mellowtigger: (dna)
phylogenetic treeTwo of the requirements for the current definition of "life" are these: the ability to self-regulate (homoeostasis) and the ability to reproduce. It turns out that these two processes might not have to be separate.

Scientists cultivate an extremophile called Haloferax volcanii which came from the extremely salty Dead Sea.  Because it survives in that harsh environment, astrobiologists wonder if we will find its relatives in the similar environment on the surface of Mars.  A recent study into this ancient form of Earth life (called "archaea") hint that this microscopic life might be very common. It revealed that a mechanism for homeostasis can be commandeered by archaea for use in replication.  This discovery has ramifications for both astrobiology and cancer research.

Normally, a cell's daily workings result in damage to its dna, so it employs processes to repair that damage.  These micro-repair mechanisms are different from those used to produce a full copy of the dna during replication.  Archaea reveals, however, that it can induce a simultaneous bloom of micro-repairs that results in a complete copy of the original dna.

However, the Nottingham study, funded by the Biotechnology and Biological Sciences Research Council (BBSRC) and the Royal Society, found that the Haloferax volcanii is able to spontaneously begin a chain reaction of replication all around its chromosomes even when its replication origins have been eliminated. In addition, the scientists discovered that far from being disadvantaged by having to employ this novel survival method, the archaea without chromosomal origins grew faster.

“The amazing thing that we found wasn’t just that deleting the origins still allowed the cells to grow, but that they now actually grew almost 10 per cent faster. Everybody was thinking, ‘where’s the catch?’ But we haven’t found one” Dr Conrad Nieduszynski said. “The way cells initiates this replication process is to use a form of DNA repair that exists in all of us, but they just hijack this process for a different purpose. By using this mechanism, they kick-start replication at multiple sites around the chromosome at the same time.”
- http://www.astrobio.net/pressrelease/5805/an-archaeas-unexpected-route-to-reproduction

Interesting news.  It offers a boost to the likelihood of panspermia theory being reality.  When we venture into the universe, we may find it a much "dirtier" (and thriving) environment than we envisioned a century ago.

(p.s. I chose the title as a play on Mr. Spock's analysis in Star Trekkin' lyrics from 1987.)
mellowtigger: (astronomy)
Humans are extremely limited in what we can see of our environment.  We cannot see the electromagnetic spectrum beyond our very narrow rainbow of colors.  We cannot see polarization of light.  We are also limited by the speed of our senses; we are no good at noticing changes that are either very fast or very slow.

Technology helps us out by enhancing our senses beyond these limitations.  For instance, high speed cameras let us see things that happen on very short timescales.  One photographer has captured some beautiful images of lightning sprites (which form high in the atmosphere far above typical weather) at 10,000 frames per second.  Pictured here is one sample of his work.  Don't miss his blog where he posts more images and video samples.

lightning sprites

So very much happens in the universe.  We don't even notice the many interesting things that happen right on our own world.  Life is unfair that way.
mellowtigger: (astronomy)
Would terraforming Mars be self-defeating? Many articles discuss how to terraform Mars, but they seem to assume that a human-friendly atmosphere would just "stay there". Mars is smaller than Earth, therefore its gravity is weaker, so would a new atmosphere just evaporate into space because the planet could not retain it gravitationally?

The short answer is: Mars can retain a human-friendly atmosphere.

The long answer is detailed below. I originally wrote this article in January 2006 while examining Earth. Since that website will disappear in coming months, I wanted to republish it here in my blog so it stays online somewhere. This version, obviously, will focus on Mars.


Retention of Atmosphere by a Planetary Body

velocity

Whether we consider small atoms or huge rocket ships, there is just one property that determines if something can escape the pull of the planet's gravity: velocity. If something travels with enough speed directly away from the planet, then it will be able to overcome the persistent force that would otherwise send it back to the surface. It doesn't matter if we measure baseballs or rockets or molecules of air. They all obey this same basic principle. If it moves fast enough, then it will escape.

Reaching escape velocity is helpful to us when we launch probes to other planets. We might worry, though, about unintended loss of material from a planet. After all, air itself can escape out into space! If a molecule of air is travelling fast enough, it will leave the atmosphere forever. Two questions become very important in understanding this effect:

1) how fast does the molecule have to move in order to reach escape velocity, and
2) what can cause it to travel that fast?

escape velocity

The effect of gravity is well studied, and determining escape velocity is an easy calculation. The only information that we need about a planet is its mass and its radius. We insert those two values into a formula and then we find the speed needed to escape the surface of the planet while traveling straight upward.

namevalueunits
escape velocity formulavelocity = √2 * G * mass / radiusm / s
gravitational constantG = 6.67 x 10-14Nm2/g2 = m3/(g * sec2)
mars massmass = 6.42 x 1026g
mars radiusradius = 3.40 x 106m
now just plug into the formula...
mars escape velocity =2 * G * mass / radius 
2 * (6.67 x 10-14) * (6.42 x 1026>) / (3.40 x 106)(m3/(g * sec2)) * (g) / (m)
2 * (1.26 x 107)(m2/sec2)
5.02 x 103m / s

So anything on Mars that moves straight upward at 5.02 kilometers per second will manage to escape the planet and travel on to other destinations. That speed is enormous! That's why space launch vehicles are so huge; they require large amounts of fuel to accelerate their payload to escape velocity. Could anything around us reach such speeds unassisted by human intervention? Could air itself travel that fast?

air temperature

It is easy to measure the speed of a large object. For example, every car comes equipped with a speedometer that informs the driver of the car's rate of movement. It seems much more difficult to measure the speed of a very small object, though. How do you watch the movement of an atom, an object so small that you can't even see it? It turns out that we do it all the time. Rather than measure the speed of a single atom, though, we measure the average speed of lots of atoms together. It's simple, really. We just take its temperature.

A speedometer measures the movement rate of a large vehicle, and a thermometer measures the relative movement rate of lots of atoms together. The higher the temperature, the faster those atoms are moving. Likewise, the colder that something gets, the slower its atoms are moving around. The relationship between speed and temperature is more obvious in a gas, but even in solids it is still true that the individual atoms are jittering quickly in their place. The Kelvin temperature scale is anchored at zero degrees at the low end of the scale because that is the point at which the atomic movement has slowed as much as it can. It's not possible for the atoms to move any slower, so they are as cold as anything can get. Zero degrees Kelvin is called "absolute zero". The relationship between speed and temperature is easy to demonstrate.

Fill a balloon with air and tie off the end of the balloon so that no air escapes. Notice the size of the baloon. It keeps that size because of the air pressure inside it. That pressure is generated by all of the small molecules of air zooming off in random directions until they hit the wall of the balloon surface. They push outward and then bounce back to travel in another direction. They ricochet inside the balloon, exerting a constant pressure trying to expand the balloon outward. Similarly the air outside is bouncing against the balloon trying to crush it inward. They eventually reach equilibrium, but you can change that balance by changing the temperature in the balloon. Hold the balloon under hot tap water (or hold over a pot of boiling water). The faster molecules hit the wall of the balloon with greater force, expanding the balloon. Hold the balloon under cold tap water (or place in the refrigerator). The slower molecules hit the wall with less force, allowing the balloon to shrink. Temperature affects air pressure (but that's just a bonus lesson to be learned) because it affects the speed of molecules.

average molecular speed

The law of temperature and pressure is also well studied, so to calculate the speed of an air molecule we can once again use a simple formula. All we need to know is the air molecule's mass and temperature.

nameformula
1.66 x 10-27 * atomic mass =
mass (in kilograms)
H, hydrogen atom1.66 x 10-27 * 1.00794 =1.67 x 10-27
H2, hydrogen gas1.66 x 10-27 * 2.01588 =3.35 x 10-27
He, helium atom1.66 x 10-27 * 4.002602 =6.65 x 10-27
C, carbon atom1.66 x 10-27 * 12.0107 =1.99 x 10-26
N, nitrogen atom1.66 x 10-27 * 14.0067 =2.33 x 10-26
O, oxygen atom1.66 x 10-27 * 15.9994 =2.66 x 10-26
H2O, water1.66 x 10-27 * 18.01528 =2.99 x 10-26
CO, carbon monoxide1.66 x 10-27 * 28.0101 =4.65 x 10-26
N2, nitrogen gas1.66 x 10-27 * 28.0134 =4.65 x 10-26
NH3, ammonia1.66 x 10-27 * 31.03722 =5.15 x 10-26
O2, oxygen gas1.66 x 10-27 * 31.9988 =5.31 x 10-26
CO2, carbon dioxide1.66 x 10-27 * 44.0095 =7.31 x 10-26
note: ultraviolet light can split water, carbon dioxide, and nitrogen molecules
into their constituent atoms

The concept that we're examining is the "kinetic energy" (energy of motion) of molecules. Physics already has two simple formulas for measuring kinetic energy. If we compare them to each other, we can solve to find the velocity that we're needing.

kinetic energy
(motion)
=kinetic energy
(average for a gas)
1/2 * (m * v2)=3/2 * (k * T)
m * v2=3 * k * T
v2=(3 * k * T) / m
v=(3 * k * T) / m

The value of "k" is the Boltzmann constant, 1.38 x 10-23 Joule / Kelvin. The average temperature "T" on Mars is 220 Kelvin. (For the rest of the world, that's -53 Celsius. And for backwater Americans, that's -63 Farenheit.) And those are the last two values that we need. Let's fill in the formula and see what we find out.

namemass
(in kilograms)
formula

(3 * k * T) / m =
average speed
(in meters/second)
H, hydrogen atom1.67 x 10-27(3 * (1.38 x 10-23) * (220)) /
(1.67 x 10-27) =
2.34 x 103
H2, hydrogen gas3.35 x 10-27(3 * (1.38 x 10-23) * (220)) /
(3.35 x 10-27) =
1.65 x 103
He, helium atom6.65 x 10-27(3 * (1.38 x 10-23) * (220)) /
(6.65 x 10-27) =
1.17 x 103
C, carbon atom1.99 x 10-26(3 * (1.38 x 10-23) * (220)) /
(1.99 x 10-26) =
6.77 x 102
N, nitrogen atom2.33 x 10-26(3 * (1.38 x 10-23) * (220)) /
(2.33 x 10-26) =
6.25 x 102
O, oxygen atom2.66 x 10-26(3 * (1.38 x 10-23) * (220)) /
(2.66 x 10-26) =
5.85 x 102
H2O, water2.99 x 10-26(3 * (1.38 x 10-23) * (220)) /
(2.99 x 10-26) =
5.52 x 102
CO, carbon monoxide4.65 x 10-26(3 * (1.38 x 10-23) * (220)) /
(4.65 x 10-26) =
4.43 x 102
N2, nitrogen gas4.65 x 10-26(3 * (1.38 x 10-23) * (220)) /
(4.65 x 10-26) =
4.43 x 102
NH3, ammonia5.15 x 10-26(3 * (1.38 x 10-23) * (220)) /
(5.15 x 10-26) =
4.21 x 102
O2, oxygen gas5.31 x 10-26(3 * (1.38 x 10-23) * (220)) /
(5.31 x 10-26) =
4.14 x 102
CO2, carbon dioxide7.31 x 10-26(3 * (1.38 x 10-23) * (220)) /
(7.31 x 10-26) =
3.53 x 102

According to these results, none of the atoms or molecules listed here could reach escape velocity on mars because they are all below the necessary 5.02 x 103 m/s. That's good news, right? Well, not really. The problem arises from the fact that we measure the temperature of a large sample of air all at once, not each individual molecule separately. The velocity that we compute is just the average velocity of all molecules in the group of air that we measured; it is not the velocity of any particular molecule. Some of them are moving faster than this calculated amount, and some are moving slower.

above-average molecular speed

Most molecules will have a velocity near the average in their group, but a few will have twice that velocity. Fewer will have four times that velocity. Even fewer will have six times that velocity. The general rule (for which I have not yet found a mathematical explanation) is that a molecule will escape into space if 6X its average velocity is sufficient to reach the planet's escape velocity. Once that threshold is reached, the planet cannot retain that type of molecule because random exchanges of energy will give too many individual molecules the boost of kinetic energy that they need to speed away from the planet.

It's time for the big question...
so how does Mars fare under this new scheme?

nameaverage speed
(in meters/second)
6X average speed
(in meters/second)
> escape speed?
(5.02 x 103 m/s)
H, hydrogen atom2.34 x 1031.40 x 104279%
H2, hydrogen gas1.65 x 1039.89 x 103197%
He, helium atom1.17 x 1037.02 x 103140%
C, carbon atom6.77 x 1024.06 x 10381%
N, nitrogen atom6.25 x 1023.75 x 10375%
O, oxygen atom5.85 x 1023.51 x 10370%
H2O, water5.52 x 1023.31 x 10366%
CO, carbon monoxide4.43 x 1022.66 x 10353%
N2, nitrogen gas4.43 x 1022.66 x 10353%
NH3, ammonia4.21 x 1022.52 x 10350%
O2, oxygen gas4.14 x 1022.49 x 10350%
CO2, carbon dioxide3.53 x 1022.12 x 10342%


By these calculations, Mars retains all but hydrogen (whether in its atomic or molecular form) and helium. So if we found a way to mimic Earth air composition on Mars, the planet could gravitationally retain the atoms and molecules. But there's still a catch...

global warming

The mean temperature on Mars is 220 Kelvin. What if we wanted to improve the temperature as well as the chemical composition of the atmosphere? Would the air at 282 Kelvin (Earth's current average) still remain bound to the planet? Plugging the new temperature into the formulas, I find very similar results. The next heaviest common atom is Carbon, and it reaches only 92% of the necessary velocity to escape. Since it doesn't usually exist in a gaseous state, we have no worries about its approach to 100%. Nitrogen reaches 85% which might be troublesome, depending on just how long a time period we want to examine, or how accurate is the "6X" rule of thumb. If "6X" is just guesswork, then Nitrogen retention might be problematic on Mars.

conclusion

Atomic and molecular hydrogen reach either double or triple the needed velocity to escape Mars. They will leave "quickly", so it's important that hydrogen is always bound together in heavier molecules or is replenished regularly. Of course, there is the ongoing problem of natural geologic processes that will affect the air composition, but we'll assume that the terraforming plan takes them into account.

Future exercise: What is the rate of hydrogen loss on Mars? How much hydrogen and helium does our sun deposit on Mars via the solar wind? Would it offset the natural gravitational losses?


Disclaimer: I am not responsible for errors caused by variation in temperature due to global warming, solar nova, or universal collapse. The rest of it is definitely my fault though.



Sources:

"Universe", 6th ed, by Roger A Freedman and William J Kaufmann III, 2002, ISBN 0-7167-4647-6, for formulas and concepts

http://physics.nist.gov/PhysRefData/Compositions/index.html, for standard atomic weights
mellowtigger: (astronomy)
Did you know that Earth has "stripes" in its atmosphere, like the big planets have? They're related to those air blowers that hang over the gate entrances to some stores. No, really.

Moving air can be used as a barrier to the cross-flow of other air. Air curtains are not as effective as physical doors for separating cold and warm air, but they do actually work nevertheless. It's easy to find descriptions here and there that explain how to configure the air curtain for maximum efficiency. The important thing is that they do have a strong effect.

The region of a planet that directly faces its sun will heat up faster than elsewhere on a planet. The atmosphere there will grow hotter, expand, and rush upward to equalize the air pressure. That one region of updraft is important in setting up cycles of air movement across the rest of the planet. On Earth, our equator is generally the most sunward-facing latitude, and that's where our primary updraft begins. As that air rushes upwards, it does two important things.

First, the air cools as it rises, and that cooling leads to rainfall. On Earth, we call this region of rainfall the Tropics. Generally, this region is where we find our rainforests. That updraft has to go somewhere, but it can go only so high. Eventually it pushes outwards instead. That up-and-out motion sets up the second big effect, because it leads to the necessary down-and-in motion of replacement air.

Second, the updraft feeds a perpetual cycle of rotating air. The air rises at the hottest points along the equator, and it falls around 30 degrees north and south of the equator. On Earth, we call these regions of downward air the Subtropics. Remember that this air previously rained out its moisture at the equator. As it comes down to the ground in the subtropics, the air is very dry. These two regions are where we find our deserts.

HadleyCell.diagramThis first loop of air current is called a Hadley cell. While its immediate environmental effects are already important, let's consider a consequence of its movement. Remember the air curtain at the store entrance? The downward motion of the air curtain inside the store (the primary loop) leads to a similar downward motion of the air outside the store (a secondary loop). The two loops interact very little, so the air temperatures don't "mix" along their interface.

Earth has these secondary loops too. Each of them is called a mid-latitude cell. They are influenced by the motion of the primary loop, although they are weaker. Those secondary loops influence the creation of even weaker tertiary loops closer to the poles. The interfaces between the different loops have the same effect on Earth as they do at the storefronts. Cold air (farther from the equator) is kept separated from warm air (closer to the equator). This separation is important to global climate change forecasts.

As one science writer points out, if the loop effect is weak, then air mixes much faster between the equator and the poles. That mixing would lead to polar regions experiencing much warmer weather than usual, which would lead to much faster glacier melt than predicted by current models. In fact, much faster melting is exactly what's happening right now in Greenland.

Other news, however, points to a strengthening of the cells. If the cells are expanding their territory range, though, then this change could actually be bad news instead of good. It would fundamentally change the local climates if the air loop interfaces moved to new areas of the planet.

Earth has atmospheric bands like other planets with thick atmospheres, and they're very important to our climate forecast. They are yet another "moving part" to the complicated machinery that have kept our ecosystems in their recent (very enjoyable) state. As you already know, I advocate against tinkering with our biosphere.  I commute by bicycle to help reduce my own carbon dioxide addition to our atmosphere, hopefully reducing the impact of humanity's effect on climate change.  I hope that education about Earth's complex systems will help encourage other people to consider their personal and collective influence on global climate.
mellowtigger: (astronomy)
This morning, I ran across a reference to a story that I'd never encountered before.  I already knew that our solar system formed with heavier elements produced by the death throes of previous generations of stars.  What I didn't know, however, is that it's possible our sun formed on top of the dead core of one of those star supernovas (SN).

"Cores of the inner planets grew in a central iron-rich region; the Sun formed on the collapsed SN core."
- http://xxx.lanl.gov/ftp/astro-ph/papers/0411/0411255.pdf

Apparently this idea has been around for decades.  Why am I just now hearing about it?  Doesn't this story have grave implications about the lifespan of our host star?

In related news about remnant pieces of star formation, a small asteroid recently flew so close to Earth that it's trajectory changed considerably.  But you already knew about that incident because you've heeded my advice to watch the local conditions and forecasts at SpaceWeather.com, right?

mellowtigger: (astronomy)
Blood raining from the sky may be a common occurrence. No kidding.

Life may be ubiquitous. Evidence slowly accumulates that panspermia is the way the universe operates. If true, then Earth is special only because it is prolific, not because it represents a unique achievement.

blood rainMany years ago, I read stories about the "red rain" that fell in India. Yeah, blood from the sky. The truly weird part of the story is that even microscopically, the strange rain still looked very similar to blood. There were "cells" in the water, and they replicated without dna. Now, finally, there is more to report on the very interesting news.

We have shown that the red cells found in the Red Rain (which fell on Kerala, India, in 2001) survive and grow after incubation for periods of up to two hours at 121 oC . Under these conditions daughter cells appear within the original mother cells and the number of cells in the samples increases with length of exposure to 121 oC. No such increase in cells occurs at room temperature, suggesting that the increase in daughter cells is brought about by exposure of the Red Rain cells to high temperatures. This is an independent confirmation of results reported earlier by two of the present authors, claiming that the cells can replicate under high pressure at temperatures up to 300 oC. The flourescence behaviour of the red cells is shown to be in remarkable correspondence with the extended red emission observed in the Red Rectangle planetary nebula and other galactic and extragalactic dust clouds, suggesting, though not proving, an extraterrestrial origin.
- http://arxiv.org/abs/1008.4960

So life might exist scattered throughout the vast expanse of "empty" space. Such life would rain down upon our tiny ball of dirt (that we affectionately call Earth) as we fly through interstellar fields of dust particles hosting microscopic "spores" of primitive life.

Ain't that a kick in the rubber parts?
mellowtigger: (astronomy)
They come in all religions. I call them "white lighters", those happy people who imagine a tranquil, peaceful future if only we noisy humans would accept it. Life, ubiquitous though it may be, is still fragile. I find no evidence that the wider universe is any more forgiving than our own little planet.

Life here on Earth is vicious. Plants wage chemical warfare against insects and other plants. Animals kill and eat other animals... while the prey is still alive and protesting vigorously. Parasites literally suck the life out of their hosts. Microbes take advantage of everything in whatever state of health or disrepair.

Even the inorganic matter poses a threat to us.



This wonderful video belongs on http://www.InformationIsBeautiful.net/ for its elegance. It shows the ever-growing sum of our knowledge about objects near us in space. Click to go to YouTube and watch the video in HD resolution (up to 1080p) that includes a calendar date as time progresses from 1980 to 2010.

The Earth is the 3rd planetary body in orbit around the sun. As that third dot circles the sun (as each year passes), watch as new asteroids are added to our knowledge. Watch the bursts of knowledge appear as money is spent on observation time. Watch the expanding reach of these bursts as money is spent on new technology. Watch as scientific inquiry illuminates the dangerous whirlpool in which we so tentatively live. Just watch.

Looking away from the bright sun, our instruments peer cleverly into the darkness to find lumps of rock hurtling through the heavens. Which one, we are left to wonder, will fall into our tiny planet and cause another immediate catastrophe? A permanent feature at http://spaceweather.com/ is the asteroid chart that shows the near-misses scheduled to approach us in the coming weeks.

The universe is not kind; it always demands entropy. Local, temporary order is exactly that: local and temporary.
mellowtigger: (economy)
We haven't even adopted it as our paradigm yet, and it's already solving problems.  ;)

A month ago, I told readers here about my idea that the reason we haven't encountered aliens yet is because they're hiding until we prove our ability to adopt a sustainable lifestyle.

In flights of fancy, I also easily wonder if other spacefaring civilizations wait to see the outcome of this very decision before they make contact. Species that opt for perpetual growth, after all, would need to use resources outside their native star system. Enforcing isolation seems a very efficient way to let unrestrained species burn themselves out (by destroying the ecosphere of their homeworld) without endangering the rest of the galactic neighborhood.
- http://mellowtigger.livejournal.com/118559.html

For those unfamiliar with the Fermi paradox, it's a logical argument about the existence of extraterrestrial civilizations.  The paradox is a result of a contradiction: there is a high probability that other civilizations are out there, and yet we have failed to detect any trace of their existence.  How can we appear to be "first" in the universe when that status would be so unlikely as to be impossible?

I learned yesterday on National Public Radio that some scientists back in June explored the idea that sustainability is the solution to the Fermi paradox.  They point out that the paradox assumes exponential growth.

Drawing on insights from the sustainability of human civilization on Earth, we propose that faster-growth may not be sustainable on the galactic scale. If this is the case, then there may exist ETI that have not expanded throughout the galaxy or have done so but collapsed. These possibilities have implications for both searches for ETI and for human civilization management.  ...
Collectively, these possibilities suggest the "Sustainability Solution" to the Fermi Paradox: The absence of ETI observation can be explained by the possibility that exponential growth is not a sustainable development pattern for intelligent civilizations.

- http://lanl.arxiv.org/abs/0906.0568

Amen!  They're preaching to the choir, here.  It remains to be seen if there is actually intelligent civilization on earth.
mellowtigger: (MrFusion)
Just how densely can you pack energy in a recoverable and portable form? Really, really dense. No, I'm not talking "Mr. Fusion" (a la "Back To The Future" fusion blender). Think "black hole" instead.

There was a flap in the news last year about the new super collider producing black holes. When they're small, though, black holes are supposed to evaporate faster than they expand. As they evaporate, they release energy. This is the radiation that made Hawking famous. So what if you were able to harness that radiation for useful purpose? Somebody did the calculations. :)

"Using the formulae from the section above, we find that a black hole with a radius of a few attometers at least roughly meets the list of criteria (see Appendix). Such BHs would have mass of the order of 1,000,000 tonnes, and lifetimes ranging from decades to centuries. A high-efficiency square solar panel a few hundred km on each side, in a circular orbit about the sun at a distance of 1,000,000 km, would absorb enough energy in a year to produce one such BH."
- http://arxiv.org/pdf/0908.1803v1

In other words:
  1. Build a massive solar cell array in space.
  2. Collect the charge for a long time, a year or more.
  3. Discharge the energy in one enormous flash through a sphere of gamma ray lasers.
  4. Their beams converge at a single point to produce a small black hole with the mass of a million tons. (The reverse usage of the E=mc2 reaction that produces nuclear bomb explosions.)
  5. Transport the black hole to your starship.
  6. Siphon the evaporation energy until the black hole finally disappears.
  7. Alternatively, feed it mass to restore its potential energy.
  8. Repeat as needed.
Their paper goes on to discuss the feasibility of producing the black hole, of producing the starship drive, of harnessing the black hole in a power plant, etc. Besides finding it feasible, they think it could surely be improved.
"A BH with a life span on the order of a century would emit enough energy to accelerate itself to relativistic velocity in a period of decades. If we could let it get smaller and hotter before feeding matter into it, we could get a better performance."

Moreover, they say that it's perfectly reasonable to think that other star-faring civilizations are already using such technology. Because this technology "would emit gravitational radiation at nuclear frequencies", they say that SETI projects should consider building new detectors that work in this range. We might be able to detect galactic neighbors already using such energy devices. (Once somebody on Earth builds any kind of gravity detector that works.)

I think the only appropriate word for it is:

WOW!
mellowtigger: (Default)
After the first snow a few weeks ago, tree leaves starting turning color in abundance.  Leaves fell to the ground soon afterward.  Most of the deciduous trees are already bare.

We changed timeclocks here on Sunday to comply with the ending of daylight saving time. The difference is obvious. As I stepped outside of work at 5pm, the sun was already about 3° below the horizon.   I know, because the full moon had already risen about 3° above the horizon.  It was almost fully dark by the time I got home.

I started thinking about how northern areas experience so much less sunlight than equatorial areas. Minnesota and Texas are very different in that regard.
sunlight

Thanks to DaylightChart and GifMake.com, I was able to produce this illustration of the difference between Minnesota and Texas.  Look at the right-hand side of the chart for winter solstice (December 21st).  Notice how much less daylight we have in Minneapolis compared to Houston.  Conversely, notice how much more sunlight we get during summer solstice (June 21).

It's cold.  It's dark.  It's bare.  This is winter.
mellowtigger: (Default)
There's a haze all across the sky this morning, so I won't be taking any photos myself this morning. There aren't any sunspots to photograph anyway. Here, though, is an interesting graph that helps to explain the mystery of the long solar minimum that we're experiencing right now.
solar cycle revealed
It shows a collection of data for the past decade or so. The yellow/red bands show the migration of solar jet streams as they move from the polar regions down to the equator. The black areas show locations of sunpot activity.

As the jet stream passes below about 22 degrees latitude (north and south), then sunspot activity intensifies around and above the jet stream. On the far right, you can see that we have had little jet stream activity below 22 degrees during the last few years, hence almost no sunspot activity.

This relationship is recently discovered. It begs the question, of course, of what is responsible for creating the solar jet stream. Scientists don't yet know the answer to that question.  This new awareness regarding solar cycles, though, is very useful to help predict future sunspot trends.

In different news, bringing the sun "a little closer to home" is basically what scientists are doing as they try to create nuclear fusion. Fusion is the only thing that I see as a possibility of keeping traditional human industry from crashing as existing fuel sources are exhausted or found to be too costly in terms of side effects (global warming, pollution, etc.). I had been hopeful that ITER would be showing the way to industrial-grade fusion in just a few years. Those hopes are now dashed.

Cost overruns and technical problems are expected to delay the operation of this new facility. There is talk of scaling back the project.
"Fusion is not going to be the alternative in the next 20, 30 or 40 years, that is correct. But there needs to a long term plan; 40 years is little more than a generation. We need to think about the next generation and the many after that."
- http://news.bbc.co.uk/2/hi/science/nature/8103557.stm
That is much too long a timespan for saving humanity from the "crash" that I think is otherwise inevitable.  :(
mellowtigger: (Default)
According to my calculations, which I already know are too simplistic, the Earth can gravitationally hold onto all of its atmosphere except for hydrogen (atomic or molecular). By the same calculations, Mars can retain all but hydrogen and helium. But then where is the atmosphere on Mars?  NASA has a new report that the solar wind (and the weird magnetosphere on Mars) may be to blame.

Earth is not a single magnetic dipole.  Instead, our planet has a series of monopoles.  They all happen to generally align well so we have a strong overall "uniform" magnetic shield around our planet.  Mars is not so lucky.  Its monopoles are apparently weaker and more distributed, so they stand out as little umbrella shields over their regional area, mostly in the southern hemisphere.  Where these mushroom bubbles spring out, general turbulence and also magnetic reconnection with the solar wind can rip out whole chunks of atmosphere at once.

Like little spiders sending out their spinner web to catch the wind and fly aloft, so does Mars lose whole pockets of air to the solar wind stream inside magnetic "balloons".

Kinda sad, in a way.  So terraforming Mars will not be as easy as I had hoped.  It will not simply be a matter of reintroducing the appropriate molecules (as in the movie Total Recall).  The planetary magnetic field would need to be altered first.

mellowtigger: (Default)
I still haven't written the increasingly-belated script for my story about The Children. It's a sci-fi story about human nature. It's set in the near future on various spaceships with human crew intended to pilot them across generations of inhabitants. Each spaceship chooses a different type of society to survive the long haul, so we learn about the long-term consequences of their choices.

This space race is initiated by two events. First, scientists publish a list of all habitable planets (nitrogen atmosphere with oxygen, plentiful water, suitable gravity and temperature) within a limited range (perhaps 200 light years) from Earth. Second, the Christian Broadcasting Network announces plans to build a spaceship to go populate one of these planets in an attempt to create a proper God-loving society. The space race ensues.

Scientists here in the real world are already making fast progress. Besides deducing mathematically the existence of planets in certain orbits around other stars, they are now starting to image them directly.

Fomalhaut bHR8799

An exoplanet is any planet orbiting a star other than our own sun. The first (red) image is of a young still-cooling planet orbiting Fomalhaut b, 25 light years away. The second (purple) image is of two huge planets orbiting HR 8799, 130 light years away. Since this image was taken, a different telescope has observed a third exoplanet at HR 8799.

None of these planets is habitable for humans, but it's just a matter of time until we find one that is.

mellowtigger: (Default)
Breaking news finally explains why NASA met with the President for an important briefing this weekend. All that the public was told at the time was that the Mars lander had not detected life but had found something also very important.

In addition to the water previously detected in the soil, they now have evidence that the soil also contains perchlorate, whose ion is ClO4-. The significance of this molecule is that it is used (in airplanes, submarines, and spacecraft) to generate breathable oxygen. NASA is still reviewing to ensure that the readings are not merely a contamination of perchlorate from an earlier stage of rocket launch, where perchlorate is used in the fuel mixture. The readings would, however, explain results from a Viking lander in 1976 which was searching for evidence of biological activity but instead found only easily available oxygen gas (and was unable to explain the source).

So, in summary, the surface of Mars contains both water and oxygen in readily available forms. We can go there.

P.S.  Oh, it also means that the environment is a little more harsh, chemically, than would be convenient for us.  I'm not sure how safe bare Martian soil would be for human skin, in either short-term or extended exposures.  It would probably make it more difficult to raise plants in the soil too.  It's a significant finding with both good and bad consequences.
mellowtigger: (Default)
Jupiter has been behind the sun (and so impossible to photograph) for a while now. It's finally come back around far enough that new photos are available. What's new? Well, yet another red spot.

Astronomers have already seen one of the many white spots evolve into a larger storm system, changing color to red by a process that is not yet fully understood.  They think it has something to do with molecules dredged up from deeper inside Jupiter and then being exposed to ultraviolet radiation from the sun.  Why all the "new" storm activity on Jupiter? More theory: global climate change.

No, not the same kind on Earth, where natural variation has been left behind in favor of new spikes of abrupt change. The idea on Jupiter is that this is part of a natural 60-year cycle (or 100-year cycle, depending on who you ask).

The path of the 3rd storm will take it to the Great Red Spot around August here on Earth.  We'll see then if the winds repel each other or if the smaller storm gets absorbed by the larger one. 
mellowtigger: (Default)
Normally astronomy is a rather "cold" endeavor. Alone, at night, in cold weather, in the dark. But it doesn't have to be that way. (Click photo for larger version at Spaceweather.com.  It's not my photo.)

Imagine trying to photograph the moon with the pleiades. And a happy dog's tail thwacking against the tripod.

moon and pleiades and dog

:)

cosmic tao

Mar. 18th, 2008 08:00 pm
mellowtigger: (Default)
I've been at least slightly ill for nearly a month now. I haven't had a fever in nearly a week, so I'm feeling ever so much better.  I still have a lingering cough, though, that's far more annoying that it is debilitating. I haven't done a good job of reading up on livejournal entries recently (or posting), but I hope to act a little more perky from now on.


This image was the Astronomy Picture Of The Day on March 9th. It is the cosmic microwave background, mapped out according to doppler shift so that we can easily see the areas moving towards (blue) and away (red) from us. It's strange that it should appear as a good approximation of the Tao.  Mapping out movement on a sphere always comes out wonky to me, so the curved division between the two halves doesn't much bother me... but what's with the dimples in each half?  That bothers me.  I'm not having any luck coming up with a logical, non-anthropocentric explanation for that effect.
mellowtigger: (Default)
Weather.com says it's currently -7F (-22C) outside. Much too cold to be working with any equipment. Still, I went out in a few brief forays to try just my little camera and see how nice a photo it could capture of tonight's lunar eclipse.

They didn't turn out very well. Same old problem with trying to use it with my telescope: vibration. In order to get the proper exposure (my Nikon Coolpix 4500 maxes out at 8-second exposure times), I need remote controls for both the camera and the telescope. My remote for the camera isn't even working, though I can't figure out why yet. So I had to take photos by hand, which introduces vibrations that mess up the image. It's impossible for me to avoid it, especially during bitterly cold nights like tonight. The effect is just magnified when trying the camera on a telescope.

Excuses aside... here's tonight astro event (fullsize images in the gallery):



Look for better images to show up soon on spaceweather.com.

(edit: 2008-02-21)
P.S.  Photos have been posted by snowboardjoe and mikiedoggie, both better than mine. :)
mellowtigger: (Default)
I noticed the warning a few days ago that our primary supply of helium is nearly exhausted. The world's largest reservoir of it is located in the Texas panhandle (near Amarillo) and will likely run dry around 2016. The article explained how helium is produced on Earth, but it also stated, "... any helium ultimately released into the atmosphere by users, drifts up and is eventually lost to the Earth." This statement contradicts my own calculations on the matter, so naturally I was curious to learn the details.

Near as I can tell, my original calculations are appropriate but they should be applied in more specialized circumstances. It is not, apparently, the temperature at the surface that matters for giving molecules their kinetic energy for escape velocity. Our atmosphere has different layers, and it is the temperature in the highest layer, the exosphere, that determines the possibility of thermal escape for various molecules of gas.  It's 1800 degrees in the exosphere, a lot hotter than down here on the surface, and that's plenty of energy for sending atoms or even whole molecules zooming off into space.
Aside: I didn't know before, but this process is called the Jean mechanism, though I can't find why it has that name. There is also the possibility of electric escape, with ions snatched away by solar flux. On Venus, in contrast, it is electric repulsion of atoms from the atmosphere itself after just the electrons are lost via thermal escape.
But then which molecules at the surface manage to make it up to the exosphere?  I don't know.  Knowing that information is necessary in order to make my calculations again.  Apparently Earth does lose more atmosphere than I originally thought.  I wish I knew better how to calculate that loss.

Back to helium though.... apparently helium exists near equilibrium these days (being produced in the Earth and lost to space at equal rates).  But with the convenient ground sources nearly exhausted, and with important scientific and medical uses for helium taking precedence, it may be only a few years before party balloons disappear unless we find another safe alternative.  I sure can't imagine anyone selling hydrogen balloons.  (Mini-Kaboom!)  Helium is already more expensive (per liquid gallon) than gasoline.  It would get a lot more expensive if producers have to harvest it from the atmosphere directly.

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