Showing posts with label mars. Show all posts
Showing posts with label mars. Show all posts

Monday, July 24, 2017

VASIMR plasma engine: Earth to Mars in 39 days?

VASIMR plasma engine: Earth to Mars in 39 days?:



Artist's impression of a 200-megawatt VASIMR spacecraft. Images Credit: Ad Astra Rocket Company
Artist’s impression of a 200-megawatt VASIMR spacecraft. Images Credit: Ad Astra Rocket Company
In Arthur C. Clarke’s classic science fiction novels and movies 2001: A Space Odyssey and 2010: Odyssey Two, the spaceships Discovery and Alexei Leonov make interplanetary journeys using plasma drives. Nuclear reactors heat hydrogen or ammonia to a plasma state that’s energetic enough to provide thrust.

In 1983, seven-time Space Shuttle Astronaut Franklin Chang Diaz turned Clarke’s speculations into reality with an engine known as the Variable Specific Impulse Magnetoplasma Rocket (VASIMR).

An electric power source ionizes hydrogen, deuterium, or helium fuel into a plasma by stripping away electrons. Magnetic fields then direct the charged gas in the proper direction to provide thrust.

“A rocket engine is a canister holding high-pressure gas,” Chang Diaz explained. “When you open a hole at one end, the gas squirts out and the rocket goes the other way. The hotter the stuff in the canister, the higher the speed it escapes and the faster the rocket goes. But if it’s too hot, it melts the canister.”

The VASIMR engine is different, Chang Diaz explained, because of the fuel’s electrical charge: “When gas gets above 10,000 [kelvins], it changes to plasma – an electrically charged soup of particles. And these particles can be held together by a magnetic field. The magnetic field becomes the canister, and there is no limit to how hot you can make the plasma.”



VASIMR operation diagram


VASIMR® operation diagram. Credit & Copyright: Ad Astra Rocket Company © all rights reserved
Chang Diaz has pointed out that hydrogen would be an advantageous fuel for the VASIMR engine because the spacecraft would not have to lift off carrying all the fuel it needs for the journey.



VASIMR system


VASIMR® System. Image Credit: Ad Astra Rocket Company
“We’re likely to find hydrogen pretty much anywhere we go in the Solar System,” he said.

A spacecraft using conventional chemical rockets would take eight months to get to Mars during opposition. However, the VASIMR engine would make the journey in as little as 39 days.

Chang Diaz explained: “Remember, you are accelerating the first half of the journey – the other half you’re slowing, so you will reach Mars but not pass it. The top speed with respect to the Sun would be about 32 miles per second [or 51.5 km/s]. But that requires a nuclear power source to heat the plasma to the proper temperature.”

The use of nuclear power in space is not without its controversy. In 1997, there was widespread public concern when NASA’s Cassini probe, which carried a plutonium battery, made a flyby of Earth to perform a gravity assist. Although NASA denied that the risk to the public, should an accident occur, was no greater than that posed every day by other sources of radiation, some scientists, including the popular theoretical physicist Michio Kaku, disagreed.

In April 1970, the Atomic Energy Commission was deeply concerned about the return of Apollo 13 to Earth. Where an Apollo mission would usually leave the lunar module’s descent stage on the Moon, the unsuccessful Apollo 13 dropped its lunar module Aquarius, with its plutonium-powered scientific experiments, into the ocean, raising concerns about radioactive contamination.

Elon Musk, CEO of Space Exploration Technologies Corporation (SpaceX), is skeptical about the viability of the VASIMR engine. One reason is the concern about radioactive debris falling to Earth in the event of an accident.

Musk is also skeptical that the VASIMR engine would be a significant improvement over chemical rockets, stating: “So people like Franklin – basically it’s a very interesting ion engine he’s got there, but it requires a big nuclear reactor. The ion engine is going to help a little bit, but not a lot in the absence of a big nuclear reactor.” Musk also points out that the big nuclear reactor would add a lot of weight to a rocket.

Chang Diaz dismisses the concerns about nuclear reactors in space, stating: “People are afraid of nuclear power. Chernobyl, Three Mile Island, Fukushima – it is a little misunderstood. But if humans are truly going to explore space, we eventually will have to come to grips with the concept.”

Another vocal critic of the VASIMR engine is Robert Zubrin, president of The Mars Society, who designed the Mars Direct plan to colonize Mars and wrote the popular book The Case For Mars. He has gone as far as to call the VASIMR engine a “hoax”.

Zubrin wrote in SpaceNews: “To achieve his much-repeated claim that VASIMR could enable a 39-day one-way transit to Mars, Chang Diaz posits a nuclear reactor system with a power of 200,000 kilowatts and a power-to-mass ratio of 1,000 watts per kilogram. In fact, the largest space nuclear reactor ever built, the Soviet[-era] Topaz, had a power of 10 kilowatts and a power-to-mass ratio of 10 watts per kilogram. There is thus no basis whatsoever for believing in the feasibility of Chang Diaz’s fantasy power system.”

Chang Diaz, however, says in his paper: “Assuming advanced technologies [emphasis added] that reduce the total specific mass to less than 2 kg/kW, trip times of less than 60 days will be possible with 200 MW of electrical power. One-way trips to Mars lasting less than 39 days are even conceivable using 200 MW of power if technological advances allow the specific mass to be reduced to near or below 1 kg/kW.”



VASIMR-200kW-Moon-Cargo-Ship_800px.jpg
Bekuo-10MW_800px.jpg


LEFT: Artist’s rendition of a lunar tug with 200 kW solar powered VASIMR®. RIGHT: Artist’s rendition of a human mission to Mars with 10 MW NEP-VASIMR®. Images Credit: Ad Astra Rocket Company
In other words, Chang Diaz is allowing for further developments that would enable such a reactor.

Zubrin, however, stated: “[T]he fact that the [Obama] administration is not making an effort to develop a space nuclear reactor of any kind, let alone the gigantic super-advanced one needed for the VASIMR hyper drive, demonstrates that the program is being conducted on false premises.”

The 2011 NASA research paper “Multi-MW Closed Cycle MHD Nuclear Space Power Via Nonequilibrium He/Xe Working Plasma” by Ron J. Litchford and Nobuhiro Harada, indicates that such developments are feasible in the near future.

Whether the VASIMR engine is viable or not, in 2015, NASA awarded Chang Diaz’s firm – Ad Astra Rocket Company™ – a three-year, $9 million contract. Up to now, the VASIMR engine has fired at fifty kilowatts for one minute – still a long way from Chang Diaz’s goal of 200 megawatts.

In its current form, the VASIMR engine uses argon for fuel. The first stage of the rocket heats the argon to plasma and injects it into the booster. There, a radio frequency excites the ions in a process called ion cyclotron resonance heating. As they pick up energy, they are spun into a stream of superheated plasma and accelerated out the back of the rocket.



Video courtesy of Ad Astra Rocket Company


The post VASIMR plasma engine: Earth to Mars in 39 days? appeared first on SpaceFlight Insider.

Giant asteroid crashed into Mars billions of years ago, study suggests

Giant asteroid crashed into Mars billions of years ago, study suggests:

Asteroid impacts on the surface of Mars NASA image
Is it possible that past asteroid impacts could have caused the two distinct geological regions that we now see on the face of Mars? Image Credit: NASA
The complex geology of Mars and the origin of its two small irregular moons has mystified planetary scientists for some time. A new study, published in June in the journal Geophysical Research Letters, reveals that the Red Planet had suffered a giant asteroid collision nearly four-and-a-half billion years ago which could account for some of Mars’ geological oddities.

Mars is known for havings two geologically distinct hemispheres. The planet has smooth lowlands in the north and cratered, high-elevation surface in the south. The origin of this dichotomy has baffled geologists for decades.



A global false-color topographic view of Mars from the Mars Orbiter Laser Altimeter (MOLA) experiment. The spatial resolution is about 15 kilometers at the equator and less at higher latitudes, with a vertical accuracy of less than 5 meters. The figure illustrates topographic features associated with resurfacing of the northern hemisphere lowlands in the vicinity of the Utopia impact basin (at the near-center of the image in blue).


A global false-color topographic view of Mars from the Mars Orbiter Laser Altimeter (MOLA) experiment. The spatial resolution is about 15 kilometers at the equator and less at higher latitudes, with a vertical accuracy of less than 5 meters. The figure illustrates topographic features associated with resurfacing of the northern hemisphere lowlands in the vicinity of the Utopia impact basin (at the near-center of the image in blue). Image Credit: MOLA Science Team
Scientists have suggested that erosion, plate tectonics, or ancient oceans could have carved these two different landscapes; however, the most plausible hypothesis is thought to be that a giant celestial body that smashed into Mars was the cause of the planet’s geological dichotomy.

A new research conducted by Stephen Mojzsis of the University of Colorado Boulder and Ramon Brasser of the Tokyo Institute of Technology in Japan, adds new evidence supporting the “single impact hypothesis”.

The researchers have analyzed Martian meteorites and found an overabundance of rare metals such as platinum, osmium, and iridium. The results indicate that most likely a huge asteroid impact enriched Mars’ mantle with these noble metals.

“It is well within the realm of possibility that the Martian hemispherical dichotomy is the result of this giant impact,” the authors wrote in the paper.

The simulations carried out by Mojzsis and Brasser show that a giant collision might have taken place some 4.43 billion years ago, during first 130 million years of Martian history. According to the calculations, the impactor would have been at least 745 miles (1,200 kilometers) in diameter in order to cause the geological dichotomy that we see today on Mars.

The study also reveals that the debris ejected after the impact could have formed Phobos and Deimos – the two oddly shaped moons of Mars. The researchers suggest that the impact generated a ring of material around the Red Planet that later merged into the two satellites. This could partially explain why Phobos and Deimos are made of a mix of native and non-Martian material.

“An impact of this magnitude would also be expected to eject a substantial amount of material into orbit around Mars, which could then be the source material that eventually formed its satellites,” the paper reads.

In concluding remarks, the scientists noted that the geological dichotomy on Mars could be one of the oldest geophysical features of the Martian crust.

Mojzsis and Brasser plan more studies of Martian meteorites that will once again test the “single impact hypothesis”. They hope that further research focused on different isotopic systems in the oldest components of the meteorites will bring more promising results and further confirm the studied hypothesis.



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Saturday, March 7, 2015

The Night Mars Was Closest to Earth

The Night Mars Was Closest to Earth:



On Earth, Don Parker’s Mars images were hard to beat, but the Hubble Space Telescope—six times larger than his 16-inch ‘scope and, more importantly, above the atmosphere—easily pulled it off. In this pair of images taken around the time of the planet’s closest approach in 2003, the giant volcano Olympus Mons is the small, bright circular feature above center. Image courtesy Andrew Chaikin.


On Earth, Don Parker’s Mars images were hard to beat, but the Hubble Space Telescope—six times larger than his 16-inch ‘scope and, more importantly, above the atmosphere—easily pulled it off. In this pair of images taken around the time of the planet’s closest approach in 2003, the giant volcano Olympus Mons is the small, bright circular feature above center. Image courtesy Andrew Chaikin.
Editor’s note: On August 27, 2003 Mars was closer to Earth than at any time in human history. Author Andrew Chaikin asked Universe Today to tell the story of how he was fortunate enough to enjoy the event with Don Parker, a “superb planetary photographer and wonderful guy,” Chaikin wrote. “I first met Don, a retired anesthesiologist from Coral Gables, Florida, several weeks earlier when I journeyed with my telescope to Florida to photograph the Moon passing in front of Mars, an event called an occultation. I’d seen Don’s work for decades in Sky & Telescope magazine, but until the occultation we’d never met. I certainly had never imagined that he would turn out to be as much fun as he was, with a warped, wickedly bawdy sense of humor. Standing under the moon and Mars we bonded, and soon we were making plans for me to come down to his place for the closest approach.”

Don passed away on February 22, 2015. In his memory here’s an excerpt from Chaikin’s book, A Passion for Mars.

Godspeed, Don. See you on Mars.




Don Parker with his 16-inch telescope, which he used to take thousands of superb images of the planets. Photo by Sean Walker.


Don Parker with his 16-inch telescope, which he used to take thousands of superb images of the planets. Photo by Sean Walker.
ON PAPER, Don Parker’s life story is pretty ordinary: Born in 1939, he grew up in an Italian neighborhood in Chicago. He spent a few years in the navy, went to medical school, and ended up living in Florida with his wife, Maureen, and their children, working as an anesthesiologist in a Miami hospital. Looking at his résumé you’d never know about his other life, the one dominated by a lifelong obsession with Mars. By the time he went to see Invaders from Mars and War of the Worlds as a teenager in 1953, he was building his first telescope, a three-inch refractor with lenses from Edmund Scientific and a body made from a stovepipe his dad got for him.

He was subscribing to Sky & Telescope magazine and following the continuing debate over whether the canals on Mars really existed. That was a question that only a handful of professional astronomers cared about, but amateur observers, like the ones whose drawings were printed in the magazine, seemed to be on the case. Parker got serious about observing Mars himself around 1954, when he tried to create a homemade reflector, but failed when he had trouble with the mirror. His aunt Hattie came to the rescue that Christmas by giving him a hundred dollar bill — quite a bit of money in those days — which he used to buy a professionally made eight-inch mirror. With help from his dad, he assembled the new telescope, using pipe fittings for the mounting.

In the summer of 1956, when Mars made its famously close appearance, he was at the eyepiece making drawings of his own, until a dust storm engulfed much of the planet that September, just as Mars came closest to Earth. “Mars looked like a cue ball,” Parker remembers. “There was nothing on it. It was very disappointing for me.” At the time, he thought the problem was with his instrument. “I even took the mirror out of the telescope,” he recalls. “You know,‘What the hell is going on here?’” Only much later, when information on Martian dust storms began to show up in the amateur astronomy literature, did he realize his view had been spoiled by an event happening on Mars.



Gullies on a Martian sand dune in this trio of images from NASA's Mars Reconnaissance Orbiter deceptively resemble features on Earth that are carved by streams of water. However, these gullies likely owe their existence to entirely different geological processes apparently related to the winter buildup of carbon-dioxide frost. Image Credit: NASA/JPL-Caltech/University of Arizona


Gullies on a Martian sand dune in this trio of images from NASA’s Mars Reconnaissance Orbiter deceptively resemble features on Earth that are carved by streams of water. However, these gullies likely owe their existence to entirely different geological processes apparently related to the winter buildup of carbon-dioxide frost. Image Credit: NASA/JPL-Caltech/University of Arizona
By that time Parker was in high school, and soon Martian canals became much less important than more earthly matters. “Football and blondes were my major,” he quips. Then it was off to college, and his telescope sat unused in its wooden shelter in the backyard. When it came time for his internship he convinced his wife, Maureen, that they should move to Florida so he could pursue his interest in scuba diving.

Needless to say he had no time for astronomy then, or during his residency. Then came a stint in the navy, and by the early 1970s he was back in Florida, beginning his career as an anesthesiologist and raising a family. By the time Mars made another close approach in 1973 Parker had brought his telescope down from Chicago; his parents had asked him to take it out of the backyard so they could put in a birdbath, and a few months after that, he remembers, “Maureen said, ‘Can you get that thing out of the garage?’”

He didn’t expect it to do him much good outside, however. The conventional wisdom was that south Florida, with its clouds and frequent storms, was a terrible place to do astronomy. But he found out differently that summer, when he trained his telescope on Mars. “I went, ‘Holy shit.’ It was just absolutely steady. I couldn’t believe it.”

Parker returned to his old practice of making drawings at the eyepiece to record as much detail as possible. He sent some of his work to Charles “Chick” Capen, an astronomer at Arizona’s Lowell Observatory and coordinator of Mars observations for the Association of Lunar and Planetary Observers. Soon he and Capen were in frequent contact, and from him Parker learned about the latest techniques for planetary photography.

In the 1970s that was a time-consuming process; he used professional-grade film ordered directly from Kodak and developed it with special, highly toxic chemicals that had to be laboriously prepared for each session. But that became a part of his life’s routine: off to the hospital in the morning, sailing with Maureen in the afternoon, nights at the telescope, and the rest of the time developing and printing his pictures. Returning to work after a beautiful Florida weekend, he says, “Everybody would come in with a nice tan; I’d come in looking like a bed sheet. Forty-eight hours in the darkroom! People would say, ‘Are you ill?’”

All that effort paid off. Parker’s planetary photos were now appearing frequently in Sky & Telescope. But they still couldn’t record the kind of details a good observer could see at the eyepiece. Soon Chick Capen was steering him, gently, toward more ambitious Martian observing projects—especially the exacting task of monitoring the planet’s north polar ice cap. Using a measuring device called a filar micrometer attached to their telescopes, Parker and fellow amateur Jeff Beish studied the cap as it shrank during the Martian spring and summer. Observations going back to the early years of the twentieth century showed that the north polar cap always shrank at the same predictable rate, but in the 1980s Parker and Beish found a surprise: The cap shrank more quickly, and to a smaller size, than ever before. Years before most people had even heard the term “global warming” (and more than a decade before evidence from NASA’s Mars Global Surveyor mission) Parker and Beish had found evidence that it was taking place on Mars.



Hubble images show cloud formations (left) and the effects of a global dust storm on Mars (Credit: NASA/Hubble)


Hubble images show cloud formations (left) and the effects of a global dust storm on Mars (Credit: NASA/Hubble)
Soon their observations were being reinforced by several kinds of data from other astronomers, a convergence that Parker remembers as tremendously thrilling. “All this stuff began to come together,” Parker says. “The dust storm frequencies, the cloud study frequencies, the polar cap shit. And it’s almost better than sex. And it came in from a lot of different observers, different times. It’s really kind of cool—when you’re in a science and something all of a sudden falls into place that you don’t expect. It’s really neat. Nothing’s better than sex, but it’s close.” His work with Beish and other observers was later published, to Parker’s great satisfaction, in the professional planetary science journal Icarus. For Parker it epitomizes the rewards of all those hours at the eyepiece. “It’s the thrill of the hunt,” he says. “That’s really the only thing that’s kept me going. Taking pretty pictures is fine and fun, but doing that for thirty years, it wears after a while. You’ve taken one pretty picture, you’ve taken them all.”

In the 1990s, though, the pictures started to get really pretty. For the first time, amateurs had access to electronic cameras using charged-coupled devices (CCDs), like the ones in NASA spacecraft and professional observatories. Around 1990 fellow amateur astronomer Richard Berry convinced Parker to invest in one of these new cameras, but he had a tough time getting used to it. “I hooked it up,” he remembers. “I didn’t know what to do with it. I was afraid of it. So I went back to film.”



Don Parker's image of Jupiter and the Great Red Spot, taken in 2012. Credit: Don Parker.


Don Parker’s image of Jupiter and the Great Red Spot, taken in 2012. Credit: Don Parker.


Some months later Berry came for a visit and showed Parker what he’d been missing. They pointed Parker’s sixteen-inch telescope at Jupiter, and when the first image came up on his computer screen, “It was ten times better than anything I’d ever gotten with film. The detail was amazing. It was really exciting.”


Before long Parker had completely switched over to using his electronic imager, and he never looked back. Unlike film, it offered instant gratification; no longer did he have to spend hours in the darkroom before he could see results. Even more important, the extraordinary sensitivity of CCDs allowed much shorter exposure times than film, making it possible to record a planet during those brief moments of good seeing. He could even create remarkably detailed color images by taking separate exposures through red, green, and blue filters, then combining the results in newly developed programs like Adobe Photoshop.

And to Parker’s great relief, electronic images proved as good as visual observations for monitoring Martian features like clouds, dust storms, and— thankfully—the changing polar ice caps. At last, he could put aside the filar micrometer and the tedious hours that went along with it. But there was no way around the fact that the whole experience of planetary observing had changed for serious amateurs like Parker, just as it had for professionals. He realized this during Richard Berry’s visit, as they filled his computer’s hard drive with electronic portraits of Jupiter. “I said to Richard, ‘We’ve been here for six hours and haven’t even looked through the telescope.’ And he said, ‘Yeah, now you’re a real astronomer!’”

August 26, 2003,
Coral Gables, Florida


With no time for a road trip, I’ve packed my webcam and flown to Miami. I arrive at Don Parker’s waterfront home shortly after he has awakened from yet another all-nighter at the telescope. Don is tall, pot bellied, and nearly bald, with a kind of leering, lopsided grin that spreads mischievously across his face. In his old hospital scrubs he reminds me of Peter Boyle in Young Frankenstein. Don wouldn’t mind hearing me say that; he often refers to himself as Mongo, after the character in another Mel Brooks film, Blazing Saddles. (For example: “Mongo got good pictures. Mongo happy.”)

When he was a practicing anesthesiologist he had a penchant for playing crude practical jokes in the O.R. to startle the nurses (the fart machine was a favorite). “It was like MASH,” he says. Now that he is retired there is nothing to stop him from spending every clear night at the telescope—and that is what he does, whenever Mars shines overhead. Back in 1984, when the seeing was even better than it is now, he and Jeff Beish logged 285 nights of making drawings, photos, and micrometer measurements. Parker says, “We were praying for rain. Going to the Seminole reservation to pay the guys to do a rain dance.” Two decades later, his “other life” has become his life. For months now, as Mars has grown from an orange speck in the predawn sky to its current brilliance, high overhead at midnight, Don has faithfully recorded its changing aspect, the shrinking polar cap, the comings and goings of blue hazes and yellow dust clouds, the parade of deserts and dark markings. Maureen is now a full-fledged Mars widow. Don calls it “The Curse of the Red Planet.”

For me this is the big night, and I am full of anticipation. About twelve hours from now, at 5:51am Eastern Daylight Time on August 27, Mars will be 34,646,418 million miles away from Coral Gables. An astronomer at JPL has figured out that this is closer than at any time since the year 57617 B.C., and closer than Mars will be again until the year 2287. For Don, though, this is just one more night in an unbroken string of nights that began last April and will continue into next spring. Don, of course, is far from the only one so afflicted. At any given moment this summer someone around the world is observing Mars, including a couple of twenty-something wizards in Hong
Kong and Singapore who are getting spectacular results with telescopes placed on their high-rise apartment balconies (when I mention them Don curses ruefully, then laughs).

Sitting in Don’s kitchen, we discuss the weather for the coming night— the continuing hurricane season has made things a bit iffy—as he mixes his standard brew of freeze-dried coffee, sugar, and nondairy creamer, a concoction that seems less like a beverage than a research project in polymer chemistry. Arthritis and weakening of the bones in his legs have left him with a limp so painful that he must use a cane, and as he leads me to his upstairs office he utters a string of profanities.

Seated at the computer he unveils his most recent images and I am astonished by their clarity. Even back in April, when Mars was a fraction of its current apparent size, Don was getting a remarkable amount of detail. Now his pictures are so good that they hold up in side-by-side comparisons with Mars images from the Hubble Space Telescope. If you know where to look, you can even spot the giant volcano, Olympus Mons.

When I was growing up, even the two-hundred-inch giant at Palomar couldn’t come close to the details Don has recorded with a telescope just sixteen inches in diameter.

By nightfall the sky is mercifully clear, and Don sets up a ten-inch scope for me to use. The view is amazing: The planet’s disc is shaded with subtle, dusky patterns, far more detailed than any previous view of Mars I’ve ever seen. But when I attach the webcam and fire up the laptop, the live video that appears before me is almost too good to be true. Mars is so big, so clear, that I can even see individual dark spots that must be huge, windblown craters, trailing streaks of dark sand across the pink deserts. At the south pole, the retreating ice cap gleams brilliantly, with an outlier of frosted ground distinctly visible adjacent to the larger white mass.

Long into the night, and again the next, Don and I gather our photographic records of this unprecedented encounter, he at one telescope, I at the other. I feel lucky to be alive at this moment, suspended between the time of the Neanderthals and the twenty-third century, when some of our descendants will be on Mars, looking back at Earth. Right now I am face-to-face with Mars in a way I have never been, and never will be again. It is not the Mars of my childhood picture books, or the one revealed by an armada of space probes, or the trackless world where men and women will someday leave footprints. At this moment, I am exploring Mars, and 35 million miles doesn’t seem like much, not much at all.



Andrew Chaikin.


Andrew Chaikin.
Find out more about Chaikin’s books “A Passion for for Mars,” “A Man on the Moon” and more at Chaikin’s website.

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Wednesday, February 25, 2015

What is Mars Made Of?

What is Mars Made Of?:



Credit: NASA/JPL


The interior of Mars, showing a molten liquid iron core similar to Earth and Venus. Image Credit: NASA/JPL
For thousands of years, human beings have stared up at the sky and wondered about the Red Planet. Easily seen from Earth with the naked eye, ancient astronomers have charted its course across the heavens with regularity. By the 19th century, with the development of powerful enough telescopes, scientists began to observe the planet’s surface and speculate about the possibility of life existing there.

However, it was not until the Space Age that research began to truly shine light on the planet’s deeper mysteries. Thanks to numerous space probes, orbiters and robot rovers, scientists have learned much about the planet’s surface, its history, and the many similarities it has to Earth. Nowhere is this more apparent than in the composition of the planet itself.

Like Earth, the interior of Mars has undergone a process known as differentiation. This is where a planet, due to its physical or chemical compositions, forms into layers, with denser materials concentrated at the center and less dense materials closer to the surface. In Mars’ case, this translates to a core that is between 1700 and 1850 km (1050 – 1150 mi) in radius and composed primarily of iron, nickel and sulfur.

This core is surrounded by a silicate mantle that clearly experienced tectonic and volcanic activity in the past, but which now appears to be dormant. Besides silicon and oxygen, the most abundant elements in the Martian crust are iron, magnesium, aluminum, calcium, and potassium. Oxidation of the iron dust is what gives the surface its reddish hue.



Composite image showing the size difference between Earth and Mars. Credit: NASA/Mars Exploration


Composite image showing the size difference between Earth and Mars. Credit: NASA/Mars Exploration
Beyond this, the similarities between Earth and Mars’ internal composition ends. Here on Earth, the core is entirely fluid, made up of molten metal and is in constant motion. The rotation of Earth’s inner core spins in a direction different from the outer core and the interaction of the two is what gives Earth it’s magnetic field. This in turn protects the surface of our planet from harmful solar radiation.

The Martian core, by contrast, is largely solid and does not move. As a result, the planet lacks a magnetic field and is constantly bombarded by radiation. It is speculated that this is one of the reasons why the surface has become lifeless in recent eons, despite the evidence of liquid, flowing water at one time.

Despite there being no magnetic field at present, there is evidence that Mars had a magnetic field at one time. According to data obtained by the Mars Global Surveyor, parts of the planet’s crust have been magnetized in the past. It also found evidence that would suggest that this magnetic field underwent polar reversals.

This observed paleomagnetism of minerals found on the Martian surface has properties that are similar to magnetic fields detected on some of Earth’s ocean floors. These findings led to a re-examination of a theory that was originally proposed in 1999 which postulated that Mars experienced plate tectonic activity four billion years ago. This activity has since ceased to function, causing the planet’s magnetic field to fade away.



Map from the Mars Global Surveyor of the current magnetic fields on Mars. Credit: NASA/JPL


Map from the Mars Global Surveyor of the current magnetic fields on Mars. Credit: NASA/JPL
Much like the core, the mantle is also dormant, with no tectonic plate action to reshape the surface or assist in removing carbon from the atmosphere. The average thickness of the planet’s crust is about 50 km (31 mi), with a maximum thickness of 125 km (78 mi). By contrast, Earth’s crust averages 40 km (25 mi) and is only one third as thick as Mars’s, relative to the sizes of the two planets.

The crust is mainly basalt from the volcanic activity that occurred billions of years ago. Given the lightness of the dust and the high speed of the Martian winds, features on the surface can be obliterated in a relatively short time frame.

Much of Mars’ composition is attributed to its position relative to the Sun. Elements with comparatively low boiling points, such as chlorine, phosphorus, and sulphur, are much more common on Mars than Earth. Scientists believe that these elements were probably removed from areas closer to the Sun by the young star’s energetic solar wind.

After its formation, Mars, like all the planets in the Solar System, was subjected to the so-called “Late Heavy Bombardment.” About 60% of the surface of Mars shows a record of impacts from that era, whereas much of the remaining surface is probably underlain by immense impact basins caused by those events.



The North Polar Basin is the large blue low-lying area at the northern end of this topographical map of Mars. Its elliptical shape is partially obscured by volcanic eruptions (red, center left). Credit: NASA/JPL/USGS


The North Polar Basin is the large blue low-lying area at the northern end of this topographical map of Mars. Credit: NASA/JPL/USGS
The largest impact event on Mars is believed to have occurred in the northern hemisphere. This area, known as the North Polar Basin, measures some 10,600 km by 8,500 km, or roughly four times larger than the Moon’s South Pole – Aitken basin, the largest impact crater yet discovered.

Though not yet confirmed to be an impact event, the current theory is that this basin was created when a Pluto-sized body collided with Mars about four billion years ago. This is thought to have been responsible for the Martian hemispheric dichotomy and created the smooth Borealis basin that now covers 40% of the planet.

Scientists are currently unclear on whether or not a huge impact may be responsible for the core and tectonic activity having become dormant. The InSight Lander, which is planned for 2016, is expected to shed some light on this and other mysteries – using a seismometer to better constrain the models of the interior.

We have many interesting articles on the subject of Mars here at Universe Today. Here is one about how Mars has been cold for billions of years.

Ask a Scientist answered the question about the composition of Mars, and here’s some general information about Mars from Nine Planets.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Source: NASA



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Author, freelance writer, educator, Taekwon-Do instructor, and loving hubby, son and Island boy!

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Tuesday, February 17, 2015

Catch a ‘Conjunction Triple Play’ on February 20th as the Moon Meets Venus & Mars

Catch a ‘Conjunction Triple Play’ on February 20th as the Moon Meets Venus & Mars:



The Moon passes Mars and Venus last month... this week's pass is much closer! (Photo by Author).


The Moon passes Mars and Venus last month… this week’s pass is much closer! (Photo by author).
Fear not, the chill of late February. This Friday gives lovers of the sky a reason to brave the cold and look westward for a spectacular close triple conjunction of the planets Mars, Venus and the waxing crescent Moon.

This week’s New Moon is auspicious for several reasons.  We discussed the vagaries of the Black Moon of February 2015 last week, and the lunacy surrounding the proliferation of the perigee supermoon. And Happy ‘Year of the Goat’ as reckoned on the Chinese luni-solar calendar, as this week’s New Moon marks the start of the Chinese New Year on February 19th. Or do you say Ram or Sheep? Technical timing for the New Moon is on Wednesday, February 18th at 23:47 UT/6:47 PM EST, marking the start of lunation 1140. The next New Moon on March 20th sees the start of the first of two eclipse seasons for 2015, with a total solar eclipse for the high Arctic. More on that next month!



Stellarium


Looking west on the evening of February 20th. Credit: Stellarium.
And today also marks Shrove Tuesday and the start of Lent, as reckoned 47 days prior to Easter Sunday. In Western Christianity, Easter falls on the first Sunday past the first Full Moon past March 21st. This is the demarcation date set for the March Equinox, which actually falls on March 20th this year. Such is the wonderful world of calendars and astronomy, as the struggle to keep recorded versus actual observed time in sync continues.



Credit and Copyright


The dawn crescent Moon paired with Venus on February 26th, 2014. Credit and Copyright: Efrain Morales.
The first sighting opportunities for the slim waxing crescent Moon will come Thursday night on February 19th. And don’t miss the main event on Friday, February 20th when Mars, Venus and the two day old waxing crescent Moon all fit within a two degree diameter circle — about four Full Moon diameters — prior to sunset.  You can’t miss brilliant Venus, shining at -4th magnitude as the 3rd brightest natural object in the sky next to the Sun and the Moon. Through a telescope, Venus presents an  88% illuminated disk 12” in size and growing, while Mars shines at +1.3 magnitude and is just 4.2” in size. The closest conjunction of Venus and Mars actually occurs just 48 hours later, when they both fit within a 30’ field of view on the evening of Sunday, February 21st.



February 21st 01 UT


The Moon, Venus and Mars February 21st at 01:00 UT. (Credit: Starry Night).
The Moon is 2.37 days old and will appear 5 % illuminated during the Friday conjunction, and together, the trio will resemble a skewed emotion smiley face… think ‘:?’. Manage to catch a time exposure of one of the numerous ISS passes near the Mars/Venus conjunction this week and you could nab a unique ‘:/’ alignment!

Venus spends the first half of 2015 as a brilliant dusk object before heading for solar conjunction on August 15th, after which it once again passes into the dawn sky.  2015 is an “opposition-less” in-between year for Mars, as it reaches solar conjunction on the far side of the Sun on June 14th before making its slow comeback in the dawn sky. Expect the Red Planet to reach a favorable opposition next on May 22nd 2016.



tri-conjunction


Getting closer…  Venus and Mars as seen from Venezuela on the evening of February 16th. (Credit and Copyright: Jose Rozada @jmrozada).
Notice that this week’s tri-conjunction occurs very near the equinoctial point where the celestial equator and the plane of the ecliptic meet. This is the position that the Sun will occupy a month from now when the equinox total solar eclipse occurs.

Want more? One evening later on February 21st, the waxing crescent Moon will actually occult the +5.9 magnitude planet Uranus in the dusk sky for eastern North American observers:



Occult 4.0


The path of the February 21st occultation of Uranus by the Moon. Credit: Occult 4.0
This is occultation number 8 in a current cycle of 19 of Uranus by the Moon.  And there’s another pass of the Moon in front of the Hyades on February 25th as it occults the bright star Aldebaran for a second time in 2015 as seen from Scandinavia.



Aldebaran Occ


The path of the February 25th occultation of Aldebaran by the Moon. Credit: Occult 4.0.
Now for the ‘wow’ factor. The Moon lies just over a light second away at 357,000 kilometres distant. This week, Venus sits 1.4 AUs/ 11.6 light minutes away at 217 million kilometres distant, while Mars is 2.2 AUs/ 18.3 light minutes away at 341 million kilometres distant.

And from the surface of Mars, you’d see a brilliant conjunction of -1.3 magnitude Earth and -1.6 magnitude Venus just one degree in separation, with the +2.5 magnitude Moon nearby.



Venus and Earth rising as seen from the surface of Mars.


Venus and Earth rising as seen from the surface of Mars. Credit: Starry Night Education Software.
Perhaps Curiosity will nab this extraterrestrial spectacle, as Earthbound sky watchers gaze back this weekend!



About 

David Dickinson is an Earth science teacher, freelance science writer, retired USAF veteran & backyard astronomer. He currently writes and ponders the universe from Tampa Bay, Florida.

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Tuesday, August 16, 2011

HELICOPTERS (helik-o-pter)

HELICOPTERS (helik-o-pter): "



“If Icarus hadn’t flown so close to the sun we would all have a second home in Mars by now””


The story of Icarus is a symbol of the human desire to fly,to explore,to escape…and when we think of flying,the airplane comes first to our mind,but helicopter flight was the first kind of flight captured by human imagination.


In the suburbs of a chinese city about 500 years ago kids playing with hand-spun bamboo made toys discovered what may be the first rotary wing in history.Eventhough we have to wait for Leonardo Da Vinci to get the first schemes of “rotary aircrafts”


In the midst of the pioneers of aviation we can’t not mention Sir George Cayley,Alphonse Penaud who developed the coaxial rotor model and Gustave de Ponton d’Amécourt who coined the word “helicopter”,deriving for ancient greek


“”helik”= “spiral” ” and “pter” = “wing”


But we have to wait for two brothers called Jacques and Louis Berget,to see a rotary wing aircraft which they called Gyroplane No1 lift vertically from the Ground


A helicopter is a rotary wing aircraft.
"

PICTURES OF NATURE & UNIVERSE PHOTOGRAPHY

Thursday, August 4, 2011

A Heartfelt Goodbye to a Spirited Mars Rover

A Heartfelt Goodbye to a Spirited Mars Rover: "


Mars Exploration Rover Project Manager John Callas sent this letter to his team shortly after the final command was sent to the Mars rover Sprit, which operated on the surface of Mars for more than six years and made numerous scientific discoveries.

Artist's concept of NASA's Mars Exploration Rover


Dear Team,


Last night, just after midnight, the last recovery command was sent to Spirit. It would be an understatement to say that this was a significant moment. Since the last communication from Spirit on March 22, 2010 (Sol 2210), as she entered her fourth Martian winter, nothing has been heard from her. There is a continued silence from the Gusev site on Mars.


We must remember that we are at this point because we did what we said we would do, to wear the rovers out exploring. For Spirit, we have done that, and then some.


Spirit was designed as a 3-month mission with a kilometer of traverse capability. The rover lasted over 6 years and drove over 7.7 kilometers [4.8 miles] and returned over 124,000 images. Importantly, it is not how long the rover lasted, but how much exploration and discovery Spirit has done.


This is a rover that faced continuous challenges and had to fight for every discovery. Nothing came easy for Spirit. When she landed, she had the Sol 18 flash memory anomaly that threatened her survival. Scientifically, Mars threw a curveball. What was to be a site for lakebed sediments at Gusev, turned out to be a plain of volcanic material as far as the rover eye could see. So Spirit dashed across the plains in an attempt to reach the distant Columbia Hills, believed to be more ancient than the plains.


Exceeding her prime mission duration and odometry, Spirit scrambled up the Columbia Hills, performing Martian mountaineering, something she was never designed to do. There Spirit found her first evidence of water-altered rocks, and later, carbonates.


The environment for Spirit was always harsher than for Opportunity. The winters are deeper and darker. And Gusev is much dustier than Meridiani. Spirit had an ever-increasing accumulation of dust on her arrays. Each winter became harder than the last.


It was after her second Earth year on Mars when Spirit descended down the other side of the Columbia Hills that she experienced the first major failure of the mission, her right-front wheel failed. Spirit had to re-learn to drive with just five wheels, driving mostly backwards dragging her failed wheel. It is out of this failure that Spirit made one of the most significant discoveries of the mission. Out of lemons, Spirit made lemonade.


Each winter was hard for Spirit. But with ever-accumulating dust and the failed wheel that limited the maximum achievable slope, Spirit had no options for surviving the looming fourth winter. So we made a hard push toward some high-value science to the south. But the first path there, up onto Home Plate, was not passable. So we went for Plan B, around to the northeast of Home Plate. That too was not passable and the clock was ticking. We were left with our last choice, the longest and most risky, to head around Home Plate to the west.


It was along this path that Spirit, with her degraded 5-wheel driving, broke through an unseen hazard and became embedded in unconsolidated fine material that trapped the rover. Even this unfortunate event turned into another exciting scientific discovery. We conducted a very ambitious extrication effort, but the extrication on Mars ran out of time with the fourth winter and was further complicated by another wheel failure.


With no favorable tilt and more dust on the arrays, Spirit likely ran out of energy and succumbed to the cold temperatures during the fourth winter. There was a plausible expectation that the rover might survive the cold and wake up in the spring, but a lack of response from the rover after more than 1,200 recovery commands were sent to rouse her indicates that Spirit will sleep forever.


But let’s remember the adventure we have had. Spirit has climbed mountains, survived rover-killing dust storms, rode out three cold, dark winters and made some of the most spectacular discoveries on Mars. She has told us that Mars was once like Earth. There was water and hot springs, the conditions that could have supported life. She has given us a foundation to further explore the Red Planet and to understand ourselves and our place in the universe.


But in addition to all the scientific discoveries Spirit has given us in her long, productive rover life, she has also given us a great intangible. Mars is no longer a strange, distant and unknown place. Mars is now our neighborhood. And we all go to work on Mars every day. Thank you, Spirit. Well done, little rover.


And to all of you, well done, too.


Sincerely,

John


› Learn more
"

FUNNY PICTURES OF NATURE & UNIVERSE PHOTOGRAPHY