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Friday, April 27, 2012

Cassini update

NASA--

These raw, unprocessed images of Saturn's moons Enceladus and Tethys were taken on April 14, 2012, by NASA's Cassini spacecraft.

Cassini flew by Enceladus at an altitude of about 46 miles (74 kilometers). This flyby was designed primarily for the ion and neutral mass spectrometer to analyze, or "taste," the composition of the moon's south polar plume as the spacecraft flew through it. Cassini's path took it along the length of Baghdad Sulcus, one of Enceladus' "tiger stripe" fractures from which jets of water ice, water vapor and organic compounds spray into space. At this time, Baghdad Sulcus is in darkness, but that was not an obstacle for another instrument, the composite infrared spectrometer, which can see features by their surface temperatures and which also took measurements during this flyby.

As soon as daylight passed into the spacecraft's remote sensing instruments' line of sight, Cassini's cameras acquired images of the surface. The wide-angle-camera image included in the new batch, taken from around the time of closest approach, has some smearing from the movement of the spacecraft during the exposure, but still shows the surface in vivid detail.

Cassini's cameras also imaged Enceladus' south polar plume at a high phase angle as the satellite appeared as a thin crescent and the plume was backlit.

After the Enceladus encounter, Cassini passed the moon Tethys with a closest approach distance of about 5,700 miles (9,100 kilometers). This was Cassini's best imaging encounter with Tethys since a targeted encounter in September 2005. The 2005 encounter, with a closest approach distance of about 930 miles (1,500 kilometers), provided the images of Tethys with the best resolution and captured views of the side of Tethys that faces Saturn in its orbit. This new encounter examined the opposite side of Tethys, providing some of the highest-resolution images of the side that faces away from Saturn. Cassini acquired a 22-frame mosaic of this side, which features the large impact basin named Odysseus. Scientists will use these new data in conjunction with images from previous encounters to create digital elevation maps of the moon's surface.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena manages the mission for the agency's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations team is based at the Space Science Institute in Boulder, Colo. JPL is a division of Caltech.

Dream Chaser

Yet another commercial space venture gone very right: Sierra Nevada Corporation's Dream Chaser. If you think it's just NASAs HL-20 Spaceplane concept redone, well, it is. I remember when they were developing this concept at Langley back in the early 1990s. For a space taxi to the International Space Station and other LEO destinations, I think this is superb.

Tuesday, April 24, 2012

Gold Rush

Two press releases from two different commercial ventures today, each announcing projects to mine for platinum and other minerals in space.

Seattle's own Planetary Resources debuted its program to mine near-earth asteroids for platinum and a water, and Moon Express in California unveiled their plan to mine the moon for the same things.

A while back I wrote about different scenarios which could lead to permanent colonization of other worlds within our solar system. At the time I specifically discounted off-world mining as a major motivator.

From December 13, 2010: "Mineral or other wealth has always been a strong motivator, but there's no reason to imagine that we'll experience a Lunar or Martian Gold-Rush anytime soon. Mars has plenty of iron, but so does earth, and earth's iron deposits are a lot closer."

So much for my powers of prognostication!

The rationale is that there are some single asteroids with more accessible platinum than all the platinum on the surface of the earth combined. My first thought on this is, if this works, I'm really glad I never invested in platinum. I'm just old enough to remember when amethyst was considered a precious gemstone, before the massive deposits were fund in Brazil. Now kids can buy fist-sized chunks of it in science-center gift shops with their baby-sitting money. If these commercial operations are successful, platinum could similarly cease to be a precious metal. But it might make a nice building material.

Will be posting much more about this, soon.

Sunday, April 22, 2012

Daisy and the Trillion Trees


In 1983 James Lovelock and Andrew Watson created a computer simulation called "Daisyworld". The premise was an ultra-simplified ecosystem, a world inhabited by only two species, white daisies and black daisies. Affecting this world's climate was the single factor of its sun's heat. The high-albedo white daisies reflect sunlight and the low-albedo black daisies absorb sunlight. The "monkey wrench" in the system is that the sun is actually slowly becoming hotter.

So, as the simulation begins, the sun's radiation is too small to germinate either the white or black daisies, but the surface of the planet is covered with evenly distributed seeds of both black and white daisies. As the sun becomes hotter and the world heats up, eventually the world becomes warm enough for the black daisies to germinate and bloom. The black flowers absorb the sun's heat, causing the world to warm even more rapidly, until it is warm enough for the white daisies to also germinate and bloom. The white flowers reflect the sunlight and begin to lower the world's temperature. As the sun continues to heat up to a level which is uncomfortable for the daisies, the white flowers, which are better able to cool themselves, out-compete the black flowers. The greater the surface-area of the world that is covered by white daisies, the greater the cooling effect of the white flowers. In this way, the white and black flowers work in tandem to regulate the temperature to a level which is comfortable for all daisies. Eventually the sun heats up beyond the ability of the white daisies to regulate it, and all of the daisies die. If, however, the sun's heat remains more or less constant, the populations of white and black daisies will equilibrate in such a way as to maintain an optimum climate for the daisies. In this way, rather than naturally selecting to adapt to the environment, the daisies modify their environment to fit their own needs.

Later generations of the Daisyworld program added many more layers of complexity (atmosphere, herbivorous and carnivorous animals, etc), but each iteration of complexity actually increases the world's ability to self-regulate.

Here is a diagram of this first Daisyworld test, in 1983:


It is serendipitous, only, that this model happens to address global warming. Lovelock and Watson could have chosen any number of variables, and the problem of anthropogenic climate change was only vaguely understood at the time. Nonetheless, it serves admirably to illustrate a possible solution to the current global warming crisis.



There are four things we know for certain about the current global warming situation.

1) It is happening, and it is the largest and fastest increase in global temperatures since eukaryotic life has existed on earth.

2) It is happening mostly as the result of human activity, especially the combination of the burning of fossil fuels and deforestation.

3) If left unmitigated, it is the single most likely cause of the extinction of the human species. If current trends continue, earth will be uninhabitable by human life by the end of this century. More importantly, there is a very real possibility that anthropogenic global warming will (if it has not done so already) trigger a runaway climatological feedback-loop which will continue to increase global temperatures long after humans are extinct. The worst-case scenario, which is unfortunately quite plausible, would result in earth becoming a hellishly hot Venus-like world devoid of all liquid water and all life, within about 600 years.

4) There are three foreseeable outcomes for the human population from this; mitigation, outmigration or extinction.

This blog has spent a lot of time exploring the possibility of outmigration, and I do believe that this is a critical step to ensure the survival of our species, and other terrestrial species. However, in the very short amount of time we have before this planet is no longer habitable, we would only be able to successfully evacuate a tiny fraction of our population. In order for the majority of humans to survive, we must directly and immediately mitigate the increase in global temperatures.

The good news is, we can. And we don't have to wait for governments or corporations to take the lead; we can do it ourselves, right now, easily and inexpensively.

As a very quick summary, the problem is this. Short-wave radiation from the sun (insolation, with an "o") enters the atmosphere, heating both the atmosphere and the earth's surface. Some of this is reflected directly back into space, both by the earth's surface or by clouds. Some of it is re-radiated as long-wave radiation from the earth and air back into space as well. Some of it, however, is trapped in the atmosphere by greenhouse gasses ("insulation", with a "u") such as carbon dioxide, water vapor and methane. For a very long time, this insolation/insulation cycle was in a state of equilibrium. Now, however, the combination of an extraordinary amount of CO2 pumped into the atmosphere since the beginning of the industrial revolution by the burning of fossil fuels, and the diminished ability of trees to scrub CO2 out of the atmosphere due to deforestation, has created an overabundance of CO2 in our atmosphere. This increases the greenhouse effect, which raises temperatures, which evaporates water which increases the greenhouse effect even more which further raises temperatures, which kills off trees which reduces the ability of forests to scrub CO2 out of the system which increases greenhouse CO2 which increases temperatures, etc.

Freeman Dyson, the same brilliant mind who invented a starship to reach Alpha Centauri in 88 years time back in 1957 (the Orion nuclear-pulse starship, I've written quite a bit about it in this blog) has proposed a simple and elegant solution to this problem.

In order to stop catastrophic global warming, we simply need to plant one trillion trees.


Right now.

Really.

Yes, it sounds like a lot. But we have over seven billion people on the planet. That works out to just under 143 trees per person. If every man, woman and child on planet earth were to plant just two trees every five days for one year, even with no reduction in our usage of fossil fuels we would actually be in some danger of shocking the climate into a mini ice-age.

Our planet has a remarkable ability to self-regulate its ecosystems. But it only works if all the "daisies" are there to do their part of the regulating.

Yes, it would actually be more helpful to plant all 143 trees at an optimal time for planting them. You can start them from seeds, just pick up a couple handfuls of seeds of some kind of tree which is indigenous to your area, and plant them in an place that they are likely to grow. If you are ridiculously slow about it, it might take you a couple of hours to do so. Then, walk away and forget about them. This isn't difficult. Entire forests have been successfully planted by a single individual.

Of course, the very best time to plant a tree is twenty years ago. Barring that, "today" is an awfully good second best.

Happy Arbor Day, whenever that happens to be where you are.

Sunday, April 15, 2012

Dune Buggies

Possible nanobacteria embedded in Martian meteorite

There are in this world a small number of very fortunate people who are able to make an honest and decent living by writing blogs. Good on them, that's an impressive accomplishment. I, on the other hand, have never made a dime writing this blog. Which is fine; this is a hobby for me, and I make my living in other ways which I love and which I think are at least as cool as blogging. However, one of the realities of the fact that I am gainfully employed in the maritime industry is that 1) there are occasionally longish gaps in this blog, some of which occur at times that I might otherwise want to contribute to it and 2) sometimes when I finally am in front of a computer I am unable to find links to news articles and other things which occurred when I did not have access to the internet.

As a rule I try to source anything I post here which I myself do not write. Due to the aforementioned, with apologies, this won't be one of those times.

So. Somewhere in the past week, I saw an article (believe it or not, I don't think it was Fox News this time) discussing the current NASA budget. Specifically it was discussing the fact that prior to landing humans on Mars, we want a robot probe to bring a sample of Martian soil back to earth to analyze for possible microbial life.

This much is essentially true.

However, the article then went on to state that the reason for this is that NASA is concerned that martian microbes might bear disease which could infect human explorers.

Oh dear.

I am, for the record, not a biologist, so perhaps my understanding of such things is too limited. But it seems to me rather unlikely that an organism which has evolved over millions of years to thrive on a parched, frozen and nearly airless world would find the warm, wet interior of a human body a very hospitable place.

On earth, disease organisms tend to be very host-species specific, and co-evolutionary with their hosts. There are a few diseases such as rabies which are transmissible between different mammals, and still fewer diseases which are transmissible between endothermic vertebrates (such as avian influenza). But this is not the general rule. Veterinarians do not need to be nearly so cautious about fluid-borne pathogens as their human-medicine counterparts, for this very reason.

Even more rare on earth are pathogens which are not transmitted by other organisms, but rather directly from the environment. Amoebic dysentery is an example of this, where a prokaryote which thrives in warm, still water also happens to thrive, unsurprisingly, in the human body. Trichophyton (athlete's foot, ringworm etc) and other fungal infections also require warm, wet environments.

Similarly, on earth there have been many examples of organisms from one region being introduced into a different region and thriving, even in some cases out-competing native organisms of similar niches. One of the most extreme examples of this is kudzu, an ornamental ivy from Japan which now threatens to eradicate most of the US states in the southeast (although probably not quickly enough to have any beneficial effect on the 2012 elections). Again, the new temperate environment was only slightly different from the old temperate environment.

When we relocate species from their native environment to a radically different one, even within the same climatological zone, we find a very different outcome. Consider two terrestrial vertebrate apex-predators, the Bengal tiger and the great white shark. A healthy adult great white shark deposited in the grasslands below the Himalayas is probably not going to successfully out-compete the native tigers. Similarly, a healthy adult Bengal tiger relocated to the middle of the Indian ocean is not going to seriously impinge upon the shark's hunting grounds. And yet, these two environments are remarkably similar, in terms of temperature, humidity, barometric pressure, gravity, environmental chemistry, solar and cosmic radiation; even the length of the day and year are similar. More importantly, the organisms themselves are remarkably similar. Form does, after all, follow function, and they also have a common evolutionary ancestor. And yet, neither can survive for more than a few minutes in the other's native habitat.

Now, consider Mars.

The average surface temperature on Mars is -63° C (-81° F). Rarely, at the equator, temperatures at the very surface reach 20° C (68° F), but even then the temperatures just a few inches above that are sub-arctic. Average barometric pressure on earth is 1013 millibars. Average barometric pressure on Mars is about 6 millibars, which is less than the inside of an early vacuum tube. Martian atmosphere is 95% carbon dioxide, with 210 ppm water vapor. Earth's atmosphere is 78% nitrogen and 21% oxygen, with about 25,000 ppm water vapor at the surface.

Martian life, if such exists, cannot survive in earth's atmosphere, or within the bodies of organisms which evolved within that atmosphere. Just as importantly, terrestrial organisms cannot survive on Mars. In the case of Mars, we do not need a "microbial Prime Directive". We could bombard Mars with terrestrial bacteria for weeks, and within minutes of their landing on the Martian surface they would all be dead and frozen. Similarly, we do not need to worry about an "Andromeda Strain" being returned from Mars to earth. The greatest difficulty will be keeping any organisms alive long enough to study them.

Cassini flies through Enceladus plumes


This happened yesterday, no report yet on what they found. For those unfamiliar with the Tiger Stripes, it's basically a 16 gigawatt power source (like, large enough to power Los Angeles) at the south pole of Saturn's moon Enceladus, where no such thing should be.
Meanwhile, I'm looking at this photo from December 2009. Several of you have already made the observation, but this particular photo kind of drives the point home. I'm not typically one to see random shapes in things and assume intelligent design, but, really this just doesn't seem like a naturally occurring thing.

NASA--
Less than three weeks after its last visit to the Saturnian moon Enceladus, NASA’s Cassini spacecraft returns for an encore. At closest approach on April 14, the spacecraft will be just as low over the moon’s south polar region as it was on March 27 -- 46 miles, or 74 kilometers.

Like the last, this latest flyby is mainly designed for Cassini’s ion and neutral mass spectrometer, which will “taste” the particles in the curious jets spraying from the moon’s south polar region. Combined with the March 27 flyby and a similar flyby on Oct. 1, 2011, this close encounter will provide a sense of the jets’ three-dimensional structure and help determine how much they change over time.

On Cassini’s outbound leg, the spacecraft will pass by another Saturnian moon, Tethys, at a distance of about 6,000 miles (9,000 kilometers). The composite infrared spectrometer will look for patterns in Tethys’ thermal signature. Other instruments will study the moon’s composition and geology. The imaging cameras are expected to obtain new views of Enceladus and Tethys.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL.

For more information about the Cassini-Huygens mission visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov/ .