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Is Normal Matter Missing From The Universe

October 20, 2017 by  
Filed under Around The Net

Astronomers and cosmologists have an inventory problem: They haven’t been able to account for a fair amount of the stuff that makes up our universe.

There are the longstanding challenges with pinpointing dark energy and dark matter, two invisible components that together make up more than 95 percent of the cosmos. But there is also the lesser-known problem of missing baryon particles.

Baryons are subatomic particles that include protons and neutrons, which form the nuclei of atoms. Baryonic matter — part of what we consider “normal matter” in the universe — makes up everything we are familiar with: stars, planets, the chair you are sitting on, the device you are using to read this, and you.

Blastoff! Progress 68 Space Station Resupply Mission Launches

An uncrewed Progress 68 cargo ship carrying supplies for the International Space Station launched from the Baikonur Cosmodrome in Kazakhstan on Oct. 14, 2017. credit: NASA

So there was understandable excitement this week when it emerged that two separate teams of researchers may have found this “missing” baryonic matter.

When astronomers observe the universe, they find just 10 percent of normal baryonic matter as easily observable matter in stars and nebulae, and another 40 percent has been found in diffuse clouds within galaxies.

It has been theorized that the remaining regular matter must exist as a diffuse gas between galaxies. And now the two new research papers indicate that baryonic matter does indeed exist in the form of filaments of gas between galaxies, making up the missing percentage.

Hideki Tanimura is from the Institute of Space Astrophysics in Orsay, France, and led one of the teams.

“The half of baryons (missing baryons) are considered to exist in filamentary structures between dark matter halos as a diffuse gas, WHIM ( warm hot intergalactic medium),” he told Seeker in an email. “We show that most of our detection is due to unbound diffuse gas in filaments between dark matter halos, not bound gas in dark matter halos.”

Tanimura’s team and another team led by Anna de Graaff at the University of Edinburgh in Scotland looked at data from the Planck satellite for a thermal signal called the Sunyaev-Zel’dovich effect. This effect allows for the detection of very faint objects, and looks for photons from the Cosmic Microwave Background as it travels through hot gas.

The interaction, which only the Planck satellite so far has been able to detect, allows astronomers to spot the presence of matter, even if it is very faint at high redshifts.

In 2015, Planck data was used to create a map of this effect throughout the observable universe. But because the filaments of gas between galaxies are so diffuse, it is very difficult to detect them directly on Planck’s map without using points of reference.

Both of the teams of researchers used data from the Sloan Digital Sky Survey to look at galaxies that were predicted to be connected by filaments of faint gas. They stacked the Planck data to look in the areas between the galaxies.

Tanimura’s group stacked data on 260,000 pairs of galaxies, and de Graaff’s team used over a million pairs. Both teams found conclusive evidence of the baryonic gas filaments between the galaxies.

Tanimura said the results between the two groups are consistent within margins.

“The biggest surprise is that the gas we detected is very low-dense, lower than expected,” Tanimura said. “It is very surprising and very important because we prove that we can detect it now! It means that we can now start to make an entire map of the universe, including filaments as well as galaxies.”

Tanimura said that the total amount of baryons has been measured by other observations such as the CMB observations and Lyman Alpha observations, and their results are consistent within margins with cosmological simulations.

“There is already a consensus about it and we prove that it is true,” he said. “But we know more than that. We estimate the distribution and physical states of the (missing) baryons. By comparing the result (which was unknown) with current models such as cosmological simulations, we can make [a] more precise picture of the current universe and constrain the evolution of the universe.”

Tanimura noted that this finding is analogous to the first maps made of the world.

“When people went out to the ocean and started making a map of our world, it was not used by most of the people then, but we use the world map now to travel abroad,” he said. “In the same way, the map of the entire universe may not be valuable now because we do not have a technology to go far out to the space. However, it could be valuable 500 years later.”

He added, “We are in the first stage of making [a] ‘map of the entire universe.'”

Courtesy-Space

Astronomers Discover Prehistoric Lake On Mars Could Have Supported Life

October 6, 2017 by  
Filed under Around The Net

An up-close view of Mars’ rocky deposits by NASA’s Curiosity rover shows a changing climate in the planet’s ancient past that would have left the surface warm and humid enough to support liquid water — and possibly life. Evidence of an ancient lake points to the prospect of two unique habitats within its shores; the lower part of the lake was devoid of oxygen compared to an oxygen-rich upper half. 

In a recent paper published in the journal Science, Redox stratification of an ancient lake in Gale crater,” Stony Brook University geoscientist Joel Hurowitz and his colleagues used more than three years of data retrieved from the rover to paint a picture of ancient conditions at Gale Crater, the lowest point in a thousand kilometers. The site, a 150-mile kilometer crater formed during an impact around 3.8 billion years ago, once flowed with rivers ending in a lake. The sedimentary rocks laid down by these rivers and onto the lakebed tell the story of how the environment changed over time.

Curiosity landed on a group of sedimentary rocks known as the Bradbury group. The rover sampled a part of this group called the Sheepbed mudstones, as well as rocks from the Murray formation at the base of the 5-kilometer high peak at the center of the crater known as Mount Sharp. Both types of rocks were deposited in the ancient lake, but the Sheepbed rocks are older and occur lower in the stratigraphic layers of rocks. Comparing the two types of rocks can lead to interesting revelations about the paleoenvironment. 

Rocks that form at the same time in the same area can nevertheless display differences in composition and other characteristics. These different groupings are known as “facies” and the Murray formation is split into two facies. One is comprised mainly of hematite and phyllosilicate, and given the name HP, while the other is the magnetite-silicate facies, known as MS. 

“The two Murray facies were probably laid down at about the same time within different parts of the lake,” explained Hurowitz. “The former laid down in shallow water, and the latter in deeper water.”

The near-shore HP facies have thicker layers in the rocks compared to the thin layers of the deeper water MS facies. This difference in layer thickness is because the river flowing into the lake would have slowed down and dumped some of its sedimentary material at the lake shore. The flow would then have spread into the lake and dropped finer material into the deeper parts of the lake. 

Curiosity landed on rocks known as the Bradbury group. The Murray formation consist of younger rocks at the base of Mount Sharp. The height is exaggerated in the diagram.

The different mineralogy of the two facies was caused by the lake becoming separated into two layers. Ultraviolet (UV) radiation along with low levels of atmospheric oxygen penetrated the upper part of the lake and acted as oxidants on molecules in the water. These ions of iron (Fe2+) and manganese (Mn2+) were brought to the lake via seepage of groundwater through the lake floor.

When the UV and oxygen interacted with these, they lost electrons, meaning that they had become “oxidized.” The oxidized iron and manganese precipitated into minerals — hematite and manganese oxide — that eventually made up the rocks sampled by Curiosity in the HP facies. However, the UV and oxygen didn’t reach all the way to the lake floor, so the iron and manganese wasn’t oxidized in the deeper part of the lake, and instead became the mineral known as magnetite, making up the MS facies. 

The difference in oxidation of the two facies in the Murray formation due to differences in layers of the lake is known as redox stratification. Identifying redox stratification in the ancient lake shows that there were two completely different types of potential habitat available to any microbial life that might have been present.

The researchers also discovered that the Murray formation has a high concentration of salts, which provide clues relating to evaporation of the lake, and thus the end of the potential habitat. High salinity is a result of water evaporating and leaving salts behind. However, evaporation leaves other tell-tale signs such as desiccation cracks — similar to what you see when mud dries and cracks — and none of these signs appear in the Murray formation. This indicates that the evaporation occurred at a later period of time and that the salts seeped through layers overlying the Murray formation before becoming deposited in the Murray rocks. 

“Curiosity will definitely be able to examine the rocks higher up in the stratigraphy to determine if lake evaporation influenced the rocks deposited in it,” said Hurowitz. “In fact, that’s exactly what the rover is doing as we speak at the area known as Vera Rubin Ridge.”

Once Curiosity examines these rocks, it will be able to confirm that the salts found in the Murray formation came from a later period of evaporation, and therefore no significant evaporation occurred during the time that the Murray formation was deposited, meaning the environment would have been stable enough to support possible life forms.

The inflowing river deposits thicker material (clastics) close to the lake shore, and finer material towards the deeper part of the lake. The incoming UV and O2 oxidizes the iron and manganese in the upper part

Another result of the research is evidence of climate change. The older Sheepbed formation shows very little evidence of chemical weathering compared to the Murray formation. The change to substantial chemical weathering in the younger rocks indicates that the climate likely changed from cold, arid conditions to a warm, wet one. 

“The timing of this climate shift is not something we can tell for sure because we haven’t seen the Sheepbed member and the Murray formation in contact with each other,” said Hurowitz. “If we had, then we might be able to tell if the change in their chemical and mineralogical properties were abrupt (indicating rapid climate change) or gradual. At best, what we can say is that the rocks that we examined were likely deposited over a timespan of tens of thousands of years to as much as around 10 million years.”

The cause of the climate change on Mars is still a matter of debate. If the climate changed in a short period of time, it could have been due to short-term variations or an asteroid impact. A slower change in climate could have been the result of changes in the obliquity cycle of the planet.

The climate change indicated in the rocks shows that the ancient Martian environment would have been warm and humid enough to sustain liquid water on the surface. The redox stratification of the lake as revealed by the different mineralogy in the Murray formation shows that there would have been two different environments within the lake itself. If microbial life was present on Mars at this time, the different potentially habitable niches could have encouraged diversity with anaerobic forms possibly living in the lower depths of the lake. 

“I’m not sure that this was something we would have predicted if we hadn’t had the opportunity to examine Gale’s rock record up close and personal,” adds Hurowitz.

Courtesy-Space

 

Astronomers Find Powerful Cosmic Rays Original Are Not From Our Galaxy

October 2, 2017 by  
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The highest-energy cosmic rays to bombard Earth apparently come from galaxies far, far away, a new study finds.

Cosmic rays are made of atomic nuclei of elements ranging from hydrogen to iron, and zip through outer space at speeds approaching that of light. Analyzing them gives scientists a way to examine matter from outside the solar system, and potentially outside the galaxy.

The sun emits relatively low-energy cosmic rays. However, for more than 50 years, scientists have also detected ultra-high-energy cosmic rays, ones far beyond the capability of any particle accelerator on Earth to generate.

“Earth sees a constant rain of these particles, but we had no idea where they come from,” study co-author Karl-Heinz Kampert, a particle astrophysicist at the University of Wuppertal in Germany and spokesman for the Pierre Auger Collaboration, told Space.com.

“The particles we detect are so energetic they have to come from astrophysical phenomena that are extremely violent,” study co-author Gregory Snow at the University of Nebraska-Lincoln, who serves as the education and outreach coordinator for the Pierre Auger Observatory project, said in a statement. “Some galaxies have an explosive, massive black hole in their centers and there are theories that these very violent centers accelerate particles of very high energy that eventually reach Earth.”

“By understanding the origins of these particles, we hope to understand more about the origin of the universe, the Big Bang, how galaxies and black holes formed and things like that,” Snow said in the statement. “These are some of the most important questions in astrophysics.”

One way to discover the origins of ultra-high-energy cosmic rays is to study their directions of travel. However, ultra-high-energy cosmic rays only rarely strike Earth’s atmosphere, with one hitting any given area about the size of a soccer field about once per century, the researchers said.

In order to detect ultra-high-energy cosmic rays, scientists look for the spray of electrons, photons and other particles that result when ultra-high-energy cosmic rays hit the top of Earth’s atmosphere. Each of these showers contains more than 10 billion particles, which fly downward in a disk shaped like a giant plate miles wide, according to the statement.

Scientists examined the sprays from ultra-high-energy cosmic rays using the largest cosmic-ray observatory yet: the Pierre Auger Observatory built in the western plains of Argentina in 2001. It consists of an array of 1,600 particle detectors deployed in a hexagonal grid over 1,160 square miles (3,000 square kilometers), an area comparable in size to Rhode Island. A connected set of telescopes is also used to see the dim fluorescent light the particles in the sprays emit at night.

The researchers analyzed data collected between 2004 and 2016. During these 12 years, the scientists detected more than 30,000 ultra-high-energy cosmic rays.

If ultra-high-energy cosmic rays came from the Milky Way, one might perhaps expect them to come from all across the sky, or perhaps mostly from the direction of the supermassive black hole at the galaxy’s center. However, the researchers saw that ultra-high-energy cosmic rays mostly came from a broad area of sky about 90 degrees away from the direction of the Milky Way’s core. 

“This is the first clear observation that ultra-high-energy cosmic rays come from outside our galaxy,” Kampert said.

This direction where most of the ultra-high-energy cosmic rays came from is a place “with an increased density of nearby galaxies,” Kampert added. “These galaxies, or some subset of these galaxies, contain the sources of these cosmic rays.”

Future research to pinpoint the exact sources of these cosmic rays will focus on the ones with the very highest energy. These are the most likely to have gotten deflected the least by intervening magnetic fields, and so their arrival directions should point closer to their birthplaces, Kampert said.

The scientists detailed their findings in the Sept. 22 issue of the journal Science.

Courtesy-Space

Astronomers Ponder The Role Of Physics In Life

September 25, 2017 by  
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Understanding the origin of life is arguably one of the most compelling quests for humanity. This quest has inevitably moved beyond the puzzle of life on Earth to whether there’s life elsewhere in the universe. Is life on Earth a fluke? Or is life as natural as the universal laws of physics?

Jeremy England, a biophysicist at the Massachusetts Institute of Technology, is trying to answer these profound questions. In 2013, he formulated a hypothesis that physics may spontaneously trigger chemicals to organize themselves in ways that seed “life-like” qualities.

Now, new research by England and a colleague suggests that physics may naturally produce self-replicating chemical reactions, one of the first steps toward creating life from inanimate substances.

This might be interpreted as life originating directly from the fundamental laws of nature, thereby removing luck from the equation. But that would be jumping the gun.

Life had to have come from something; there wasn’t always biology. Biology is born from the raw and lifeless chemical components that somehow organized themselves into prebiotic compounds, created the building blocks of life, formed basic microbes and then eventually evolved into the spectacular array of creatures that exist on our planet today.  

“Abiogenesis” is when something nonbiological turns into something biological and England thinks thermodynamics might provide the framework that drives life-like behavior in otherwise lifeless chemicals. However, this research doesn’t bridge life-like qualities of a physical system with the biological processes themselves, England said.

“I would not say I have done anything to investigate the ‘origin of life’ per se,” England told Live Science. “I think what’s interesting to me is the proof of principle – what are the physical requirements for the emergence of life-like behaviors?”

Self-organization in physical systems

When energy is applied to a system, the laws of physics dictate how that energy dissipates. If an external heat source is applied to that system, it will dissipate and reach thermal equilibrium with its surroundings, like a cooling cup of coffee left on a desk. Entropy, or the amount of disorder in the system, will increase as heat dissipates. But some physical systems may be  sufficiently out of equilibrium that they “self-organize” to make best use of an external energy source, triggering interesting self-sustaining chemical reactions that prevent the system from reaching thermodynamic equilibrium and thus maintaining an out-of-equilibrium state, England speculates. (It’s as if that cup of coffee spontaneously produces a chemical reaction that sustains a hotspot in the center of the fluid, preventing the coffee from cooling to an equilibrium state.) He calls this situation “dissipation-driven adaptation” and this mechanism is what drives life-like qualities in England’s otherwise lifeless physical system.

A key life-like behavior is self-replication, or (from a biological viewpoint) reproduction. This is the basis for all life: It starts simple, replicates, becomes more complex and replicates again. It just so happens that self-replication is also a very efficient way of dissipating heat and increasing entropy in that system.

In a study published July 18 in the journal Proceedings of the National Academy of Sciences,  England and co-author Jordan Horowitz tested their hypothesis. They carried out computer simulations on a closed system (or a system that doesn’t exchange heat or matter with its surroundings) containing a “soup” of 25 chemicals. Although their setup is very simple, a similar type of soup may have pooled on the surface of a primordial and lifeless Earth. If, say, these chemicals are concentrated and heated by an external source – a hydrothermal vent, for example – the pool of chemicals would need to dissipate that heat in accordance with the second law of thermodynamics. Heat must dissipate and the entropy of the system will inevitably increase.

Under certain initial conditions, he found that these chemicals may optimize the energy applied to the system by self-organizing and undergoing intense reactions to self-replicate. The chemicals fine-tuned themselves naturally. These reactions generate heat that obeys the second law of thermodynamics; entropy will always increase in the system and the chemicals would self-organize and exhibit the life-like behavior of self-replication.

“Essentially, the system tries a bunch of things on a small scale, and once one of them starts experiencing positive feedback, it does not take that long for it to take over the character of organization in the system,” England told Live Science.

This is a very simple model of what goes on in biology: chemical energy is burned in cells that are – by their nature – out of equilibrium, driving the metabolic processes that maintain life. But, as England admits, there’s a big difference between finding life-like qualities in a virtual chemical soup and life itself.

Sara Imari Walker, a theoretical physicist and astrobiologist at Arizona State University who was not involved in the current research, agrees.

“There’s a two-way bridge that needs to be crossed to try to bridge biology and physics; one is to understand how you get life-like qualities from simple physical systems and the other is to understand how physics can give rise to life,” Imari Walker told Live Science. “You need to do both to really understand what properties are unique to life and what properties are characteristic of things that you consider to be almost alive […] like a prebiotic system.”

Emergence of life beyond Earth?

Before we can even begin to answer the big question of whether these simple physical systems may influence the emergence of life elsewhere in the universe, it would be better to understand where these systems exist on Earth first.

“If, when you say ‘life,’ you mean stuff that is as stunningly impressive as a bacterium or anything else with polymerases and DNA, my work doesn’t yet tell us anything about how easy or difficult it is to make something that complex, so I shouldn’t speculate about what we’d be likely to find elsewhere than Earth,”  England said. (Polymerases are proteins that assemble DNA and RNA.)

This research doesn’t specifically identify how biology emerges from nonbiological systems, only that in some complex chemical situations, surprising self-organization occurs. These simulations do not consider other life-like qualities – such as adaptation to environment or reaction to stimuli. Also, this thermodynamics test on a closed system does not consider the role of information reproduction in life’s origins, said Michael Lässig, a statistical physicist and quantitative biologist at the University of Cologne in Germany.

“[This] work is indeed a fascinating result on non-equilibrium chemical networks but it is still a long way from a physics explanation of the origins of life, which requires the reproduction of information,” Lässig, who was not involved in the research, told Live Science.

There’s a critical role for information in living systems, added Imari Walker. Just because there appears to be natural self-organization exhibited by a soup of chemicals, it doesn’t necessarily mean living organization.

“I think there’s a lot of intermediate stages that we have to get through to go from simple ordering to having a full-on information processing architecture like a living cell, which requires something like memory and hereditary,” said Imari Walker. “We can clearly get order in physics and non-equilibrium systems, but that doesn’t necessarily make it life.”

To say England’s work could be the “smoking gun” for the origin of life is premature, and there are many other hypotheses as to how life may have emerged from nothing, experts said. But it is a fascinating insight into how physical systems may self-organize in nature. Now that researchers have a general idea about how this thermodynamic system behaves, it would be a nice next step to identify sufficiently out-of-equilibrium physical systems that naturally occur on Earth, England said.

Courtesy-Space

Astronomers Find Titanium Oxide On Aline Planet

September 22, 2017 by  
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For the first time ever, titanium oxide has been spotted in an exoplanet’s skies, a new study reports.

Astronomers using the European Southern Observatory’s Very Large Telescope (VLT) in Chile detected the substance in the atmosphere of WASP-19b, a huge, scorching-hot planet located 815 light-years from Earth.

The presence of titanium oxide in the atmosphere of WASP-19b can have substantial effects on the atmospheric temperature structure and circulation,” study co-author Ryan MacDonald, an astronomer at the University of Cambridge in England, said in a statement.  

One possible effect is “thermal inversion.” If enough titanium oxide is present, the stuff can keep heat from entering or exiting an atmosphere, causing upper layers to be hotter than lower layers, researchers said. (This phenomenon occurs in Earth’s stratosphere, but the culprit is ozone, not titanium oxide.)

Artist’s illustration showing the exoplanet WASP-19b, whose atmosphere contains titanium oxide. In large enough quantities, titanium oxide can prevent heat from entering or escaping an atmosphere, leading to a “thermal inversion” in which temperatures are higher in the upper atmosphere than lower down.

WASP-19b is a bizarre world about the mass of Jupiter. The alien planet lies incredibly close to its host star, completing one orbit every 19 hours. As a result, WASP-19b’s atmospheric temperatures are thought to hover around 3,600 degrees Fahrenheit (2,000 degrees Celsius).

The research team — led by Elyar Sedaghati of the European Southern Observatory, the German Aerospace Center and the Technical University of Berlin — studied WASP-19b for more than a year using the VLT’s refurbished FORS2 instrument. These observations allowed them to determine that small amounts of titanium oxide, along with water and wisps of sodium, swirl around in the exoplanet’s blistering air.

“Detecting such molecules is, however, no simple feat,” Sedaghati said in the same statement. “Not only do we need data of exceptional quality, but we also need to perform a sophisticated analysis. We used an algorithm that explores many millions of spectra spanning a wide range of chemical compositions, temperatures, and cloud or haze properties in order to draw our conclusions.”

In addition to shedding new light on WASP-19b, the new study — which was published online today (Sept. 13) in the journal Nature — should improve researchers’ modeling of exoplanet atmospheres in general, team members said.

“To be able to examine exoplanets at this level of detail is promising and very exciting,” said co-author Nikku Madhusudhan, also of the University of Cambridge. 

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With Boron On Mars Prove Life Once Existed

September 21, 2017 by  
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NASA’s Mars rover Curiosity has discovered boron in Gale Crater — new evidence that the Red Planet may have been able to support life on its surface in the ancient past.

Boron is a very interesting element to astrologists; on Earth, it’s thought to stabilize the sugary molecule ribose. Ribose is a key component of ribonucleic acid (RNA), a molecule that’s present in all living cells and drives metabolic processes. But ribose is notoriously unstable, and to form RNA, it is thought that boron is required to stabilize it. When dissolved in water, boron becomes borate, which, in turn, reacts with ribose, making RNA possible.

In a new study published in the journal Geophysical Research Letters, researchers analyzed data gathered by Curiosity’s ChemCam (Chemistry and Camera) instrument, which zaps rocks with a powerful laser to see what minerals they contain. ChemCam detected the chemical fingerprint of boron in calcium-sulfate mineral veins that have been found zigzagging their way through bedrock in Gale Crater, the 96-mile-wide (154 kilometers) crater that the rover is exploring. These veins were formed by the presence of ancient groundwater, meaning the water contained borate.

The find raises exciting possibilities, the researchers said.

“Because borates may play an important role in making RNA — one of the building blocks of life — finding boron on Mars further opens the possibility that life could have once arisen on the planet,” study lead author Patrick Gasda, a postdoctoral researcher at Los Alamos National Laboratory in New Mexico, said in a statement. 

“Borates are one possible bridge from simple organic molecules to RNA,” he added. “Without RNA, you have no life. The presence of boron tells us that, if organics were present on Mars, these chemical reactions could have occurred.”

Scientists have long hypothesized that the earliest “proto-life” on Earth emerged from an “RNA World,” where individual RNA strands containing genetic information had the ability to copy themselves. The replication of information is one of the key requirements for basic lifelike systems. Therefore, the detection of boron on Mars, locked in calcium-sulfate veins that we know were deposited by ancient water, shows that borates were present in water “0 to 60 degrees Celsius (32 to 140 degrees Fahrenheit) and with neutral-to-alkaline pH,” the researchers said.

“We detected borates in a crater on Mars that’s 3.8 billion years old, younger than the likely formation of life on Earth,” Gasda added. “Essentially, this tells us that the conditions from which life could have potentially grown may have existed on ancient Mars, independent from Earth.”

Since landing on Mars in 2012, Curiosity has uncovered compelling evidence that the planet used to be a far wetter place than it is now. For example, the rover has found evidence of a lake-and-stream system inside Gale Crater that lasted for long stretches in the distant past. And, by climbing the slopes of Mount Sharp — the 3.4-mile-high (5.5 km) mountain in the crater’s center — Curiosity has been able to examine various layers of sedimentary minerals that formed in the presence of ancient water. 

These studies are helping scientists gain a better understanding of how long these minerals were dissolved in the water, where they were deposited and, ultimately, how they impacted the habitability of the Red Planet. The detection of boron is another strand of evidence supporting the idea that ancient life might have existed on our neighboring planet.

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Cassini Captures On Saturn’s Rings

September 19, 2017 by  
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NASA’s Cassini spacecraft has captured a spectacular photo of a perplexing wave structure in one of Saturn’s rings as the probe heads into its final days at the gas giant. 

The rings of Saturn are embedded with billions of water-ice particles ranging in size from grains of sand to monstrous chunks. Saturn’s rings also feature waves that propagate outward in spiral patterns. 

The new image from Cassini captures an up-close view of a spiral density wave visible in Saturn’s B ring. The wave structure is a buildup of material that has formed from the gravitational pull of Saturn’s moons, NASA officials said.

The density wave visible in Saturn’s B ring originates 59,796 miles (96,233 kilometers) from the planet, where the “ring particles orbit Saturn twice for every time the moon Janus orbits

In the new image, the wave structure — aptly named the Janus 2:1 spiral density wave — appears to ricochet outward, away from Saturn and toward the upper-left corner of the photo, creating hundreds of bright wave crests. 

The density wave is generated by the gravitational pull of Saturn’s moon Janus. However, Janus and one of Saturn’s other moons, Epimetheus, share practically the same orbit and swap places every four years, creating a new crest in the wave, according to the statement. 

As a result, the distance between any pair of crests corresponds to four years’ worth of wave oscillations. This pattern represents the orbital history of Janus and Epimetheus, much like the rings of a tree reveal information about its growth. 

Based on this idea, the crests of the wave at the very upper left of the new Cassini image correspond to the positions of Janus and Epimetheus during the Saturn flybys of NASA’s twin Voyager probes in 1980 and 1981, according to the statement.

The recent images of Saturn’s B ring were taken on June 4, 2017, using Cassini’s narrow-angle camera. After 20 historic years in space, the Cassini mission will come to a close on Sept. 15, when the spacecraft will intentionally dive into Saturn’s atmosphere. 

 

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Can The James Webb Telescope Find Life In Our Solar System

September 18, 2017 by  
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The soon-to-launch James Webb Space Telescope will turn its powerful eye on two of the solar system’s top candidates for hosting alien life: the icy moons Enceladus and Europa, the agency confirmed in a statement this month.

Both Europa (a moon of Jupiter) and Enceladus (a moon of Saturn) are thought to possess subsurface oceans of liquid water beneath thick outer layers of ice. Both moons have also shown evidence of enormous plumes of liquid shooting up through cracks in the surface ice; these plumes could be caused by subsurface geysers, which could provide a source of heat and nutrients to life-forms there, scientists have said.

“We chose these two moons because of their potential to exhibit chemical signatures of astrobiological interest,” said Heidi Hammel, executive vice president of the Association of Universities for Research in Astronomy (AURA), who is leading an effort to use the telescope to study objects in Earth’s solar system.  

The James Webb Space Telescope, nicknamed “Webb,” will capture infrared light, which can be used to identify objects that generate heat but are not hot enough to radiate light (including humans, which is why many night-vision systems utilize infrared light). Researchers are hoping that Webb can help to identify regions on the surfaces of these moons where geologic activity, such as plume eruptions, are taking place. 

Enceladus’ plumes were studied in detail by the Cassini probe at Saturn. The spacecraft spotted hundreds of plumes, and even flew through some of them and sampled their composition. Europa’s plumes were spotted by the Hubble Space Telescope, and researchers know far less about them than those on Europa.

“Are they made of water ice? Is hot water vapor being released? What is the temperature of the active regions and the emitted water?” Geronimo Villanueva, lead scientist on the Webbobservation of Europa and Enceladus, said in the statement. “Webb telescope’s measurements will allow us to address these questions with unprecedented accuracy and precision.”

Webb’s observations will help pave the way for the Europa Clipper mission, a $2 billion orbital mission to the icy moon. Scheduled to launch in the 2020s, Europa Clipper will search for signs of life on Europa. The observations with Webb could identify areas of interest for the Europa Clipper mission to investigate, according to the statement.

As seen by Webb, the Saturn moon Enceladus will appear about 10 times smaller than Europa, so scientists will not be able to capture high-resolution views of Enceladus’ surface, according to the statement. However, Webb can still analyze the molecular composition of Enceladus’ plumes. 

But it’s also possible that the observations won’t catch a plume erupting from Europa’s surface; scientists don’t know how frequently these geysers erupt, and the limited observing time with Webb may not coincide with one of them. The telescope can detect organics — elements such as carbon that are essential to the formation of life as we know it — in the plumes. However, Villanueva cautioned that Webb does not have the power to directly detect life-forms in the plumes.

Webb is set to launch in 2018 and will orbit the sun at the L2 Lagrange point, which is about one million miles (1.7 million km) farther from the sun than the Earth’s orbit around the sun. The telescope will provide high-resolution views of both the very distant and very nearby universe. Scientists have already begun submitting ideas for objects or regions that should be observed using Webb’s powerful eye, and Europa and Enceladus are among the objects that are now guaranteed observing time.

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Project Blue Telescope Goes CrowdFunding

September 15, 2017 by  
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The private space telescope initiative Project Blue launched a new crowdfunding campaign Sept. 6 in a second attempt to raise money for its mission to directly image Earth-like exoplanets. 

The initiative aims to launch a small space telescope into low-Earth orbit. The telescope will spy on our interstellar neighbor Alpha Centauri and image any Earth-like planets that might orbit the star system.

In support of Project Blue, BoldlyGo Institute and numerous organizations, including the SETI (Search for Extraterrestrial Intelligence) Institute, the University of Massachusetts Lowell and Mission Centaur, launched an IndieGoGo campaign to raise $175,000 over the next two months. The funds will be used to establish mission requirements, design the initial system architecture and test its capability for detecting exoplanets. Project leaders will also begin looking for potential partners who could manufacture parts of the space telescope, representatives said in a statement. 

“We’re very excited to pursue such an impactful space mission and, as a privately-funded effort, to include a global community of explorers and space science advocates in Project Blue from the beginning,” Jon Morse, CEO of BoldlyGo Institute, said in the statement.

Last year, Project Blue organizers attempted to raise $1 million through the crowdfunding platform Kickstarter, but the campaign was canceled after only $335,597 was contributed and Project Blue received none of the funds (as is Kickstarter’s policy). 

With the IndieGoGo campaign, however, the organizers have a more flexible goal and will be able to keep all contributions from supporters, even if the initial goal of $175,000 is not reached. So far, more than $45,000 has been raised through the campaign.

The neighboring star system Alpha Centauri is located only 4.37 light-years from Earth, making it a target for scientific research. Project Blue estimates it will take about $50 million to build the special-purpose telescope, which is planned to launch in 2021. 

The small space telescope will use a specialized coronagraph to block the bright glare of Alpha Centauri’s stars and detect planets that may be orbiting there. One planet, Proxima b, has already been detected around Proxima Centauri. 

However, Proxima b was discovered indirectly, by measuring the planet’s gravitational effect on its host star. Instead, the Project Blue telescope will be designed to directly image Earth-like planets in Alpha Centauri’s neighborhood.

 

Courtesy-Space

Astronomers Examine Light Through The Dark Ages Of The Universe

September 12, 2017 by  
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How was light able to burst out of the gloom of the cosmic “dark ages,” approximately 500 million years after the Big Bang? New research may provide insight into one of the universe’s longest standing mysteries, and the surprising hero in this story might be everyone’s favorite astronomical villain: black holes.

The story starts within the fractions of a second after the Big Bang, when the universe expanded exponentially. It became a cosmic soup of fundamental particles that cooled relatively quickly in about 400,000 years, creating a dense hydrogen gas. This began what is known as the cosmic dark ages, during which the universe was shrouded in murk.

Any light emitted by early stars and galaxies would have been almost immediately absorbed by the surrounding thick neutral hydrogen medium. But somehow, the intergalactic medium changed from being cold and neutral to become warm and ionized.

Cosmologists have theorized that enough intense ultraviolet light was produced by early stars and galaxies to burn off the dense hydrogen, sparking the epoch of re-ionization that transformed the universe into the light-filled marvel we know today.

How this happened is not well understood, as other theories say the UV radiation from the stars and galaxies in the dark ages would not have been powerful enough to blow through the neutral hydrogen.

But a new study of recent observations by the Chandra X-ray Observatory, whose results were just published in the journal Monthly Notices of the Royal Astronomical Society, might provide a clue. 

While black holes are famous for devouring all the light and matter around them, some of them are known to be spitting out powerful jets of high-energy x-ray particles.

“As matter falls into a black hole, it starts to spin and the rapid rotation pushes some fraction of the matter out,” said lead author Philip Kaaret, from the University of Iowa, in a statement. “They’re producing these strong winds that could be opening an escape route for ultraviolet light. That could be what happened with the early galaxies.”

Kaaret and his team looked at Chandra data from a galaxy called Tol 1247-232, located about 600 million light years from Earth. It is one of only three nearby galaxies from which ultraviolet light has been found to escape. In May 2016, Chandra observed a single X-ray source from Tol 1247-232 whose brightness waxed and waned. Kaaret and his colleagues determined the source couldn’t be a star.

“Stars don’t have changes in brightness,” said Kaaret. “Our sun is a good example of that. To change in brightness, you have to be a small object, and that really narrows it down to a black hole.”

Jets of X-ray material shooting out from the black hole appear to have blown out cavities in the nearby gaseous medium, allowing the UV light to escape.

“It’s possible the black hole is creating winds that help the ionizing radiation from the stars escape,” Kaaret said. “Thus, black holes may have helped make the universe transparent.”

He compared the process to a figure skater spinning with outstretched arms. As the skater brings her arms closer to her body, she spins faster. Black holes operate in a similar fashion. As gravity pulls matter inward toward a black hole, the black hole likewise spins faster. As the black hole’s gravitational pull increases, the speed also creates energy.

As in Tol 1247-232, the blasts of X-rays in the early universe would have had enough heat and energy to blow the neutral gas and dust away, the team said, allowing the ultraviolet radiation to “leak” out.

Kaaret explained in an email to Seeker that many of the early stars in the universe were massive.

“These stars age very quickly and die as black holes,” he wrote. “The stuff around black holes is very hot (millions of Kelvin) and creates X-rays.  Then the UV in the story comes from hot stars, and is 10,000s to 100,000s of Kelvin.”

While black holes are the likely mechanism, the team would like to narrow down the type of black hole. They also said there are still other possibilities to explain their observations.

“Another possible origin of the X-ray emission,” the team wrote in their paper, “is from an ultraluminous (ULX) or hyper-luminous (HLX) X-ray source. ULXs are thought to be X-ray binaries that contain stellarmass black holes or neutron stars. HLXs may be super-Eddington accretors [possibly quasars] or intermediate mass black holes.”

They said that repeated X-ray imaging of Tol1247 with Chandra could reveal whether the X-ray emission arises from a single source or multiple sources. Additionally, the team has been looking at a similar galaxy, Haro 11, and said that since “it is not possible to draw robust conclusions from a sample of two objects,” they hope to be able to observe more galaxies where jets of material shooting out have blown out large cavities in the surrounding gas.

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Do Trappist-1 Planets Have Enough Water For Alien Life

September 11, 2017 by  
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The new study looks at how much ultraviolet (UV) radiation is received by each of the planets, because this could affect how much water the worlds could sustain over billions of years, according to the study. Lower-energy UV light can break apart water molecules into hydrogen and oxygen atoms on a planet’s surface, while higher-energy UV light (along with X-rays from the star) can heat a planet’s upper atmosphere and free the separated hydrogen and oxygen atoms into space, according to the study. (It’s also possible that the star’s radiation destroyed the planets’ atmospheres long ago.)

The researchers measured the amount of UV radiation bathing the TRAPPIST-1 planets using NASA’s Hubble Space Telescope, and in their paper they estimate just how much water each of the worlds could have lost in the 8 billion years since the system formed.

It’s possible that the six innermost planets (identified by the letters b, c, d, e, f and g), pelted with the highest levels of UV radiation, could have lost up to 20 Earth-oceans’ worth of water, according to the paper. But it’s also possible that the outermost four planets (e, f, g and h — the first three of which are in the star’s habitable zone) lost less than three Earth-oceans’ worth of water.

If the planets had little or no water to start with, the destruction of water molecules by UV radiation could spell the end of the planets’ habitability. But it’s possible that the planets were initially so rich in liquid water that, even with the water loss caused by UV radiation, they haven’t dried up,  according to one of the study’s authors, Michaël Gillon, an astronomer at the University of Liège in Belgium. Gillon was also lead author on two studies that first identified the seven TRAPPIST-1 planets.

“It is very likely that the planets formed much farther away from the star [than they are now] and migrated inwards during the first 10 million years of the system,” Gillon told Space.com in an email.

Farther away from their parent star, the planets might have formed in an environment rich in water ice, meaning the planets could have initially had very water-rich compositions.

“We’re talking about dozens, and maybe even hundreds of Earth-oceans, so a loss of 20 Earth-oceans wouldn’t matter much,” Gillon said. “What our results show is that even if the outer planets were initially quite water-poor like the original Earth, they could still have some water on their surfaces.”

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NASA Researching The Stripes On Venus

September 8, 2017 by  
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A proposed NASA mission could solve the mystery of how Venus got its stripes.  

To the human eye, the cloud tops of Venus may look smooth and monochrome, but in ultraviolet light, dark and light streaks decorate Earth’s sister planet. The cause of these stripes is unknown, and Venus’ thick, blistering atmosphere (which is hot enough to melt lead) has made the world a difficult planet to study.

Now, NASA has invested money in a proposed mission that could help researchers figure out what causes the Venusian bands, according to a statement from the agency. The mission would use a very small space probe, equipped with cutting-edge technology, the statement said. 

The CubeSat UV Experiment, or CUVE, would orbit Venus over the poles and study the planet’s atmosphere in ultraviolet and visible wavelengths of light. Venus’ cloud tops scatter visible light, which makes the planet look like a smooth, featureless globe. But some of the material in the clouds absorbs ultraviolet light, creating the dark stripes, according to the statement. 

“The exact nature of the cloud-top absorber has not been established,” Valeria Cottini, CUVE principal investigator and a researcher at the University of Maryland, said in the statement. “This is one of the unanswered questions, and it’s an important one.”

One hypothesis that could explain how Venus gets its stripes posits that material from
“deep within Venus’ thick cloud cover” could rise into the cloud tops via convection (in which hot material in a fluid naturally rises above cold material). Winds would then disperse the material along breezy pathways, creating streaks. 

The CUVE team has now received additional funding from NASA’s Planetary Science Deep Space SmallSat Studies, or PSDS3, to further develop the mission concept. 

The spacecraft would be a cubesat, or a miniature satellite that typically consists of single unites that are about 10 inches (25.4 centimeters) cubed. CUVE would include a miniaturized ultraviolet camera “to add contextual information and capture the contrast features,” according to the statement, and a spectrometer to study the UV and visible light in detail.  

CUVE could also carry a “lightweight telescope equipped with a mirror made of carbon nanotubes in an epoxy resin,” officials said in the statement. “To date, no one has been able to make a mirror using this resin.” 

Planet Venus is often likened to Earth but with a runaway greenhouse problem. The 2nd planet from the sun is hot shrouded with deadly clouds. Those are hints. Now test your knowledge of Venus facts.

The nanotubes and epoxy would be poured into a mold, heated to harden the epoxy and then coated with a reflective material. This telescope would be lightweight and easy to reproduce, and would not require polishing, which is typically time-consuming and expensive, according to the statement.

“This is a highly focused mission — perfect for a cubesat application,” Cottini said in the statement. She later added, “CUVE would complement past, current and future Venus missions and provide great science return at lower cost.”

Courtesy-Space

Why Is Dark Matter Elusive

September 5, 2017 by  
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Dark matter is more than a name — it’s a part of our universe. But it’s totally unfamiliar to our everyday experience. Based on the evidence, scientists think it’s invisible in the truest sense of the word: It simply doesn’t interact with light. Gravity, however, is universal, and so dark matter can still have an influence on the shape and motions of galaxies. But we’ll never see it. At least, not directly.

As much as we would prefer to live in a simpler universe, dark matter is not the product of some astronomer’s fever dream after a late-night observing session. It’s only after decades of careful observations that cosmologists have come to the inescapable conclusion that most of the matter in our universe is simply invisible.

Farewell Cassini! Why Epic Saturn Mission Must End

On September 15, 2017, the historic NASA mission will come to an end as the probe burns up in Saturn’s upper atmosphere. Credit: Space.com / edited by Steve Spaleta

The initial hints of dark matter came in the 1930s as astronomer Fritz Zwicky made the first X-ray observations of the Coma Cluster, a dense knot of a thousand galaxies over 300 million light-years away. The galaxies themselves aren’t very bright in X-ray light, but the galaxies in a cluster swim in a hot, thin soup of plasma (a gas with some unique properties), which does emit high-energy radiation. In his initial measurements, Zwicky noticed an inconsistency: The plasma was much too hot.

Stable systems like galaxy clusters are a study in balance. In this case, the tendency of a hot gas to expand is balanced by the inward pull of its own gravity. If clusters are to survive for billions of years — which they must, in order for us to actually observe them all over the universe — then these two forces must be in equilibrium. But when Zwicky added up the masses of all the galaxies and the plasma itself, it was far too small; the inward gravitational pull of all that matter wasn’t enough to overcome the natural expansion of the gas. In other words, the cluster should’ve — well, I don’t want to say exploded, but you get the idea, long ago.

He named the missing mass “dunkle materie” (“dark matter” in German) and went on to figure out other problems.

Too fast

The concept of dark matter was largely ignored until the 1970s, when astronomer Vera Rubin made her groundbreaking measurements of the rotation speeds of stars within galaxies. Here, again, was a mystery: The stars appear to be orbiting far too fast. The galaxies should’ve flung themselves apart like a broken-down carnival ride long ago. Instead, there they were, stable as could be.

At this point, a dilemma emerged. Maybe there’s some invisible matter floating around inside galaxies and clusters, keeping them gravitationally glued together. But maybe our understanding of how gravity works is just wrong; perhaps Newton’s work can explain the way planets move in our solar system but not larger systems.

Without further evidence, two competing hypotheses, dark matter versus modified

Newtonian dynamics (which attempts to explain the mysteries mentioned above by adjusting the details of Newton’s work), were on equal scientific footing. We simply couldn’t tell them apart.

Too bumpy

That is, until more evidence came in. The first strong hints of a dark universe came from observations of the cosmic microwave background, the ancient afterglow light pattern from the hot and sweaty early years of the universe. That light is uniform to 1 part in 10,000, but buried in that all-surrounding glow are tiny variations, bumps and wiggles that give us a map of the universe at that age.

Those bumps and wiggles are also a study in balance, as multiple competing forces vied for dominance in the hot, dense plasma of the young cosmos. The outward pressure of radiation was resisted by the inward pull of matter’s gravity, and that struggle was captured in a snapshot when the CMB was formed. By observing the patterns in the CMB, we can play a straightforward guess-the-recipe game: put various ingredients (normal matter, dark matter, radiation, modified gravity, etc.) into a pot, see what comes out, and compare directly to observations.

And try as we could, we just couldn’t make those modified Newtonian dynamics and altered forces of gravity work. But an invisible component to the universe, one that didn’t interact with radiation all? It seemed to fit the bill.

Too wide

Still, as is usual in science, there was room for debate. Perhaps not all the observations could be explained by the presence of dark matter, scientists thought. Maybe general relativity — still the most advanced theory we have on the nature of gravity — was not the be-all-end-all gravitational theory.

Those hopes were largely dashed in the most violent way possible — with a bullet. The Bullet Cluster, that is. Two massive galaxy clusters, each weighing in at hundreds of quadrillions of solar masses, slammed into each other long ago. One of the most energetic events in all of nature, the collision turned the clusters inside out, giving us a clue to their contents.

Different observations reveal different components of the Bullet Cluster. Visible light pinpoints the locations of the member galaxies, and they did about what you would expect after the collision: nothing much. The galaxies are so small compared to the volume of the cluster, they simply flew past each other like a swarm of bees.

X-rays expose the fate of the hot plasma between the galaxies. The gas got all tangled up at the midpoint of the collision, with all the complicated bow shocks, cold fronts and turbulence one would expect. This was space weather played out on the grandest of scales.

Also helpful was gravitational lensing, which allows scientists to map the location of matter (whether it interacts directly with radiation or not) based on the way its gravity bends the path of background light. The lensing maps for the Bullet Cluster show an intriguing pattern: most of the stuff in the Bullet Cluster is not tangled up in the center with the hot plasma, and it’s not exactly associated with the galaxies, either.

Whatever material the majority of the Bullet Cluster is made of, it doesn’t interact with light (otherwise we would see it) and it doesn’t interact with itself (otherwise it would’ve gotten all twisted up during the interaction).

No. 1 with a Bullet

The Bullet Cluster, and a myriad of observations of similar objects, tie together our picture of dark matter along with other lines of evidence like stellar velocities in galaxies, the cosmic microwave background, and more. Nature is trying to tell us something, and we’re doing our best to listen: The inescapable conclusion from multiple independent lines of evidence is that most of the matter in our universe is a new kind of particle; one that doesn’t interact with light or even itself. It’s dark matter.

We still haven’t pinned down the exact character of the dark matter particle, but we are closing in on its properties. Sooner or later, nature will reveal to us even its darkest secrets.

Courtesy-Space

The Voyage Of Cassini-Huygens

August 29, 2017 by  
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The Cassini spacecraft has been orbiting Saturn since 2004. The mission is known for discoveries such as finding jets of water erupting from Enceladus, and tracking down a few new moons for Saturn. Now low on fuel, the spacecraft will make a suicidal plunge into the ringed planet in 2017 and capture some data about Saturn’s interior on the way. (This will avoid the possibility of Cassini crashing someday onto a potentially habitable icy moon, such as Enceladus or Rhea.)

The ambitious mission is a joint project among several space agencies, which is a contrast from the large NASA probes of the past such as Pioneer and Voyager. In this case, the main participants are NASA, the European Space Agency and Agenzia Spaziale Italiana (the Italian space agency).

Cassini is the first dedicated spacecraft to look at Saturn and its system. It was named for Giovanni Cassini, a 17th-century astronomer who was the first to observe four of Saturn’s moons — Iapetus (1671), Rhea (1672), Tethys (1684) and Dione (1684). 

Before this spacecraft came several flybys of Saturn by Pioneer 11 (1979), Voyager 1 (1980) and Voyager 2 (1981). Some of the discoveries that came out of these missions included finding out that Titan’s surface can’t be seen in visible wavelengths (due to its thick atmosphere), and spotting several rings of Saturn that were not visible with ground-based telescopes.

It was shortly after the last flyby, in 1982, that scientific committees in both the United States and Europe formed a working group to discuss possible future collaborations. The group suggested a flagship mission that would orbit Saturn, and would send an atmospheric probe into Titan. However, there was a difficult “fiscal climate” in the early 1980s, NASA’s Jet Propulsion Laboratory noted in a brief history of the mission, which pushed approval of Cassini to 1989.

The Europeans and the Americans each considered either working together, or working solo. A 1987 report by former astronaut Sally Ride, for example, advocated for a solo mission to Saturn. Called “NASA’s Leadership and America’s Future in Space,” the report said that studying the outer gas giant planets (such as Saturn) help scientists learn about their atmospheres and internal structure. (Today, we also know that this kind of study helps us predict the structure of exoplanets, but the first exoplanets were not discovered until the early 1990s.) 

“Titan is an especially interesting target for exploration because the organic chemistry now taking place there provides the only planetary-scale laboratory for studying processes that may have been important in the prebiotic terrestrial atmosphere,” the report added, meaning that on Titan is chemistry that could have been similar to what was present on Earth before life arose.

Cassini’s development came with at least two major challenges to proceeding. By 1993 and 1994, the mission had a $3.3 billion price tag (roughly $5 billion in 2017 dollars, or about half the cost of the James Webb Space Telescope.) Some critics perceived this as overly high for the mission. In response, NASA pointed out that the European Space Agency was also contributing funds, and added that the technologies from Cassini were helping to fund lower-cost NASA missions such as the Mars Global Surveyor, Mars Pathfinder and the Spitzer Space Telescope, according to JPL. 

Cassini also received flak from environmental groups who were concerned that when the spacecraft flew by Earth, its radioisotope thermoelectric generator (nuclear power) could pose a threat to our planet, JPL added. These groups filed a legal challenge in Hawaii shortly before launch in 1997, but the challenge was rejected by the federal district court in Hawaii and the Ninth Circuit Court of Appeals.

To address concerns about the spacecraft’s radioisotope thermoelectric generators, which are commonly used for NASA missions, NASA responded by issuing a supplementary document about the flyby and detailing the agency’s methodology for protecting the planet, saying there was less than a one-in-a-million chance of an impact occurring.

Cassini didn’t head straight to Saturn. Rather, its mission involved complicated orbital mechanics. It went past several planets — including Venus (twice), Earth and Jupiter — to get a speed boost by taking advantage of each planet’s gravity.

The nearly 12,600-lb. (about 5,700 kilograms) spacecraft was hefted off Earth on Oct. 15, 1997. It went by Venus in April 1998 and June 1999, Earth in August 1999 and Jupiter in December 2000.

Cassini settled into orbit around Saturn on July 1, 2004. Among its prime objectives were to look for more moons, to figure out what caused Saturn’s rings and the colors in the rings, and understanding more about the planet’s moons.

Perhaps Cassini’s most detailed look came after releasing the Huygens lander toward Titan, Saturn’s largest moon. The lander was named for Dutch scientist Christiaan Huygens, who in 1654 turned a telescope toward Saturn and observed that its odd blob-like shape — Galileo Galilei had first seen the shape in a telescope and drew it in his notebook as something like ears on the planet — was in fact caused by rings. 

The Huygens lander descended through the mysterious haze surrounding the moon and landed on Jan. 14, 2005. It beamed information back to Earth for nearly 2.5 hours during its descent, and then continued to relay what it was seeing from the surface for 1 hour 12 minutes.

In that brief window of time, researchers saw pictures of a rock field and got information back about the moon’s wind and gases on the atmosphere and the surface.

One of the defining features of Saturn is its number of moons. Excluding the trillions of tons of little rocks that make up its rings, Saturn has 62 discovered moons as of September 2012. NASA lists 53 named moons on one of its websites.

In fact, Cassini discovered two new moons almost immediately after arriving (Methone and Pallene) and before 2004 had ended, it detected Polydeuces.

As the probe wandered past Saturn’s moons, the findings it brought back to Earth revealed new things about their environments and appearances. Some of the more notable findings include:

Saturn has not gone ignored, either. For example, in 2012, a NASA study postulated that Saturn’s jet streams in the atmosphere may be powered by internal heat, instead of energy from the sun. Scientists believe that heat brings up water vapor from the inside of the planet, which condenses as it rises and produces heat. That heat is believed to be behind jet stream formation, as well as that of storms.

Mission extension and end

Cassini was originally slated to last four years at Saturn, until 2008, but its mission has been extended multiple times. Its last and final leg was called the Cassini Solstice Mission, named because the planet and its moons reached the solstice again toward the mission end. Saturn orbits the sun every 29 Earth-years. With Cassini’s mission lasting 13 years, this meant that the spacecraft observed almost half of Saturn’s seasonal change as the planet went around its orbit.

In 2016, the spacecraft was set on a series of final maneuvers to provide close-up views of the rings, with the ultimate goal of plunging Cassini into Saturn on Sept. 15, 2017. This protected Enceladus and other potentially habitable moons from the (small) chance of Cassini colliding with the surface, spreading Earth microbe.

Major milestones of the finale included:

Ring-grazing orbits: Every week between Nov. 30, 2016, and April 22, 2017, Cassini did loops around Saturn’s poles to look at the outer edge of the rings, to learn more about their particles, gases and structure. It also observed small moons in this region, including Atlas, Daphnis, Pan and Pandora.

On April 22, 2017, Cassini made the final flyby of Titan. The flyby was done in such a way to change Cassini’s orbit so that it began 22 dives (once a week) between the planet and its rings. This was the first time any spacecraft explored this zone, and it entailed some risk because the orbit brought it between the outer part of the atmosphere and the inner zone of the rings (where it is at risk of striking particles or gas molecules). 

On Sept. 15, 2017, Cassini will make a suicidal plunge into Saturn, taking measurements for as long as its instruments can make communications back to Earth.

Some of the science Cassini performed during this period included creating maps of the planet’s gravity and magnetic fields, estimating how much material is in the rings, and taking high-resolution images of Saturn and its rings from close-up. 

The spacecraft made an interesting discovery from its new vantage point. It found that Saturn’s magnetic field is closely aligned with the planet’s axis of rotation, which baffled scientists because of how they think magnetic fields are generated — through a difference of tilt between the magnetic field and a planet’s rotation. As of late July 2017, however, scientists planned to gather more data to see if perhaps Saturn’s internal processes confused their measurements.

 

Courtesy-Space

 

Is “Opportunity” The Longest Running Rover On Mars

August 24, 2017 by  
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Opportunity is a rover that has been working on Mars since January 2004. Originally intended to last 90 days, the machine is still trekking after 13 years on the Red Planet. In 2015, it passed a driving milestone, reaching more than a marathon’s worth of distance (26.2 miles, or 42.1 kilometers) – and the rover keeps racking up driving time.

Lately, however, it has been showing its age. In 2014 and early 2015, NASA made several attempts to restore Opportunity’s flash memory capabilities after the rover experienced problems. Flash memory allows the rover to store information even when it is powered off. In 2015, NASA decided to continue most operations with random-access memory instead, which keeps data only when the power in the rover is on. At the time, NASA said the only change to operations will be requiring Opportunity to send high-priority data right away, as it cannot be stored if the rover is turned off. 

That said, the mission has been extremely productive on the Red Planet. Opportunity has explored two large craters — Victoria and Endeavour — among many other locations. Along the way, the rover has found multiple signs of water — while surviving a sand trap and bad dust storm.

Making an orphan’s dream come true

Opportunity and its twin rover, Spirit, received their names from 9-year-old Sofi Collis. She was the winner of a naming contest NASA held (with assistance from the Planetary Society and sponsorship from Lego) to find monikers for the Mars Exploration Rovers. Siberian-born Collis was adopted at age 2 and came to live with her new family in Scottsdale, Arizona.

“I used to live in an orphanage,” Collis wrote in her winning essay. “It was dark and cold and lonely. At night, I looked up at the sparkly sky and felt better. I dreamed I could fly there. In America, I can make all my dreams come true. Thank you for the ‘Spirit’ and the ‘Opportunity.'”

The Mars Exploration Rovers launched in 2003 on a 283-million-mile (455.4 million kilometers) journey to hunt for water on Mars. The $800-million cost for the two of them covered a suite of science instruments. Site survey tools included a panoramic camera, as well as a mini-thermal emission spectrometer that was supposed to search for signs of heat. Each rover also had a small arm with tools such as spectrometers and a microscopic imager.

Cruise to Mars

Opportunity left Earth July 7, 2003, aboard a Delta II rocket en route to a landing site at the Martian equator called Meridiani Planum. NASA was intrigued by a layer of hematite that the orbiting Mars Global Surveyor spotted from above. As hematite (an iron oxide) often forms in a spot that had liquid water, NASA was curious about how the water got there in the first place and where the water went.

The 384-pound rover made its final approach to Mars on Jan. 25, 2004. It plowed through the Martian atmosphere, popped out a parachute and then vaulted to the surface in a cocoon of airbags.

Opportunity rolled to a stop inside a shallow crater just 66 feet (20 meters) across, delighting scientists as the first pictures beamed back from the Red Planet. “We have scored a 300-million mile interplanetary hole-in-one,” quipped Cornell University’s Steve Squyres, principal investigator for the rover’s science instruments, in a press release in the days after the landing.

Early sols of science

Opportunity and Spirit (which had landed successfully three weeks earlier, on Jan. 3, 2004) had a primary goal to “follow the water” during their time on Mars. They would hunt for any environments that showed evidence of water activity, particularly looking for minerals that may have been left behind after water came through.

Both rovers met that goal quickly. In early March, just six weeks after landing, Opportunity identified a rock outcrop that showed evidence of a liquid past. The rocks at “Guadalupe” had sulfates as well as crystals inside of niches, which are both signs of water. Spirit found water evidence of its own that same week.

Two weeks later, Opportunity found hematite inside some small spheres that NASA dubbed “blueberries” because of their size and shape. Using a spectrometer, Opportunity found evidence of iron inside a group of berries when comparing it to the bare, underlying rock.

The month wasn’t yet over when Opportunity discovered more evidence of water, this time from images of a rock outcrop that probably formed from a deposit of saltwater in the ancient past. Chlorine and bromine found in the rocks helped solidify the theory.

It was a positive start to Opportunity’s mission — and it hadn’t even left the crater where it had landed yet. Before Opportunity’s 90-day prime mission was over, the golf-cart size rover clambered out of Eagle Crater and ventured to its next science target about half a mile away: Endurance Crater. It spotted more water signs there in October.

One of Opportunity’s most dangerous moments came in 2005, when the rover was mired in the sand for five weeks. NASA had put the rover into a “blind drive” on April 26, 2005, meaning the rover was not checking for obstacles as it went. Opportunity then plowed into a 12-inch-high (30 cm) sand dune, where the six-wheeled rover initially had trouble getting out.

To save the stranded rover, NASA ran tests on a model of the rover in a simulated Martian “sandbox” at the Jet Propulsion Laboratory. Based on what they learned in the sandbox, the rover drivers then sent a series of commands to Opportunity. It took the rover about 629 feet (191 meters) of wheel rotations before it was able to move forward three feet, but it cut itself free in early June 2005.

NASA chose to move the rover forward in more careful increments, which was especially important because Opportunity lost the full use of its right-front wheel (because of a seized steering motor) just days before it got stuck in the sand. The rover could still move around just fine with its other three steerable wheels, NASA said.

Opportunity’s experience in the sand came in handy in October 2005, when NASA detected unusual traction problems on Sol 603. Just 16 feet into a planned 148-foot drive, a slip check system on board automatically stopped the rover when it went past a programmed limit. Two Martian days later, Opportunity backed itself out of the problem and kept on going.

Victoria Crater

In late September 2006, Opportunity wheeled up to Victoria Crater after 21 months on the road. It circled the rim for a few months snapping pictures and getting a close look at some layered rocks surrounding the crater. NASA then made a gutsy decision in June 2007 to take Opportunity inside the crater. It was a risk to the rover as it might not have been able to climb up again, but NASA said the science was worth it.

“The scientific allure is the chance to examine and investigate the compositions and textures of exposed materials in the crater’s depths for clues about ancient, wet environments,” NASA stated in a press release. “As the rover travels farther down the slope, it will be able to examine increasingly older rocks in the exposed walls of the crater.”

The trek down was interrupted by a severe dust storm in July 2007. Opportunity’s power-generating capabilities dropped by 80 percent in only one week as its solar panels became covered in dust. Late in the month, Opportunity’s power dipped to critical levels. NASA worried the rover would stop working, but Opportunity pulled through.

It wasn’t until late August that the skies cleared enough for Opportunity to resume work and head into the crater. Opportunity spent about a year wandering through Victoria Crater, getting an up-close look at the layers on the bottom and figuring that these were likely shaped by water.

Opportunity climbed out successfully in August 2008 and began a gradual journey to Endeavour, an incredible 13 miles (21 km) away. It took about three years to get there, as the rover was stopping to look at interesting science targets on the way. But Opportunity successfully arrived in August 2011.

Opportunity’s water history examinations continued at Endeavour, with one example being a 2013 probe of a rock called “Esperance.” The rock not only has clay minerals produced by water, but there was enough of the liquid to “flush out ions set loose by those reactions,” stated Opportunity long-term planned Scott McLennan of the State University of New York, at the time.

By mid-year 2014, however, Opportunity was experiencing problems with its aging memory. The rover used Flash memory to store information when it went into hibernation during the Martian nights, which take place about as frequently as they do on Earth. 

Controllers did a remote memory wipe from Earth, but memory issues and resets continued to plague the rover through the end of the year. Eventually, officials elected to stop using Flash memory, move storage over to random access memory (RAM) instead, and find a way to address the problem more thoroughly. In 2015, NASA decided to use RAM in most situations, which requires Opportunity to send high-priority data right away as the information cannot be stored if the rover is off.

Despite these issues, Opportunity continues rolling on the Red Planet. It set an off-world driving record in July 2014 when it successfully passed 25.01 miles (40.2 kilometers), exceeding the distance from the Soviet Union’s remote-controlled lunar Lunokhod 2 rover in 1973. In March 2015, it passed another huge milestone: completing a marathon on Mars.

The rover successfully imaged Comet Siding Spring when the celestial body sped fairly close to Mars in October 2014. In January 2015, Opportunity took pictures from a “high point” on the rim of Endeavour, about 440 feet (134 feet) above the surrounding crater floor. In March 2015, NASA announced that the rover – while overlooking an area nicknamed “Marathon Valley” – had seen some rocks with a composition unlike others studied by Spirit or Opportunity; one of the features was high concentrations of aluminum and silicon. 

After working through a Martian winter, in March 2016, Opportunity tackled its steepest slope ever — reaching a tilt of 32 degrees — while trying to reach a target on “Knudsen Ridge” inside Marathon Valley. As engineers watched the rover’s wheels slip in the sand, they decided (with some reluctance) to skip the target and move to the next thing. 

NASA announced it was wrapping up operations in Marathon Valley in June 2016, and added that Opportunity recently got a close-up look of “red-toned, crumbly material” on the southern slope of the valley. Opportunity scuffed some of this material with a wheel, revealing material with some of the highest sulfur content seen on Mars. NASA said the scuff had strong evidence of magnesium sulfate, a substance expected to precipitate from water. 

As of August 2017, Opportunity was in a location called “Perseverance Valley” on the rim of Endeavour Crater, and the rover had traveled 27.95 miles (44.97 kilometers).

Courtesy-Space

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