

Fraser: Right, so I know that the Space Station is constantly being having its orbit boosted back up.

Pamela: And it’s constantly also doing things like dodging space debris, so they’re moving that giant spacecraft way more than you would think about.

Fraser: So it’s really an inherently unstable orbit…that any object placed in low Earth orbit is really just on a…it’s just a matter of time before it de-orbits itself and crashes somewhere.

Pamela: Yeah, yeah, and so…yeah, it’s just, it’s just bad.

Fraser: Yeah, so then what’s a more stable orbit? Where do they go next?

Pamela: Once you start getting about 10,000 km up, then you start hitting the point where there’s sufficiently little atmospheric leftover bits that you’re pretty much good to go up that high, but that’s pretty high up. You’re still not geosynchronous, but you’re starting to get there.

Fraser: So now what are the advantages of placing a spacecraft into that kind of orbit?

Pamela: Well, at a certain level, there’s…you need less fuel to stay put.

Fraser: Right. Stability.

Pamela: But beyond that, at that sort of altitude, it’s a kind of weird timing — you’re not geosynchronous, so you’re just slowly drifting over the planet, you’re not synchronous with shadows, it’s stable, but it’s kind of…I don’t know what you’re trying to do at that orbit.

Fraser: Well, I know that in some cases, there’s like a funny orbit where you can be sort of geostationary at the same time every day.

Pamela: Oh, that’s the Molniya.

Fraser: Yeah, right? So there’s a special kind of orbit you can do that doesn’t require as much energy to get to geostationary, but it still gives you a fairly stable orbit, and there’s also more elliptical orbits, so they’re lots of orbits that aren’t perfectly circular. They go in elliptical orbits where they go way far out. We actually talked about this last week with the XMM satellite.

Pamela: And the orbit you were talking about a moment ago – the Molniya orbit – it’s an orbit that gets used for communications with very northern and very southern latitudes. It comes close to the Earth on one part of its orbit and then goes sufficiently far out on the other side of its orbit that it’s moving at roughly the same rate that the planet is rotating, and so this highly elliptical orbit allows it to act like a communication satellite when it’s over extreme northern or extreme southern latitudes on the planet. Zip around the other side of the planet and one of the problems we run into with normal geosynchronous satellites is they’re happily straight above the equator, and if you want to watch television from Juneau, Alaska, or…I don’t know, somewhere in Siberia, that’s not going to help you because the satellite is so close to the horizon, you’re looking through so much atmosphere. So it’s with these highly elliptical orbits you’re able to get some sort of television station or something up over these extreme northern and southern latitudes.

Fraser: And also, as you mentioned, there’s the elliptical orbit where the satellite is orbiting around the equator, but you’ve also got these polar orbits, where the satellite is going pole to pole, and that gives you a chance to get complete coverage of the whole planet.

Pamela: And one of the neat things that you can do with the polar orbits is you can time them just right so that you’re always seeing the planet at the exact same elimination angle, and so that has the benefit (especially if you’re a spy satellite) of allowing you to very easily make out differences from orbit to orbit in what you’re seeing on the planet below you.

Fraser: Hmm…so a lot of spy satellites are launched into polar orbits?

Pamela: Yes. Yes, they are.

Fraser: Good to know.

Pamela: There are also weather satellites, so it’s not just…it’s also useful for weather.

Fraser: And let’s go to the granddaddy of all the orbits, which is the Geostationary orbit.

Pamela: Right, so these are orbits that are always over the exact same point on the planet if they’re above the equator.

Fraser: Why don’t they fall into the Earth then? This is impossible!

Pamela: [laughing] Well, so they’re orbiting at the same rate the planet is rotating. It’s the same way the Moon is going around the Earth at the same rate that it’s rotating about its axis.

Fraser: Right, so the satellite is going around, but you’re seeing…it appears stationary overhead.

Pamela: Yes, so these are a little more than 40,000 km up, a little more than 25,000 miles up, and what’s interesting is occasionally asteroids, including the week that we’re recording this, occasionally asteroids come closer to the Earth than these Geosynchronous satellites, and it gives you an idea of how empty space is that so far we haven’t lost any of our satellites to an interloping asteroid. I’m waiting for this to happen. That’s going to be such a blast to watch how badly the television news covers it. It needs to be like some dead satellite that gets destroyed by an asteroid, but still it’s on my bucket list of things to see.

Fraser: So why would you want to put a satellite into a Geostationary orbit?

Pamela: Well, if you put it into a Geostationary orbit, it’s directly over the equator of the planet. It’s going to happily stay over the same point on the planet as the planet rotates. This means that if you’re a communications satellite, you’re not budging. Someone points their satellite dish at you, you point your satellite at them — it’s a nice friendly uplink. Now, the problem is if you’re not directly over the equator, you’re going to be oscillating north and south as you go around, but you will stay over the same band as the planet, so you’re just going to drift north and south as it orbits. This has its uses as well, but it’s not generally what you’re going for.

Fraser: Right. Now, are there any other orbits that are possibly used, especially around Earth? We talked about this sort of an increasing orbit, you know, getting further and further away?

Pamela: Things get thrown into all sorts of different orbits; it depends on what you’re trying to do. There’s transfer orbits of all sorts of various kinds, there’s…it’s useful to put things in elliptical orbits that keep them below the radiation belts where they can send back their signals back to earth easier, and above the radiation belts for doing astronomical observations, this is what x-ray satellites like to do, so there’s all sorts of different things you can do depending on what your purpose is, but the big-named orbit that we haven’t touched on so far is the Hohmann transfer orbit. It’s a type of transfer orbit that requires the least amount of energy in order to get from one type of orbit to another. This is what we use to get from Earth to Mars most of the time.

Fraser: Yeah, and I’ve seen those animations. You can see the little spacecraft is a little dot, and it leaves Earth, and it’s on this increasing orbit, and then its orbit matches Mars, and then it happens to be in orbit at the same place where Mars is, so that’s how it gets to Mars.

Pamela: So the goal here is you just create an elliptical orbit, where one point on the ellipse is the planet Earth, and the opposite point on the ellipse…because with Earth to Mars you’re increasing your distance from the Sun, so closest point to the Sun is Planet Earth, furthest point from the Sun is planet Mars, and the trick here is just timing it so that you end up with Mars and Earth at the points they need to be at the times they need to be at those points, and this is why we talk about “launch windows” that allow us to get to various planets with the correct low energy transfer orbits.

Fraser: Right, and that’s really the trick is you want to use the minimum amount of fuel possible to get from point A to point B. You can always burn more fuel if you want to get there faster, but many cases there’s a limit to how much…how heavy an object, I mean, at that point, the rockets are massive and the payloads are tiny because of the energies involved, so… Well, cool! Well, this was great, Pamela. Thank you very much, and I think we’ve covered orbit top to bottom, back to front.

Pamela: Sounds good.

Fraser: Alright, well, we’ll see you next week.

Pamela: OK, bye-bye.

Fraser: Bye.

This transcript is not an exact match to the audio file. It has been edited for clarity.

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