Archive for category Space
Scientists may have an extra challenge when it comes to detecting alien civilizations: a time limit.
A new study suggests that intelligent aliens, if their technological progression is similar to that of humanity’s, are likely to have moved away from noisy radio transmissions to harder-to-hear digital signals within a 100-year time frame. That offers Earth just a narrow window in which to pick up any signals from extraterrestrial civilizations.
“Based on the results that we looked at, if we assume that the civilizations are humanlike with similar technological progress to us, we calculate the probability of making contact is roughly one in 10 million,” the study’s lead author, Duncan Forgan, told SPACE.com.
The time it takes a planet to go “radio quiet” dramatically restricts the types of signal it sends into space and our chances for eavesdropping on them, said Forgan, a postgraduate researcher at the University of Edinborough in Scotland. [Poll – Is Earth Ready to Meet an Alien Civilization?]
Forgan and his team applied their technology-development time scale to a simulation of the galaxy, based on the assumption that the pace of an alien civilization’s technological progress would be similar to that on Earth. Based on this simulation, the researchers determined the 1-in-10 million odds of humans accidentally stumbling across a transmission from aliens.
The researchers, whose study will appear in an upcoming edition of the International Journal of Astrobiology, focused their work on the expected eavesdropping capabilities of the Square-Kilometer Telescope, a radio telescope slated to be completed by 2023.
A radio century
In the early 20th century, the only options for communicating quickly over long distances were by telegram or wireless radio. As radio technology improved, so did the quality of its broadcasts and receivers.
“In the past, the detector would only take up a chunk of that energy, and the rest would go out into the universe,” Forgan said. “Now, instead of firing off a huge amount of energy and picking up a trace, we send out a very small amount and soak up almost all of it, so the amount of lost energy is much lower.”
Traditional radio communication is being replaced by innovations in the use of light to send digital signals through fiber-optic cable and the emergence of the Internet. The transition from analog to digital broadcasts, which in the last few decades recoded radio signals into formats that preserved their clarity over long distances, have further cut down on Earth’s signal leakage into the universe.
The Drake equation
To determine the Square-Kilometer Telescope’s chances of picking up a radio broadcast from intelligent extraterrestrials, scientists used simulations similar in structure to that of the famous Drake Equation.
While that formula (created by astronomer Frank Drake) spat out a single number for the amount of contactable civilizations by stringing together seven factors deemed critical to the formation of intelligent life, the program used probabilities to create a spatial distribution of a galaxy’s stars and planets.
“What we’re doing is approaching it from a different angle,” Forgan said. “Instead of squeezing huge amounts of astronomical data into several numbers, we’re going to use as much of it as possible.”
The scientists attempted to create a statistically accurate picture of our galaxy by using data on typical star masses, locations, number and masses of planets, and their habitability. According to their simulations, civilizations on par with the technological development of humans could be separated by distances of at least 1,000 light-years or so.
One type of simulation examined a scenario in which all intelligent alien life became radio quiet — a realistic scenario, Forgan said, because signal leakage lessens steadily as technology improves. Another type looked at civilizations that Earth could see during the planet’s entire lifetime.
“When you do that, the possibilities improve immensely; it goes from being a remote impossibility to being much, much higher,” Forgan said.
The concept of radio quiet doesn’t affect the change in distance, but it affects the time scale during which you can hear the signal, he added.
“If your target is broadcasting for 1,000 years, then this gives you more time to find it before the signal switches off than if they were only broadcasting for 100 years,” Forgan said. “The ‘radio quiet’ concept reduces the time scale to a very low number, which means your chances of hearing it are very small.”
What this means is that searching only for radio leakages could cause scientists to miss “quite a lot” of civilizations, Forgan said.
“These results aren’t as new as you may think, but they are exciting because it shows that even the most powerful radio telescopes in the world will still struggle to find E.T. unless we design the search carefully,” Forgan said.
Previous studies on the observation limits of the Square-Kilometer Telescope showed it could detect extraterrestrial signals from up to about 300 light-years away within two months, assuming that the other civilization’s broadcasts were at least as strong as the military radar used by Earth’s governments.
Will we ever detect life?
Scientists continue to use radio waves to search for life because of the scarcity of natural sources of radio waves in the universe, and the fact that they are less easily lost by absorption than other forms of electromagnetic radiation, which includes light.
Even the smallest snippet from an alien broadcast could count as evidence of an extraterrestrial intelligence.
“An artificial signal will have patterns in it that usually do not appear in nature, even if distorted,” Forgan said.
Alternate search targets include technologies that possess a distinct radiation signature, such as the exotic matter created inside a particle accelerator, and technologies that have not been invented yet on Earth, such as communication by lasers or neutrinos.
Neutrinos are very light particles that constantly stream through our bodies and the Earth. (If anyone found a way to capture neutrino emissions in a device, Forgan said, the technology surely would replace Megahertz light waves for cell phones, because the signals would never be obstructed by a building.)
But doesn’t mean humanity should give up on radio: Rather than look at the steady drip of leakage that results from our televisions, radio or radar, we could look for alien civilizations that are making a general effort to communicate with us, Forgan said.
That approach, he admitted, is likely to mean a long wait for any cosmic callbacks.
“If we send a signal right now, it will take four years to reach the nearest star,” Forgan said. “It’s much more likely we will receive a return message in hundreds or thousands of years.
“On the other hand, other civilizations may have a different outlook. They may be desperate to make communication with other civilizations.”
One of the two moons of Mars most likely formed from rubble catapulted into space after a comet or meteorite slammed into the Red Planet, a new study finds.
The moon, Phobos, looks a lot like an asteroid: It’s lumpy, potato-shaped and very small. It has an average radius of just 11 kilometers (6.8 miles).
Scientists have long wondered about the origin of Phobos — is it merely a captured asteroid, the leftovers from Mars’ formation or evidence of a cosmic Martian hit-and-run with another object?
The new study found that the moon’s composition and density strongly indicate that, like the leading theory for Earth’s own moon, Phobos is the result of a catastrophic impact with its parent planet.
Phobos is one of two moons of Mars. The other, Deimos, is smaller than its partner.
What makes a Phobos?
Researchers used data from the European Space Agency’s Mars Express spacecraft to study Phobos’ composition.
By analyzing the probe’s infrared observations, astronomers found that Phobos and asteroids don’t seem to be made of the same stuff. Instead, the moon has many minerals also seen on Mars, suggesting a common origin for the two bodies.
The team also found so-called phyllosilicates — minerals that can form in the presence of water — on Phobos. Phyllosilicates have been detected on Mars, too.
“This is very intriguing as it implies the interaction of silicate materials with liquid water on the parent body prior to incorporation into Phobos,” said study co-author Marco Giuranna of the Istituto Nazionale di Astrofisica in Rome, Italy. “Alternatively, phyllosilicates may have formed in situ, but this would mean that Phobos required sufficient internal heating to enable liquid water to remain stable.”
Independent observations from NASA’s Mars Global Surveyor spacecraft support the composition data from Mars Express, the researchers said.
The research was presented Sept. 20 at the European Planetary Science Congress in Rome, Italy, and has been submitted to the journal Planetary and Space Science.
Too spongy for an asteroid
During the study, evidence piled up to rule out the captured-asteroid scenario for Phobos, researchers said.
The first sign came while they were studying the Martian moon’s density to see how it matched with that of asteroids. They determined the density of Phobos to be about 1.86 grams per cubic centimeter.
“This number is significantly lower than the density of meteoritic material associated with asteroids,” said Pascal Rosenblatt of the Royal Observatory of Belgium. “It implies a sponge-like structure with voids making up 25 to 45 percent of Phobos’ interior.”
Other evidence points toward a relatively spongy Phobos, too.
If it were denser, the moon probably wouldn’t have survived the massive impact that created its Stickney Crater, Giuranna said. Stickney is about 10 km (6 miles) across — nearly half as wide as all of Phobos.
In addition, the researchers said, a highly porous asteroid — if that’s what Phobos once was — probably would not have survived being captured by Mars’ gravity.
Yet sponginess is consistent with the impact-formation hypothesis for Phobos, they added. Chunks of rock and rubble blown off Mars’ surface would accrete somewhat haphazardly in its orbit, leaving interior pockets and voids.
Finally, the motion of both Phobos and its sister moon Deimos — which is also small, rocky and lumpy—argue against the asteroid-capture scenario, according to the researchers. Their orbits are too neat — too circular and too close to the Martian equator — for a couple of snagged space rocks, researchers said.
More missions, more data
Despite the evidence from Mars Express, more observations are still needed before scientists can conclusively determine the origin of Phobos, the researchers said.
The Russian Phobos-Grunt mission, set to launch in 2011, could help settle the question. Phobos-Grunt aims to land on Phobos, grab soil samples (“Grunt” being the Russian word for “soil”) and return with them to Earth. Such samples could be compared to Martian meteorites that have landed on Earth.
Similar studies of lunar soil samples have shown that Earth and our moon are likely made of the same stuff. This determination helped scientists come up with the leading theory of our moon’s formation: A long-ago catastrophic impact
We live on a sphere of extremes and oddities. In fact it’s not really a sphere, but it is a wild planet, mottled with deadly volcanoes, rattled by killer earthquakes, drenched in disastrous deluges. But do you know which were the worst?
Some of Earth’s valleys dip below sea level. Mountains soar into thin air. Can you name the lowest spot? The tallest peak? Do you know how far it is to the center of the planet or what’s there?
Where are the planet’s hottest, coldest, driest and windiest places?
The following list of Earth’s extremes and other amazing facts is presented in Q&A format, so you can cover the answers to test your knowledge of the home planet. Sources include the U.S. Geological Survey and the National Oceanic and Atmospheric Administration, with other SPACE.com reporting.
1. What is the hottest place on Earth?
Count one wrong if you guessed Death Valley in California. True enough on many days. But El Azizia in Libya recorded a temperature of 136 degrees Fahrenheit (57.8 Celsius) on Sept. 13, 1922 — the hottest ever measured. In Death Valley, it got up to 134 Fahrenheit on July 10, 1913.
2. And the coldest place around here?
Far and away, the coldest temperature ever measured on Earth was -129 Fahrenheit (-89 Celsius) at Vostok, Antarctica, on July 21, 1983.
3. What makes thunder?
If you thought, “Lightning!” then hats off to you. But I had a more illuminating answer in mind. The air around a lightning bolt is superheated to about five times the temperature of the Sun. This sudden heating causes the air to expand faster than the speed of sound, which compresses the air and forms a shock wave; we hear it as thunder.
4. Can rocks float?
In a volcanic eruption, the violent separation of gas from lava produces a “frothy” rock called pumice, loaded with gas bubbles. Some of it can float, geologists say. I’ve never seen this happen, and I’m thankful for that.
5. Can rocks grow?
Yes, but observing the process is less interesting than watching paint dry. Rocks called iron-manganese crusts grow on mountains under the sea. The crusts precipitate material slowly from seawater, growing about 1 millimeter every million years. Your fingernails grow about the same amount every two weeks.
6. How much space dust falls to Earth each year?
Estimates vary, but the USGS says at least 1,000 million grams, or roughly 1,000 tons of material enters the atmosphere every year and makes its way to Earths surface. One group of scientists claims microbes rain down from space, too, and that extraterrestrial organisms are responsible for flu epidemics. There’s been no proof of this, and I’m not holding my breath.
7. How far does regular dust blow in the wind?
A 1999 study showed that African dust finds its way to Florida and can help push parts of the state over the prescribed air quality limit for particulate matter set by the U.S. Environmental Protection Agency. The dust is kicked up by high winds in North Africa and carried as high as 20,000 feet (6,100 meters), where it’s caught up in the trade winds and carried across the sea. Dust from China makes its way to North America, too.
8. Where is the worlds highest waterfall?
The water of Angel Falls in Venezuela drops 3,212 feet (979 meters).
9. What two great American cities are destined to merge?
The San Andreas fault, which runs north-south, is slipping at a rate of about 2 inches (5 centimeters) per year, causing Los Angeles to move towards San Francisco. Scientists forecast LA will be a suburb of the City by the Bay in about 15 million years.
10. Is Earth a sphere?
Because the planet rotates and is more flexible than you might imagine, it bulges at the midsection, creating a sort of pumpkin shape. The bulge was lessening for centuries but now, suddenly, it is growing, a recent study showed. Accelerated melting of Earth’s glaciers is taking the blame for the gain in equatorial girth.
11. What would a 100-pound person weigh on Mars?
The gravity on Mars is 38 percent of that found on Earth at sea level. So a 100-pound person on Earth would weigh 38 pounds on Mars. Based on NASA’s present plans, it’ll be decades before this assumption can be observationally proved, however.
12. How long is a Martian year?
It’s a year long, if you’re from Mars. To an earthling, it’s nearly twice as long. The red planet takes 687 Earth-days to go around the Sun — compared to 365 days for Earth. Taking into account Mars’ different rotational time (see #13 below) calendars on Mars would be about 670 days long with some leap days needed to keep things square. If you find one, please mail it to me. I’m curious how they worked out the months, given they have two moons. [The initial publication of this fact mistakenly said a Mars calendar would have 687 days.]
13. How long is the average Martian day?
A Martian can sleep (or work) and extra half-hour every day compared to you. Mars days are 24 hours and 37 minutes long, compared to 23 hours, 56 minutes on Earth. A day on any planet in our solar system is determined by how long it takes the world to spin once on its axis, making the Sun appear to rise in the morning and sending it down in the evening.
14. What is the largest volcano?
The Mauna Loa volcano in Hawaii holds the title here on Earth. It rises more than 50,000 feet (9.5 miles or 15.2 kilometers) above its base, which sits under the surface of the sea. But that’s all volcanic chump change. Olympus Mons on Mars rises 16 miles (26 kilometers) into the Martian sky. Its base would almost cover the entire state of Arizona.
15. What was the deadliest known earthquake?
The world’s deadliest recorded earthquake occurred in 1557 in central China. It struck a region where most people lived in caves carved from soft rock. The dwellings collapsed, killing an estimated 830,000 people. In 1976 another deadly temblor struck Tangshan, China. More than 250,000 people were killed.
16. What was the strongest earthquake in recent times?
A 1960 Chilean earthquake, which occurred off the coast, had a magnitude of 9.6 and broke a fault more than 1,000 miles (1,600 kilometers) long. An earthquake like that under a major city would challenge the best construction techniques.
17. Which earthquake was more catastrophic: Kobe, Japan or Northridge, California?
The 1994 Northridge earthquake had a magnitude of 6.7 was responsible for approximately 60 deaths, 9,000 injuries, and more than $40 billion in damage. The Kobe earthquake of 1995 was magnitude 6.8 and killed 5,530 people. There were some 37,000 injuries and more than $100 billion in economic loss.
18. How far is it to the center of the Earth?
The distance from the surface of Earth to the center is about 3,963 miles (6,378 kilometers). Much of Earth is fluid. The mostly solid skin of the planet is only 41 miles (66 kilometers) thick — thinner than the skin of an apple, relatively speaking.
19. What is the highest mountain?
Climbers who brave Mt. Everest in the Nepal-Tibet section of the Himalayas reach 29,035 feet (nearly 9 kilometers) above sea level. Its height was revised upward by 7 feet based on measurements made in 1999 using the satellite-based Global Positioning System.
20. Has the Moon always been so close?
It used to be much closer! A billion years ago, the Moon was in a tighter orbit, taking just 20 days to go around us and make a month. A day on Earth back then was only 18 hours long. The Moon is still moving away — about 1.6 inches (4 centimeters) a year. Meanwhile, Earth’s rotation is slowing down, lengthening our days. In the distant future, a day will be 960 hours long!
21. Where is the lowest dry point on Earth?
The shore of the Dead Sea in the Middle East is about 1,300 feet (400 meters) below sea level. Not even a close second is Bad Water in Death Valley, California, at a mere 282 feet below sea level.
22. Good thing California isn’t sinking further, right?
Actually parts of it are, which is so interesting that I snuck this non-question onto the list. In a problem repeated elsewhere in the country, the pumping of natural underground water reservoirs in California is causing the ground to sink up to 4 inches (11 centimeters) per year in places. Water and sewage systems may soon be threatened.
23. What is the longest river?
The Nile River in Africa is 4,160 miles (6,695 kilometers) long.
24. What is the most earthquake-prone state in the United States?
Alaska experiences a magnitude 7 earthquake almost every year, and a magnitude 8 or greater earthquake on average every 14 years. Florida and North Dakota get the fewest earthquakes in the states, even fewer than New York.
25. What’s the driest place on Earth?
A place called Arica, in Chile, gets just 0.03 inches (0.76 millimeters) of rain per year. At that rate, it would take a century to fill a coffee cup.
26. What causes a landslide?
Intense rainfall over a short period of time can trigger shallow, fast-moving mud and debris flows. Slow, steady rainfall over a long period of time may trigger deeper, slow-moving landslides. Different materials behave differently, too. Every year as much as $2 billion in landslide damage occurs in the United States. In a record-breaking storm in the San Francisco area in January 1982, some 18,000 debris flows were triggered during a single night! Property damage was over $66 million, and 25 people died.
27. How fast can mud flow?
Debris flows are like mud avalanches that can move at speeds in excess of 100 mph (160 kph).
28. Do things inside Earth flow?
You bet. In fact, scientists found in 1999 that molten material in and around Earth’s core moves in vortices, swirling pockets whose dynamics are similar to tornadoes and hurricanes. And as you’ll learn later in this list, the planet’s core moves in other strange ways, too.
29. What is the wettest place on Earth?
Lloro, Colombia averages 523.6 inches of rainfall a year, or more than 40 feet (13 meters). That’s about 10 times more than fairly wet major cities in Europe or the United States.
30. Does Earth go through phases, like the Moon?
From Mars, Earth would be seen to go through distinct phases (just as we see Venus change phases). Earth is inside the orbit of Mars, and as the two planets travel around the Sun, sunlight would strike our home planet from different angles during the year. Earth phases can be seen in recent photographs taken by Mars Global Surveyor and the European Mars Express.
31. What is the largest canyon?
The Grand Canyon is billed as the world’s largest canyon system. Its main branch is 277 miles (446 kilometers) long. But let’s compare. Valles Marineris on Mars extends for about 3,000 miles (4,800 kilometers). If added it to a U.S. map, it would stretch from New York City to Los Angeles. In places this vast scar on the Martian surface is 5 miles (8 kilometers) deep.
32. What is the deepest canyon in the United States?
Over the eons, the Snake River dug Hell’s Canyon along the Oregon-Idaho border. It is more than 8,000 feet (2.4 kilometers) deep. In contrast, the Grand Canyon is less than 6,000 feet deep — a bit more than a mile.
33. Is Earth the largest rocky planet in the solar system?
Just barely! Earth’s diameter at the equator is 7,926 miles (12,756 kilometers). Venus is 7,521 miles (12,104 kilometers) wide. Mercury and Mars, the other two inner rocky planets, are much smaller. Pluto is rocky, too, but it’s comparatively tiny (and some say it is not a planet at all).
34. How many of Earth’s volcanoes are known to have erupted in historic time?
About 540 volcanoes on land are known. No one knows how many undersea volcanoes have erupted through history.
35. Is air mostly oxygen?
Earth’s atmosphere is actually about 80 percent nitrogen. Most of the rest is oxygen, with tiny amounts of other stuff thrown in.
|Venus is almost as big as Earth. Despite sweltering heat at the surface, its clouds might support life, some scientists say.|
36. What is the highest waterfall in the United States?
Yosemite Falls in California is 2,425 feet (739 meters).
37. What percentage of the world’s water is in the oceans?
About 97 percent. Oceans make up about two-thirds of Earth’s surface, which means that when the next asteroid hits the planet, odds are good it will splash down.
38. Which two landmasses contain the vast majority of the Earth’s fresh water supply?
Nearly 70 percent of the Earth’s fresh-water supply is locked up in the icecaps of Antarctica and Greenland. The remaining fresh-water supply exists in the atmosphere, streams, lakes, or groundwater and accounts for a mere 1 percent of the Earth’s total.
39. Which of the Earth’s oceans is the largest?
The Pacific Ocean covers 64 million square miles (165 million square kilometers). It is more than two times the size of the Atlantic. It has an average depth of 2.4 miles (3.9 kilometers).
40. Why is Earth mostly crater-free compared to the pockmarked Moon?
Earth is more active, in terms of both geology and weather. Much of our planet’s geologic history was long ago folded back inside. Some of that is regurgitated by volcanoes, but the results are pretty hard to study. Even more recent events evident on the surface — craters that can by millions of years old — get overgrown by vegetation, weathered by wind and rain, and modified by earthquakes and landslides. The Moon, meanwhile, is geologically quiet and has almost no weather; its craters tell a billions-year-long tale of catastrophic collisions. Interestingly, some of the oldest Earth rocks might be awaiting discovery on the Moon, having been blasted there billions of years ago by the very asteroid impacts that rattle both worlds.
41. How much surface area does Earth contain?
There are 196,950,711 square miles (510,100,000 square kilometers).
42. What is the largest lake in the world?
By size and volume it is the Caspian Sea, located between southeast Europe and west Asia.
43. Where do most earthquakes and volcanic eruptions occur on Earth?
The majority occur along boundaries of the dozen or so major plates that more or less float on the surface of Earth. One of the most active plate boundaries where earthquakes and eruptions are frequent, for example, is around the massive Pacific Plate commonly referred to as the Pacific Ring of Fire. It fuels shaking and baking from Japan to Alaska to South America.
44. How hot are the planet’s innards?
The temperature of Earth increases about 36 degrees Fahrenheit (20 degrees Celsius) for every kilometer (about 0.62 miles) you go down. Near the center, its thought to be at least 7,000 degrees Fahrenheit (3,870 Celsius).
45. What three countries have the greatest number of historically active volcanoes?
The top three countries are Indonesia, Japan, and the United States in descending order of activity.
46. How many people worldwide are at risk from volcanoes?
As of the year 2000, USGS scientists estimated that volcanoes posed a tangible risk to at least 500 million people. This is comparable to the entire population of the world at the beginning of the seventeenth century!
47. Which of the following sources stores the greatest volume of fresh water worldwide: lakes, streams or ground water?
Groundwater comprises a 30 times greater volume than all freshwater lakes, and more than 3,000 times what’s in the world’s streams and rivers at any given time. Groundwater is housed in natural underground aquifers, in which the water typically runs around and through the stone and other material.
48. Which earthquake was larger, the 1906 San Francisco earthquake or the 1964 Anchorage, Alaska, temblor?
The Anchorage earthquake had a magnitude of 9.2, whereas the San Francisco earthquake was a magnitude 7.8. This difference in magnitude equates to 125 times more energy being released in the 1964 quake and accounts for why the Anchorage earthquake was felt over an area of almost 500,000 square miles (1,295,000 square kilometers).
49. Which earthquake was more destructive in terms of loss of life and relative damage costs, the 1906 San Francisco earthquake or the 1964 Anchorage earthquake?
The 1906 San Francisco earthquake tops this category. It was responsible for 700 deaths versus 114 from the Anchorage earthquake. Property damage in San Francisco was also greater in relative terms due to the destructive fires that destroyed mostly wooden structures of the time.
50. Is Earth’s core solid?
The inner portion of the core is thought to be solid. But the outer portion of the core appears molten. We’ve never been there though, so scientists aren’t sure of the exact composition. A radical Hollywood-like idea was recently put forth to blow a crack in the planet and send a probe down there to learn more. An interesting bit of recent evidence shows Mars’ core may be similarly squishy. Scientists figured this out by studying tides on Mars (tides on Mars?).
51. Does all of Earth spin at the same rate?
The solid inner core — a mass of iron comparable to the size of the Moon — spins faster than the outer portion of the iron core, which is liquid. A study in 1996 showed that over the previous century, the extra speed caused the inner core to gain a quarter-turn on the planet as a whole. So the inner core makes a complete revolution with respect to the rest of Earth in about 400 years. Immense pressure keeps it solid.
52. How many people have been killed by volcanoes during the last 500 years?
At least 300,000. Between 1980 and 1990, volcanic activity killed at least 26,000 people.
53. How much of the Earth’s surface consists of volcanic rock?
Scientists estimate that more than three-quarters of Earth’s surface is of volcanic origin– that is, rocks either erupted by volcanoes or molten rock that cooled below ground and has subsequently been exposed at the surface. Most of Earth’s volcanic rocks are found on the sea floor.
54. Can an earthquake cause a tsunami?
If the earthquake originates under the ocean, yes. Near the earthquake’s epicenter, the sea floor rises and falls, pushing all the water above it up and down. This motion produces a wave that travels outward in all directions. A tsunami can be massive but remain relatively low in height in deep water. Upon nearing the shore, it is forced up and can reach the height of tall buildings. One in 1964 was triggered in Alaska and swamped the small northern California town of Crescent City, moving train cars several blocks and killing several people there. Asteroids can cause tsunami, too.
55. Are all tsunamis high waves when they strike a coastline?
No, contrary to many artistic images of tsunamis, most do not result in giant breaking waves. Rather, most tsunamis come onshore more like very strong and fast tides. The water can rise higher than anyone along a given shore area has ever seen, however. [Model of an East Coast tsunami]
56. How much of the Earth’s land surface is desert?
57. What’s the deepest place in the ocean?
The greatest known depth is 36,198 feet (6.9 miles or 11 kilometers) at the Mariana Trench, in the Pacific Ocean well south of Japan near the Mariana Islands.
58. What is the fastest surface wind ever recorded?
The fastest “regular” wind that’s widely agreed upon was 231 mph (372 kph), recorded at Mount Washington, New Hampshire, on April 12, 1934. But during a May 1999 tornado in Oklahoma, researchers clocked the wind at 318 mph (513 kph). For comparison, Neptune’s winds can rage to 900 mph (1,448 kph).
59. How much fresh water is stored in the Earth?
More than two million cubic miles of fresh water is stored in the planet, nearly half of it within a half-mile of the surface. Mars, too, appears to have a lot of water near its surface, but what’s been detected so far is locked up as ice; nobody has estimated how much might be there.
60. How old is Earth?
Our planet is more than 4.5 billion years old, just a shade younger than the Sun. Recent evidence actually shows that Earth was formed much earlier than previously believed, just 10 million years after the birth of the Sun, a stellar event typically put at 4.6 billion years ago.
61. What is the world’s largest desert?
The Sahara Desert in northern Africa is more than 23 times the size of southern California’s Mojave Desert. [Several readers have e-mailed to suggest that arid Antarctica technically tops this category; true, some researchers put it there, but most lists of deserts don’t include it.]
62. Which planet has more moons, Earth or Mars?
Mars has two satellites, Phobos and Deimos. The Earth has only one natural satellite, but it’s the Moon. The outer planets have lots of Moon, most of them found fairly recently and leading to the possibility that scientists might one day need to redefine what it means to be a moon.
63. What is the world’s deepest lake?
Lake Baikal in the south central part of Siberia is 5,712 feet (1.7 kilometers) deep. It’s about 20 million years old and contains 20 percent of Earth’s fresh liquid water.
64. What is the origin of the word “volcano”?
It derives from Vulcan, the Roman god of fire.
65. How many minerals are known to exist?
There are roughly 4,000 known minerals, although only about 200 are of major importance. Approximately 50-100 new minerals are described each year.
66. What is the total water supply of the world?
The total water supply of the world is 326 million cubic miles (1 cubic mile of water equals more than 1 trillion gallons).
67. What is the world’s largest island?
Greenland covers 840,000 square miles (2,176,000 square kilometers). Continents are typically defined as landmasses made of low-density rock that essentially floats on the molten material below. Greenland fits this description, but it’s only about one-third the size of Australia. Some scientists call Greenland an island, others say it’s a continent.
68. Where are most of Earth’s volcanoes?
The most prominent topographic feature on Earth is the immense volcanic mountain chain that encircles the planet beneath the sea — the chain is more than 30,000 miles (48,000 kilometers) long and rises an average of 18,000 feet (5.5 kilometers) above the seafloor. It is called the mid-ocean ridge and is where Earth’s plates spread apart as new crust bubbles up — volcanic activity. There are more volcanoes here than on land. The spreading, however, leads to scrunching when these plates slam into the continents. The result: More volcanoes and earthquakes in places like California and Japan.
69. What volcano killed the most people?
The eruption of Tambora volcano in Indonesia in 1815 is estimated to have killed 90,000 people. Most died from starvation after the eruption, though, because of widespread crop destruction, and from water contamination and disease.
70. Were Earth and the Moon separated at birth?
Not quite. But leading theory holds that our favorite satellite was carved partly from Earth shortly after the Earth formed. A Mars-sized object slammed into our fledgling planet. The impactor was destroyed. Stuff flew everywhere and a lot of it went into orbit around Earth. The Moon gathered itself together out of the largely vaporized remains of the collision, while Earth hung in there pretty much intact.
71. How many lightning strikes occur worldwide every second?
On average, about 100. Those are just the ones that hit the ground, though. During any given minute, there are more than a thousand thunderstorms around the Earth causing some 6,000 flashes of lightning. A lot of it goes from cloud-to-cloud.
72. Are rivers alive?
Not in the traditional sense, of course. But like all living creatures, rivers have a life span. They are born, grow in size, and they age. They can even die during the span of geological time.
73. Can asteroids create islands?
Speculation has existed for decades that ancient asteroid impacts might create hot spots of volcanic activity, which could give rise to mountains that poke up through seas that didn’t used to be there. There’s no firm answer to this question, but a recent computer model suggested Hawaii might have been formed in this manner.
74. Is the state of Louisiana growing or shrinking?
Louisiana loses about 30 square miles (78 square kilometers) of land each year to coastal erosion, hurricanes, other natural and human causes and a thing called subsidence, which means sinking. Much of New Orleans actually sits 11 feet (3.4 meters) below sea level. Parts of the French quarter have sunk 2 feet in the past six decades. The city is protected by dikes, but all experts agree that storm tides from a direct hit by a major hurricane would breach the system and swamp much of the city. In 2000, the director of the U.S. Geological Survey, Chip Groat, said: “With the projected rate of subsidence, wetland loss and sea-level rise, New Orleans will likely be on the verge of extinction by this time next century.”
75. How much would seas rise if the Antarctic Ice Sheet melted?
The Antarctic Ice Sheet holds nearly 90 percent of the world’s ice and 70 percent of its fresh water. If the entire ice sheet were to melt, sea level would rise by nearly 220 feet, or the height of a 20-story building. Scientists know there’s a melting trend underway. The United Nations has said that in a worst-case scenario — depending on how much global air temperatures increase — seas could jump 3 feet (1 meter) by 2100.
77. Is ice a mineral?
Yes, ice is a mineral and is formally described as such in Dana’s System of Mineralogy.
77. What is the softest of all minerals?
Talc is the softest of minerals. It is commonly used to make talcum powder.
78. What is the hardest of all minerals?
The one that becomes emotionally useless after a divorce but still retains monetary value.
79. How are colors produced in fireworks?
Mineral elements taken from Earth provide the colors. Strontium yields deep reds, copper produces blue, sodium yields yellow, and iron filings and charcoal pieces produce gold sparks. Bright flashes and loud bangs come from aluminum powder.
80. Does Earth have the worst weather in the solar system?
Right now, it’s the worst that most humans I know ever experience. But there’s lots of wilder weather elsewhere. Mars can whip up hurricane-like storms four times bigger than Texas. Dust storms on the red planet can obscure the entire globe! Jupiter has a hurricane twice the size our entire planet, and it’s lasted for at least three centuries (another storm on Jupiter is even bigger). Venus is a living hell, and Pluto is routinely more frigid than the coldest place on Earth (though may change one day, and Pluto may in fact become the last oasis for life).
81. Where are the highest tides?
In Burntcoat Head, Minas Basin, part of the Bay of Fundy in Nova Scotia, tides can range 38.4 feet (11.7 meters). The bay is funnel shaped — its bottom slopes upward continuously from the ocean inlet. The result is an extreme “tidal bore,” a wave-like phenomenon at the leading edge of the changing tide. Bores in Fundy can travel up feeder rivers at 8 mph (13 kph) and be more than 3 feet (1 meter) tall.
82. Where is the world’s only equatorial glacier?
Mt. Cotopaxi in Ecuador supports the only glacier on the equator.
83. What is the largest lake in North America?
84. What’s the deadliest hurricane to ever hit the United States?
A Category 4 hurricane hit Galveston, Texas in 1900 and killed more than 6,000 people (read about the history of it here). The next closest death toll was less than 1,900 from a 1928 Florida hurricane.
85. What is the longest mountain chain on Earth?
The Mid-Atlantic Ridge, which splits nearly the entire Atlantic Ocean north to south. Iceland is one place where this submarine mountain chain rises above the sea surface.
86. How much gold has been discovered worldwide to date?
More than 193,000 metric tons (425 million pounds). If you stuck it all together, it would make a cube-shaped, seven-story structure that might resemble one of Donald Trump’s buildings. First you’d have to find all those rings that have gone down the drain.
87. What are the two major gold-producing countries?
South Africa produces 5,300 metric tons per year, and the United States produces more than 3,200 metric tons.
88. What North American plant can live for thousands of years?
The creosote bush, which grows in the Mojave, Sonoran, and Chihuahuan deserts, has been shown by radiocarbon dating to have lived since the birth of Christ. Some of these plants may endure 10,000 years, scientists say. If only they could talk.
89. On average, how much water is used worldwide each day?
About 400 billion gallons.
90. Is Saturn the only ringed planet?
Saturn has the most obvious rings. But Jupiter and Neptune both have subtle ring systems, [as does Uranus, readers reminded me]. And even Earth may once have been a ringed planet, the result of some space rock’s glancing blow.
91. What is the highest, driest, and coldest continent on Earth?
That would be Antarctica.
92. At what depth do most earthquakes occur?
Most are triggered less than 50 miles (80 kilometers) from the Earth’s surface. Shallower earthquakes have more damage potential, but a temblor’s destruction also depends largely on rock and soil conditions as well as building methods.
93. Where are the oldest rocks on Earth found?
Since the ocean floor is being continually regenerated as the continental plates move across the Earth’s surface, the oldest rocks on the ocean floor are less than 300 million years. In contrast, the oldest continental rocks are 4.5 billion years old.
94. What percentage of the world’s fresh water is stored as glacial ice?
About 70 percent. And if you had to replace it all, you’d need 60 years of the entire globe’s rainfall, and then you’d have to figure out a way to freeze it all.
95. What is the largest alpine lake in North America?
Lake Tahoe on the California-Nevada border has a 105,000-acre surface, holds 39 trillion gallons of water, and is almost 1,600 feet (488 meters) deep.
96. Have there always been continents?
Not as we know them today. Many scientists figure Earth began as one huge continent — dry as a bone. Water was delivered in comets, the thinking goes, and the oceans developed. Much more recently, all the world’s landmasses were huddled into one supercontinent called Pangaea. It began to break up about 225 million years ago, eventually fragmenting into the continents as we know them today.
97. How much volcanic ash can fall in a day?
I can only give an example. During the 9-hour period of most vigorous activity on May 18, 1980, Mount St. Helens dumped more than 540 million tons of ash over an area of more than 22,000 square miles (56,980 square kilometers). It was the most destructive volcanic eruption known to occur in the United States. Fifty-seven people were killed by the eruption including USGS scientist Dr. David Johnston, who was at a monitoring site 5 miles (8 kilometers) from the volcano. An estimated $1 billion damage was caused by the eruption, through mudflows and landslides as well as what fell from the sky.
98. What is feldspar?
A better question might be, “Who but a geologists could love feldspar?” It happens to be the most common mineral in Earth’s crust. But I couldn’t find anything about it that most of us really need to know.
99. What are the most extreme locations in the United States, compass-wise?
This one is a bit tricky, and as it turns out three or even four of the answers may catch you off guard. The westernmost point is the aptly named West Point of Amatignak Island, Alaska. The northernmost point is Point Barrow, Alaska. The southernmost point is the southern tip of the island of Hawaii. The easternmost point — go ahead, take a guess! — is Pochnoi Point at Semisopochnoi, Alaska. Huh? Look at a world map. The tip of the Aleutian Islands lies on the other side of the 180-degree longitude line — the International Dateline — putting Pochnoi Point barely but officially in the Eastern Hemisphere.
100. If you were to arrange Earth, the Moon and Mars like Matryoshka nesting dolls, how would they be ordered?
Mars would nest inside Earth, and the Moon would fit neatly inside Mars. Earth is about twice as big as Mars, which is about twice as big as the Moon.
101. Will Earth always be here?
Astronomers know that over the next few billion years, the Sun will swell so large as to envelop Earth. If we’re still here, we’ll probably fry and the planet will be vaporized. There’s a chance, however, that the changing mass of the Sun will cause Earth to move into a more distant and pleasant orbit. One mathematical calculation shows it would be theoretically possible for humans to engineer such a move before it’s too late.
On August 1, 2010, almost the entire Earth-facing side of the sun erupted in a tumult of activity. This image from the Solar Dynamics Observatory of the news-making solar event on August 1 shows the C3-class solar flare (white area on upper left), a solar tsunami (wave-like structure, upper right), multiple filaments of magnetism lifting off the stellar surface, large-scale shaking of the solar corona, radio bursts, a coronal mass ejection and more.
This multi-wavelength extreme ultraviolet snapshot from the Solar Dynamics Observatory shows the sun’s northern hemisphere in mid-eruption. Different colors in the image represent different gas temperatures. Earth’s magnetic field is still reverberating from the solar flare impact on August 3, 2010, which sparked aurorae as far south as Wisconsin and Iowa in the United States. Analysts believe a second solar flare is following behind the first flare and could re-energize the fading geomagnetic storm and spark a new round of Northern Lights.
Sigma APO 200-500 F/2.8
Perhaps the most “sensible” of the items presented in this list, this is nevertheless one of the heftiest tele zoom lenses for SLR cameras around. While the zoom range of 200-500mm is nothing new or exciting, it’s the maximum aperture of an incredible f/2.8 throughout the focal range that makes this such a special lens.
While a lot of tele lenses have a distinct cannon barrel look, Sigma have apparently done all they can to enhance that trait, giving the lens a leafy green finish. The end result is an extremely fast tele zoom lens that could easily be confused with a surface-to-air missile launcher.
Zeiss Apo Sonnar T* 1700 mm F4
For people who have been into photography for a while, the name Carl Zeiss means top of the line optical quality, usually with a matching price tag. While continuing to produce their top-of-the-line optics for various camera systems, Zeiss have more recently also begun cooperating with Nokia and Sony, making optics for their mobile phones and digital cameras.
Two years ago, the company presented a remarkable one-off tele lens, reportedly custom built for a wealthy Qatari. Weighing in at 256 kilos, it’s is a 1700mm f/4 lens designed for medium format (which roughly equals 750mm in 35mm SLR format). The monster bears more than a fleeting resemblance to a jet engine; given the size the ‘super tele lens’ labeling on the side seems a little superfluous – it isn’t very likely that it would be mistaken for an average 70-200mm, after all.
The little black lump at the end is your average 6×6 medium format camera, in itself a quite bulky piece of equipment, but completely dwarfed by the Zeiss lens. Upon it’s unveiling, it was said to be the largest non-military tele lens in the world. One wonders what the largest military tele lens might look like.
Drawing from their experience in manufacturing large telescopes and instruments for astronomical sciences, Zeiss had to develop an entirely new focussing system, Due to the massive size of the glass elements, the lens had to be equipped with extremely powerful focussing motors, capable of moving all that heavy glass around. The rear end of the lens has a dedicated LCD monitor built in to display focussing distance, aperture etc. No price has been published, but Zeiss hinted at a price of at least several million Euros.
The intended use for the lens is reportedly “antelope photography”. This doesn’t immediately strike one as the kind of kit you want to bring along on a safari to photograh fast moving and easily startled animals – hiding in the bushes is certainly off the agenda – but the uncompromising construction is said to allow the lens to autofocus as fast as a ‘regular’ telephoto lens.
Polaroid 20×24” Camera
Image: Joyce Vanman / www.mammothcamera.com
The average film camera has for the last 50 years used either 120 rollfilm or so-called 135 film, 135 being by far the most commonly used type. Each frame of 135 film is 36×24 milimeters, while the average consumer dSLR camera today has a sensor size of approximately 60% of this, around 23×15 milimeters. The sensors in digital compacts are much smaller still. Within this tiny space, the camera and its lens has to compress the vast amount of detail visible to the human eye. The resulting replications of reality are far from perfect, they can’t be.
One way of partially overcoming this problem is quite simply to use larger film formats or digital sensors. Within the digital realm, the 48x36mm sensor size available in certain medium format digital backs is pretty much as large as it gets without substantial R&D resources (like what a major corporation, national government or army might have at their disposal).
In film, things are a bit simpler. While constructing huge digital sensors is a challenging task, creating a huge sheet of film or photographic paper is really – simply put – just a matter of making it bigger than usual, and building a camera large enough to house it.
The biggest ‘instant’ camera I know of is Polaroid’s 20×24” behemot. It’s 1.5 meters tall and weighs in at 106 kilos. The Polaroid paper sheets used in this camera is, as the name implies, 20 x 24”, which equals 50×60 cm. Keeping in mind that the aforementioned 135 film is a mere 3.6 x 2.4 cm, it’s easy to see why such a larger-than-life camera would be capable of producing prints of far superior detail compared to smaller formats.
A number of these cameras are available for hire, complete with a dedicated studio space, in San Fransisco, New York and Prague. Following Polaroid’s recent announcement that they will completely cease the production of their signature instant film, there is a certain risk that these cameras will be destined for the museum soon.
Seitz 6×17” digital panoramic camera
Instead of the common digital camera sensor which records the entire scene at once, the Seitz 6×17” uses a scanner to literally scan the view through the lens. The end result is 160 megapixel images in a panoramic format. It does the job a bit faster than your average flatbed scanner though, recording a full-sized frame (21 250 x 7500 pixels) in two seconds. It’s big, it’s heavy (5 kilos if you wish to use it outside a studio) and quite silly, but it turns out huge, amazing photos – and it should, costing as it does $42 000.
Swedish camera manufacturer Hasselblad (or “‘blad” as they are often called) has for a long time been ranked among the very best when it comes to cameras. Indeed, NASA’s space programme chose Hasselblad as their camera provider, and three Hasseblads where carried aboard the Apollo 11 mission, perhaps the company’s most famous feat.
Priced at around $40 000, a Hasselblad H3DII with a 39 megapixel backpiece is one of the most expensive photo kits available in ordinairy retail sale. It’s fairly large, fabulously expensive and capable of creating huge, extremely detailed image files with its 39 megapixel, 48x36mm sensor.
For photographing your cat, you can probably make do without this camera, but if you’re shooting supermodels for Vogue, you might just need a camera of this caliber. If you ever watch TV shows like “Top Model”, there’s a fair chance you’ll see a ‘blad involved in a shoot every now and then.
Canon EF 1200mm f/5.6L USM
While the 1700mm lens mentioned earlier is all fine and dandy if you’ve got a truck to mount it onto, some may prefer a more lightweight, nimble sollution. Weighing a mere 16.5 kilos and being only 83 centimeters long (without the bucket-like hood), this delicate little flower will nevertheless magnify faraway objects (or perhaps more relevant, faraway people) to a degree that will leave little to the imagination. To my knowledge, this is the longest focal length available to autofocus SLR cameras without using any extra magnifiers.
Due to its size, limited area of use and robust price tag, it has only been available from Canon built to order, and to date they have apparently produced fewer than 20 samples of this lens. The company recently announced that they would be slashing the 1200mm from their catalogue, so if you want one, better be quick about it.
The suggested price of the lens upon unveiling in 1993, converted to present day money puts it at apx. $120 000, or the cost of “a small sports car” which is the most common price comparison given for the lens.
The Gigapxl Project
Launched by physicist Graham Flint, the Gigapxl Project set about creating a camera system that would allow the creation of photos with billions of pixels (or thousands of megapixels if you like). The Gigapxl Project employs a large format camera with 9×18” film sheets to shoot big panorama photos of places of interest, primarily in the USA.
The film sheets are then scanned using a highly sophisticated technique, resulting in digital files that contain the equivalent resolution of several gigapixels. Though the original aim was to reach a single gigapixel (1000 megapixels), the project website now claims it is able to create images with a resolution of aproximately 6 gigapixels.
Nowadays, camera manufactureres like to stick very dense sensors into tiny consumer cameras with mediocre optics, which results in images that despite the 12 or 14 megapixel resolution aren’t really any better than 4 megapixels. It’s a way of cheating customers who don’t know much about digital photography as most people seem to think that more megapixels equals better photos, which is a truth with great limitations.
It would be easy to think that the Gigapxl Project is much the same, just a whole lot of pixels wasted on creating huge digital files that contain little in terms of actual details. However, at the project website, it’s made very clear that the technology and knowledge put into these photos means that the 2, 4 or 6 gigapixel photos they produce are in fact as detailed as their pixel size suggests. But why take my word for it? Check out the amazing images in their gallery for an idea of what I’m talking about!
A pinhole camera is perhaps the simplest kind of camera there is. You make a tiny hole in an otherwise light-sealed container, but in a sheet of film or other photo-sensitive media, point it towards what you want to photograph and let light pass through the hole for a set period of time. The reflected light will, just like the light reflected through the lens of an ordinairy camera result in a photo, be it through a digital sensor or on a piece of film.
But it could also be built out of a box truck, which is exactly what an inventive bunch of spaniards and americans did. By drilling a hole in its side and attaching huge sheets of photographic paper (100×30 cm) to the inside of a truck, they created a huge mobile pinhole camera.
“The Great Picture”
But why stop at a truck, when you could convert an entire airplane hangar into a pinhole camera? While the Cameratruck above is touted as the world’s largest mobile camera, this hangar is certified by the Guinness Book of Records as the largest camera in existance, albeit immobile.
It’s basically an old hangar building at the disused El Toro Marine Corps Air Station in Southern California, which has been made light tight to ensure no light gets in except through the little pinhole in one of the hangar’s sides. To create the image alluringly described as “The Great Picture”, a huge sheet of made-to-order canvas was suspended inside the hangar and coated in 80 litres of Liquid Light, making it photosensitive.
The exposure time of the world’s largest camera was set to aproximately 35 minutes, after which the canvas was chemically developed (in a pool of 2300 litres of developer – photography at this scale does not come cheap!) into the world’s largest photo, 313 square meters (3375 square feet) in size.
Compare that to a standard 135 film frame, which you might remember from earlier on in the article is 36×24 milimeters, equalling 8.64 square centimeters, or 0.00864 square meters.
A great collection of thrilling and fantastic space photos taken by NASA.
In the 1960s-80s in the USSR there was fulfilled a great number of satellite killers tests. During this warfare there were launched land ballistic missiles, antimissiles, military satellites (including counterweapons) and it made a great impression on the USA. This warfare of the Soviet nuclear force was called “7-hours Nuclear War”, it forced America to start creation of antisatellite and anti-missile systems of new generation. GA_googleFillSlot(“ER-inside-post-unit”);
“Star Wars” program – the Strategic Defense Initiative proclaimed by Ronald Reagan (1983).
In the USA there were a lot of exotic projects of space battle station with use of kinetic, laser and particle beam weapons.
The Soviet maneuverable satellites “Polyot-1” and “Polyot”-2 (Flight-1 and 2) made to fight American military spy-satellites.
NPO Energia – a military missile station equipped with laser and missile weapons.
On the basis of NPO Energia there were developed two weapon systems: 17F19 “Skif” – applying laser weapons and 17F111 “Kaskad” – a system applying missile weapons.
The missile station “Kaskad”.
For orbiting rockets testing it was decided to mount them on cargo vehicles “Progress”.
The space station for terrestrial targets destruction applying self-contained modules with destruct units of ballistic and glide types.
The Remote Weapon Station is on its mission.
“Buran” shuttle. In fact its destructive units represent glide nuclear bombs.
“Skif-D” project. The vehicle was 40m long, its max. diameter was 4.1m and weight was approximately 95 tons.
“Stilet” for 17F19S was a space version of terrestrial “Stilet”.
The space complex 17F19U “Skif-U”. The practical project implementation.
Gorbachev praises the cosmodrome employees and space technology inventors.
Russian engineers have developed the universal space vehicle military concept. Such a vehicle should have a nuclear 150-500 kW power sources. Such power will allow to monitor territories and air space providing the informational superiority particularly in the armed conflicts. It will be able to perform the destruction missions as well.
The following discussion is based on a presentation by Ilan Kroo entitled, Reinventing the Airplane: New Concepts for Flight in the 21st Century.
When we think about what may appear in future aircraft designs, we might look at recent history. The look may be frightening. From first appearances, anyway, nothing has happened in the last 40 years!
There are many causes of this apparent stagnation. The first is the enormous economic risk involved. Along with the investment risk, there is a liability risk which is of especially great concern to U.S. manufacturers of small aircraft. One might also argue that the commercial aircraft manufacturers are not doing too badly, so why argue with success and do something new? These issues are discussed in the previous section on the origins of aircraft.
Because of the development of new technologies or processes, or because new roles and missions appear for aircraft, we expect that aircraft will indeed change. Most new aircraft will change in evolutionary ways, but more revolutionary ideas are possible too.
This section will discuss several aspects of future aircraft including the following:
- Improving the modern airplane
- New configurations
- New roles and requirements
Improving the Modern Airplane
Breakthroughs in many fields have provided evolutionary improvements in performance. Although the aircraft configuration looks similar, reductions in cost by nearly a factor of 3 since the 707 have been achieved through improvements in aerodynamics, structures and materials, control systems, and (primarily) propulsion technology. Some of these areas are described in the following sections.
Active flight control can be used in many ways, ranging from the relatively simple angle of attack limiting found on airplanes such as the Boeing 727, to maneuver and gust load control investigated early with L-1011 aircraft, to more recent applications on the Airbus and 777 aircraft for stability augmentation.
Reduced structural loads permit larger spans for a given structural weight and thus a lower induced drag. As we will see, a 10% reduction in maneuver bending load can be translated into a 3% span increase without increasing wing weight. This produces about a 6% reduction in induced drag.
Reduced stability requirements permit smaller tail surfaces or reduced trim loads which often provide both drag and weight reductions.
Such systems may also enable new configuration concepts, although even when applied to conventional designs, improvements in performance are achievable. In addition to performance advantages the use of these systems may be suggested for reasons of reliability, improved safety or ride quality, and reduced pilot workload, although some of the advantages are arguable.
New Airfoil Concepts
Airfoil design has improved dramatically in the past 40 years, from the transonic “peaky” sections used on aircraft in the 60’s and 70’s to the more aggressive supercritical sections used on today’s aircraft. The figure below illustrates some of the rather different airfoil concepts used over the past several decades.
Continuing progress in airfoil design is likely in the next few years, due in part to advances in viscous computational capabilities. One example of an emerging area in airfoil design is the constructive use of separation. The examples below show the divergent trailing edge section developed for the MD-11 and a cross-section of the Aerobie, a flying ring toy that uses this unusual section to enhance the ring’s stability.
Flow Near Trailing Edge of DTE Airfoil and Aerobie Cross-Section
Subtle manipulation of aircraft aerodynamics, principally the wing and fuselage boundary layers, can be used to increase performance and provide control. From laminar flow control, which seeks to reduce drag by maintaining extensive runs of laminar flow, to vortex flow control (through blowing or small vortex generators), and more recent concepts using MEMS devices or synthetic jets, the concept of controlling aerodynamic flows by making small changes in the right way is a major area of aerodynamic research. Although some of the more unusual concepts (including active control of turbulence) are far from practical realization, vortex control and hybrid laminar flow control are more likely possibilities.
Structural materials and design concepts are evolving rapidly. Despite the conservative approach taken by commercial airlines, composite materials are finally finding their way into a larger fraction of the aircraft structure. At the moment composite materials are used in empennage primary structure on commercial transports and on the small ATR-72 outer wing boxes, but it is expected that in the next 10-20 years the airlines and the FAA will be more ready to adopt this technology.
New materials and processes are critical for high speed aircraft, UAV’s, and military aircraft, but even for subsonic applications concepts such as stitched resin film infusion (RFI) are beginning to make cost-competitive composite applications more believable.
Propulsion is the area in which most evolutionary progress has been made in the last few decades and which will continue to improve the economics of aircraft. Very high efficiency, unbelievably large turbines are continuing to evolve, while low cost small turbine engines may well revolutionize small aircraft design in the next 20 years. Interest in very clean, low noise engines is growing for aircraft ranging from commuters and regional jets to supersonic transports.
In addition to advances in disciplinary technologies, improved methods for integrating discipline-based design into a better system are being developed. The field of multidisciplinary optimization permits detailed analyses and design methods in several disciplines to be combined to best advantage for the system as a whole.
The figure here shows the problem with sequential optimization of a design in individual disciplines. If the aerodynamics group assumes a certain structural design and optimizes the design with respect to aerodynamic design variables (corresponding to horizontal motion in the conceptual plot shown on the right), then the structures group finds the best design (in the vertical degree of freedom), and this process is repeated, we arrive at a converged solution, but one that is not the best solution. Conventional trade studies in 1 or 2 or several parameters are fine, but when hundreds or thousands of design degrees of freedom are available, the use of more formal optimization methods are necessary.
Although a specific technology may provide a certain drag savings, the advantages may be amplified by exploiting these savings in a re-optimized design. The figure to the right shows how an aircraft was redesigned to incorporate active control technologies. While the reduced static margin provides small performance gains, the re-designed aircraft provides many times that advantage. Some typical estimates for fuel savings associated with “advanced” technologies are given below. Note that these are sometimes optimistic, and cannot be simply added together.
New Configuration Concepts
Apart from evolutionary improvements in conventional aircraft, revolutionary changes are possible when the “rules” are changed. This is possible when the configuration concept iteself is changed and when new roles or requirements are introduced.
The following images give some idea of the range of concepts that have been studied over the past few years, some of which are currently being pursued by NASA and industry.
Blended Wing Body
The BWB design is intended to improve airplane efficiency through a major change in the airframe configuration. The thick centerbody accommodates passengers and cargo without the extra wetted area and weight of a fuselage. Orginally designed as a very large aircraft with as many as 800 passengers, versions of the BWB has been designed with as few as 250 passengers and more conventional twin, podded engines.
The joined wing design was developed principally by Dr. Julian Wolkovitch in the 1980’s as an efficient structural arrangement in which the horizontal tail was used as a sturcural support for the main wing as well as a stabilizing surface. It is currently being considered for application to high altitiude long endurance UAVs.
Oblique Flying Wing
One of the most unusual concepts for passenger flight is the oblique wing, studied by Robert T. Jones at NASA from 1945 through the 1990s. Theoretical considerations suggest that the concept is well suited to low drag supersonic flight, while providing a structurally efficient means of achieving variable geometry.
New Roles and Requirements
In addition to new configuration ideas, new roles and requirements for aircrafrt may lead to new aircraft concepts. Some of these are summarized below.
Pacific Rim Travel
As global commerce continues to increase, the need for passenger and cargo transportation grows as well. Many have speculated that growth in pacific rim travel may be the impetus for high speed aircraft development. The figure above suggests how the time required for flight from Los Angeles to Tokyo varies with cruise Mach number. (The somewhat facetious Mach 8 aircraft requires extra time to cool off before passengers can deplane.)
Supersonic transportation (Boeing High Speed Civil Transport Concept)
Ground Effect Cargo Tranport Concept
Vehicles designed for missions other than carrying passengers include military aircraft with new constraints on radar detection (low observables), very high altitude aircraft, such as the Helios solar powered aircraft intended for atmospheric science and earth observation studies, and vehicles such as the Proteus, designed as a communications platform.
Low Observables (B2 Bomber)
Autonomous Air Vehicles (Pathfinder: a prototype for Helios solar UAV)
Halo Autonomous Air Vehicle for Communications Services (an AeroSat)
Finally a new class of air vehicles intended to provide lower cost access to space is under study. The near-term future of such designs depends on the economic health of the commercial space enterprise and it presently appears that these concepts are not likely to be seen soon.
Access to Space
- Improved understanding and analysis capabilities permit continued improvement in aircraft designs
- Exploiting new technologies can change the rules of the game, permitting very different solutions
- New objectives and constraints may require unconventional configurations
- Future progress requires unprecedented communication among aircraft designers, scientists, and computational specialists
Two giant planets circling a dying star about 223 light-years away sweep past one another closer than any other planetary pair, demonstrating orbital mechanics that break the bounds of what scientists thought possible.
The planets, which are about the size of Jupiter, likely formed 2.5 billion to 3 billion years ago from of disk of dust and gas circling a massive newborn star, now known as HD200964.
Typically, gravity ends up balancing planet pairs so that the inner world completes two orbits for every one made by its outlying sibling, among other configurations. HD200964’s inner Jupiter is making four orbits for every three completed by its partner.
The closer the planets, the trickier the balancing act due to the planets’ increasingly powerful gravitational influences on each other.
“The tighter you get the planets, the more fine-tuned their steps have to be or they’re going to force each other out,” astronomer John Johnson, with the California Institute of Technology, told Discovery News.
The synchronicity at HD200964 is particularly exquisite. An orbital dance brings the two giant planets as close as about 33 million miles to one another. In our solar system, Jupiter and its nearest neighbor Saturn are never closer than 10 times that distance. The planetary pair orbiting HD200964 is separated by a distance similar to the divide between Earth and Mars.
“They’re an island of stability in a sea of instability,” said University of Florida’s Eric Ford. “In the case of HD200964, it is particularly dramatic because it’s a pretty small island.”
Astronomers have been keeping a close watch on HD200964 for about five years, teasing out details from weird wobbles in its light waves, due to the planets’ gravitational tugs. They then run the data in computer models. The star is among 450 similar targets being scanned for planetary systems.
“One of the things we’d like to understand is how planet formation is impacted by the type of star,” Ford told Discovery News.
HD200964 is not the only star in the study that has closely orbiting planets. A pair of planets circling 24 Sextanis, located 244 light-years away, pass as close as about 70 million miles from one another.
Johnson estimates that about 20 or even 25 percent of massive stars like HD2000964 and 24 Sextanis have large, Jupiter-class planets.