Archive for the 'Space' Category

Creationist Double Fail

A common creationist objection to the theory of evolution is the orbital recession of the Moon. It is well known that the distance between the Earth and Moon is gradually getting larger. Every year, the Moon is roughly 3.8 cm farther away than it was the year before. What creationists claim is that if you run the clock backwards, and let the Moon approach the Earth at that rate, it ends up colliding with the Earth long before the supposed age of the Earth-Moon system, thus showing that the world couldn’t be that old.

The usual objection is over the past 4.6 billion years (the age of the Moon), the rate that it’s been moving away at hasn’t been constant. The mechanics of lunar recession is complicated, having to do with the distribution of oceans and landmasses on the Earth (different distributions produce different gravitational “tugs” on the Moon as it orbits). Today’s rate is actually quite a bit higher than it has been in the past. So directly extrapolating today’s rate into the past won’t actually give you the correct answer.

And then…there’s this:

The Moon is currently 385,000 km away (on average. The Moon’s orbit is actually somewhat eccentric).

385,000 km / 3.8 cm per year = 10.1 billion years. Far older than the accepted age of the Earth.

So even if you do blindly extrapolate backwards, the Moon doesn’t actually end up colliding with the Earth. So not only do creationists not do their research, they also suck at math!

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HUGE Planet Discovery!

Scientists from the Kepler mission have just announced that they’ve potentially found more that 1,200 new planets orbiting other stars. That’s incredible!

Here’s a brief rundown: out of the potential 1,235 planets, 68 are approximately Earth-size, 288 are super-Earth-size (i.e. rocky planets that are several times the mass of Earth), 662 are Neptune-size, 165 are the size of Jupiter and 19 are larger than Jupiter.

Furthermore, they’ve found that 54 of these planets orbit within their star’s habitable zone, and that of these 5 are roughly Earth-sized.

Now, the Kepler survey covers roughly 156,000 stars, and detects planets by watching them transit across the face of their star, measuring the small dip in the star’s brightness. Naturally, the odds of an orbiting planet actually passing in front of its star is very low. Still, I estimate that, assuming there is a planet orbiting within its habitable zone, there is 0.3% it will be lined up correctly, which translates into about 450 stars.

Think about that, out of 450 candidate stars, 5 have Earth-sized planets in Earth-like orbits, or 1 out of every 90.  That would imply that there are a few billion potentially Earth-like planets in the galaxy, the closest likely being no more than 20 light-years away.

Even considering other planets, 54 out of 450 equates to 1 out of 9. Which means that there’s likely some Jovian planet (possibly with habitable moons) within 10 light-years.

Note, however that I say Earth-sized, not Earth-like. The survey can’t measure the atmosphere or anything like that, so they could all actually be uninhabitable. Venus would count along one of the five if it were in the survey. But still, given what it implies about the abundance of Earth-like planets, this is a HUGE discovery.

Potential Ocean Planet Found!

A few days ago, it was announced that the star GJ 1214 has a planet orbiting it, dubbed GJ 1214b. The massively interestesting part is they were able to measure this planet’s diameter as it transited across its star, and measure its mass via its star’s wobble like you do. Anyway, using this they calculated the planet’s density, which is estimated to be around only 1800 kg/m^3.

For comparison, Earth is around 5500 kg/m^3, while water is about 1000 kg/m^3. In other words this planet is mostly made of liquid water! At least that’s the most likely answer. The next most likely liquids (like liquid carbon dioxide) boil at a much lower temperature than what the planet is estimated be at (between 250 – 550 degrees F).

Now, the more astute among may notice that the planet is also above the boiling point of water. The thing is, as pressure goes up, so does the boiling point (the reverse is also true, which is why at higher elevations the boiling point drops and it take longer to cook food). For example, at 100 atmospheres, the boiling point of water is around 520 degrees F. So it’s possible for there to be a huge global ocean, as long as a sufficiently dense atmosphere is also there. That sounds like a pretty big conjecture, but the density of the planet is known, meaning there must be some sort of atmosphere dense enough to hold it in. My bet is that its mostly water vapor (most astronomers are saying its likely hydrogen and helium, but at the same time there’s substantial loss to space due to its proximity to the star, and there’s really no way for the planet to make more hydrogen and helium to replenish it).

So, lets explore this world together! First, based on its density, scientists calculate that it composed of roughly 25% rock and 75% water. Obviously, the rock will be in the core since rock is denser than water and will sink towards the center. The planet’s diameter is estimated to be 34,000 km across, so its core, taking up about one-fourth the volume, would be around 21,000 kilomteters across. On top of that is water, an ocean 6500 km deep. That’s roughly 1000 times as deep as Earth’s oceans!

Now some interesting things happen when you consider how that all fits together. As I said before the atmosphere is likely composed of water vapor. Water vapor is a greenhouse gas, and will cause the temperature to rise, causing more water to evaporate, thus increasing the greenhouse effect. This will likely continue until some sort of equilibrium is reached, where the influx of heat from the star is the same as the amount radiated away. This might be beyond the point where water goes supercritical (that is,  the line between liquid and gas vanishes and they sort ‘blend into’ each other). That means that the water vapor atmosphere likely just gets denser and denser until it reaches the density of water, at which point it can’t compress anymore.

Even more interesting is what happens down in the depths of this massive ocean. There, the pressure become high enough that the water will become solid, making an exotic form of ice known as Ice VII. This is not like ordinary ice. This is hot ice, denser than water, and probably forms a layer around the rocky core.

In short, this planet most likely looks like a miniature Jovian planet, with water as the gas present instead of hydrogen.

So what about the most obvious question: if there water, what about life? I don’t know. With supercritical water I don’t think that organic structures could even form. But, if the atmosphere really is made of hydrogen (which isn’t a greehouse gas) the temperature would stay much lower, low enough for water to retain all its life-assisting properties. Anyway, here’s a nice graphic (I like graphics) to help illustrate what this planet is like:

 

Kaboom! On Jupiter!

Breaking news: something has impacted on the planet Jupiter.

There isn’t any confirmation of what it is was yet but my money’s on a small asteroid, probably no bigger than a mile across.

Anyway, for anyone with a telescope, this site details when the spot is visible. All times are in UT so subtract 5 hours for Eastern Time and 8 hours for Pacific. I know I’ll be looking up. It’s times like this that I’m glad I have a relatively big ‘scope.

The History of the Universe: A Poem

In the beginning, the universe began. All points expanded away from all other points in an unimaginably colossal explosion. It was everywhere hot. Naked particles careened and collided through dense-packed space, barely moving a billionth of an inch before running into its neighbor.

But soon the universe began to cool. Particles began sticking to one another and quickly the universe became transparent.  It expanded still until a relatively weak force, gravity, pulled these collections of particles and forged them into new particles. The first stars were born.

These stars also were pulled together by gravity into great clouds, spinning, orbiting each other, in various shapes such as spirals and spheroids. The first galaxies had formed. After a few billion years and generations of stars formed, grew up, and exploded in supernova, the heavy elements began building up in the universe. Eventually, newly formed stars would have curious companions along with them: planets, formed out of this heavier material.

These planets circled their respective star, occasionally being tossed out into interstellar space or nudged into their parent stars by unruly bigger brothers. On rare occasions, they even collided, smashing their contents and filling the local space with debris.

On many of these planets another unusual form of matter arose out of the heavy elements: life. This life had many different forms and nearly just as many beginnings, but all were in essence the same: a self-replicating, negative entropy phenomenon, an apparent rebellion against the laws of thermodynamics.

But this life by and large was merely a local curiosity. It did little beyond float, swimming, flying, or crawling around its native planet. It wholly reconfigured the faces of their planets, but still remained confined there, trapped by the pull of gravity and the harsh environment of space. When their local star died, they too also died.

On one planet, however, orbiting a yellow dwarf star almost indistinguishable from any other, a special kind of life developed. This life had the means to get off their world and into space. This life could figure out how the universe operated, and used that knowledge to better its own existence. This life called itself humanity.

Not that anything was special about this particular planet to allow the development of humanity. The emergence of intelligent life could have happened anywhere. It just happened to have evolved here first. A random roll of the dice that, by chance, smiled on these fortunate creatures.

The development of this type of life progressed swiftly. As soon as it learned to walk, it ran. As soon as it learned to jump, it flew. As soon as it discovered fire, it lit the machinery that carried it to the heavens. And as soon as it learned the true nature of its own existence it moved beyond it, into post-biology.

These new members of humanity were no longer made of the same material that had made their predecessors. They were stronger, more durable, and ultimately indestructible. And they lived in worlds of their own creations, simulations in which they were gods.

In the middle of the era that humanity called the 21st century, they became immortal in this way, or as immortal as one could get given the laws of physics. They realized that the resources of the universe, no matter how vast, were finite and their own survival depended on the acquisition of these resources.

So they launched into space and in doing so forever transformed the universe. They deconstructed their own solar system and reformed it into a giant hollow sphere to collect every drop of raw energy and store it for later use. They then realized that the entire universe was running through its energy reserves far too quickly for them and they sent out automated servants to colonize and exploit the resources of their whole galaxy. The galaxy itself grew dim. The light of a hundred billion stars no longer radiated wastefully into empty space, but was captured and stored, frozen in blocks of matter and antimatter and hurled towards the small sector of space where humanity still called its home.

But the galaxy itself was not enough. Billions more galaxies lay beyond in the void of intergalactic space. So humanity sent its robotic servants there as well, colonizing and enclosing countless trillions upon trillions of stars, distilling their photonic essence and shipping it back home across the millions of light-years.

Eventually, the entire universe was dark. Not a single photon was wasted, and humanity remained living in it small sector of space, enjoying its mastery of the universe. After trillions of years, the stars themselves wound down and the enormous galactic power plants which gave them their store of energy were switched off.

But it was not yet time for humanity’s time to go. No, for its life had barely begun. For quadrillions of years, quintillions of years, humanity remained in its simulated paradise, slowly feeding off their enormous store of energy. They would occasionally find and colonize coalescing black holes, bleeding off their enormous store of rotational energy, but it was merely a stop-gap until their reserves ran out.

Eventually it would run out, the laws of physics demanded that. As humanity lived on even the particles that they had stored their vast wealth of energy began decaying. Protons spontaneously transmuted into positrons and gamma-rays, the probabilistic nature of quantum mechanics magnified over trillion trillion trillion years.

And at last humanity would take its last breath, having essentially become the universe itself, and passed on as everything else had.

But the universe itself continued in unconscious slumber. It would never end. It would expand beyond measure, until perhaps one day the process started over again.

Success! Well for Steven Colbert Anyway…

Apparently the next International Space Station module is going to be named after Steven Colbert. He won the write-in contest by an enormous margin.

Of course, the final decision is NASA’s, and I highly doubt that they’ll name it after him. But I think they should serious consider it: NASA relies on government funding which is reliant on public opinion. If people don’t want NASA around, they’ll vote people into office which will take away their funding and NASA will disappear. This, to put it mildly, would suck.

Unfortunately NASA as a probably-deserved reputation for being old and stodgy and if they do name it something else, it will probably just fan the flames of anti-NASA sentiment.

Well, however it ends up, it’s still pretty funny, much like Colbert himself.

There’s A Lot of Space in, er, Space

Last time I discussed the terraformation of the inner planets and of the Moon, which I think might happen more along the lines of an art project rather than a necessity. An uploaded human can live just as easily in the vacuum of space as on the surface of the Earth.

But planets are actually quite small compared to the size of the solar system. Whenever you see a representation of the solar system, you’ll usually see something like this: a large sun with large planets orbiting around it, with the gaps between planets only a few times larger than the planets itself. But, in reality, the solar system is a bunch of specks orbiting another very bright speck, with vast amounts of space in between. Roughly one million Earths lined up would stretch across the diameter of the entire solar system.

So what if we were to fill that space up as much as we could with places people could live, namely, space habitats? The idea of space habitats goes back decades. It was found in the 1970’s that even simple materials like steel and glass could be used to create giant space stations that could support thousands, if not millions of people in space. In the future, we’d be more likely to use more advanced materials like carbon fiber or even carbon nanotubes, which are lighter and stronger, and so allow for more habitats to be constructed per unit mass.

Let’s assume a typical space habitat is a cylindrical shell 10 km long and 2 km wide. It is so shaped in order to be rotated to produce artificial gravity. At this size 1 g of acceleration could be maintained by rotating the habitat at a little under one rotation per minute. Inside, this will produce a livable space of about 62.8 km2. I estimate that the average human needs about 500 m2 of space for a comfortable living space and area to grow food and other necessities, and accounting for future advances in the technology necessary to create those things. This leads to the habitat being able to support about 125,000 people.

Let’s also assume that the hull’s thickness is 10 meters, and that the average density of the hull is 2000 kg/m3 (made primarily of composite materials). At this size, and accounting for the mass of the air that will fill the inner volume, a single habitat will mass about 1.5 trillion kg.

This is way too large to launch from Earth, even if launched piece by piece and assembled on site. But there are vast quantities of resources in the asteroid belt and they are out of the deep gravity well that makes things so difficult to get into space from Earth. The total mass of the asteroid belt is estimated to be around 3 x 1021 kg. A quick bit of division shows that this amount of matter could be used to construct 2 billion space habitats. At 125,000 per habitat, that’s enough room to support 250 trillion people. That’s old fashioned biological humans, mind you, not the shiny brand-new uploaded humans that severely reduce demand on resources.

Even if we were to admit that A) not every single gram of asteroid material is usable and B) we might want to keep some asteroids around for posterity, it still leaves the potential to support trillions of humans relatively close by.

Of course, why bother terraforming Mars, or moving to a space habitat, if you’re uploaded and can have whatever you want in virtual space (including living on a terraformed Mars or inside a space habitat)? I think, given the vast number of people that exist, and will likely exist in the future, there will be supporters for all of these possibilities, and we’ll undertake them all, not just one to the exclusion of the others.