On this day in science history: Mars 5 launched

In 1973, the USSR launched Mars 5, on a Proton SL-12/D-1-e booster. It was one of several Soviet Mars probes - Mars 4, 5, 6, and 7 - launched in Jul-Aug 1973. The Mars 5 mission was to orbit Mars, which was achieved on 12 Feb 1974. Each orbit took about 25 hours. It was designed to return information on the composition, structure, and properties of the martian atmosphere and surface. However, after only 22 orbits, the mission ended prematurely due to loss of pressurization in the transmitter housing. Before the failure, data for a small portion of the martian southern hemisphere was captured with about 60 images forwarded over a nine day period. The probe also sent more measurements made by other instruments.

Mars in natural colour in 2007. By ESA - European Space Agency & Max-Planck Institute for Solar System Research for OSIRIS Team ESA/MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA [CC BY-SA 3.0-igo (http://creativecommons.org/licenses/by-sa/3.0-igo)], via Wikimedia Commons

Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is often referred to as the "Red Planet" because the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth.

The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, as is the tilt that produces the seasons. Mars is the site of Olympus Mons, the largest volcano and second-highest known mountain in the Solar System, and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature. Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars trojan.

There are ongoing investigations assessing the past habitability potential of Mars, as well as the possibility of extant life. Liquid water cannot exist on the surface of Mars due to low atmospheric pressure, which is less than 1% of the Earth's, except at the lowest elevations for short periods. The two polar ice caps appear to be made largely of water. The volume of water ice in the south polar ice cap, if melted, would be sufficient to cover the entire planetary surface to a depth of 11 meters (36 ft). In November 2016, NASA reported finding a large amount of underground ice in the Utopia Planitia region of Mars. 

The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior.

Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Its apparent magnitude reaches −2.91, which is surpassed only by Jupiter, Venus, the Moon, and the Sun. Optical ground-based telescopes are typically limited to resolving features about 300 kilometers (190 mi) across when Earth and Mars are closest because of Earth's atmosphere.

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Reconciling predictions of climate change

Harvard University researchers have resolved a conflict in estimates of how much the Earth will warm in response to a doubling of carbon dioxide in the atmosphere.

That conflict - between temperature ranges based on global climate models and paleoclimate records and ranges generated from historical observations - prevented the United Nations' Intergovernmental Panel on Climate Change (IPCC) from providing a best estimate in its most recent report for how much the Earth will warm as a result of a doubling of CO2 emissions.

The researchers found that the low range of temperature increase - between 1 and 3 degrees Celsius - offered by the historical observations did not take into account long-term warming patterns. When these patterns are taken into account, the researchers found that not only do temperatures fall within the canonical range of 1.5 to 4.5 degrees Celsius but that even higher ranges, perhaps up to 6 degrees, may also be possible.

The research is published in Science Advances.

CO2 in Earth's atmosphere if half of global-warming emissions are not absorbed (NASA simulation). By NASA/GSFC [Public domain], via Wikimedia Commons

It's well documented that different parts of the planet warm at different speeds. The land over the northern hemisphere, for example, warms significantly faster than water in the Southern Ocean.

"The historical pattern of warming is that most of the warming has occurred over land, in particular over the northern hemisphere," said Cristian Proistosescu, PhD '17, and first author of the paper. "This pattern of warming is known as the fast mode - you put CO2 in the atmosphere and very quickly after that, the land in the northern hemisphere is going to warm."

But there is also a slow mode of warming, which can take centuries to realize. That warming, which is most associated with the Southern Ocean and the Eastern Equatorial Pacific, comes with positive feedback loops that amplify the process. For example, as the oceans warm, cloud cover decreases and a white reflecting surface is replaced with a dark absorbent surface.

The researchers developed a mathematical model to parse the two different modes within different climate models.

"The models simulate a warming pattern like today's, but indicate that strong feedbacks kick in when the Southern Ocean and Eastern Equatorial Pacific eventually warm, leading to higher overall temperatures than would simply be extrapolated from the warming seen to date," said Peter Huybers, Professor of Earth and Planetary Sciences and of Environmental Science and Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and co-author of the paper.

Huybers and Proistosescu found that while the slow mode of warming contributes a great deal to the ultimate amount of global warming, it is barely present in present-day warming patterns. "Historical observations give us a lot of insight into how climate changes and are an important test of our climate models," said Huybers, "but there is no perfect analogue for the changes that are coming."

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On this day in science history - Galileo spacecraft orbits Jupiter

In 1995, the Galileo spacecraft arrived at Jupiter and entered orbit after 6 years of travel including a flyby of Venus and two asteroids, Gaspra and Ida. The orbiter had also carried an atmospheric probe with scientific instruments, which it had released from the main spacecraft in July 1995, five months before reaching Jupiter. Galileo then spent a further 8 years examining Jupiter and its moons Io and Europa. 

Jupiter. By NASA, ESA, and A. Simon (Goddard Space Flight Center) [Public domain], via Wikimedia Commons

In 1994, the Galileo orbiter was present to watch the fragments of comet Shoemaker-Levy 9 crash into Jupiter. Its mission was concluded 21 September 2003 by sending the orbiter into Jupiter's atmosphere at a speed of nearly 50 km/sec, destroying it to avoid any chance of it contaminating local moons with bacteria from Earth.

Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, but two and a half times that of all the other planets in the Solar System combined. Jupiter is a gas giant, along with Saturn, with the other two giant planets, Uranus and Neptune, being ice giants. Jupiter was known to astronomers of ancient times. The Romans named it after their god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, bright enough for its reflected light to cast shadows, and making it on average the third-brightest object in the night sky after the Moon and Venus.

Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, though helium comprises only about a tenth of the number of molecules. It may also have a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well-defined solid surface. Because of its rapid rotation, the planet's shape is that of an oblate spheroid (it has a slight but noticeable bulge around the equator). The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries. 

A prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope. Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere. Jupiter has at least 67 moons, including the four large Galilean moons discovered by Galileo Galilei in 1610. Ganymede, the largest of these, has a diameter greater than that of the planet Mercury.

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On this day in science history: Jupiter orbiter Galileo launched

In 1989, the Galileo space orbiter was released from the STS 34 flight of the Atlantis orbiter. Then the orbiter's inertial upper stage rocket pushed it into a course through the inner solar system. The craft gained speed from gravity assists in encounters with Venus and Earth before heading outward to Jupiter. During its six year journey to Jupiter, Galileo's instruments made interplanetary studies, using its dust detector, magnetometer, and various plasma and particles detectors. It also made close-up studies of two asteroids, Gaspra and Ida in the asteroid belt. The Galileo orbiter's primary mission was to study Jupiter, its satellites, and its magnetosphere for two years. It released an atmospheric probe into Jupiter's atmosphere on 7 Dec 1995.

Jupiter and its shrunken great red spot. By NASA, ESA, and A. Simon (Goddard Space Flight Center) [Public domain], via Wikimedia Commons

Jupiter's mass is 2.5 times that of all the other planets in the Solar System combined—this is so massive that its barycenter with the Sun lies above the Sun's surface at 1.068 solar radii from the Sun's center. Jupiter is much larger than Earth and considerably less dense: its volume is that of about 1,321 Earths, but it is only 318 times as massive. Jupiter's radius is about 1/10 the radius of the Sun, and its mass is 0.001 times the mass of the Sun, so the densities of the two bodies are similar. A "Jupiter mass" (MJ or MJup) is often used as a unit to describe masses of other objects, particularly extrasolar planets and brown dwarfs. So, for example, the extrasolar planet HD 209458 b has a mass of 0.69 MJ, while Kappa Andromedae b has a mass of 12.8 MJ.

Theoretical models indicate that if Jupiter had much more mass than it does at present, it would shrink. For small changes in mass, the radius would not change appreciably, and above about 500 M⊕ (1.6 Jupiter masses) the interior would become so much more compressed under the increased pressure that its volume would decrease despite the increasing amount of matter. As a result, Jupiter is thought to have about as large a diameter as a planet of its composition and evolutionary history can achieve. The process of further shrinkage with increasing mass would continue until appreciable stellar ignition is achieved as in high-mass brown dwarfs having around 50 Jupiter masses.

Although Jupiter would need to be about 75 times as massive to fuse hydrogen and become a star, the smallest red dwarf is only about 30 percent larger in radius than Jupiter. Despite this, Jupiter still radiates more heat than it receives from the Sun; the amount of heat produced inside it is similar to the total solar radiation it receives. This additional heat is generated by the Kelvin–Helmholtz mechanism through contraction. This process causes Jupiter to shrink by about 2 cm each year.  When it was first formed, Jupiter was much hotter and was about twice its current diameter.

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Methane muted: How did early Earth stay warm?

For at least a billion years of the distant past, planet Earth should have been frozen over but wasn't. Scientists thought they knew why, but a new modeling study from the Alternative Earths team of the NASA Astrobiology Institute has fired the lead actor in that long-accepted scenario.

Humans worry about greenhouse gases, but between 1.8 billion and 800 million years ago, microscopic ocean dwellers really needed them. The sun was 10 to 15 percent dimmer than it is today - too weak to warm the planet on its own. Earth required a potent mix of heat-trapping gases to keep the oceans liquid and livable.

For decades, atmospheric scientists cast methane in the leading role. The thinking was that methane, with 34 times the heat-trapping capacity of carbon dioxide, could have reigned supreme for most of the first 3.5 billion years of Earth history, when oxygen was absent initially and little more than a whiff later on. (Nowadays oxygen is one-fifth of the air we breathe, and it destroys methane in a matter of years.)

Full structural formula of the methane molecule

"A proper accounting of biogeochemical cycles in the oceans reveals that methane has a much more powerful foe than oxygen," said Stephanie Olson, a graduate student at the University of California, Riverside, a member of the Alternative Earths team and lead author of the new study published September 26 in the Proceedings of the National Academy of Sciences. "You can't get significant methane out of the ocean once there is sulfate."

Sulfate wasn't a factor until oxygen appeared in the atmosphere and triggered oxidative weathering of rocks on land. The breakdown of minerals such as pyrite produces sulfate, which then flows down rivers to the oceans. Less oxygen means less sulfate, but even 1 percent of the modern abundance is sufficient to kill methane, Olson said.

Olson and her Alternative Earths coauthors, Chris Reinhard, an assistant professor of earth and atmospheric sciences at Georgia Tech University, and Timothy Lyons, a distinguished professor of biogeochemistry at UC Riverside, assert that during the billion years they assessed, sulfate in the ocean limited atmospheric methane to only 1 to 10 parts per million - a tiny fraction of the copious 300 parts per million touted by some previous models.

The fatal flaw of those past climate models and their predictions for atmospheric composition, Olson said, is that they ignore what happens in the oceans, where most methane originates as specialized bacteria decompose organic matter.

Seawater sulfate is a problem for methane in two ways: Sulfate destroys methane directly, which limits how much of the gas can escape the oceans and accumulate in the atmosphere. Sulfate also limits the production of methane. Life can extract more energy by reducing sulfate than it can by making methane, so sulfate consumption dominates over methane production in nearly all marine environments.

The numerical model used in this study calculated sulfate reduction, methane production, and a broad array of other biogeochemical cycles in the ocean for the billion years between 1.8 billion and 800 million years ago. This model, which divides the ocean into nearly 15,000 three-dimensional regions and calculates the cycles for each region, is by far the highest resolution model ever applied to the ancient Earth. By comparison, other biogeochemical models divide the entire ocean into a two-dimensional grid of no more than five regions.

"Free oxygen [O2] in the atmosphere is required to form a protective layer of ozone [O3], which can shield methane from photochemical destruction," Reinhard said. When the researchers ran their model with the lower oxygen estimates, the ozone shield never formed, leaving the modest puffs of methane that escaped the oceans at the mercy of destructive photochemistry.

With methane demoted, scientists face a serious new challenge to determine the greenhouse cocktail that explains our planet's climate and life story, including a billion years devoid of glaciers, Lyons said. Knowing the right combination other warming agents, such as water vapor, nitrous oxide, and carbon dioxide, will also help us assess habitability of the hundreds of billions of other Earth-like planets estimated to reside in our galaxy.

"If we detect methane on an exoplanet, it is one of our best candidates as a biosignature, and methane dominates many conversations in the search for life on Mars," Lyons said. "Yet methane almost certainly would not have been detected by an alien civilization looking at our planet a billion years ago - despite the likelihood of its biological production over most of Earth history."

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Ancient air pockets changing the history of Earth’s oxygen

Ancient air trapped in rock salt for 813 million years is changing the timeline of atmospheric changes and life on Earth.

Defining past atmospheric compositions is an important yet daunting task for geologists. Most methods for determining past Earth surface conditions rely on indirect proxies gleaned from ancient sedimentary rocks. Further complicating matters, sedimentary rocks are notoriously difficult to date because they contain remnants of other rocks formed at various times.

As a result, oxygenation, or the rise of oxygen in the Earth's atmosphere, has been presumed to occur about 550 million years ago near the boundary between the Precambrian and Paleozoic geologic periods.

The Earth seeen from Apollo 17. By NASA/Apollo 17 crew; taken by either Harrison Schmitt or Ron Evans [Public domain or Public domain], via Wikimedia Commons

West Virginia University geologist Kathleen Benison is part of a research team using new direct methods to measure the Earth's oxygenation.

The team's study identifies, for the first time, exactly how much oxygen was in Earth's atmosphere 813 million years ago - 10.9 percent. This finding, they say, demonstrates that oxygenation on Earth occurred 300 million years earlier than previously concluded from indirect measurements.

"Diversity of life emerges right around this time period," Benison said. "We used to think that to have diversity of life we needed specific things, including a certain amount of oxygen. (The findings) show that not as much oxygen is required for organisms to develop."

Fluid inclusions, the microscopic bubbles of liquids and gases in rock salt, can contain trapped air. Analysis of this trapped air allows researchers to understand past surface conditions and how oxygen has changed over the course of geologic history.

The team used a quadrupole mass spectrometer to study the air pockets. Carefully crushing minute rock salt crystals released water and gases into the mass spectrometer, which then analyzed for various compounds of oxygen and other gases.

"There are a lot of different environmental conditions specific from the past that we can find occurring in modern samples," Benison said. "This tells us about the range of conditions on Earth and also has implications for Mars."

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Methane production reduced in ruminants

Livestock farming is responsible for 18 percent of the world's greenhouse gases, and ruminants such as cattle, sheep and goats generate 35 percent of one of these gases - methane, and according to experts they make a significant contribution to climate change.

Researchers at the Spanish National Research Council (CSIC) have taken part in a study of the effect of one molecule, 3-nitrooxypropanol, in inhibiting methane production in ruminants. The work has been published in the magazine, Proceedings of the National Academy of Sciences (PNAS).

Stereo, skeletal formula of methane with some measurements added. By Jynto [Public domain], via Wikimedia Commons.

Ruminants are animals which digest their food through fermentation carried out by microorganisms living in the rumen. This process produces organic acids: acetic acid, propionic acid, and butyric acid, all of which are absorbed and metabolized by the organism as a source of energy. But, in addition, it also produces methane, which escapes into the atmosphere in the form of gas.

How 3-nitrooxypropanol works

By 2014, scientists had demonstrated the effectiveness of this molecule in sheep, but were unaware of how it actually worked. Now, in vivo research, using incubated anaerobic microorganisms from ruminants' digestive systems have revealed how the compound 3-nitrooxypropanol only had an effect on methane producing microorganisms (arqueas methanogens) and not on those which contribute to digestion (bacterias). As David Yáñez, a CSIC researcher at the Zaidin Experimental Research Centre in Granada (southern Spain) explains, "Up until now, no-one had described the mode of action of a compound which can repeatedly reduce (by 30%) methane production in animals without any risks, either to the animal's health, or to their productivity."

The results of this work open up the possibility of reducing methane emissions and of contributing to a reduction in global temperatures which is caused by greenhouse gases. In addition, "We will see an increase in the efficiency of ruminant production systems as better use is made of the energy taken in in animal feed, given that methane production accounts for a loss of up to 12% of the energy an animal ingests" notes Yáñez.

Both the University of Auburn in the USA and the Max Planck Institute in Germany collaborated on this project as did the Swiss company, DSM Nutritional Products, which developed and owns the patent to 3-nitrooxypropanol.

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Rising sea levels will threaten residents of many countries, say researchers.

At the rate humans are emitting carbon into the atmosphere, Earth may suffer irreparable damage that could last tens of thousands of years, according to a new analysis published this week.

Rising sea levels will threaten residents of many countries, say researchers.

Too much of the climate change policy debate has focused on observations of the past 150 years and their impact on global warming and sea level rise by the end of this century, the authors say. Instead, policy-makers and the public should also be considering the longer-term impacts of climate change.

"Much of the carbon we are putting in the air from burning fossil fuels will stay there for thousands of years - and some of it will be there for more than 100,000 years," said Peter Clark, an Oregon State University paleoclimatologist and lead author on the article. "People need to understand that the effects of climate change on the planet won't go away, at least not for thousands of generations."

The researchers' analysis is being published this week in the journal Nature Climate Change.

Thomas Stocker of the University of Bern in Switzerland, who is past-co-chair of the IPCC's Working Group I, said the focus on climate change at the end of the 21st century needs to be shifted toward a much longer-term perspective.

"Our greenhouse gas emissions today produce climate-change commitments for many centuries to millennia," said Stocker, a climate modeler and co-author on the Nature Climate Change article. "It is high time that this essential irreversibility is placed into the focus of policy-makers.

"The long-term view sends the chilling message (about) what the real risks and consequences are of the fossil fuel era," Stocker added. "It will commit us to massive adaptation efforts so that for many, dislocation and migration becomes the only option."

Sea level rise is one of the most compelling impacts of global warming, yet its effects are just starting to be seen. The latest IPCC report, for example, calls for sea level rise of just one meter by the year 2100. In their analysis, however, the authors look at four difference sea level-rise scenarios based on different rates of warming, from a low end that could only be reached with massive efforts to eliminate fossil fuel use over the next few decades, to a higher rate based on the consumption of half the remaining fossil fuels over the next few centuries.

With just two degrees (Celsius) warming in the low-end scenario, sea levels are predicted to eventually rise by about 25 meters. With seven degrees warming at the high-end scenario, the rise is estimated at 50 meters, although over a period of several centuries to millennia.

"It takes sea level rise a very long time to react - on the order of centuries," Clark said. "It's like heating a pot of water on the stove; it doesn't boil for quite a while after the heat is turned on - but then it will continue to boil as long as the heat persists. Once carbon is in the atmosphere, it will stay there for tens or hundreds of thousands of years, and the warming, as well as the higher seas, will remain."

Clark said for the low-end scenario, an estimated 122 countries have at least 10 percent of their population in areas that will be directly affected by rising sea levels, and that some 1.3 billion - or 20 percent of the global population - live on lands that may be directly affected. The impacts become greater as the warming and sea level rise increases.

"We can't keep building seawalls that are 25 meters high," noted Clark, a professor in OSU's College of Earth, Ocean, and Atmospheric Sciences. "Entire populations of cities will eventually have to move."

Daniel Schrag, the Sturgis Hooper Professor of Geology at Harvard University, said there are moral questions about "what kind of environment we are passing along to future generations."

"Sea level rise may not seem like such a big deal today, but we are making choices that will affect our grandchildren's grandchildren - and beyond," said Schrag, a co-author on the analysis and director of Harvard's Center for the Environment. "We need to think carefully about the long time-scales of what we are unleashing."

The new paper makes the fundamental point that considering the long time scales of the carbon cycle and of climate change means that reducing emissions slightly or even significantly is not sufficient. "To spare future generations from the worst impacts of climate change, the target must be zero - or even negative carbon emissions - as soon as possible," Clark said.

"Taking the first steps is important, but it is essential to see these as the start of a path toward total decarbonization," Schrag pointed out. "This means continuing to invest in innovation that can someday replace fossil fuels altogether. Partial reductions are not going to do the job."

Stocker said that in the last 50 years alone, humans have changed the climate on a global scale, initiating the Anthropocene, a new geological era with fundamentally altered living conditions for the next many thousands of years.

"Because we do not know to what extent adaptation will be possible for humans and ecosystems, all our efforts must focus on a rapid and complete decarbonization -the only option to limit climate change," Stocker said.

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Enough oxygen on Earth long before animals rose

Oxygen is crucial for the existence of animals on Earth. But, an increase in oxygen did not apparently lead to the rise of the first animals. New research shows that 1.4 billion years ago there was enough oxygen for animals - and yet over 800 million years went by before the first animals appeared on Earth.

The Earth seen from Apollo 17 by NASA/Apollo 17 crew; taken by either Harrison Schmitt or Ron Evans 

Animals evolved by about 600 million years ago, which was late in Earth's history. The late evolution of animals, and the fact that oxygen is central for animal respiration, has led to the widely promoted idea that animal evolution corresponded with a late a rise in atmospheric oxygen concentrations.

"But sufficient oxygen in itself does not seem to be enough for animals to rise. This is indicated by our studies," say postdoc Emma Hammarlund and Professor Don Canfield, Nordic Center for Earth Evolution, University of Southern Denmark.

Together with colleagues from the China National Petroleum Corporation and the University of Copenhagen, Hammarlund and Canfield have analyzed sediment samples from the Xiamaling Formation in China. Their analyses reveal that a deep ocean 1.4 billion years ago contained at least 4% of modern oxygen concentrations.

The new study is published in the journal Proceedings of National Academy of Sciences.

Usually it is very difficult to precisely determine past oxygen concentrations. The new study, however, combines several approaches to break new ground in understanding oxygen concentrations 1.4 billion years ago.

The study uses trace metal distributions to show that the bottom waters where the Xiamaling Formation sediments deposited contain oxygen. The distribution of biomarkers, molecules derived from ancient organisms, demonstrate that waters of intermediate depth contain no oxygen. Therefore, the Xiamaling Formation deposited in an ancient oxygen-minimum zone, similar to (but also different) from those found off the present coasts of Chile and Peru.

With this backdrop, the researchers used a simple ocean model to estimate the minimum concentrations to atmospheric oxygen required to reproduce the distribution of water-column oxygen in the Xiamaling Formation.

"The water column had an oxygen concentration at least 4 % of present atmospheric levels (PAL). That should be sufficient for animals to exist and evolve," says Canfield.

"Having determined the lowest concentration of oxygen in the air almost one and a half billion years ago is unique," says Hammarlund, adding:

"Researchers know of simple animals, such as sponges and worms, that today are capable of managing with less than 4% PAL, even much less."

"Sponges probably resemble some of the first animals on Earth. If they manage with less than 4 % today's oxygen levels, it is likely that the first animals could do with these concentrations or less," says Canfield.

The results differ from other studies and raise several questions, such as: Why then did animals rise so late in Earth's history?

"The sudden diversification of animals probably was a result of many factors. Maybe the oxygen rise had less to do with the animal revolution than we previously assumed," says Hammarlund.

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On this day in history: the first manned voyage of a hydrogen balloon left Paris

In 1783, the first manned voyage of a hydrogen balloon left Paris carrying Professor Jacques Alexander Cesar Charles and Marie-Noel Robert to about 600 m and landed 43 km away after 2 hours in the air.

Robert then left the balloon, and Charles continued the flight briefly to 2700 m altitude, measured by a barometer. This hydrogen-filled balloon was generally spherical and used a net, load ring, valve, open appendix and sand ballast, all of which were to be universally adopted later. His hydrogen generator mixed huge quantities of sulfuric acid with iron filings.

On 27 Aug 1783, Charles had launched an unmanned hydrogen balloon, just before the Montgolfiers' flight.

Hot air balloon, by Kropsoq (photo taken by Kropsoq) [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/), CC BY-SA 2.5 (http://creativecommons.org/licenses/by-sa/2.5) or CC BY-SA 2.1 jp (http://creativecommons.org/licenses/by-sa/2.1/jp/deed.en)], via Wikimedia Commons

There are three main types of balloon:

The hot air balloon or Montgolfière obtains its buoyancy by heating the air inside the balloon; it has become the most common type.

The gas balloon or Charlière is inflated with a gas of lower molecular weight than the ambient atmosphere; most gas balloons operate with the internal pressure of the gas the same as the pressure of the surrounding atmosphere; a superpressure balloon can operate with the lifting gas at pressure that exceeds that of the surrounding air, with the objective of limiting or eliminating the loss of gas from day-time heating; gas balloons are filled with gases such as:

• Hydrogen – originally used extensively but, since the Hindenburg disaster, is now seldom used due to its high flammability;
• Coal gas – although giving around half the lift of hydrogen, extensively used during the nineteenth and early twentieth century, since it was cheaper than hydrogen and readily available;
• Helium – used today for all airships and most manned gas balloons;

Other gases have included ammonia and methane, but these have poor lifting capacity and other safety defects and have never been widely used.

The Rozière type has both heated and unheated lifting gases in separate gasbags. This type of balloon is sometimes used for long-distance record flights, such as the recent circumnavigations, but is not otherwise in use.

Both the hot air, or Montgolfière, balloon and the gas balloon are still in common use. Montgolfière balloons are relatively inexpensive, as they do not require high-grade materials for their envelopes, and they are popular for balloonist sport activity.

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Whiffs from cyanobacteria likely responsible for Earth's oxygen

Earth's oxygen-rich atmosphere emerged in whiffs from a kind of cyanobacteria in shallow oceans around 2.5 billion years ago, according to new research from Canadian and US scientists.

The Earth by NASA/Apollo 17 crew; taken by either Harrison Schmitt or Ron Evans.

These whiffs of oxygen likely happened in the following 100 million years, changing the levels of oxygen in Earth's atmosphere until enough accumulated to create a permanently oxygenated atmosphere around 2.4 billion years ago - a transition widely known as the Great Oxidation Event.

"The onset of Earth's surface oxygenation was likely a complex process characterized by multiple whiffs of oxygen until a tipping point was crossed," said Brian Kendall, a professor of Earth and Environmental Sciences at the University of Waterloo. "Until now, we haven't been able to tell whether oxygen concentrations 2.5 billion years ago were stable or not. These new data provide a much more conclusive answer to that question."

The findings are presented in a paper published this month in Science Advances from researchers at Waterloo, University of Alberta, Arizona State University, University of California Riverside, and Georgia Institute of Technology. The team presents new isotopic data showing that a burst of oxygen production by photosynthetic cyanobacteria temporarily increased oxygen concentrations in Earth's atmosphere.

"One of the questions we ask is: 'did the evolution of photosynthesis lead directly to an oxygen-rich atmosphere? Or did the transition to today's world happen in fits and starts?" said Professor Ariel Anbar of Arizona State University. "How and why Earth developed an oxygenated atmosphere is one of the most profound puzzles in understanding the history of our planet."

The new data supports a hypothesis proposed by Anbar and his team in 2007. In Western Australia, they found preliminary evidence of these oxygen whiffs in black shales deposited on the seafloor of an ancient ocean.

The black shales contained high concentrations of the elements molybdenum and rhenium, long before the Great Oxidation Event.

These elements are found in land-based sulphide minerals, which are particularly sensitive to the presence of atmospheric oxygen. Once these minerals react with oxygen, the molybdenum and rhenium are released into rivers and eventually end up deposited on the sea floor.

In the new paper, researchers analyzed the same black shales for the relative abundance of an additional element: osmium. Like molybdenum and rhenium, osmium is also present in continental sulfide minerals. The ratio of two osmium isotopes - 187Os to 188Os - can tell us if the source of osmium was continental sulfide minerals or underwater volcanoes in the deep ocean.

The osmium isotope evidence found in black shales correlates with higher continental weathering as a result of oxygen in the atmosphere. By comparison, slightly younger deposits with lower molybdenum and rhenium concentrations had osmium isotope evidence for less continental input, indicating the oxygen in the atmosphere had disappeared.

The paper's authors also include Professor Robert Creaser of the University of Alberta, Professor Timothy Lyons from the University of California Riverside and Professor Chris Reinhard from the Georgia Institute of Technology.

For more information visit:-

http://www.sciencedaily.com/releases/2015/11/151120182620.htm

https://www.prlabs.co.uk/lab-supplies.php?N=oxygen-emptied-cylinder&Id=60499

Unexpected information about Earth's climate history from Yellow River sediment

By meticulously examining sediments in China's Yellow River, a Swedish-Chinese research group are showing that the history of tectonic and climate evolution on Earth may need to be rewritten. 

Their findings are published today in the highly reputed journal Nature Communications.

To reconstruct how the global climate and topography of the Earth's surface have developed over millions of years, deposits of eroded land sediment transported by rivers to ocean depths are often used. This process is assumed to have been rapid and, by the same token, not to have resulted in any major storages of this sediment as large deposits along the way.

However, knowledge gaps and contradictory data in research to date are impeding an understanding of climate and landscape history. In an attempt to fill the gaps and reconcile the contradictions, the researchers have been investigating present-day and ancient sediment deposits in the world's most sediment-rich river: the Yellow River in China.

The researchers, from Uppsala University (led by Dr. Thomas Stevens) and Lanzhou University (led by Dr. Junsheng Nie), China, analysed Yellow River sediment from source to sink and determined its mineral composition. They also determined the age of mineral grains of zircon, a very hard silicate mineral that is highly resistant to weathering.

Zircon ages serve as a unique fingerprint that yields information about the sources of these sediment residues from mountain chains, according to Thomas Stevens of Uppsala University's Department of Earth Sciences, one of the principal authors of the study.

The Yellow River is believed to gain most of its sediment from wind-blown mineral dust deposits called loess, concentrated on the Chinese Loess Plateau. This plateau is the largest and one of the most important past climate archives on land, and also records past atmospheric dust activity: a major driver of climate change.

The scientists found that the composition of sediment from the Yellow River underwent radical change after passing the Chinese Loess Plateau. Contrary to their expectations, however, the windborne loess was not the main source of the sediment. Instead, they found that the Loess Plateau acts as a sink for Yellow River material eroded from the uplifting Tibetan plateau.

This finding completely changes our understanding of the origin of the Chinese Loess Plateau. It also demonstrates large scale sediment storage on land, which explains the previously contradictory findings in this area.

'Our results suggest that a major change in the monsoon around 3.6 million years ago caused the onset of Yellow River drainage, accelerated erosion of the Tibetan plateau and drove loess deposition,' Thomas Stevens writes.

Weathering of this eroded material also constitutes a further mechanism that may explain the reduced levels of atmospheric carbon dioxide at the beginning of the Ice Age. The researchers' next step will be to compare terrestrial and marine records of erosion to gauge how far sediment storage on land has impacted the marine record.

'Only then will we be able to assess the true rates of erosion and its effect on atmospheric CO2 and thus the climate in geologic time,' says Stevens.

For more information visit:-

http://www.sciencedaily.com/releases/2015/10/151009083037.htm

http://www.prlabs.co.uk/lab-supplies.php?N=gastube-carbon-dioxide-hr-05-20&Id=11735

Sprites!

Sprites are a fleeting, ethereal and a relatively unknown aspect of lightning storms.
 
Since the 1960s, and probably before then, pilots have been seeing but seldom reporting what have become known as sprites and elves above the clouds. Sprites are electrically-charged lightning funnels which shoot up from the top of a cloud as much as 60 miles into the atmosphere. These charges are vivid red and usually occur in clusters of three or more but are only visible for nanoseconds. They are sometimes preceded by lower altitude red flashes known as elves, and can have striking blue tendrils which are easily mistaken for blue jets. While they are a similar visual phenomenon, blue jets are less powerful than the sprites and travel neither as quickly nor as far.

 

Because 'everyone knows' lightning goes to ground, pilots were naturally reluctant to report this phenomenon in case they found themselves grounded for hallucinating. As a result, serious research was delayed until the last 15 years or so.

While sprites are more common during positively-charged lightning storms, this is not due to any preference on the part of the sprite, but rather due to the greater internal energy of a positively charged storm. It was not until 1999 that the first sprites of a negatively-charged storm were recorded.

 

During a powerful storm it is possible to see red sprites, elves and blue  jets, but the exact atmospheric conditions which create such a show are uncertain.
 
As sprites are relatively new to the science world there is still a lot more to learn about them.

It is only with the advent of high speed photography that the existence of these light shows could be confirmed, and even with that they were first photographed by accident in 1989. Amazingly, there have since been more than 10,000 confirmed sightings. They are also known to create a very low-frequency thunder which was only recently captured with the use of specialist listening equipment.

 

As their energy is spread more thinly than the traditional thunderbolt due to the cone like dispersal from cloud to atmosphere, they are thought to be relatively weak. Sprites are cold plasma phenomena that lack the hot channel temperatures of tropospheric lightning, so they are more akin to fluorescent tube discharges than to lightning discharges.

The effects of sprites are currently being investigated by various agencies including NASA who seriously addressed them as a possible cause for the tragic loss of the space shuttle Columbia, which was, incidentally, on a mission to record data about the very same sprite phenomenon.
 
The link below shows footage from the ISS and shows a red sprite over East Asia at around 0:06.
http://upload.wikimedia.org/wikipedia/commons/f/f8/Red_Sprite.ogv

Sprite Halos
Sprites are sometimes preceded, by about 1 millisecond, by a sprite halo, a pancake-shaped region of weak, transient optical emissions approximately 50 kilometres (31 mi) across and 10 kilometres (6.2 mi) thick. The halo is centred at about 70 kilometres (43 mi) altitude above the initiating lightning strike. These halos are thought to be produced by the same physical process that produces sprites, but for which the ionization is too weak to cross the threshold required for streamer formation.

Recent research carried out at the University of Houston in 2002 indicates that some normal (negative) lightning discharges produce a sprite halo, and that every lightning bolt between cloud and ground attempts to produce a sprite or a sprite halo.

For more information visit:-
http://en.wikipedia.org/wiki/Sprite_(lightning)
http://h2g2.com/approved_entry/A13492398
http://apod.nasa.gov/apod/ap990616.html