Rocks From Mars

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Scientists studying life on Mars got a late Christmas present this year: confirmation that meteorites found in Morocco in December are of Martian origin. It’s a significant discovery; Martian meteorites fall to Earth only about once every 50 years making this a once-in-a-lifetime, and for many a once-in-a-career, event. The Mars rocks are worth more than their weight in gold, but what they can tell us could be even more valuable. 

Astronomers suspect that the meteorite has been wandering around the solar system for millions of years, ever since something big smashed into the red planet and sent debris flying all directions. One of those pieces has wandered its way towards Earth and plunged through the atmosphere.

ALH 84001, the meteorite found in Antarctica in 1984. Evidence of fossilized life inside the rock sparked a search for life on Mars. Image credit: NASA/ JSC

This is only the fifth time scientists have chemically confirmed the Martian origin of meteorites. Rocks found in France in 1815, in India in 1865, in Egypt in 1911, and in Nigeria in 1962 have all been positively identified as being from Mars.

The chemical signature of the Moroccan rocks and the Martian air match said Tony Irving of the University of Washington who did the scientific analysis. But this discovery is different. The rocks weren’t just found, they were seen streaking through the sky in July 2011, which makes them extremely valuable.

These rocks have only had six months to accumulate Earth-based materials and traces of life; typically Martian meteorites found on Earth have been here anywhere from decades to millennia, giving them ample time to become tainted.

These new rocks, while still contaminated because they have been on Earth for months, are relatively pure. “It’s incredibly fresh. It’s highly valuable for that reason,” said Carl Agee, director of the Institute of Meteoritics and curator at the University of New Mexico.

It’s also a rare find. This new sample, about 15 pounds of rocks, brings the total weight of all Martian samples on Earth to just 240 pounds.

Meteorite dealer Darryl Pitt is cashing in on the rocks’ rarity and selling pieces for $11,000 to $22,500 an ounce and has sold most of his supply already. At that price, the Martian meteorite costs about 10 times as much as gold.

An artist's conception of early Mars being hit by an asteroid wider than Texas. Scientists believe the impact melted the planet's crust in its northern hemisphere, flung crust into space, and sent shock wave through the planet's molten core (inset). This explains why Mars' crust is thinner in the northern hemisphere, according to three new studies. Image courtesy Jeff Andrews-Hanna; inset courtesy Francis Nimmo.

Cornell University astronomer Steve Squyres, the principal investigator for NASA’s Mars Exploration Rover Program, is less excited. The rocks, he said, are not the kind scientists are most hoping for. They are hard, igneous or volcanic rock. A softer kind of rock capable of holding water or life would be better. But he also points that these rocks aren’t likely to come streaking through the atmosphere. Any soft rock would be unlikely to survive the fiery entry through Earth’s atmosphere.

Former NASA sciences chief Alan Stern, director of the Florida Space Institute at the University of Central Florida, takes a brighter outlook. “It’s nice to have Mars sending samples to Earth,” he said, “particularly when our pockets are too empty to go get them ourselves.”

Until we manage a sample return mission from Mars, this is the best shot scientists have to study the red planet up close.

Source: physorg.

 

Who Owns Space History, the Public or the Astronauts?

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Former NASA astronaut Jim Lovell came under fire last week when he sold a personal memento from his tenure with the space agency at an auction – the 70-page checklist from the famous Apollo 13 mission that didn’t land on the Moon. The sale has reopened the ongoing debate over who owns NASA artifacts and photographs, the astronauts or the public.

Apollo 13 commander Lovell with a model Lunar module. Image credit: NASA

In Lovell’s case, the checklist is so valuable because it contains Lovell’s hand written calculations he used to navigate the crippled Apollo 13 spacecraft after its oxygen tank exploded. That’s a pretty important piece of history for many collectors. Bids on the historic item surpassed $388,000.

But now NASA is questioning whether Lovell had the right to sell the item and profit from its sale. For now, the checklist – along with a lunar module identification plate and a hand controller from Apollo 9 sold by former astronaut Rusty Schweickart and a glove Al Shepard wore on the Moon on Apollo 14 sold at the same auction – is locked in a Heritage Auctions vault until the issue is resolved.

NASA administrator Charles Bolden released a statement saying that there have been “fundamental misunderstandings and unclear policies” regarding items astronauts took home from the Mercury, Gemini, Apollo and Skylab mission.

These “misunderstandings and unclear policies” aren’t new. Last summer, NASA filed a lawsuit against Apollo 14 astronaut Ed Mitchell after he tried to sell a 16mm video camera he used on the Moon. NASA claimed Mitchell was selling the camera illegally and sued the former astronaut for ownership rights. Mitchell countered that the camera would have been left on the Moon had he not brought it home. It’s been sitting in his personal safe since 1971.

Mitchell isn’t wrong in his self defense. In the 1960s and 1970s, NASA officials told the astronauts that they could keep certain equipment from the missions.

In 2002, former Flight Director Chris Kraft said that he approved the policy. Apollo astronauts were allowed to keep personal items that flew with them as well anything from the lunar landing module that would otherwise have been abandoned on the Moon. The astronaut had great freedom in choosing what they wanted to keep.

Rusty Schweickart during an EVA on Apollo 9. Image credit: NASA/courtesy of nasaimages.org

“It was generally accepted that the astronauts could bring back pieces of equipment or hardware from this spacecraft for a keepsake of these journeys,” Kraft wrote.

Since the end of the space race, collectors around the world have paid millions to own pieces of history themselves. NASA’s problem isn’t with these former astronauts keeping pieces of history for themselves, it’s when they sell these artifacts for personal gain that creates a problem.

Kraft’s 2002 letter doesn’t address whether or not astronauts have the right to sell their mementos. In its recent letter to the auction house, NASA insisted only the agency can approve such artifacts for sale.

Bolden said the ownership discussions will explore “all policy, legislative and other legal means” to resolve ownership issues “and ensure that appropriate artifacts are preserved and available for display to the American people.” The agency has agreed to work cooperatively with the astronauts to resolve what’s recently become a contentious issue.

Apollo 14 Lunar Module pilot Mitchell. Image credit: NASA

It is a bit of a grey area. The astronauts did the work, they trained for difficult mission and went to the Moon. But NASA footed the bill, and American tax payers funded NASA. The space agency argues that artifacts from the Apollo era should be available to the public. Everyone should be able to view and experience these pieces of one of the nation’s historic achievements.

Source: Yahoo! News

India has Red Planet Fever

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Mars fever has gripped India. In a recent report from the Planetary Science and Exploration conference that was held in December 2011, scientists from the Indian Space Research Organization (ISRO) are making preliminary plans for a robotic mission to the Red Planet sometime next year. 

The possibility of an Indian mission to Mars first came up during a brainstorming session at the Physical Research Laboratory (PRL), an affiliate of the ISRO, last March. For two days, scientists and students developed their plans and proposals for a mission to the red planet.

A Mars Mission Study Team has been established to review proposed scenarios for the future mission, and an Indian chapter of the Mars Society formed last year at IIT-Mumbai.

Viking 2's view of Mars in 1976. Image credit: NASA/courtesy of nasaimages.org

The report from the meeting last month gives a concrete look at what Indian scientists have on their Martian wish list. In all, ten instruments and experiments comprise the ultimate mission.

En route to Mars, a Mars Radiation Spectrometer (Maris) will measure and characterize background levels of charged particles in interplanetary space. This data will play a vital role in determining radiation levels facing humans going to Mars.

Once at Mars, the proposed Indian mission will focus on the Martian atmosphere.

A Probe For Infrared Spectroscopy for Mars (Prism) is designed to study the spatial and seasonal variations of atmospheric gases on Mars’ atmosphere throughout the mission’s lifetime. The Mars Exospheric Neutral Composition Analyzer (Menca) is designed to analyze the planet’s upper atmosphere-exosphere, the region roughly 400 km (248 miles) above the surface.

Specific instruments are designed to study the composition of the atmosphere. A Methane Sensor For Mars (MSM) has been proposed to detect traces of the gas in the atmosphere. Another instrument, Tis, will measure thermal emissions to help scientists generate a map reflecting the composition and mineralogy of the planet. It will also help the team monitor carbon dioxide levels.

A Plasma and Current Experiment (Pace) will assess the escape rate of the atmosphere and the structure of the “tail” this escaping atmosphere creates. Radio and microwave instruments will also be on board the spacecraft to measure the planet’s surface activity. A suite of instruments will also be on hand to detect plasma waves in the atmosphere.

Mars's atmosphere is only 1 percent as thick as Earth's. Image credit: NASA

Visual measurements are also part of the proposed mission. The Mars Color Camera (MCC) is designed to photograph the Martian surface from a highly elliptical orbit, roughly 500 km by 80,000 km (310 miles by 49,700 miles). The camera will be able to take high resolution images of the topography of the surface and map the polar caps, both of which are expected to help scientists understand surface events like dust storms.

According to ISRO scientists, the proposed mission could launch as early as November 2013, which would have the spacecraft enter into orbit around Mars in September 2014. A launch so relatively soon is appealing to many Indian scientists, many of whom argue that a mission to Mars should take priority over a mission to the Moon.

After all, India has already reached the Moon with the successful Chandrayaan-2 spacecraft. Why not keep the momentum going and aim for a new and exciting target with the next mission?

Source: Asian Scientist

Astronomers Find Saturn’s Possible Cosmic Doppelgänger

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By analyzing the silhouette of an exoplanet passing in front of its parent star some 420 light years from Earth, a team of astrophysicists has discovered an exoplanet that just might turn out to be Saturn’s cosmic doppelgänger. 

Assistant Professor of Physics and Astronomy at Rochester University Eric Mamajek and graduate student Mark Pecaut studied data from the international SuperWASP (Wide Angle Search for Planets) and All Sky Automated Survey (ASAS) project.

An artist's impression of a brown dwarf surrounded by a cloud of proto-planet dust. Image credit: JPL

They were looking at the star’s light pattern; periodic dimming is a telltale sign that a planet is passing in front of it. A spherical planet will dim a star’s light regularly. As seen from Earth, the star’s light will dim as the planet starts to cross it, getting darker until it reaches a point of maximum dimness – the point when the planet is directly between the Earth and the star. Then, the light will get brighter at the same pace as it previously dimmed.

But in December 2010, they noticed something odd. As they analyzed data gathered over a 54 day period in early 2007, the star 1SWASP J140747.93-394542.6 dimmed irregularly. The object passing in front of it couldn’t be a spherical planet, so what was it?

The object had an elliptical silhouette, it was blocking the star’s light in an intermittent and irregular pattern, and was obscuring a significant portion of the star’s light. At one point in the pass, 95 percent of the star’s light was obscured, most likely by dust.

“When I first saw the light curve, I knew we had found a very weird and unique object,” said Mamajek. “After we ruled out the eclipse being due to a spherical star or a circumstellar disk passing in front of the star, I realized that the only plausible explanation was some sort of dust ring system orbiting a smaller companion—basically a ‘Saturn on steroids.'” Rings were the likeliest culprit of the oscillating dimness in the star’s light.

“This marks the first time astronomers have detected an extrasolar ring system transiting a Sun-like star, and the first system of discrete, thin, dust rings detected around a very low-mass object outside of our solar system,” said Mamajek. But there are still some major questions about what exactly has been discovered.

A size comparison between the Sun, a low mass star, a brown dwarf, Jupiter, and the Earth. Image credit: NASA

It could be a very low-mass star, brown dwarf, or gas giant planet. But it’s still too early to know either way. To arrive at some answer, they will need to determine the object’s mass.

A planet that size will exert a gravitational pull on its star in the same way that Jupiter tugs on the Sun. The amount of wobbling this gravitational interaction creates can reveal the mass of the object and give astronomers a clue about what it might be. If it has a mass between 13 and 75 times that of Jupiter, it will likely be a brown dwarf. If it’s any smaller, astronomers will know that it’s likely a planet more similar to Saturn.

Two of Saturn's shepherd moons keep the planet's F ring in check. Image Credit: NASA/JPL

The object itself isn’t the only interesting part of the find; Mamajek is particularly interested in the gaps between the apparent rings that are optically similar to those around Saturn. Gaps are usually indicative of objects within the rings with enough gravitational influence to shape them, like Saturn’s shepherd moons.

But even if the rings turn out to be a cloud of dust, the discovery will be no less exciting. If the object turns out to be a brown dwarf with a cloud of dust, Mamajek thinks it’s likely his team has observed the late stages of planet formation. Or, if the object is a large planet, they may be observing the formation of moons around the giant planet.

Either way it’s an awesome discovery. As cool as finding Saturn’s twin would be, watching moons form around another planet would be equally fascinating. The team’s findings will be published in an upcoming issue of the Astronomical Journal.

Source: University of Rochester.

Scientists Find Trio of Tiny Exoplanets

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NASA’s Kepler mission has detected no shortage of planets; more than a thousand candidates were discovered in 2011, a handful of which were Earth-like in size. As data from the mission keeps pouring in, astronomers are continuing to confirm and classify these possible exoplanets. Today, a team of astronomers from the California Institute of Technology added three more to the growing list. They have confirmed the three smallest exoplanets yet discovered.

Kepler searches for planets by looking at stars. The light from the star flickers or dips when a planet passes in front of it. At least three passes are required to confirm that the signal is from a planet, and further ground-based observations are necessary before a discovery can be confirmed.

An artist's impression of Kepler's field of view, the area in which it is constantly searching for new planets. Image Credit: Jon Lomberg/NASA

The Cal Tech team’s discovery was made with old data from Kepler. They found that the three planets are rocky like Earth and orbit a single star called KOI-961. They are also smaller than our planet; their radii are 0.78, 0.73 and 0.57 times that of Earth. As a comparison, the smallest of the three is roughly the size of Mars.

That these planets are so small is big news; they were thought to be much bigger when they were first found. Finding a planet as small as Mars is particularly amazing, said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington. It “hints that there may be a bounty of rocky planets all around us.”

The whole system is also small. The planets orbit so close to their star that their year lasts only two days. “This is the tiniest solar system found so far,” said John Johnson, the principal investigator of the research from NASA’s Exoplanet Science Institute at Cal Tech in Pasadena.

A view of Kepler's search area as seen from Earth. Image credit: Carter Roberts / Eastbay Astronomical Society

Their star, KOI-961, is a red dwarf with a diameter one-sixth that of our Sun and it is only 70 percent larger than Jupiter. This makes the system’s scale much closer to that of Jupiter and its moons than that of the Sun and the planets in our Solar System. As Johnson explains, this speaks to “the diversity of planetary systems in our galaxy.”

The type of star is also significant. Red dwarfs are the most common stars in the Milky Way galaxy, and the discovery of three rocky planets around one suggests that the galaxy could be teeming with similar rocky planets.

The team’s find, however, isn’t going to provide us with intergalactic vacation homes anytime soon. The planets are all too close to their star to be in the habitable zone, an orbit where water can exist as a liquid on the surface. Nevertheless, the tiny planets are a significant find. “These types of systems could be ubiquitous in the universe,” said Phil Muirhead, lead author of the new study from Caltech. “This is a really exciting time for planet hunters.”

Source: NASA’s Kepler Mission Find Three Smallest Exoplanets.

Does Life on the Seafloor Predict Life on Other Worlds?

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Scientists have recently discovered communities of previously unknown species living on the seafloor near Antarctica clustered around hydrothermal vents. This discovery is certainly exciting for biologists, but it’s also important for astrobiologists. It begs the question — if life can thrive in the deep, dark oceans without sunlight, could similar life thrive elsewhere in our solar system or the universe?

For decades, scientists assumed the deep oceans were barren; sunlight can’t reach the ocean floor, making it an impossible environment for life as we know it to arise. But in 1977, oceanographers from the Scripps Institute discovered hydrothermal vents.

A schematic diagram of deep sea vent chemistry. Image credit: National Oceanic and Atmospheric Administration

These fissures, found along mid-ocean ridges on the seafloor of the Pacific, Atlantic, and Indian Oceans, create a natural, deep-sea plumbing system. Heat and minerals from the Earth’s interior vents out, providing a complex ecosystem that can reach up to 382 degrees Celsius (almost 720 degrees Fahrenheit). These ecosystems can support unique life forms that get their energy not from the Sun but from breaking down chemicals issued from the vents such as hydrogen sulphide.

The latest life forms, discovered in the Antarctic region by teams from the University of Oxford, University of Southampton and British Antarctic Survey, include a new species of yeti crab, starfish, barnacles, sea anemones, and potentially an octopus.

“These findings are yet more evidence of the precious diversity to be found throughout the world’s oceans,” said Professor Rogers of Oxford University’s Department of Zoology. “Everywhere we look, whether it is in the sunlit coral reefs of tropical waters or these Antarctic vents shrouded in eternal darkness, we find unique ecosystems that we need to understand and protect.”

Jupiter's moon Europa. The lines on the surface are breaks in the ice that lie on top of vast oceans. Image credit: NASA/courtesy of nasaimages.org

But it isn’t only biologists studying life on Earth that can benefit from this latest discovery. These peculiar environments on and beneath the seafloor could be a model for the origin of life on Earth and on other planets.

One particular target is Jupiter’s moon Europa. Recent research has confirmed that the moon has vast oceans buried beneath its frozen surface ice; it’s estimated to hold twice as much water as Earth. As such, it is a target for NASA in the search for life. It could be the case that some type of hydrothermal vent system exists on Europa, making its distance from the Sun irrelevant for life.

But just because sulfur or methane-based life on Earth can thrive around deep-ocean vents doesn’t mean the same is true on Europa. The presence of hydrothermal vents depends on geologic activity and a hot interior, neither of which has been confirmed. The possibility remains that light energy from the Sun could travel the distance to the moon and provide shallower portions of the subsurface oceans with life-giving light.

In any case, as scientists discover life in the more extreme environments on Earth, analogies are drawn with other worlds. If life is discovered in hostile parts of our planet, the same could theoretically arise in similar environments on other worlds.

Source: ‘Lost World’ discovered around Antarctic vents.

Missions that Weren’t: One-Way Mission to the Moon

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When President Kennedy promised America a lunar landing in 1961, he effectively set the Moon as the finish line in the space race. In the wake of his speech, NASA began scrambling to find a way to reach the Moon in advance of the Soviet Union, which at the time held a commanding lead in space. Apollo, already on the drawing board as an Earth orbiting program, was revised to reflect the lunar goal and Gemini was established as the interim program.

The pieces were in place; all NASA needed was a way to get to the Moon. Against this pressing background, two men proposed a desperate and direct mission to get an American on the Moon as quickly as possible. 

A schematic showing three different flight modes for Apollo lunar missions. Image credit: NASA

The proposal came from two Bell Aerosystems Company employees. John M. Cord was a Project Engineer in the Advanced Design Division and Leonard M. Seale was a psychologist in charge of the Human Factors Division. At the Institute of Aerospace Sciences in Los Angeles in 1962, the pair unveiled their “One-Way Manned Space Mission” proposal.

The plan called for a one-man spacecraft to follow a direct ascent path to the Moon. Ten feet wide and seven feet tall, the empty spacecraft weighed less than half the much smaller Mercury capsule. Inside, the astronaut would have enough water for 12 days, oxygen for 18 with a 12-day emergency reserve, a battery-powered suit and backpack, and all the tools and medical supplies he might need.

He would land on the Moon after a two-and-a-half day trip and have just under ten days to set up his habitat. As part of his payload, the astronaut would arrive with four cargo modules with pre-installed life support systems and a nuclear reactor to generate electrical power. Two mated modules would become his primary living quarters, while the others placed in caves or buried in rubble — a feature Cord and Seale assumed would dominate the lunar landscape — would provide a shelter from solar storms.

A possible configuration for a direct ascent Apollo spacecraft. Image credit: NASA

With his temporary home set up, he would wait a little over two years for another mission to come and collect him. Cord and Seale estimated that this mission could be launched as early as 1965, a year of expected minimal solar activity. Larger launch vehicles capable of sending the three-man Apollo spacecraft would be ready by 1967. The one-way spaceman would have a long but finite stay on the Moon.

This proposal was incredibly practical. Since the astronaut wouldn’t be launching from the lunar surface, he wouldn’t need to carry the necessary propellant. Since he would return to Earth in another spacecraft, his own spacecraft wouldn’t need a heavy heat shield or parachutes. The one-way mission was a light and efficient proposal.

But it was also dangerous. The proposal didn’t include any redundancies; the direct ascent path gave the astronaut no chance to abort his mission after launch. He would have to deal with any problems that arose knowing he wouldn’t be able to make a quick return home.

Luckily for the possible astronaut the proposal was never seriously considered. In July 1962, a few weeks after the one-way mission was proposed, NASA announced its selection of the more complicated but safer Lunar Orbit Rendezvous (LOR) mode for Apollo missions.

John Houbolt explains the benefits of Lunar Orbit Rendezvous over Direct Ascent. Image credit: NASA/courtesy of nasaimages.org

Slower than Light Neutrinos

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Earlier this year, an international team of scientists announced they had found neutrinos — tiny particles with an equally tiny but non-zero mass — traveling faster than the speed of light. Unable to find a flaw themselves, the team put out a call for physicists worldwide to check their experiment. One physicist who answered the call was Dr. Ramanath Cowsik. He found a potentially fatal flaw in the experiment that challenged the existence of faster than light neutrinos. 

Superluminal (faster than light) neutrinos were the result of the OPERA experiment, a collaboration between the CERN physics laboratory in Geneva, Switzerland, and the Laboratori Nazionali del Gran Sasso in Gran Sasso, Italy.

Scientists at CERN managed to repeat their result of neutrinos travelling faster than the speed of light. Image credit: Cern/Science Photo Library

The experiment timed neutrinos as they traveled 730 kilometres (about 450 miles) through Earth from their origin point at CERN to a detector in Gran Sasso. The team was shocked to find that the neutrinos arrived at Gran Sasso 60 nanoseconds sooner than they would have if they were traveling at the speed of light in a vacuum. In short, they appeared to be superluminal.

This result created either a problem for physics or a breakthrough. According to Einstein’s theory of special relativity, any particle with mass can come close to the speed of light but can’t reach it. Since neutrinos have mass, superluminal neutrinos shouldn’t exist. But, somehow, they did.

But Cowsik questioned the neutrinos’ genesis. The OPERA experiments generated neutrinos by slamming protons into a stationary target. This produced a pulse of pions, unstable particles that were magnetically focused into a tunnel where they decayed into neutrinos and muons (another tiny elementary particle). The muons never went further than the tunnel, but the neutrinos, which can slip through matter like a ghost passes through a wall, kept going towards Gran Sasso.

The creation of a neutrino and a muon. Image credit: J. Sonier

Cowsik’s and his team looked closely at this first step of the OPERA experiment. They investigated whether “pion decays would produce superluminal neutrinos, assuming energy and momentum are conserved,” he said. The OPERA neutrinos had a lot of energy but very little mass, so the question was whether they could really move faster than light.

What Cowsik and his team found was that if neutrinos produced from a pion decay were traveling faster than light, the pion lifetime would get longer and each neutrino would carry a smaller fraction of the energy it shares with the muon. Within the present framework of physics, superluminal neutrinos would be very difficult to produce. “What’s more,”Cowsik explains, “these difficulties would only increase as the pion energy increases.

There is an experimental check of Cowsik’s theoretical conclusion. CERN’s method of producing neutrinos is duplicated naturally when cosmic rays hit Earth’s atmosphere. An observatory called IceCube is set up to observe these naturally occurring neutrinos in Antarctica; as neutrinos collide with other particles, they generate muons that leave trails of light flashes as they pass through a nearly 2.5 kilometre (1.5 mile) thick block of clear ice.

A schematic image of IceCube. ICE.WISC.EDU / PETE GUEST

IceCube has detected neutrinos with energy 10,000 times higher than any generated as part of the OPERA experiment, leading Cowsik to conclude that their parent pions must have correspondingly high energy levels. His team’s calculations based on laws of the conservation of energy and momentum revealed that the lifetimes of those pions should be too long for them to decay into superluminal neutrinos.

As Cowsik explains, IceCube’s detection of high-energy neutrinos is indicative that pions do decay according to standard ideas of physics, but the neutrinos will only approach the speed of light; they will never exceed it.

Source: Pions Don’t Want to Decay into Faster the Light Neutrinos

Faster than Light Neutrinos (maybe): Field Trip!

What if the Earth had Two Moons?

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The idea of an Earth with two moons has been a science fiction staple for decades. More recently, real possibilities of an Earth with two moons have popped up. The properties of the Moon’s far side has many scientists thinking that another moon used to orbit the Earth before smashing into the Moon and becoming part of its mass. Since 2006, astronomers have been tracking smaller secondary moons that our own Earth-Moon system captures; these metre-wide moons stay for a few months then leave.

But what if the Earth actually had a second permanent moon today? How different would life be? Astronomer and physicist Neil F. Comins delves into this thought experiment, and suggests some very interesting consequences. 

This shot of Io orbiting Jupiter shows the scale between other moons and their planet. Image credit:NASA/courtesy of nasaimages.org

Our Earth-Moon system is unique in the solar system. The Moon is 1/81 the mass of Earth while most moons are only about 3/10,000 the mass of their planet. The size of the Moon is a major contributing factor to complex life on Earth. It is responsible for the high tides that stirred up the primordial soup of the early Earth, it’s the reason our day is 24 hours long, it gives light for the variety of life forms that live and hunt during the night, and it keeps our planet’s axis tilted at the same angle to give us a constant cycle of seasons.

A second moon would change that.

For his two-mooned Earth thought experiment, Comins proposes that our Earth-Moon system formed as it did — he needs the same early conditions that allowed life to form — before capturing a third body. This moon, which I will call Luna, sits halfway between the Earth and the Moon.

Luna’s arrival would wreak havoc on Earth. Its gravity would tug on the planet causing absolutely massive tsunamis, earthquakes, and increased volcanic activity. The ash and chemicals raining down would cause a mass extinction on Earth.

But after a few weeks, things would start to settle.

Luna would adjust to its new position between the Earth and the Moon. The pull from both bodies would cause land tides and volcanic activity on the new moon; it would develop activity akin to Jupiter’s volcanic moon Io. The constant volcanic activity would make Luna smooth and uniform, as well as a beautiful fixture in the night sky.

New Horizons captured this image of volcanic activity on Io. The same sight could be seen of Luna from Earth. Image credit: NASA/courtesy of nasaimages.org

The Earth would also adjust to its two moons, giving life a chance to arise. But life on a two-mooned Earth would be different.

The combined light from the Moon and Luna would make for much brighter nights, and their different orbital periods will mean the Earth would have fewer fully dark nights. This will lead to different kinds of nocturnal beings; nighttime hunters would have an easier time seeing their prey, but the prey would develop better camouflage mechanisms. The need to survive could lead to more cunning and intelligent breeds of nocturnal animals.

Humans would have to adapt to the challenges of this two-mooned Earth. The higher tides created by Luna would make shoreline living almost impossible — the difference between high and low tides would be measured in thousands of feet. Proximity to the water is a necessity for sewage draining and transport of goods, but with higher tides and stronger erosion, humans would have to develop different ways of using the oceans for transfer and travel. The habitable area of Earth, then, would be much smaller.

The measurement of time would also be different. Our months would be irrelevant. Instead, a system of full and partials months would be necessary to account for the movement of two moons.

A scale comparison of the Earth, the Moon, and Jupiter's largest moons (the Jovian moons). Image credit:Image Credit: NASA/courtesy of nasaimages.org

Eventually, the Moon and Luna would collide; like the Moon is now, both moons would be receding from Earth. Their eventual collision would send debris raining through Earth’s atmosphere and lead to another mass extinction. The end result would be one moon orbiting the Earth, and life another era of life would be primed to start.

Source: Neil Comins’ What if the Earth had Two Moons? And Nine Other Thought Provoking Speculations on the Solar System.

Why Do We Live in Three Dimensions?

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Day to day life has made us all comfortable with 3 dimensions; we constantly interact with objects that have height, width, and depth. But why our universe has three spatial dimensions has been a problem for physicists, especially since the 3-dimensional universe isn’t easily explained within superstring theory or Big Bang cosmology. Recently, three researchers have come up with an explanation.  

The history of the universe starting the with the Big Bang. Image credit: grandunificationtheory.com

Most astronomers subscribe to Big Bang cosmology, the model that proposes that the universe was born from the explosion of an infinitely tiny point. The theory is supported by observations of the cosmic microwave background and the abundance of certain naturally occurring elements. But Big Bang cosmology is at odds with Einstein’s theory of general relativity – general relativity doesn’t allow for any situation in which the whole universe is one tiny point, which means this theory alone can’t explain the origin of the universe.

The incompatibility between general relativity and Big Bang cosmology has stumped cosmologists. But almost 40 years ago, superstring theory arose as a possible unifying theory of everything.

A visualization of strings. Image credit: R. Dijkgraaf.

Superstring theory suggests that the four fundamental interactions among elementary particles – electromagnetic force, weak interaction, strong interaction, and gravity – are represented as various oscillation modes of very tiny strings. Because gravity is one of the fundamental forces, superstring theory includes an explanation of general relativity. The problem is, superstring theory predicts that there are 10 dimensions – 9 spatial and one temporal. How does this work with our 3 dimensional universe?

Superstring theory has remained little more than a theory for years. Investigations have been restricted to discussing models and scenarios since performing the actual calculations have been incredibly difficult. As such, superstring theory’s validity and usefulness have remained unclear.

But a group of three researchers, associate professor at KEK Jun Nishimura, associate professor at Shizuoka University Asato Tsuchiya, and project researcher at Osaka University Sang-Woo Kim, has succeeded in generating a model of the universe’s birth based on superstring theory.

Using a supercomputer, they found that at the moment of the Big Bang, the universe had 10 dimensions – 9 spatial and 1 temporal – but only 3 of these spatial dimensions expanded.

This "baby picture" of the universe shows tiny variations in the microwave background radiation temperature. Hot spots show as red, cold spots as dark blue.Credit: NASA/WMAP Science Team

The team developed a method for calculating matrices that represent the interactions of strings. They used these matrices to calculate how 9 dimensional space changes over time. As they moved further back in time, they found that space is extended in 9 directions, but at one point only 3 directions start to expand rapidly.

In short, the 3 dimensional space that we live in can result from the 9 original spatial dimensions string theory predicts.

This result is only part of the solution to the space-time dimensionality puzzle, but it strongly supports the validity of superstring theory. It’s possible, though, that this new method of analyzing superstring theory with supercomputers will lead to its application towards solving other cosmological questions.

 Source: The mechanism that explains why our universe was born with 3 dimensions.