Sunlight passing through a prism. Image credit: NASA
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Of all the wavelengths in the electromagnetic spectrum, those that lie between 400 nm to 700 nm are the ones most familiar to us. That’s because these are the waves that comprise what we call visible light.
When we see objects, it’s because they’re being illuminated by visible light. When we see that the sky is blue, or the grass is green, or hair black, or that an apple is red, that’s because we’re seeing different wavelengths within the 400nm-700nm band. Because of the waves in this band, a lot has been learned about the properties of electromagnetic waves.
Through visible light, reflection & refraction are easily observed. So are interference and diffraction. Mirrors, lenses, prisms, diffraction gratings, and spectrometers have all been put to use to understand and manifest the qualities of the light that we see through our naked eyes.
Galileo’s telescope, which was composed of a simple set of lenses, made use of the refractive properties of light to magnify distant objects. Today’s binoculars and periscopes capitalize on the optical phenomenon called Total Internal Reflection by using prisms to improve on what early refractive telescopes were capable of achieving.
As mentioned earlier, visible light is made up of the wavelengths that range from 400 nm to 700 nm. Each wavelength is characterized by a unique color, with violet on one end (adjacent to ultraviolet light) and red on the other (adjacent to infrared light). When all these wavelengths are combined together, they make up what is known as white light.
You can separate these wavelengths (and the corresponding colors) by letting them pass through either a prism or a diffraction grating. The magnificent array of colors that we see in a rainbow, on a diamond, or even a peacock’s tail are examples of this separation.
All phenomena of visible light such as reflection, refraction, interference, and diffraction are also exhibited by non-visible wavelengths. Hence, by understanding these phenomena, and applying them to the non-visible wavelengths, scientists were able to unearth many of nature’s secrets. In fact, if we trace back the roots of modern physics, particularly the wave-particle duality of matter, we will be led back to its manifestation in visible light.
The study of visible light falls under the realm of optics. Among the scientists who have contributed substantially to the development of optics are Christiaan Huygens for his wavelets and a wave theory of light, Isaac Newton for his contributions on reflection and refraction, James Clerk Maxwell for the propagation of electromagnetic waves as explained in a series of equations, and Heinrich Hertz for verifying the truth of those equations through experiments.
Magnificent Desolation, the new autobiography by Buzz Aldrin
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I very much enjoyed chatting with Buzz Aldrin a couple of weeks ago, for some stories leading up to the 40th anniversary of the July 20, 1969 Apollo 11 landing on the moon. I found him honest, personable and generous with his time.
But when his publicist offered to send a copy of his new book, “Magnificent Desolation,” I didn’t set my expectations too high. I didn’t know what to make of an autobiography by a retired Air Force pilot and astronaut. Doesn’t that history put the “Rocket Hero” pretty squarely in the category of techie or a jock — a non-writer type?
Well, color me impressed. The book arrived late last week, and I turned the last page this morning — looking for more to read!
Courtsey of Buzz Aldrin
Granted, Aldrin got help when he teamed up with writer Ken Abraham. But no writer can spin a book like “Magnificent Desolation” without an incredible story, and Aldrin is a master of that.
The book opens with a few chapters on the Apollo program that made him famous. Even though I’ve dabbled in some research the past few weeks — including catching up on the movie “In the Shadow of the Moon” and leafing through some books — I learned new details both whimsical and serious.
Who knew, for example, that American astronauts traditionally eat steak and eggs prior to launch? Or that Aldrin is such a font of deep thoughts, which has apparently been true for a long time:
“From space there were no observable borders between nations, no observable reasons for the wars we were leaving behind,” he remembers musing as the Earth got smaller in Apollo 11’s windows.
“Magnificent Desolation” is about as revealing as you can get in personal realms. Aldrin engages in a lengthy discussion of his decade of deep depression and alcoholism following the Apollo years, from which he eventually escaped. At his rock bottom, Aldrin had lost faith in himself, had no vision for his purpose in life, and was failing at his job — as a salesman of Cadillacs.
During our interview, Aldrin said he turned his life around by deciding that he could share his experiences for a greater good.
“Do you continue to descend into an abyss? Or do you try to make a difference with what you know best?” he remembers thinking.
These days, Aldrin lives a life fitting for a hero. He hobnobs with greats in every field, from journalists and athletes to international leaders, scientists and movie stars. He and his wife, Lois, have traveled the world for scuba diving excursions, ski trips and unflagging efforts to promote his primary passion (besides Lois): a return to the collective national motivation that helped fuel the lunar landings. He desperately wants to see America lead the charge toward space exploration — to Mars and/or a moon of Mars, and beyond.
Aldrin admits he’s been criticized in the past, even by some of his astronaut peers, for garnering so much publicity as the second man (after Neil Armstrong) to set foot on the moon.
“The truth was, no other astronaut, active or inactive, was out in the public trying to raise awareness about America’s dying space program. None of them,” he writes. He points out that he is not promoting himself: “I did not want ‘a giant leap for mankind’ to be nothing more than a phrase from the past.”
Besides pushing for a new era of space exploration, the book is also a testament to the benefits of citizen space travel, which Aldrin avidly promotes through his outreach efforts, including his non-profit Sharespace Foundation. Among them: “The United States will capture the lion’s share of the global satellite market,” and “NASA’s planetary probes will become far more affordable.”
Aldrin has used traditional channels to advance his ideas, addressing international audiences of all stripes and testifying before Congress. But the really fun stuff comes when he reaches out to younger audiences. He seems to stop at nothing to reach out to the next generations, to ensure that his space exploration dreams will stay alive.
“I look forward to these things happening during my lifetime,” he writes, “but if they don’t, please keep this dream alive; please keep going; Mars is waiting for your footsteps.”
This review is cross-posted at the writer’s website, anneminard.com.
Apollo 11 crew in quarantine talking with President Richard Nixon. Credit: NASA
50 lbs. of moon rocks. That’s how much weight was allocated for the Apollo 11 astronauts to bring back lunar samples to Earth. But this would be the first time materials from another world would be brought to our planet. What should be done with these alien rocks, and could they possibly be a threat to life as we know it?
What started out as a seemingly straightforward idea of building a facility to store and study rocks from the Moon ended up becoming a power struggle between engineers building the facility and scientists who wanted to study the rocks and those who wanted to save the world from biological disaster — not to mention even more squabbling between the various governmental agencies and politicians. In the middle of it all was James McLane, Jr. one of the engineers tasked with the early planning for the Manned Spaceflight Center –now known as Johnson Space Center in Houston — and in particular, he led a group to determine the requirements and design concept of NASA’s Lunar Receiving Laboratory.
James C. McLane Jr. in 1971. Photo courtesy of James McLane Jr.
“We started the Manned Spaceflight Center from scratch and a cadre of people envisioned what we should have for the space program’s ground facilities,” said McLane, in an interview from his home with Universe Today. “A whole range of facilities were recommended. For a year or so I went from one design review to another to add my two bits as to how things might be done. The new facilities included a big manned centrifuge, electronics labs, and a thermal vacuum lab with a couple of very big space simulation chambers to test the Apollo spacecraft and its onboard crew under conditions similar to those to be found during the lunar missions. There was just about everything you could think of that was needed to support the Apollo program.”
While engineers at the MSC were intent on designing unique, world-class facilities (as well as rockets and spacecraft to take humans to the moon) scientists were excited about the prospect of researching pristine lunar materials. Lunar Receiving lab concept drawing. Credit: NASA
During this time, a couple of young MSC scientists, chemist Don Flory and geologist Elbert King had been given responsibility of designing the airtight sample return containers in which lunar samples would be brought back to Earth. But, said McLane, no one had given much thought as to how the rocks should be handled or stored once they were brought back to Earth. “There really wasn’t much direction on what should be done after we got them back to Earth,” he said. “Oh, there were scientific committees of course, but for some reason this was down low on their priority list. I think they were thinking more about the research they were going to do with the rocks.”
But one day Flory and King showed up in their boss’s office and said since they had the responsibility for the container they were a little concerned what would be done with it after the astronauts returned the samples. They suggested that, at least, the containers ought to be opened in a vacuum chamber.
“They asked, ‘Does anyone around the Center have a small vacuum chamber where we can open these boxes?’ And that started the whole business of what would happen to the lunar samples and what was required to do that,” said McLane. “A small office was setup under the Assistant Director of Engineering, Aleck Bond, and I was assigned to head it. We were charged with determining what was needed to receive, protect, catalog, and distribute the materials collected from the surface of the moon. We were guided and assisted by a committee appointed by NASA headquarters, consisting mostly of people who had been selected, or expected to be selected as principal investigators for some of the many examinations and experiments proposed for the lunar samples.”
The initial plan called for a clean room approximately “ten feet by ten feet by seven feet” where the sample box could be opened under vacuum conditions and repackaged for distribution to various researchers.
But some NASA officials concluded just a single room wouldn’t be sufficient, and quickly came up with a plan for a 2,500 square foot research facility where the lunar samples would not only be stored, but studied as well. After more discussion, an 8,000 square-foot version was proposed. Scientists in the Lunar Receiving Laboratory. Credit: NASA
Working with the scientific advisory committee to develop a workable plan for the ever-growing and changing proposed facility turned out to be an interesting challenge for McLane and his team.
“The biggest challenges were political,” McLane said. “All the scientists involved in studying the samples had laboratories of their own. They didn’t want to do anything unless it was going to benefit their facility back home. Others were suspicious that we were trying to appropriate activities that weren’t in the Manned Spacecraft Center’s charter at the expense of other NASA Centers. So, it was difficult to get everybody to cooperate and agree on just on the initial receiving procedure. A few of the experiments such as those to determine low level radiation properties of the samples were very time dependant. Thus it became evident that the facility and equipment required to perform those experiments would have to be located very near the point where the samples were first available. That point was Houston, and it particularly rankled some of the scientists to see new state-of-the-art facilities and equipment being located at Houston rather than at their home laboratories.”
“I had never worked with high level scientists before, and our advisory committee usually consisted of people who were at the level of principal assistants to Nobel Prize winners,” McLane continued.”Overall, it was a great group to work with, with one important exception. They each reserved the right to change his mind. It was not unusual for us to settle a contentious issue only to have it brought up again some weeks later. This caused some real schedule problems, but the instigator would plead ’Well, I was just wrong before’, or ‘I changed my mind’, often ignoring schedule and reality.
For example, one issue was whether to use glove boxes or use a closed container with mechanical manipulators (McLane equated them to the toy grappling machines in restaurants, only a little fancier) to work with the moon rocks. It took many discussions and debates to decide, and the decision would make a big different on what direction the engineers needed to go for building the lab, and they had a limited amount of time to decide.
McLane was also surprised about all the different scientific speculation that took place. “Some of the leading scientists of this country thought the moon was covered with several hundred feet of lunar dust and thought that when we landed on the moon the spacecraft would sink into the dust,” he said. “Fortunately that didn’t happen. Others thought the rocks on the moon, sitting in hard vacuum and bombarded with radiation and meteorites, that when first exposed to air they might catch on fire or explode. The speculations by good, smart, reputable people were just unlimited. But I guess they were trying to think of all the possibilities. We were fortunate that no one forced us to plan for any of these extreme speculations. Overall, our advisors did a good job of things.” The Lunar Receving Lab shortly after it was built. Credit: NASA
But then at one of the meetings in Washington to meet with advisors at NASA Headquarters, a scientist from the Public Health Service showed up and asked how NASA was going to protect against contamination of the Earth by lunar microorganisms.
McLane said the initial reaction by everyone else was, “What?”
For a couple of years a small group of scientists (which included a young and relatively unknown scientist named Carl Sagan) had been discussing the remote possibility that lunar samples brought back to Earth might contain deadly organisms that could destroy life on Earth. Even the spacecraft and the astronauts themselves could possibly bring back non-terrestrial organisms that could be harmful. Several governmental agencies, including the Department of Agriculture, the US Army, and the National Institute of Health got wind of this idea — and perhaps blew it a little out of proportion — and NASA was forced to take action to prevent a possible biological disaster.
“The ‘lunar bugs’ as we called them,” said McLane, “well, nobody really believed there was life on the Moon, especially something that might affect people – make them sick or kill off our civilization, that sort of thing.”
McLane said that the first time Deke Slayton, head astronaut at the time, heard about this, he just about “flew out the window.”
“He said, ‘No way is somebody going to step in and put these restraints on the program. It’s difficult enough to just fly to the moon without all these precautions about contamination.’ But NASA had meetings with the Surgeon General of the US, and he took the attitude, ‘How much is the Apollo program going to cost – $20 billion or so? I don’t think it is outlandish to set aside one percent of that to guard against great catastrophe on Earth.'”
“We said that we would take on the challenge of guarding against organisms, but the Surgeon General would have to justify it to the Congress, about the increased costs to the program,” McLane recalled. “And he did. So that got settled. We developed a scheme and it was approved. Everyone had to accept it, there wasn’t any choice.”
That changed the entire complexion of what McLane and his team had to accomplish before astronauts could go to the Moon. What started out a just a small clean room would now have to be a research lab, plus a quarantine facility. Plans for the facility grew to an 86,000 square foot structure that would cost over $9 million. Lunar Receiving Lab. This drawing illustrates the complex design of the LRL, with its several different components including Lunar Sample Laboratory, Astronaut Reception Area, Radiation Laboratory, and Support and Administration. Credit: NASA
“We had to devise all the precautions,” said McLane, “as well as the facilities and procedures for quarantine of the astronauts, as well as accepting the samples and initiating tests on the rocks that had to be done quickly behind absolute biological barriers to test for any contamination before anything could be distributed to the scientific community. It was very interesting work.”
The LRL had accommodations for all the people and equipment that needed to be quarantined. “The astronauts were picked up in the ocean and they had to wear a special suit that was supposedly impervious to ‘lunar bugs,'” McLane said. “The astronauts were put into a modified Grumman Airstream trailer and delivered to Houston, trailer and all, waving at everyone through the windows, and talking to the president. They were taken to the Lunar Receiving Lab and placed in quarantine. It was comfortable in there, but the astronauts didn’t particularly like being in quarantine. We tried to limit the number of people who went into quarantine with them, but inevitably there were a few people– mostly ambitious secretaries and that sort of thing— who intentionally violated procedure and exposed themselves to the hypothetical lunar bugs and had move into the quarantine quarters.” The astronauts stayed in quarantine for three weeks. First lunar samples arrive from Apollo 11. Credit: NASA
By the time Apollo 11 launched McLane had moved on to other projects. “My part of the organization was the engineering directorate, and I was only charged with determining the requirements for the facility and staffing the facility,” he said. “Once we reached the point where the design had come along and the staffing was pretty well up, leading the lab required someone with an interest in science as opposed to engineering.”
But he watched with interest as the first mission to the Moon unfolded. He even had a place in the Mission Control VIP viewing gallery for the launch, sitting just behind science-fiction writer Arthur C. Clarke.
Of course, it was determined that there were no “lunar bugs” and the quarantine requirement was dropped after Apollo 14. But the LRL safely stored, distributed and allowed for study of the lunar samples. In 1976 a portion of the samples were moved to Brooks Air Force Base in San Antonio, Texas for second-site storage.
The LRL building is currently occupied by NASA’s Life Sciences division. It contains biomedical and environment labs, and is used for experiments involving human adaptation to microgravity. James C. McLane Jr today. Photo courtesy of James McLane Jr.
The lessons learned from creating the LRL will certainly be used in preparing for the first Mars sample return mission. Now, 86 years of age, will McLane offer any words of advice?
“The best that I hear now is that the techniques of isolation we used wouldn’t be adequate for a sample coming back from Mars,” he said, “so somebody else has a big job on their hands.”
McLane will be attending a special Apollo 11 celebration at Johnson Space Center – “just for the old timers,” he said.
Plane of the ecliptic, also known as the ecliptic plane, is a phrase you will often hear in astronomy. A basic definition is that the plane of the ecliptic is the plane of the Earth’s orbit, but that does not mean much to most people. Space is a three-dimensional vacuum, which you can think of as a kind of pool with the planets suspended in it. The Earth orbits the Sun on a particular angle and its orbit is elliptical in shape. The orbit is often shown as an ellipse made of dotted lines with the Sun at its center. If you made this ellipse a solid surface and extended it infinitively, then you would have the plane of the ecliptic. Actually our entire Solar System can be thought of as flat because all of the planets’ orbits are near or on this plane.
The ecliptic plane is used as the main reference when describing the position of other celestial objects in our Solar System. The angle between the plane of the ecliptic and the plane of an orbit is called the inclination. Until it was stripped of its status as a planet, Pluto was the planet with the most extreme inclination – 17°. Mercury is the only other planet with a significant inclination of 7°. There is also a 7° inclination between the plane of the Sun’s equator and the ecliptic plane. There are other celestial bodies that have a much greater inclination than any of the planets, such as Eris with a 44° inclination or Pallas with a 34° inclination.
The ecliptic plane got its name from the fact that a solar eclipse can only happen when the Moon crosses this plane to block out the Sun. Our Moon crosses the ecliptic about twice a month. A solar eclipse occurs when a new Moon crosses the ecliptic, and a lunar eclipse occurs when a full Moon crosses it.
Seasons on Earth are caused by our planet’s axial tilt of 23.5°, which causes variations in the amount of sunlight different parts of the Earth receive. This goes for all the other planets too. For example, Uranus rotates on its side with an axial tilt of 97.8°, which results in extreme variations in its seasons. The eclipse is also home to the constellations of the zodiac. There are twelve constellations in the zodiac, which are important symbols in astrology and can also be found in the Chinese calendar. Here’s a list of all the zodiac symbols.
Ceres, the recently promoted dwarf planet in the asteroid belt is still too small to be easily seen by Hubble credit: NASA/ESA/STScI
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Minor planet is a term used to refer to a celestial object – that is not a planet or comet – which orbits the Sun. Found in 1801, Ceres, also known as a dwarf planet, was the first minor planet discovered. The term minor planet has been in use since the 1800’s. Planetoids, asteroids, and minor planets have all been used interchangeably, but the situation became even more confusing when the International Astronomical Union (IAU) committee reclassified minor planets and comets into the new categories of dwarf planets and small solar system bodies. At the same time, the IAU created a new definition of what a planet is, and Pluto was reclassified as a dwarf planet. Hydrostatic equilibrium – the ability to maintain a roughly spherical shape – is what separates dwarf planets from the more irregularly shaped small solar system bodies. The names become even more confusing because the IAU still recognizes the use of the term minor planets.
Minor planets are extremely common with over 400,000 registered and thousands more found each month. Approximately 15,000 minor planets have been given official names while the rest are numbered. When asteroids were first discovered, they were named after characters from Greek and Roman mythology like Ceres was. At first, astronomers thought that the asteroids, especially Ceres and Pallas were actually planets. Astronomers also created symbols for the first asteroids found. There were symbols created for 14 asteroids and some of them were very complex like Victoria’s symbol, which looks like a plant with three leaves growing out of an off center starburst. Soon, astronomers ran out of mythological names and started christening asteroids after television characters, famous people, and relatives of discoverers. Most names were feminine, attesting to an unnamed tradition. As the numbers ran into the thousands, scientists started using their pets as inspiration. After an asteroid was named 2309 Mr. Spock, pet’s names were banned. That did not stop the oddness though because names such as 9007 James Bond and 6402 Chesirecat have been suggested and actually accepted.
There are a number of different categories that minor planets fall into including asteroids, Trans-Neptunian objects, and centaurs. There are various types of asteroids, although most of them can be found in the asteroid belt, which is the region of space between Mars and Jupiter. Trans-Neptunian objects are celestial bodies found orbiting beyond Neptune, and centaurs are celestial bodies with unstable orbits located between Jupiter and Neptune. The categories also overlap, making classifying things a nightmare. For example, Ceres is a dwarf planet and minor planet, additionally it can also be classified as an asteroid.
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The term “habitable planet” seems rather broad. Does it mean that it is habitable for humans? Is it merely capable of supporting some other form of life? Quite simply, planetary habitability refers to a planet’s ability to both develop and sustain life.
Unfortunately, scientists have had to base their calculations for a habitable planet on Earth’s characteristics and do some guesswork. Some of the factors that astronomers look at when evaluating a planet’s habitability are mass, surface characteristics, orbit, rotation, and geochemistry.
One of the most basic assumptions that astronomers make when searching for a habitable planet is that it has to be terrestrial. This means that the planet is composed mostly of rock and metal and has a solid surface. A gas giant on the other hand has no solid surface, which makes it an unlikely candidate for supporting life. Mass is also an important factor, because low mass planets have too little gravity to keep their atmosphere. They also do not have live volcanoes and other geologic activity, which helps temper the surface to support life, because they lose energy as a result of a small diameter. Planets with high orbital eccentricity – the irregularity of the orbit – have a greater fluctuation in surface temperatures because they are closer to the Sun at some points and much further away at other points in the orbit. In order to be habitable, a planet has to have a moderate rotation. If there is no axial tilt then there are no change of seasons, and if the axial tilt is too severe than the planet will have a difficult time achieving homeostasis – balance. Another assumption astronomers make when determining planetary habitability is that life on other planets will also be carbon-based. The four elements most important for life are oxygen, nitrogen, carbon, and hydrogen. With so many considerations, it is not surprising that scientists have a difficult time determining whether a planet can sustain life.
Astronomers are searching for habitable planets in other solar systems too. They have started by searching in the habitable zones of other solar systems. A habitable zone is the region in space with conditions most favorable for supporting life. Astronomers are unsure exactly what the extent of the habitable zone of our Solar System is. Earth is located in the center of it, but it may even extend as far as Mars, and it almost reaches Venus. The habitable zone and planetary habitability focus on carbon-based life, so they do not help predict other forms of life.
Newscaster Walter Cronkite has passed away at the age of 92. He was admired and known for his enthusiastic coverage NASA’s space missions, from the early Mercury launches, through the ground-breaking Gemini missions, to the subsequent moon landings — which at times left him speechless — and the space shuttle program. Continue reading ““That’s the Way It Is” — Apollo Supporter Walter Cronkite Dies”
Researchers have discovered a link between the 11-year solar cycle and tropical Pacific weather patterns that resemble La Niña and El Niño events.
When it comes to influencing Earth’s climate, the Sun’s variability pales in recent decades compared to greehouse gases — but the new research shows it still plays a distinguishable part.
The total energy reaching Earth from the sun varies by only 0.1 percent across the solar cycle. Scientists have sought for decades to link these ups and downs to natural weather and climate variations and distinguish their subtle effects from the larger pattern of human-caused global warming.
Co-authors Gerald Meehl and Julie Arblaster, both affiliated with the National Center for Atmospheric Research in Boulder, Colorado, analyzed computer models of global climate and more than a century of ocean temperature records. Arblaster is also affiliated with the Australian Bureau of Meteorology.
In the new paper and a previous one with additional colleagues, the researchers have been able to show that, as the sun’s output reaches a peak, the small amount of extra sunshine over several years causes a slight increase in local atmospheric heating, especially across parts of the tropical and subtropical Pacific where Sun-blocking clouds are normally scarce.
That small amount of extra heat leads to more evaporation, producing extra water vapor. In turn, the moisture is carried by trade winds to the normally rainy areas of the western tropical Pacific, fueling heavier rains.
As this climatic loop intensifies, the trade winds strengthen. That keeps the eastern Pacific even cooler and drier than usual, producing La Niña-like conditions.
“We have fleshed out the effects of a new mechanism to understand what happens in the tropical Pacific when there is a maximum of solar activity,” Meehl said. “When the sun’s output peaks, it has far-ranging and often subtle impacts on tropical precipitation and on weather systems around much of the world.”
The result of this chain of events is similar to a La Niña event, although the cooling of about 1-2 degrees Fahrenheit is focused further east and is only about half as strong as for a typical La Niña.
True La Niña and El Nino events are associated with changes in the temperatures of surface waters of the eastern Pacific Ocean. They can affect weather patterns worldwide.
Although the Pacific pattern in the new paper is produced by the solar maximum, the authors found that its switch to an El Niño-like state is likely triggered by the same kind of processes that normally lead from La Niña to El Niño.
The transition starts when the changes of the strength of the trade winds produce slow-moving off-equatorial pulses known as Rossby waves in the upper ocean, which take about a year to travel back west across the Pacific.
The energy then reflects from the western boundary of the tropical Pacific and ricochets eastward along the equator, deepening the upper layer of water and warming the ocean surface.
As a result, the Pacific experiences an El Niño-like event about two years after solar maximum — also about half as strong as a true El Niño. The event settles down after about a year, and the system returns to a neutral state.
“El Niño and La Niña seem to have their own separate mechanisms,” Meehl said, “but the solar maximum can come along and tilt the probabilities toward a weak La Niña. If the system was heading toward a La Niña anyway,” he adds, “it would presumably be a larger one.”
The study authors say the new research may pave the way toward predictions of temperature and precipitation patterns at certain times during the approximately 11-year solar cycle.
In an email, Meehl noted that previous work by his team and other research groups has shown that “most of the warming trend in the first half of the 20th Century was due to an increasing trend of solar output, while most of the warming trend in the last half of the 20th Century and ever since has been due to ever-increasing GHG (greenhouse gas) concentrations in the atmosphere from the burning of fossil fuels.”
The new paper appears this month in the Journal of Climate, a publication of the American Meteorological Society. (Sorry, it’s not yet available online.)
Ancient, dome-like rock structures contain clues that life was active on Earth 3.45 billion years ago, according to new research — and the findings could help shed light on life’s history on Earth and other planets, including Mars.
Abigail Allwood, who studies planetary habitability at NASA’s Jet Propulsion Laboratory, led the research. She and her colleagues studied stromatolites, which are dome- or column-like sedimentary rock structures formed in shallow water, layer by layer, over long periods of geologic time.
Geologists have long known that the large majority of the relatively young stromatolites they study—those half a billion years old or so—have a biological origin; they’re formed with the help of layers of microbes that grow in a thin film on the seafloor.
The microbes’ surface is coated in a mucilaginous substance to which sediment particles rolling past get stuck.
“It has a strong flypaper effect,” said John Grotzinger, a Caltech geologist and a study co-author. In addition, the microbes sprout a tangle of filaments that almost seem to grab the particles as they move along. “The end result,” Grotzinger explains, “is that wherever the mat is, sediment gets trapped.”
So in a young stromalite, dark bands like those seen in the close-up cross section at left indicate organic material. But 3.45 billion years ago, in the early Archean period of geologic history, things weren’t quite so simple.
“Because stromatolites from this period of time have been around longer, more geologic processing has happened,” Grotzinger says. Pushed deeper toward the center of Earth as time went by, these stromatolites were exposed to increasing, unrelenting heat. This is a problem when it comes to examining the stromatolites’ potential biological beginnings, he explains, because heat degrades organic matter. “The hydrocarbons are driven off,” he says. “What’s left behind is a residue of nothing but carbon.”
As such, geologists debate whether or not the carbon found in these ancient rocks is diagnostic of life.
Allwood and her team turned to the texture and morphology of the rocks themselves, from samples gathered in Western Australia. The samples, says Grotzinger, were “incredibly well preserved.” Dark lines of what was potentially organic matter were “clearly associated with the lamination, just like we see in younger rocks. That sort of relationship would be hard to explain without a biological mechanism.”
Allwood set about trying to find other types of evidence. She looked at what she calls the “microscale textures and fabrics in the rocks, patterns of textural variation through the stromatolites and—importantly—organic layers that looked like actual fossilized organic remnants of microbial mats within the stromatolites.”
She saw “discrete, matlike layers of organic material that contoured the stromatolites from edge to edge, following steep slopes and continuing along low areas without thickening.” She also found pieces of microbial mat incorporated into storm deposits, which disproved the idea that the organic material had been introduced into the rock more recently, rather than being laid down with the original sediment.
“In addition,” Allwood notes, “Raman spectroscopy showed that the organics had been ‘cooked’ to the same burial temperature as the host rock, again indicating the organics are not young contaminants.”
Allwood said she, Grotzinger, and their team have collected enough evidence that it’s no longer a great leap to accept the stromatolites as biological in origin. And the researchers say the implications of the findings don’t stop at life on Earth.
“One of my motivations for understanding stromatolites,” Allwood says, “is the knowledge that if microbial communities once flourished on Mars, of all the traces they might leave in the rock record for us to discover, stromatolite and microbial reefs are arguably the most easily preserved and readily detected. Moreover, they’re particularly likely to form in evaporative, mineral-precipitating settings such as those that have been identified on Mars. But to be able to interpret stromatolitic structures, we need a much more detailed understanding of how they form.”
Both images courtesy of Abigail Allwood.
Source: Eurekalert, a media service of the American Association for the Advancement of Science (AAAS). The research appeared in online June 10 and in print June 16 in the Proceedings of the National Academy of Sciences (PNAS).
The Apollo 14 landing site imaged by LRO. Credit: NASA
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As anticipated, NASA released images of the Apollo landing sites taken by the Lunar Reconnaissance Orbiter (LRO). The pictures show the Apollo missions’ lunar module descent stages sitting on the moon’s surface, as long shadows from a low sun angle make the modules’ locations evident. Also visible are the tracks left where the astronauts walked repeatedly in a “high traffic zone” and perhaps by the Modularized Equipment Transporter (MET) wheelbarrow-like carrier used on Apollo 14. Wow.
As a journalist, I (most of the time) try to remain objective and calm. But there’s only one response to these images: W00T!
Apollo 11 landing site as imaged by LRO. Credit: NASA
These first images were taken between July 11 and 15, and the spacecraft is not yet in its final mapping orbit. Future LROC images from these sites will have two to three times greater resolution. Apollo 15 site by LRO. Credit: NASA
These images are the first glimpses from LRO,” said Michael Wargo, chief lunar scientist, NASA Headquarters, Washington. “Things are only going to get better.”
The Japanese Kaguya spacecraft previously took images of some of the Apollo landing sites, but not at a high enough resolution to show any of the details of the lander or any other details. But here on these images, the hardware is visible. “It’s great to see the hardware on the surface, waiting for us to return,” said Mark Robinson, principal investigator for LRO.
Robinson said the LROC team anxiously awaited each image. “We were very interested in getting our first peek at the lunar module descent stages just for the thrill — and to see how well the cameras had come into focus. Indeed, the images are fantastic and so is the focus.”
Apollo 16 by LRO. Credit: NASA
The Lunar Reconnaissance Orbiter Camera, or LROC, was able to image five of the six Apollo sites, with the remaining Apollo 12 site expected to be photographed in the coming weeks.
The spacecraft’s current elliptical orbit resulted in image resolutions that were slightly different for each site but were all around four feet per pixel. Because the deck of the descent stage is about 12 feet in diameter, the Apollo relics themselves fill an area of about nine pixels. However, because the sun was low to the horizon when the images were made, even subtle variations in topography create long shadows. Standing slightly more than ten feet above the surface, each Apollo descent stage creates a distinct shadow that fills roughly 20 pixels. Apollo 17 LRO. Credit: NASA
The image of the Apollo 14 landing site had a particularly desirable lighting condition that allowed visibility of additional details. The Apollo Lunar Surface Experiment Package, a set of scientific instruments placed by the astronauts at the landing site, is discernable, as are the faint trails between the module and instrument package left by the astronauts’ footprints. Zoomed in Apollo 14 image by LRO. Credit: NASA
