Archive for the ‘Space’ Category

The Two Sides of the Moon

June 19, 2014

One of the things everyone notices when looking at the Moon are the dark spots or the Man in the Moon.


The Near Side of the Moon

These dark places are called “maria” from the Latin word for seas. I suppose early astronomers speculated that they really were oceans on the Moon. There is, of course no water on the Moon and the “seas” are, in fact, plains of basalt formed by volcanic eruptions when the Moon was first formed. The maria are richer in iron than the lunar highlands and so are darker.

Naturally, astronomers expected the far side of the Moon to be much like the near side. Until the space age, however, there was no way to know what the Moon’s far side was like. When the Soviet space probe Luna 3 sent back the first photographs of the far side of the Moon, in 1959, astronomers were surprised to discover that there are fewer maria on the far side.

The Far Side of the Moon

The Far Side of the Moon

Why there should be so few maria on the far side has been something of a mystery. It seems clear that the Earth must have something to do with it, but what exactly? Does the fact that the Moon has two faces have anything to do with the way it was formed? The study of exoplanets, planets orbiting other stars, may have helped to solve the mystery. Here is the article I read at Yahoo News.

Heat radiating from the young Earth could help solve the more than 50-year-old mystery of why the far side of the moon, which faces away from Earth, lacks the dark, vast expanses of volcanic rock that define the face of the Man in the Moon as seen from Earth, researchers say.

The Man in the Moon was born when cosmic impacts struck the near side of the moon, the side that faces Earth. These collisions punched holes in the moon’s crust, which later filled with vast lakes of lava that formed the dark areas known as maria or “seas.”


Now scientists may have solved the 55-year-old mystery; heat from the young Earth as the newborn moon was cooling caused the difference. The researchers came up with the solution during their work on exoplanets, which are worlds outside the solar system.

“There are many exoplanets that are really close to their host stars,”lead study author Arpita Roy, also of Penn State, told “That really affects the geology of those planets.”

Similarly, the moon and Earth are generally thought to have orbited very close together after they formed. The leading idea explaining the moon’s formation suggests that it arose shortly after the nascent Earth collided with a Mars-size planet about 4.5 billion years ago, with the resulting debris coalescing into the moon. Scientists say the newborn moon and Earth were 10 to 20 times closer to each other than they are now.

“The moon and Earth loomed large in each other’s skies when they formed, ” Roy said in a statement.

I would have liked to have seen such a sight.

Since the moon was so close to Earth, the mutual pull of gravity was strong. The gravitational tidal forces the moon and Earth exerted on each other braked their rotations, resulting in the moon always showing the same face to Earth, a situation known as tidal lock.

The moon and Earth were very hot shortly after the giant impact that formed the moon. The moon, being much smaller than Earth, cooled more quickly. Since the moon and Earth were tidally locked early on, the still-hot Earth — more than 4,530 degrees Fahrenheit (2,500 degrees Celsius) — would have cooked the near side of the moon, keeping it molten. On the other hand, the far side of the moon would have cooled, albeit slowly.

The difference in temperature between the moon’s halves influenced the formation of its crust. The lunar crust possesses high concentrations of aluminum and calcium, elements that are very hard to vaporize.

“When rock vapor starts to cool, the very first elements that snow out are aluminum and calcium,” study co-author Steinn Sigurdsson of Penn State said in a statement.

Aluminum and calcium would have more easily condensed in the atmosphere on the colder far side of the moon. Eventually, these elements combined with silicates in the mantle of the moon to form minerals known as plagioclase feldspars, making the crust of the far side about twice as thick as that of the near side.

“Earthshine, the heat of Earth soon after the giant impact, was a really important factor shaping the moon,” Roy said.

When collisions from asteroids or comets blasted the moon’s surface, they could punch through the near side’s crust to generate maria. In contrast, impacts on the far side’s thicker crust failed to penetrate deeply enough to cause lava to well up, instead leaving the far side of the moon with a surface of valleys, craters and highlands, but almost no maria.

“It’s really cool that our understanding of exoplanets is affecting our understanding of the solar system,” Roy said.

I did not know that astronomers had progressed so far in the study of exoplanets that they were able to learn some details about the geology of those planets. I am glad to be living in an age in which we are learning so much about the universe we live in.




Brown Dwarf

April 29, 2014

Astronomers have recently discovered a previously unknown star only 7.2 light years away. You might wonder how they could miss a star that close to us. Well, Wise J085510.83-071442.5 is not a regular star. It is a brown dwarf, a star that doesn’t actually shine. Here is the story according to the Daily Mail

A brown dwarf star that appears to be the coldest of its kind – as frosty as Earth’s North Pole – has been spotted by an American astronomer.

The discovery was made using Nasa’s Wide-field Infrared Survey Explorer (Wise) and the Spitzer Space Telescope.

Images from the space telescopes also pinpointed the object’s distance at 7.2 light years away, making it the fourth closest system to our sun.

‘It is very exciting to discover a new neighbour of our solar system that is so close,’ said Kevin Luhman, an associate professor of astronomy and astrophysics at Penn State and a researcher in the Penn State Center for Exoplanets and Habitable Worlds.

‘In addition, its extreme temperature should tell us a lot about the atmospheres of planets, which often have similarly cold temperatures.’

Brown dwarfs start their lives like stars, as collapsing balls of gas, but they lack the mass to burn nuclear fuel and radiate starlight.

The newly-found brown dwarf, named Wise J085510.83-071442.5, is thought to have a chilly temperature between -48°C to -13°C (-54°F to 9°F).

Previous record holders for coldest brown dwarfs, also found by Wise and Spitzer, were about room temperature.

To understand what a brown dwarf actually is, you must realize that like people, stars are born, they live, and eventually they die. A star’s lifespan is measured in eons rather than years and they take little notice of such microscopic mayflies such as we are. A star is born when a massive cloud of gas collapses in on itself. If you recall your high school physics class, you may remember that when a gas is compressed, in this case by the protostar’s gravity, it will heat up. The energy used in compressing the gas is converted into heat. If the protostar’s mass is greater than about .08 solar masses (8% of our Sun), the center of the cloud will become dense enough and hot enough to begin fusing hydrogen into helium. A new star is born. If the mass is less than .08 solar masses than fusion will never begin and the star is stillborn. It becomes a brown dwarf.

Some of the more massive brown dwarves, around 13 to 65 Jupiter masses may fuse deuterium and lithium. They emit mostly infrared radiation. Interestingly, brown dwarves are about the same volume as Jupiter, regardless of their masses. Gravity compresses them to about the same volume. In a way, Jupiter, Saturn, and Neptune could be considered to be very low mass brown dwarves. They emit more energy than they receive from the sun. Perhaps the precise line between a massive planet and a very low mass star is not so easy to define.

General size comparison between a low mass sta...

 (Photo credit: Wikipedia)

A brown dwarf should not be confused with a red dwarf or a white dwarf. A red dwarf is a real star with a mass from about .08 to .5 solar masses. They are small and dim but they do fuse hydrogen in their core and they emit visible light. A white dwarf is a dead star. It has run out of fuel and has collapsed under its own mass until only electron degeneracy, the pressure of electrons crammed together, prevents it from collapsing any further.

But stellar corpses are another topic which I will have to write about another time.

Enhanced by Zemanta

No Muslims on Mars

February 20, 2014
Marvin the Martian

Probably not a Muslim



As humanity spreads out into space and begins to colonize other planets, it is possible that Muslims will not be among the first wave of space explorers, at least not if they obey a fatwa reportedly issued recently. I read the story in the Telegraph.


Muslims have been warned in a Fatwa not to go and live on Mars because it would pose “a real risk to life”, according to a Dubai news organisation.

The General Authority of Islamic Affairs and Endowment (GAIAE) in the United Arab Emirates said that anyone making such a “hazardous trip” is likely to die for “no righteous reason”.

They would therefore be liable to a “punishment similar to that of suicide in the Hereafter”, the Khaleej Times reported.

The Fatwa was apparently issued in response to the proposal from the Dutch company Mars One last year to send four people on a one-way journey to the red planet in 2022.

“Such a one-way journey poses a real risk to life, and that can never be justified in Islam,” the committee said. “There is a possibility that an individual who travels to planet Mars may not be able to remain alive there, and is more vulnerable to death.”

“Protecting life against all possible dangers and keeping it safe is an issue agreed upon by all religions and is clearly stipulated in verse 4/29 of the Holy Koran: Do not kill yourselves or one another. Indeed, Allah is to you ever Merciful,” the committee, chaired by Professor Dr Farooq Hamada, said.

Over 200,000 people have applied to be civilian-astronauts on the Mars One mission. Experts have questioned both the financial and practical viability of the mission.

The Mars One website states: “It is Mars One’s goal to establish a human settlement on Mars. Human settlement of Mars is the next giant leap for humankind.

“Exploring the solar system as a united humanity will bring us all closer together. Mars is the stepping stone of the human race on its voyage into the universe.”


I wonder what Dr. Farooq Hamada thinks about suicide bombers. I don’t think that risking death to explore space is the same thing as suicide. Space is a dangerous place, but we all have to die sometime and I don’t think I would mind dying while exploring strange new worlds, not that I would ever have that opportunity. I am not sure I would want to live on Mars as part of a four person colony, especially if there were no possibility of returning to Earth. When Mars One first announced their proposal to settle Mars, I thought the first colony would involve hundreds, or at least tens of colonists. I think having just three other people on a whole planet might get old after a time.

It occurs to me that Muslims might have another problem with living on another planet, besides the risk traveling there. Muslims are required to pray five times a day while facing toward the holy city of Mecca. Islamic religious authorities have already determined that a Muslim in orbit should pray facing the Earth, but what direction should a Muslim on Mars face? Perhaps they could face the Earth, but what if the Earth is on the other side of the Sun? I suppose they will work out some solution eventually, or just stay behind on Earth.

Whatever happens, I will be looking forward to seeing the colonization of Mars. It is too bad that I am not going to live long enough to see the development of terraforming techniques to make Mars and Venus livable.





Enhanced by Zemanta

The Nativity According to Matthew

December 24, 2013
The Adoration of the Magi (circa 1305) by Giot...

The Adoration of the Magi

Matthew begins his Gospel with the genealogy of Jesus. I’ll skip the genealogy and go straight to his account of Jesus’s birth.

18 This is how the birth of Jesus the Messiah came about: His mother Mary was pledged to be married to Joseph, but before they came together, she was found to be pregnant through the Holy Spirit. 19 Because Joseph her husband was faithful to the law, and yet did not want to expose her to public disgrace, he had in mind to divorce her quietly.

20 But after he had considered this, an angel of the Lord appeared to him in a dream and said, “Joseph son of David, do not be afraid to take Mary home as your wife, because what is conceived in her is from the Holy Spirit. 21 She will give birth to a son, and you are to give him the name Jesus, because he will save his people from their sins.”

22 All this took place to fulfill what the Lord had said through the prophet: 23 “The virgin will conceive and give birth to a son, and they will call him Immanuel” (which means “God with us”).

24 When Joseph woke up, he did what the angel of the Lord had commanded him and took Mary home as his wife. 25 But he did not consummate their marriage until she gave birth to a son. And he gave him the name Jesus.

After Jesus was born in Bethlehem in Judea, during the time of King Herod, Magi from the east came to Jerusalem and asked, “Where is the one who has been born king of the Jews? We saw his star when it rose and have come to worship him.”

When King Herod heard this he was disturbed, and all Jerusalem with him. When he had called together all the people’s chief priests and teachers of the law, he asked them where the Messiah was to be born. “In Bethlehem in Judea,” they replied, “for this is what the prophet has written:

“‘But you, Bethlehem, in the land of Judah,
are by no means least among the rulers of Judah;
for out of you will come a ruler
who will shepherd my people Israel.’

Then Herod called the Magi secretly and found out from them the exact time the star had appeared. He sent them to Bethlehem and said, “Go and search carefully for the child. As soon as you find him, report to me, so that I too may go and worship him.”

After they had heard the king, they went on their way, and the star they had seen when it rose went ahead of them until it stopped over the place where the child was. 10 When they saw the star, they were overjoyed. 11 On coming to the house, they saw the child with his mother Mary, and they bowed down and worshiped him. Then they opened their treasures and presented him with gifts of gold, frankincense and myrrh. 12 And having been warned in a dream not to go back to Herod, they returned to their country by another route.

13 When they had gone, an angel of the Lord appeared to Joseph in a dream. “Get up,” he said, “take the child and his mother and escape to Egypt. Stay there until I tell you, for Herod is going to search for the child to kill him.”

14 So he got up, took the child and his mother during the night and left for Egypt, 15 where he stayed until the death of Herod. And so was fulfilled what the Lord had said through the prophet: “Out of Egypt I called my son.”

16 When Herod realized that he had been outwitted by the Magi, he was furious, and he gave orders to kill all the boys in Bethlehem and its vicinity who were two years old and under, in accordance with the time he had learned from the Magi. 17 Then what was said through the prophet Jeremiah was fulfilled:

18 “A voice is heard in Ramah,
weeping and great mourning,
Rachel weeping for her children
and refusing to be comforted,
because they are no more.”

19 After Herod died, an angel of the Lord appeared in a dream to Joseph in Egypt 20 and said, “Get up, take the child and his mother and go to the land of Israel, for those who were trying to take the child’s life are dead.” (Matthew 1:18-2:20)

Most people think that the slaughter of the baby boys in Bethlehem involved the murder of hundreds or thousands of innocents. Remember, though, that Bethlehem was a small village in this time with a likely population of a few hundred. It is doubtful that more than half a dozen children were killed, not enough to make it into any other sources we have for Herod’s rule. Herod was certainly ruthless enough to order such a massacre. He had no trouble killing members of his own family if he thought they threatened his rule. In fact, Herod being an Idumean (or Edomite) and not a Jew, was a foreigner and so was as despised by many Judeans as a Roman governor would have been. If he had heard that there was a potential rival to his throne, even a child, that the Jews might rally around, he would have wasted no time in disposing of that rival.

The word Magi usually refers to Zoroastrian priests. In Greco-Roman usage the term Magi had connotations of magicians or sorcerers, exotic figures from distant lands. It is not clear just who the Magi actually were. They may indeed have been Zoroastrians. The references to the Star of Bethlehem suggest that they may have been astrologers. The Babylonians had a reputation for being skilled in astrology and magic so the Magi may have come from Mesopotamia. They may also have been Jewish since they were seeking for a king of the Jews. The fact that they were unfamiliar with the prophets may prove that they were Gentiles. The number of the Magi is not given in the Gospel. The reason that three are usually pictured  is that there were three gifts; gold, frankincense,and myrrh.

It is also not clear just what the Star of Bethlehem actually was. There have been several theories presented, but none of them are entirely satisfactory. The star might have been a supernova, perhaps in a nearby galaxy. There is no way to know for certain since any supernova remnant so far away would be difficult, perhaps impossible, to detect. It might also have been a comet. This is rather unlikely. Although a comet would behave much as the star is said to behave, hanging in the sky over a certain location for several nights, comets were universally perceived as being harbingers of disaster in ancient, and not so ancient, times. The most likely explanation is a conjunction of the planets Jupiter and Saturn. The astronomer Keppler discovered that there was indeed such a conjunction in the year 7 BC. The following year there was another conjunction of Mars, Jupiter, and Saturn. This might have been very impressive to the Magi. It may also be that the Star was a supernatural phenomenon and one that cannot be studied today. Whatever the truth of the matter is, I hope everyone has a wonderful Christmas.

Snow in Israel and Egypt

December 13, 2013

These are strange times we are living in. Right now, there is a snowstorm in Israel. I didn’t think it ever snowed there. It is even snowing in Egypt. Here is the story at the Israel National News via the Drudge Report.

Snow continues to fall across Israel Friday morning, reaching new regions of the country and causing major power outages and road closures. Jerusalem Mayor Nir Barkat released a statement saying “we are battling a storm of rare ferocity.” The capital has over 37 centimeters (15 inches) of snow, with deeper snowfall in other areas.

A weather forecaster on public radio described the storm as “historic,” as Jerusalem temperatures already dropped to 2 degrees celsius (35.6 Fahrenheit), and are expected to drop below freezing. Snow is anticipated to continue falling through Saturday.

The views in Jerusalem are spectacular, as the hills of the city turn white and the rooftops in older neighborhoods wear a white contrast to the Jerusalem stone.

A power outage has affected more than half of Jerusalem, although some areas are reporting a return of electricity. In Kiryat Moshe, Merkaz Harav Yeshiva opened its dormitory and dining room to stranded families who reached the entrance of the city, where the yeshiva is located, but could not get to their destination.

Many more drivers were stuck on the roads in the city overnight, without food and water, after attempting to reach the city to see the snow.

The Jerusalem municipality is continuing with the rescue operations that began Thursday night and have so far saved over 2,000 people. The IDF and the Border Police are assisting in the operation.

Drivers who have been rescued have been taken to the Binyanei HaUma (International Convention Center), a community center in Mevaseret Zion and the Ofer Camp on Highway 443.

The Israeli police have released a particularly strong warning to drivers in affected areas against going out in blizzard conditions. Police have warned residents across the country to avoid leaving their homes for any reason during the snowfall.

Judea and Central Samaria villages are also receiving more snow – some for the first time in over ten years – including in Ariel, Nofim, Yakir, and Barkan.

In light of the situation, schools are closed in the following places: Yakir, Ariel, Barkan, Revava, Tapuah, Alei Zahav, Peduel, Rehalim, Nofei Nehemia, Bruhin, Kiryat Netafim, Yitzhar, Har Braha, Itamar, Alon Moreh, and Karnei Shomron.

Power outages have been reported across the central Samaria area; all roads are closed. The Shomron Regional Council is working to help Judea and Samaria residents and to provide aid.

I wonder if drivers there even know how to handle snow. Here is the story about the snow in Egypt from the LA Times again via the Drudge Report.

Snow coated domes and minarets Friday as a record Middle East storm compounded the suffering of Syrian refugees, sent the Israeli army scrambling to dig out stranded motorists and gave Egyptians a rare glimpse of snow in their capital.

Nearly three feet of snow closed roads in and out of Jerusalem, which is set in high hills, and thousands in and around the city were left without power. Israeli soldiers and police rescued  hundreds trapped in their cars by snow and ice. In the West Bank, the branches of olive trees groaned under the weight of snow.

In Cairo, where local news reports said the last recorded snowfall was more than 100 years ago, children in outlying districts capered in white-covered streets, and adults marveled at the sight, tweeting pictures of snow-dusted parks and squares. In other parts of the city, rain and hail rocketed down.

I’m surprised the Egyptians even know what snow is. Before, they could only have known snow from watching movies and television. There have also been records in cold and snow set here in the United States, as I have noticed whenever I have gone outside.

Meanwhile, solar activity is the weakest it has been observed for a century. Could this have some effect on the Earth’s climate? Perhaps we are in for a cold winter and a cool summer next year. Maybe even a repeat of the Little Ice Age. It may be that in the not too distant future we will be longing for some global warming.

The Sun is Acting Strangely

November 14, 2013
History of sunspot number observations showing...

History of sunspot number observations showing the recent elevated activity. (Photo credit: Wikipedia)



Glenn Reynolds linked to this story at about the puzzling behavior of the Sun. I wrote something about the worrisome lack of solar activity since the last cycle almost two years ago and it does not look as if things are getting any better. The Sun ought to be approaching the maximum point of its eleven year cycle but so far this maximum has not amounted to vary much.


“Robert Lee Hotz reports in the WSJ that current solar activity is stranger than it has been in a century or more. The sun is producing barely half the number of sunspots as expected, and its magnetic poles are oddly out of sync. Based on historical records, astronomers say the sun this fall ought to be nearing the explosive climax of its approximate 11-year cycle of activity—the so-called solar maximum. But this peak is ‘a total punk,’ says Jonathan Cirtain. ‘I would say it is the weakest in 200 years,’ adds David Hathaway, head of the solar physics group at NASA’s Marshall Space Flight Center. Researchers are puzzled. They can’t tell if the lull is temporary or the onset of a decades-long decline, which might ease global warming a bit by altering the sun’s brightness or the wavelengths of its light. To complicate the riddle, the sun also is undergoing one of its oddest magnetic reversals on record, with the sun’s magnetic poles out of sync for the past year so the sun technically has two South Poles. Several solar scientists speculate that the sun may be returning to a more relaxed state after an era of unusually high activity that started in the 1940s (PDF). ‘More than half of solar physicists would say we are returning to a norm,’ says Mark Miesch. ‘We might be in for a longer state of suppressed activity.’ If so, the decline in magnetic activity could ease global warming, the scientists say. But such a subtle change in the sun—lowering its luminosity by about 0.1%—wouldn’t be enough to outweigh the build-up of greenhouse gases and soot that most researchers consider the main cause of rising world temperatures over the past century or so. ‘Given our current understanding of how the sun varies and how climate responds, were the sun to enter a new Maunder Minimum, it would not mean a new Little Ice Age,’ says Judith Lean. ‘It would simply slow down the current warming by a modest amount.’”


I’m worried. We could be in for another Little Ice Age, which really wouldn’t be much fun at all. Wouldn’t be ironic, though, if all the carbon dioxide we are emitting was the only thing keeping the glaciers from moving south again? I think I read a science fiction book about that once.




Star Birth

August 22, 2013

Everybody in Britain was excited about the birth of the new prince. That’s understandable, considering the importance of continuing the royal line, but astronomers have been recording a somewhat more significant birth, the birth of a new star. Here is the story and pictures from Yahoo News.

A huge radio telescope in Chile has captured dazzling new views of a baby star lighting up an interstellar cloud with jets of gas streaking through deep space at record-breaking speeds.

The ALMA radio telescope, a joint project between North America, Europe and Asia, recorded the star birth images. They show the nascent star about 1,400 light-years from Earth unleashing material at nearly 84,477 mph (144,000 km/h), which then crashes into surrounding gas, causing it to glow.

The glowing object spawned by the newborn star is what scientists call a Herbig-Haro object. European Southern Observatory officials used the new views to create a video tour of new star birth images.

These new, detailed images showed that the material is streaking out of the star at about 40 kilometers per second (nearly 25 miles per second), which is about four times faster than any previous observation of carbon monoxide jets, scientists said. The discovery may help researchers understand the complex processes stars undergo during their birth.

The sun is a star, so if we want to understand how our solar system was created, we need to understand how stars are formed,” Héctor Arce, the lead author of the study appearing in the Astrophysical Journal on Aug. 20, said in a statement.

 The new image of Herbig-Haro 46/47 (HH 46/47) produced by the ALMA telescope, its name is short for Atacama Large Millimeter/submillimeter Array, reveals two jets of material streaming away from the newborn star, one of which was never detected before.

 One jet appears on the left side of the photo in pink and purple streaming partially toward Earth, while the orange and green jet on the right-hand-side show a jet pointed away from Earth.

 “This system is similar to most isolated low mass stars during their formation and birth,” Diego Mardones, a co-author of the study detailing the stellar findings said in a statement. “But it is also unusual because the outflow impacts the cloud directly on one side of the young star and escapes out of the cloud on the other. This makes it an excellent system for studying the impact of the stellar winds on the parent cloud from which the young star is formed.”

ALMA’s sensitive instruments took five hours to get these results. Earlier photos taken with other telescopes did not catch the second (orange and green) jet stream because dust surrounding the star obscured their views.

“ALMA’s exquisite sensitivity allows the detection of previously unseen features in this source, like this very fast outflow,” Arce said. “It also seems to be a textbook example of a simple model where the molecular outflow is generated by a wide-angle wind from the young star.”

 The $1.3 billion ALMA radio telescope is an array of 66 of individual radio telescopes that create one of the most powerful telescopes ever built. Each dish is up to 40 feet wide (12 meters) and can weigh 115 tons. The combined effort of the telescopes allows scientists to see celestial sights invisible in optical light because they are masked by gas and dust.

Here are some baby pictures.

Isn’t he the cutest thing. I think we should name him George.





Ion Propulsion

March 9, 2013

Improved designs in ion engines may be the ticket for making trips to the outer solar system quicker and more feasible both for unmanned probes and (I hope) manned spacecraft. I haven’t been keeping up with space exploration as much as I used to, so I am glad to find this article in Gizmag which explains a little about ion engines and how scientists have been making them better.

The phrase “engage the ion drive” still has the ring of a line from Star Wars, but these engines have been used in space missions for more than four decades and remain the subject of ongoing research. Ion engines have incredible fuel efficiency, but their low thrust requires very long operating times … and therein lies the rub. To date, erosion within such an engine seriously limits its operational lifetime. Now a group of researchers at NASA’s Jet Propulsion Laboratory (JPL) has developed a new design that largely eliminates this erosion, opening the gates for higher thrust and more efficient drives for manned and unmanned missions to the reaches of the Solar System.

There are many varieties and more proposals (the VASMIR engine comes to mind), but the operating principle is quite simple. There are two basic styles of ion engines, electrostatic and electromagnetic.

An electrostatic ion engine works by ionizing a fuel (often xenon or argon gas) by knocking off an electron to make a positive ion. The positive ions then diffuse into a region between two charged grids that contain an electrostatic field. This accelerates the positive ions out of the engine and away from the spacecraft, thereby generating thrust. Finally, an neutralizer sprays electrons into the exhaust plume at a rate that keeps the spacecraft electrically neutral.

An electromagnetic ion engine also works by ionizing a fuel. In this case a plasma is created that carries current between the ionizing anode and a cathode. The current in turn generates a magnetic field at right angles to the electric field, and thereby accelerates the positive ions out of the engine via the Lorentz force – basically the same effect on which railguns are based. Again a neutralizer keeps the spacecraft electrically neutral.

There are many varieties and more proposals (the VASMIR engine comes to mind), but the operating principle is quite simple. There are two basic styles of ion engines, electrostatic and electromagnetic.


There is a lot more in the article.

Even Scotty would be impressed by this.

Though, what we really need is warp drive. Anyone doing research on that?


The Asteroid that Killed the Dinosaurs

February 9, 2013

The hypothesis that an asteroid collision was the cause of the extinction of the dinosaurs has been around for several decades now, but recent research has provided new support for the theory.

The idea that a cosmic impact ended the age of dinosaurs in what is now Mexico now has fresh new support, researchers say.

The most recent and most familiar mass extinction is the one that finished the reign of the dinosaurs — the end-Cretaceous or Cretaceous-Tertiary extinction event, often known as K-T. The only survivors among the dinosaurs are the birds.

Currently, the main suspect behind this catastrophe is a cosmic impact from an asteroid or comet, an idea first proposed by physicist Luis Alvarez and his son geologist Walter Alvarez. Scientists later found that signs of this collision seemed evident near the town of Chicxulub (CHEEK-sheh-loob) in Mexico in the form of a gargantuan crater more than 110 miles (180 kilometers) wide. The explosion, likely caused by an object about 6 miles (10 km) across, would have released as much energy as 100 trillion tons of TNT, more than a billion times more than the atom bombs that destroyed Hiroshima and Nagasaki.

New findings using high-precision radiometric dating analysis of debris kicked up by the impact now suggest the K-T event and the Chicxulub collision happened no more than 33,000 years apart. In radiometric dating, scientists estimate the ages of samples based on the relative proportions of specific radioactive materials within them. [Wipe Out: History's Most Mysterious Mass Extinctions]

“We’ve shown the impact and the mass extinction coincided as much as one can possibly demonstrate with existing dating techniques,” researcher Paul Renne, a geochronologist and director of the Berkeley Geochronology Center in California, told LiveScience.

“It’s gratifying to see these results, for those of us who’ve been arguing a long time that there was an impact at the time of this mass extinction,” geologist Walter Alvarez at the University of California at Berkeley, who did not participate in this study, told LiveScience. “This research is just a tour de force, a demonstration of really skillful geochronology to resolve time that well.”

The fact the impact and mass extinction may have been virtually simultaneous in time supports the idea that the cosmic impact dealt the age of dinosaurs its deathblow.

“The impact was clearly the final straw that pushed Earth past the tipping point,” Renne said. “We have shown that these events are synchronous to within a gnat’s eyebrow, and therefore, the impact clearly played a major role in extinctions, but it probably wasn’t just the impact.”

The new extinction date is precise to within 11,000 years.

“When I got started in the field, the error bars on these events were plus or minus a million years,” added paleontologist William Clemens at the University of California at Berkeley, who did not participate in this research. “It’s an exciting time right now, a lot of which we can attribute to the work that Paul and his colleagues are doing in refining the precision of the time scale with which we work.”

I can’t help wondering if there is any chance that some species of dinosaur might have been intelligence, perhaps even civilized. No fossils suggesting such a possibility have ever been uncovered, but given the haphazard way in which fossils are made and preserved, it is doubtful that that we know of even 1% of all the organisms that existed at any given time. If an asteroid were to kill us off, I wonder if any remains of our civilization would be recognizable after 65 million years. Considering that it seems that quite a few asteroids have passed, and will be passing extremely close by, maybe a far future paleontologist will be wondering what happened to the mammals.

By the way, I have been reading The Peshawar Lancers by S. M. Stirling. The book takes place in an alternate history in which an asteroid or comet struck the Earth in 1878, destroying civilization in the Northern hemisphere. One hundred fifty years later, the descendants of the survivors are finally reaching the levels of technology we had around 1920.


Life on Mars

January 21, 2013

I read some interesting news in the Telegraph on the search for extraterrestrial life.

Prof John Parnell, 55, has co-written a theory with Dr Joseph Michalski, a planetary geologist at the Natural History Museum, that suggests they have discovered the best signs of life in the huge McLaughlin Crater on the surface of Mars.

The document, published today in Nature Geoscience journal, describes how they assessed the crater, created by a meteorite which smashed into the surface of Mars, flinging up rocks from miles below.

The rocks appear to be made up of clays and minerals which have been altered by water – the essential element to support life.

Speaking from his laboratory at the University of Aberdeen, geochemist Prof Parnell said: “We could be so close to discovering if there is, or was, life on Mars.

“We know from studies that a substantial proportion of all life on Earth is also in the subsurface and by studying the McLaughlin Crater we can see similar conditions beneath the surface of Mars thanks to observations on the rocks brought up by the meteorite strike.

“There can be no life on the surface of Mars because it is bathed in radiation and it’s completely frozen. However, life in the sub surface would be protected from that.

“And there is no reason why there isn’t bacteria or other microbes that were or still are living in the small cracks well below the surface of Mars.

“One of the other things we have discussed in our paper is that this bacteria could be living off hydrogen, which is exactly the same as what microbes beneath the surface of the Earth are doing too.

“Unfortunately, we won’t find any evidence of animals as the most complex life you might get in the sub surface would be fungi.

“But fungi aren’t even that far removed from plants and animals, so I think you could say that life on Mars could be complex, but small.”

I think that any life on,or in, Mars is likely to be very simple, perhaps similar to bacteria, assuming that there is any at all. We are going to actually go there and look specifically for life. Fortunately, that may be the next step.

Prof Parnell reckons that although the next mission to Mars will have a drill to examine possibilities of life beneath the surface of Mars, he says his new study suggests looking around the edges of craters would be easier and more beneficial.

He said: “What we’re really doing is emphasising that if we are going to explore for life on Mars, we need to go beneath the surface. So we need to find an approach beneath the surface.

“One approach to do that might be to drill and indeed the next European mission to Mars will have a drill on it, but that will only go down about two metres.

“And although drilling two metres on Earth would be a fantastic technological achievement, it’s only really scratching the surface.

I think they meant to write Mars instead of Earth.

“So the alternative is to use what nature has done for us and that’s why we are are particularly interested in the McLaughlin Crater that we have investigated in our paper.

“Because when a meteor lands, it excavates a big hole in the ground and throws rocks from the bottom of the hole outside the crater to where we could conceivably go and sample them.”

And while the craters on Mars may uncover secrets about the planet’s possibility of supporting life, Prof Parnell also revealed the results could show us how life on Earth began.

He said: “It’s very easy to draw parallels between what Mars looks like and what the early Earth might have looked like, because the rocks on Earth that we see now have been recycled a lot in ways that they have not been recycled on Mars.

“Mars has not had things like erosion and shifting of mountain ranges to destroy vital evidence from the past.

“So studying meteorite craters of Mars may well actually give us an indication to how life on Earth began.

“Although we all live on the surface of Earth, life did not originate here, but actually in the sub surface.

“It was only when life had taken hold below the surface that it gradually expanded and came up to the surface.

“In fact, there’s so much life below the surface of our planet that we are actually the unusual ones living above it.”

This sounds a lot like The Deep Hot Biosphere.



Get every new post delivered to your Inbox.

Join 386 other followers

%d bloggers like this: