Starts With A Bang! » Solar System Ethan Siegel's blog/video blog about Cosmology, the Universe, and everything else Sat, 04 Apr 2009 20:12:38 +0000 en Naming the new ISS module: a suggestion Thu, 26 Mar 2009 21:20:20 +0000 ethan As many of you have heard, NASA has had a public vote to help name the new node of the International Space Station — node 3 — shown here in its full glory:

Although the name Serenity for the new node got 70% of the vote on the NASA site, that’s totally misleading. Because someone started a write-in campaign to get the module named after himself:

And the name Colbert beat Serenity by over 40,000 votes! Before you shout, “curse you, Colbert” (I already did), I bring up the sad fact that NASA has said the results are not binding, and that this dubiously-qualified megalomaniac may not get his name on the module due to a technicality.

But if NASA had a sense of humor (or any sense of increasing positive publicity), they would listen to my advice:

Name the node COLBERT.

But pronounce it KOHL-burt.

Trust me, he’ll hate it. Loathe it. Perhaps even have someone on his show to throw one of his patented tirades at. Because it won’t be his name, but it completely follows the expressed will of the public. And that, my friends, is the way to make democracy work.

Book Review: The Hunt for Planet X Fri, 13 Mar 2009 19:49:33 +0000 ethan Pluto, try as some people may to belittle it, is too beloved to simply go away. Even anti-Plutonians are fascinated by it. So to celebrate the state of Illinois’ very first Pluto Day, since Pluto was discovered exactly 79 years ago today, I present to you a review of Govert Schilling’s newly released book, The Hunt for Planet X: New Worlds and the Fate of Pluto.

This is one of the most detailed books about the Solar System, its history, and the neighborhood at and around our Sun. Schilling starts in the 18th Century, when the Solar System was “well known” with its six planets: Mercury, Venus, Earth, Mars, Jupiter, and Saturn. He tells fascinating versions of the discovery of Uranus, including its naming and its impact on those interested in Astronomy, a great version of the discovery of Neptune, a personal favorite historical story of mine, and spares no detail in telling about the important people and personalities involved.

There’s also a very intricate history given of the asteroid belt, including of a time when the asteroids Ceres, Pallas, and Vesta were all called planets. But the star of this book is no star at all, but the small, icy, distant world, Pluto.

The book talks about Clyde Tombaugh and the discovery of Pluto, omitting practically no detail, and continues to go on about the discovery of its major moon, Charon (and later the theory of its formation), and its two far smaller moons, Nix and Hydra. Throughout this, the reader gets a genuine feeling of the good fortune that goes into such a discovery, as well as the myriad of hours and patience that being a good observational astronomer requires. Amateur astronomers, especially, will find much to identify with in this book, including a kinship with many who share their passion for the heavens.

The last great thing that I really enjoyed about this book was its discussion of the Kuiper Belt and the many objects that have been discovered there so far. It really keeps in perspective that the first Kuiper Belt object other than Pluto and Charon was only discovered in 1992, and yet already, we know that there are many other icy worlds just as important to our Solar System as Pluto:

The book is very well illustrated throughout, with some wonderful pictures in both color and black and white, of the astronomical objects themselves, the astronomers who discovered them, and on special occasions, the actual astronomical data that were used in their discovery.

There are some negatives to this book, and I would be remiss if I didn’t tell you what they are. There is a sense of despair when he discusses theories that didn’t pan out, such as the Nemesis theory (that the Sun has a super-long-period binary companion), the search for a fifth very massive giant planet, and the idea of Vulcan (a planet closer to the Sun than Mercury). This is also not a quick, easy read. Because the book is so dense with details, it often takes quite some time to digest all the information that’s being related. This book could have also used an editor, as every story in the book is given the same weight, whereas many are clearly both more important to the book overall and also are simply more interesting. And this is a personal distaste, but the sheer amount of time and space devoted to the naming of Solar System objects is way out of proportion to their actual importance. Finally, there’s hardly any mention at all of planets around other stars, which would certainly not be out of place in this book.

But to anyone really interested in Pluto and in understanding our Solar System in general, this book contains all the latest, up-to-date scientific information, including on Neptune’s Moon, Triton, and on things as esoteric as what you can learn from an occultation. This book will probably be obsolete when the New Horizons mission gets to Pluto in 2015, but until then, you won’t find a better, more comprehensive source of information that’s accessible to a non-scientist about the Solar System. Overall, to anyone interested in learning about some of the lesser-known worlds in our Solar System and the stories of their discovery, The Hunt For Planet X is for you.

Happy Pluto Day!

Why is Venus the Brightest? Wed, 11 Mar 2009 16:59:00 +0000 ethan Sometimes, when you look up in either the early, pre-dawn morning or early, post-sunset evening sky, there’s one point of light that outshines all the others. It’s usually relatively close to where the Sun was, and unlike most points of light you see in the night sky, this one doesn’t twinkle. I’m talking, of course, about the planet Venus:

Yes, it isn’t nearly as bright as the Moon, but it’s certainly much brighter than everything else you can see. Well, it was only a matter of time before someone wrote in and asked why. Reader Dan asks:

Can you explain why Venus is so bright in the sky right now? I don’t think I have ever seen it so bright in my life.

Venus, as we’ve talked about before, is covered in a very thick layer of greenhouse gases. This makes its surface extremely reflective, so that about 70% of the sunlight that comes in to Venus gets reflected as visible light.

But Venus is also extremely close to Earth. In fact, Venus gets within about 40 million km of Earth, which is less than 1/3 of the distance to the Sun. At its farthest, Venus is about 250 million km from Earth. Why? Because Venus and Earth both orbit the Sun; sometimes they’re on the same side as one another, and sometimes they’re on opposite sides. When they’re both on the same side, Venus has its closest approach to Earth:

But I’m going to force you to think about the geometry of this a little bit. One side of Venus faces the Sun, and gets illuminated; the other one is dark. Imagine that the Earth is far away from Venus. What will the planet Venus then look like from Earth? It will be mostly “full”, and the closer to being in direct opposition to Earth, the more “full” Venus will appear. But the more “full” it appears, the further away it is, and so it should also look smaller. Take a look at these shots of Venus, through the same telescope, when it’s far away from Earth:

When it’s more full, it’s also smaller. But when less of it is illuminated, it’s closer to us. Take a look at what Venus looks like when it’s closest to us:

So when Venus is close to us, it looks like a crescent, but it looks like a very large crescent, and when it’s far from us, it looks like a disc, but a much smaller disc. Which of these two things is more important for the brightness of Venus?

Well, we can find out. You see, Dan is right; Venus is nearly at its brightest right now. Have a pair of binoculars? Well, about 11 days ago, somebody did, and photographed Venus and the Moon together in the sky. Here’s what they saw:

Venus is at its brightest when it’s a crescent! It turns out that being closer to us means everything. Astronomers use magnitudes to measure brightness, and the smaller your number is, the brighter you are. This is useful for stars, where very bright stars are typically 0 or 1 (the very brightest, Sirius, is -1.5), and the dimmest ones visible with the naked eye are 5 or 6.

What about things that aren’t stars, though? Not surprisingly, the Sun is the brightest, at -26.7, and the Full Moon is second, at -12.6. But Venus is third! When Venus is a crescent, it’s -4.6, and when it’s full (but far away), it’s -3.8, which is interesting! Why? Because when it’s full, you can’t see it during the day, even under optimal conditions. But right now, when it’s a crescent, you can! Check out this photograph by John Harper of Venus during the day:

It’s a crescent, just like we said it should be! So that is why Venus is the brightest thing in the sky, and that’s why it’s brighter now than it usually is. Get out your binoculars and have a look! And if you do it tonight, look on the other side of you too, because the Moon is full and it rises at 8:30 PM! Enjoy!

Pluto is a Planet — in Illinois! Sat, 07 Mar 2009 00:32:16 +0000 ethan I was going to write about something else today, but when I saw this story, I simply couldn’t resist. Apparently, the Illinois state legislature not only declared that Pluto is a planet like the other eight:

They also declared that March 13, 2009 is going to be the very first Pluto Day, in honor of the discovery of Pluto on March 13, 1930, by Illinois-born Astronomer, Clyde Tombaugh:

People talk about how small, insignificant, and far away Pluto is, and they’re right. But what they’re missing is just how lucky Tombaugh was to find it. Sure, there are many, many Kuiper Belt objects out there, and we know of lots of them at this point:

But after the discovery of Pluto, people searched, in earnest, for the 10th planet. It took a loooong time for the next Kuiper Belt object to be found. And when it was found, you know what it was?

Pluto’s moon, Charon! Do you know how long it took, after the discovery of Pluto, to find Charon? Almost 50 years! So yes, we know of many other Kuiper Belt objects now, and some of them are even more impressive than Pluto.

But Pluto holds a very special place as:

  • The first and only planet in our Solar System (even if it was only temporarily a planet) discovered by an American.
  • The very first Kuiper Belt object discovered.
  • The first trans-Neptunian object discovered.
  • And as being the 9th planet for about 70 years.

You know what I think about this? Good for Illinois. Good for them! This raises awareness of Astronomy, gives them something to be proud of and a great historical achievement to celebrate, and helps Pluto from fading into the obscurity that the other Kuiper Belt objects currently have to deal with.

So good for Illinois, good for Pluto, and good for you for not forgetting it. Someday, I would love for Pluto to be given a real, useful designation by the IAU, like “King of the Ice Dwarfs.”

Perhaps we’ll discover some wonderful things about it when New Horizons gets there; April of 2015, folks, and don’t forget to celebrate Pluto day on March 13th!

Hunting The Great Red Spot Fri, 27 Feb 2009 23:47:16 +0000 ethan I’ve been interested in the planet Jupiter ever since I was told, as a little boy, that it was the place I needed to go. Although, come to think of it, I was lumped in with all boys, and told that we “go to Jupiter to get more stupider,” which isn’t a very good reason, in hindsight. Jupiter is one of the brightest objects in the entire night sky, beaten only by the Moon and Venus, and occasionally by Mars.

The above photo is of the Moon, Venus, and Jupiter on a slightly cloudy night. Sure, the Moon and Venus are brighter. But they’re also way closer than Jupiter is. It’s sheer coincidence that it’s named after the ruler of the Roman Pantheon and also happens to be the largest planet in our Solar System. But it is huge; if you wanted to compare Jupiter to Earth, Jupiter doesn’t just have us beat, it makes us look like an insignificant moon in comparison:

And once you get past its giant size, you start noticing other things about Jupiter, such as the different bands of moving air at different latitudes. But what I’ve always been fascinated by is that huge birthmark on its face: the great red spot, bigger than Earth in its own right.

And even though this animation that I’ve placed below is 30 years old, it’s still the best thing I know of to illustrate what Jupiter actually does; take a good look!

Unlike Earth, where the weather is transient, and even the greatest storms only last a few weeks, Jupiter is practically all weather. That great red spot is totally obvious, even without the red. This counterclockwise hurricane is about 2-3 times the size of Earth, and has been a fixture on Jupiter’s surface for as long as we’ve been able to see Jupiter’s surface features: more than 300 years!

So how impressive is this great red spot? Some impressive facts:

  • Width — anywhere from 24,000 km to 40,000 km
  • Height — anywhere from 12,000 km to 14,000 km
  • Time to rotate — 6 Earth days
  • Maximum Wind Speed — 250 miles per hour (400 km / hour)

But what’s the big news? See that big variety in width above? It turns out that Jupiter’s great red spot is shrinking! In fact, the great red spot, right now, is smaller than it’s ever been. We don’t think it’s going to disappear or dissipate, but it’s definitely shrinking right now. It’s possible that this is just a fluctuation, and the system is stable, like this animation of Hurricane Isabel on Earth.

But it’s also possible that if you’d like to see the great red spot, you’re best off doing it sooner rather than later! Remember, Jupiter rotates quickly (in under 10 hours), so you have to get lucky to have the great red spot facing you. You can see great details on Jupiter with just a 10″ telescope, but if you don’t plan ahead, the great red spot will be on the other side of the planet:

My advice? Use this handy calculator. And the great red spot isn’t just for professionals; here are six pictures of Jupiter, with the great red spot visible, taken by the amateurs Damian Peach, Christopher Go, and Anthony Wesley:

Remember, Jupiter has phases (as seen from Earth) too, so try to catch it when Jupiter is “full”! So, hopefully this shrinkage of the great red spot is just temporary, but my advice is to get out and have a look while you still can! Happy hunting!

When The Oceans Boil… Mon, 23 Feb 2009 19:19:39 +0000 ethan The Earth and the Sun. So inextricably linked, with both of them being so necessary for the life we observe today. We live in a fortuitous, wet world, in just the right spot for liquid water to thrive.

And we’ve been in just the right spot for over four billion years. But time is running out. Why? Because the same thing that happens to all stars is happening to our Sun: as it starts to run out of fuel, it burns hotter and faster!

As the Sun burns its nuclear fuel, the core accumulates more and more helium, and the rate of hydrogen fusion increases. What does all of this mean? As the Sun gets older, it puts out more and more energy. Over the past 4.5 billion years, this has “only” increased the output from the Sun by about 20%, but that’s an awful lot. Things are going to get worse relatively quickly. Over the next (roughly) 1 billion years, the Sun’s output will increase by about another 10%. After 1 or 2 billion years more, this will be hot enough that the oceans will boil.

This boiling of the oceans will be different from dumping lava in them — modern ocean boiling is temporary — but when the Sun heats up enough, our oceans will boil permanently. And when this happens, we’ll experience the ultimate in the greenhouse effect. How drastic will it be? Let’s figure out what effect boiling the oceans will have on our atmosphere:

The total mass of the atmosphere, right now, is about 5.1480 × 1018 kg, or about 10,000 kg per square meter (14.4 pounds per square inch) at the Earth’s surface. But the oceans are tremendous. Over 1000 times denser than air and extending down more than six miles at its deepest, oceans cover 71% of the Earth’s surface. Thanks to satellite surveys, we know how deep the oceans are everywhere:

The oceans have an average depth of 3,790 meters. And from this information, we can figure out that the total mass of the Earth’s oceans is about 1.4 × 1021 kg, or 272 times more massive than the entire current atmosphere. Once the oceans boil, the pressure from the Earth’s atmosphere will be nearly 4,000 pounds per square inch (280,000 kg per square meter), or certainly enough to not only kill you, but to turn our planet into an inferno hotter than Venus’ temperature of over 450 degrees Celsius!

And you can be sure that our planet won’t look so blue after this! So that’s what we have to look forward to: the ultimate greenhouse effect. And you thought global warming was bad now?

Terraforming Mars: What it takes Wed, 21 Jan 2009 20:01:41 +0000 ethan Ahhh, Mars. The bright, red dot in the sky. The one planet, other than Earth, that is the most likely candidate for life in our Solar System.

But we couldn’t live on it now, at least, not yet. Reader kampfgestfj writes in to ask about the prospects of terraforming Mars, to make it habitable by humans. Right now, we could reasonably go there with spacesuits, and bring our own supplies, food, water, air, etc., just like we do on the international space station (artist’s impression shown below):

But what if we wanted to make Mars like a second Earth? What if we wanted to breathe the air, grow plants and flowers, raise animals, and perhaps even have rivers and oceans? What if we wanted to turn Mars from this:

Into a place like this:

Or, in other words, how do we transform Mars into a more Earth-like planet? Ideally, once we did that, it would be suitable for us to live there. Amazingly, there are only three things we’d need to do to Mars to make it ready to populate, and they’re all related to one another.

1.) Thicken Mars’ atmosphere, and make it more like Earth’s. Earth’s atmosphere is about 78% Nitrogen and 21% Oxygen, and is about 140 times thicker than Mars’ atmosphere. Since Mars is so much smaller than Earth (about 53% of the Earth’s radius), all we’d have to do is bring about 20% of the Earth’s atmosphere over to Mars. If we did that, not only would Earth be, relatively unaffected, but the Martian atmosphere, although it would be thin (since the force of gravity on Mars is only about 40% of what it is on Earth), would be breathable, and about the equivalent consistency of breathing the air in Santa Fe, NM. So that’s nice; breathing is good. What else?

2.) Mars needs to be heated up, by a lot, to support Earth-like life. Mars is cold. Mars is damned cold. At night, in the winter, temperatures on Mars get down to about -160 degrees! (If you ask, “Celcius or Fahrenheit?”, the answer is first one, then the other.) But there’s an easy fix for this: add greenhouse gases. This has the effect of letting sunlight in, but preventing the heat from escaping. In order to keep Mars at about the same temperature as Earth, all we’d have to do is add enough Carbon Dioxide, Methane, and Water Vapor to Mars’ atmosphere. Want to know something neat? If we’re going to move 20% of our atmosphere over there, we may want to move 50% of our greenhouse gases with it, solving some of our environmental problems in the process.

These greenhouse gases would keep temperatures stable on Mars and would warm the planet enough to melt the icecaps, covering Mars with oceans. All we’d have to do then is bring some lifeforms over and, very quickly, they’d multiply and cover the Martian planet in life. As we see on Earth, if you give life a suitable environment and the seeds for growth/regrowth, it fills it up very quickly. Look at this clear-cut forest and the regrowth there after only 10 years:

So the prospects for life on a planet with an Earth-like atmosphere, temperature ranges, and oceans are excellent. With oceans and an atmosphere, Mars wouldn’t be a red planet any longer. It would turn blue like Earth! This would also be good for when the Sun heated up in several hundred million years, since Mars will still be habitable when the oceans on Earth boil. But there’s one problem Mars has that Earth doesn’t, that could cause Mars to lose its atmosphere very quickly and go back to being the desert wasteland that it is right now: Mars doesn’t have a magnetic field to protect it from the Solar Wind. The Earth’s magnetic field, sustained in our molten core, protects us from the Solar Wind:

But on geologically dead Mars, where the core has cooled and solidified, there is no magnetic field there. This means that it has no defense against the Solar Wind, which will, relatively quickly, simply blow the atmosphere off of the planet:

So what’s the fix?

3.) Mars needs to be given a magnetic field to shield it from the Solar Wind. This can be accomplished by either permanently magnetizing Mars, the same way you’d magnetize a block of iron to make a magnet, or by re-heating the core of Mars sufficiently to make the center of the planet molten. In either case, this allows Mars to have its own magnetic field, shielding it from the Solar Wind (the same way Earth gets shielded by our magnetic field) and allowing it to keep its atmosphere, oceans, and any life we’ve placed there.

But this doesn’t tell us how to accomplish these three things. The third one seems to me to be especially difficult, since it would take a tremendous amount of energy to do. Still, if you wanted to terraform Mars, simply these three steps would give you a habitable* planet!

* — Seeds of life not included. Bring your own.

The Solar System and the Greenhouse Effect Mon, 19 Jan 2009 20:43:53 +0000 ethan When people talk about global warming, they talk about the greenhouse effect and carbon dioxide. I realized, recently, that a lot of people still don’t believe that global average temperature and carbon dioxide levels are linked, despite a ridiculous amount of evidence clearly showing the link, like this:

Perhaps this will make sense to people if I explain it, clearly and simply, and perhaps this will help those of you who are interested readers to explain it clearly to others. Let’s show you the science of how the greenhouse effect works.

It begins in space: the Sun shines on the Earth. What’s the simplest thing that could happen? 100% of the Sun’s energy that hits Earth would be absorbed by the Earth, and then the Earth re-emits all of that energy back into space. This would give us nice, warm temperatures during the day, when the Sun shines on us, but freezing, abhorrently cold temperatures at night, where all we do is radiate our heat away. The temperature swing between night and day would be over a hundred degrees (Fahrenheit; it would be about an 80 degree swing in Celcius).

Luckily, this doesn’t happen on Earth. It happens on the Moon and Mercury, and even on Mars, but not on the Earth. Why not? Because Earth has this:

An atmosphere. A nice, thick, layered atmosphere. The atmosphere on Earth does two things: it keeps some of the light out, and it also keeps some of the heat in. Mercury and the Moon don’t have atmospheres, and Mars’ is so thin (only 0.7% as thick as Earth’s) that it can’t really do much of anything. The atmosphere on Earth means that instead of over a hundred degrees, the temperature difference between night and day is small. This is good.

But the atmosphere can lead to a greenhouse effect, which can be bad. Let’s take a look at how the greenhouse effect works. (See picture at right.) The Sun gives off light, most of which is visible to our eyes. Some of that light, when it strikes the atmosphere, gets reflected away off of water molecules, ozone molecules, and other particles. Some of it gets absorbed by clouds, and some gets scattered randomly. Some of these things happen whether there are clouds or not, others are very sensitive to the thickness and coverage of clouds. A thick cloud cover will block up to an extra 30% of the energy from the Sun and prevent it from reaching the Earth. Why are clouds so effective? Because the Sun gives off mostly visible light, and although visible light is sensitive to clouds, without them, it passes through the atmosphere, mostly unhindered. A typical day is shown below:

That’s the first part: the atmosphere preventing some light from getting through to the Earth’s surface in the first place. But when the Earth tries to re-emit that energy it absorbed, that light isn’t visible anymore: it’s infrared light, commonly known (and felt) as heat. When the Earth emits that heat, some of the heat gets absorbed by the atmosphere and re-emitted back down towards the Earth. That’s how the atmosphere keeps the heat in. So what’s the Greenhouse Effect?

The fact that the atmosphere will let visible light in pretty easily, but won’t let infrared light out. This is how a greenhouse works: it lets in the visible light and then reflects the infrared light around, keeping temperatures inside very warm even when it’s very cold outside. Carbon dioxide is so important because it’s really good at absorbing infrared radiation, and so the more CO2 there is in the atmosphere, the hotter the Earth is going to get. I thought you might need to see some numbers to help you see the effects that greenhouse gases can have; they don’t really affect how much light gets transmitted to the Earth in the first place, but they do affect how much heat gets kept inside. Numbers, anyone? I’m going to show three numbers: the percentage of light that gets to the Earth, initially, through the atmosphere, the percentage of heat that gets kept in by the atmosphere, and the total amount of energy relative to there being no atmosphere at all. Let’s have a look at what happens for just a little bit of greenhouse gas:

  • Light in: 70% Heat reflected (no greenhouse gases): 30% Total energy: 100%
  • Light in: 70% Heat reflected (slight greenhouse gases): 32% Total energy: 102.9%
  • Light in: 70% Heat reflected (moderate greenhouse gases): 35% Total energy: 107.7%
  • Light in: 70% Heat reflected (heavy greenhouse gases): 40% Total energy: 116.7%
  • Light in: 70% Heat reflected (extreme greenhouse gases): 50% Total energy: 140%

Just by adding more greenhouse gases, and doing nothing else, we could literally boil the planet. How do we know? We have an example in our Solar System:

Venus. The average temperature of Venus is higher than the hottest temperature on Mercury, even though Venus is nearly twice as far from the Sun as Mercury is! How is this possible? Let’s look at some estimated stats for Venus, which blocks more light but has a tremendous greenhouse effect:

  • Light in: 40% Heat reflected (Venus’ greenhouse gases): 90% Total energy: 400%

Venus is four times as hot as it would be if it didn’t have an atmosphere! And that’s why Venus is even hotter than Mercury — because of its greenhouse effect. And that’s why we need to be really careful about the amount of Carbon Dioxide, Methane, Water Vapor, and other greenhouse gases in our atmosphere! And we’ve already been over how to fix it:

Will we reforest our planet? Or will we end up like Venus?

Rocketry: How much Fuel to get us to Space? Tue, 13 Jan 2009 01:49:54 +0000 ethan The US space shuttle program is finally winding down. To date, there have been 123 total launches (122 of which were successful, the lone exception being Challenger). I got asked a bizarre question last week: is NASA considering any alternatives to the fuel it uses to get into space, and how environmentally friendly is it?

The big problem with launching things into space is that it requires a lot of energy. But the good news is that we launch things pretty rarely, so it’s conceivable that you driving your car all year long is just as bad for the environment as launching a shuttle to the ISS. Let’s find out which is worse:

Let’s start with the cars. A typical American drives somewhere around 12,000 miles per year. At about 30 miles per gallon, that means the typical American car owner burns through 400 gallons of gasoline every year. That’s not so terrible, is it? Let’s even be generous, and assume that there’s no carbon monoxide, no nitrous oxides, and no ozone produced (although this is unrealistically generous). Even at that, a gallon of gasoline contains about 6 pounds of carbon in it, meaning that over the year, the typical American car released four tonnes of Carbon Dioxide into the atmosphere. This is just a drop in the bucket, considering that as a nation, America releases over one billion tonnes of Carbon Dioxide into the atmosphere every year. Can we see the effects of this on our planet?

I’d say it’s pretty noticeable. But what about the shuttle? Its uses a combination of three fuels. The first is a solid fuel for the solid rocket boosters, which are the white-colored rockets. The total amount of fuel used in these is 1,000 tonnes per launch. It’s a particularly noxious fuel as well, Ammonium Perchlorate Composite Propellant. So no, it is not environmentally friendly, especially considering that one of the major exhaust products is hydrogen chloride, which you chemistry buffs will know creates hydrochloric acid when it mixes with water!

So of the 1,000 tonnes of solid rocket fuel, about 1/3 of that becomes HCl, or roughly 340 tonnes of hydrochloric acid. Now, see that rust-colored external tank? That’s full of liquid hydrogen fuel: completely environmentally friendly! You burn it and it just becomes water: hooray for some good environmental consciousness on NASA’s part! The third fuel-burning stage is for the shuttle’s main engines:

But the fuel on the shuttle itself is so insignificant compared to the 340 tonnes of stage one that it isn’t even worth including here. So let’s be honest about this: if NASA managed to get rid of the solid rocket boosters altogether and replace them with hydrogen fuel, they would have saved a total, over the last 28 years, of 42,000 tonnes of pollutants in the atmosphere. On the other hand, American cars, of which there are about 125 million on the road in any year, have emitted about 14 billion tonnes of your favorite greenhouse gas (Carbon Dioxide) into the atmosphere over that time. NASA’s contribution vs. the automobile’s contribution? 0.0003% for NASA. Meanwhile, the auto industry is responsible for about 50% of the greenhouse gas emission for the entire country. Solution?

Hydrogen powered cars, anyone? It’s still not completely green, since it takes energy to make the hydrogen cells, but it’s a whole lot closer than using rocket fuel, or even than using gasoline. And so yes, while NASA emits a lot of pollutants to launch rockets and shuttles, it’s a tiny, tiny amount compared to the damage we do every day.

And I’d rather think about what I can do to help the planet, realistically, than to yell at NASA for the small harm that they’re doing. What do you think?

Can the Moon Help Solve Earth’s Problems? Fri, 02 Jan 2009 22:13:34 +0000 ethan As we begin 2009, I’d like to take a look at one of the biggest problems facing humanity: the fact that the human presence on Earth is really affecting the planet Earth itself. We can see this by looking at the planet at night, and finding that it’s still lit up due to the human presence:

We can see this by looking at, just over the last 60 years and projected into the future, how the human population on Earth continues to rise:

But I’d like to ask a question to everybody:

How many humans can the planet support before we need to either reduce the population or expand to other worlds?

We’ve already talked about how forests and wild places are needed to remove Carbon Dioxide from the atmosphere and reverse global warming, but let’s put that aside. We’ve got lots of arable land on this planet, and as the population goes up, more and more of that land is needed for farming, to feed the world. In order to do that, we need fewer forests:

And we need to take that land and turn it into farmland for production of staple foods:

The Earth currently produces staple foods (rice, grains, cereals, potatoes, etc.) in quantities of 2,264 million metric tonnes per year, enough to feed about 10 billion people assuming everyone eats a 2,000 calorie-per-day diet. One third of those grains go towards feeding animals, which is horrendously inefficient, bringing the food total down to about enough to feed 7 billion people. We’re close to that already (about 6.7 billion), and we’re already using about half of all the arable land in the world.

So assuming we want to do the following:

  • Keep our forests,
  • Continue reproducing, and
  • Continue feeding ourselves (and eating the good food, too),

what are our options? We clearly need more land, and we clearly can’t take any more from Earth, as we need more wild places and forests to help repair the damage that’s already been done. Where should we look?

The Moon. That’s right, the Moon. You think I’m being ridiculous, but this is a reasonable, powerful long-term goal. And this is a problem that quick-fixes won’t ameliorate; we need a long-term solution. This is part of the reason why there’s such an initiative to go back to the Moon, because if we can get crops to grow on the Moon, we’ll have just as much arable land there as we have here, even though the Moon has only 7.5% of the surface area of the Earth, because not all of the Earth is land, and not all of the Earth’s land is arable.

You might think I’m talking crazy, but these aren’t my words.

“The Moon is a place where you can study how to expand life beyond Earth,” the European Space Agency’s senior scientist Bernard Foing told BBC News.

“You can take the elements needed and seed, germinate, grow and make a flower blossom on the Moon,” Professor Foing explained.

“We also have ideas about taking other types of plants that could make a first generation “mini biosphere”, from which we could grow more complex plants.

“From this, we could learn how to develop a self-sufficient life support system that could help us live off the (lunar) land.”

And the part about growing flowers on the Moon? We’ve already covered that; that’s part of something we’re able to do today. Can you imagine, by the time we’re old men and women, a world where humans live on more than one rock in our Solar System? It’s a great dream, and a great thing to be hopeful for, as a long-term vision, as we begin our new year.

And while you think about that, check out both the new Carnival of Space, done on the cheap over at Cheap Astro, and the top 100 space and astronomy blogs, in no particular order, where I come in at number 47. And finally, for a little old-school perspective on our place in the Universe, I leave you with the old Monty Python song about the Universe: