INTRODUCTION Professional surveyors measure, map, and analyze relatively large portions of the Earth’s surface. Armed with precision instruments, they define and record accurate land contours and property boundaries. And they pinpoint the locations of natural landmarks and man-made structures. Surveying has, for centuries, been an essential element of civilized human existence. But it’s practical, everyday […]
Professional surveyors measure, map, and analyze relatively large portions of the Earth’s surface. Armed with precision instruments, they define and record accurate land contours and property boundaries. And they pinpoint the locations of natural landmarks and man-made structures. Surveying has, for centuries, been an essential element of civilized human existence. But it’s practical, everyday im-portance is often overlooked.
Accurate surveying measurements, and the maps that result, make individual property ownership possible. And property ownership, in turn, fosters fruitful human interactions, accentuates the steady accumulation of wealth, and en-hances social prosperity.
“Property is that which is necessary for all civil societies,” observed the famous Scottish philosopher David Hume. America’s 12th president, Abraham Lincoln, echoed a similar sentiment when he concluded that: Property is the fruit of labor . . . It is a positive good in the world. Journalist Leo Rosen was not inclined to contradict President Lincoln’s enthusiastic endorsement. “Property is a sacred trust,” he once concluded, “expressly granted by God, the Bible, and the Recorder’s Office.”
Compelling evidence that property boundaries were being established by sur-veyors as early as 1400 BC has been found among stone carvings found on the broad floodplains and the fertile valleys of ancient Egypt. During the Roman occupation of that prosperous and fertile kingdom, Roman technicians studied, absorbed, and copied the techniques the Egyptians had perfected while they were constructing the great pyramid at Giza.with its nearly perfect proportions and its surprisingly precise north-south alignment.
Around 15 BC, Roman engineers made at least one innovative contribution to the art and science of surveying when they mounted a large, thin wheel in barrel-fashioned on the bottom of a sturdy cart.
When their clever mechanism was pushed along the ground, it automatically dropped a single pebble into a small container with each 360-degree revolution. The number of pebbles rattling around in the container provided a direct measure of the distance traveled by the device. When perfected, it became the world’s first crude, but reliable, odometer!
Roman surveyors refined the methods and mechanisms pioneered by the Egyptians and used their techniques in surveying more than 40,000 miles of Roman roads and in laying out hundreds of miles of aqueducts funneling water to their thirsty cities.
SURVEYING INVENTIONS THAT SPROUTED UP DURING THE RENAISSANCE
In 1620 the famous English mathematician Edmund Gunter develop the earliest surveying chain. It was widely used by surveyors until the steel tape carne into existence 400 years later.
The vernier, a precise auxiliary scale that permitted more accurate readings of dis-tances and angles, was invented in 1631. It was followed by the micrometer micro-scope in 1638 and telescope sights in 1669. The spirit level followed around 1700.A spirit level relies on a small bubble floating in a liquid-filled glass cylinder that is precisely centered when the device is perpendicular the local direction of gravity. .
By the 1920s photogrammetry–the science of constructing accurate maps from aerial photographs–came into general use. And, 50 years later, in the 1970s, orbiting satellites began to serve as dedicated reference points for measuring millions of attitude angles and distances. These measurements allowed contem-porary experts to construct ground-level maps with unprecedented levels of accuracy and convenience. By the 1990s spaceborne centimeter-level surveying had become convenient, practical, and considerably less expensive, too.
Surveying methodologies can be divided into two broad categories: plane surveying – which typically involves distances shorter than 12 miles, and geodetic surveying–which spans areas so large the curvature of the earth must come into play.
Plane surveying assumes that the earth is flat in a small local area. Under this con-dition, relatively simple computational algorithms from Euclidean geometry and plane trigonometry can be employed in processing the measurements the surveyor makes. The region being surveyed is typically divided into a small chain of triangles or quadrangles.
When the simpler triangles.are employed, the three interior angles for each tri-angle must sum to 180 degrees and the common side being shared by a pair of the adjacent triangles must be constrained to have the same length in both of the relevant trigonometric calculations. Specialized numerical adjustments force the computations to produce mutually consistent results.
The approach that relies on quadrangles involves four sides, eight angles, and two diagonals. All shared dimensions are forced to end up with mutually consistent results.
GEODETIC SURVEYING ON A MUCH LARGER. SCALE
Geodetic surveying must be applied when the areas being surveyed are so ex-tensive the Earth’s curvature has an appreciable effect on the surveyor’s measurements. In this case spherical trigonometry is required despite the fact that it involves greater complexity and more intricate visualization for those in-terpreting the results.
In 1687 Sir Isaac Newton demonstrated that the earth exhibits a pronounced bulge at the equator. Its first-order spherical shape is distorted by the centrifugal forces induced by its daily rotation.The shape it assumes can be approximated as a oblate spheroid with an equatorial diameter approximately 27 miles longer than its polar diameter.
Huge numbers of measurements affecting the Earth’s non-spherical shape have been incorporated into a variety of mathematical reconstructions of the Earth’s equatorial bulge. These approximations are called datums when they are being used in connection with geodetic surveying.
Leveling measurements establishing a fictitious local sea level are often used in constructing the precise oblate spheroids used in modeling and analyzing surveying operations. One of the earliest and most popular of these models is the Clark ellipsoid of 1866. For more than a century it has been employed as an engineering model defining the shape and gravitational characteristics of our home planet.
Surfaces determined by leveling measurements approximate the average long-term sea level of our home planet. Such surfaces are distorted slightly because, at high northern and southern latitudes, the outer edge of the oblate spheroid is in closer proximity to the Earth’s center where most of its gravity is concentrated.
MODERN ACCOMPLISHMENTS IN AERIAL PHOTOGRAPHY
Military commanders have always struggled to capture and hold the “high ground” because an elevated vantage point often provides an unobstructed view of enemy activities on the ground below. During the American Civil War (circa 1860) hot-air balloons carried reconnaissance experts up among the clouds where they could observe enemy troop deployments and equipment placements.
During World War I and World War II, substantial resources were expended by the various combatants in attempting to survey the sprawling battlefields scattered across continent-wide dimensions. And, when peace ascended over though the smoke-powder battlegrounds, the accuracy and convenience of military surveying and mapmaking operations were appreciably accentuated by aerial observations.
Later in Kentucky (the author’s home state) tobacco acreages were measured, estimated, and controlled by precise government-sponsored surveys of this type. Indeed, this allotment system is still1 .. today, controlled by that same highly efficient approach to terrestrial surveying.
SURVEYING GOD’S GREEN EARTH WITH ORBITING SATELLITES
Orbiting satellites became relatively inaccurate surveying tools shortly after the Rus-sians launched their first Sputnik into outer space in October of 1957. The earliest American satellites used in this manner were the two 100-foot Echo Balloons clearly visible from the surface of the earth. These aluminum-coated mylar balloons allowed crude, but convenient, mapping of otherwise inaccessible regions of the Earth. This could be accomplished by bouncing a sequence of brief radar pulses off the skin of the balloon and timing the bent-pipe signal travel-times between a known location on earth and the one that was yet to be determined.
Camera-equipped satellites have also found widespread applications in surveying and mapmaking enterprises. Shortly after the first Sputnik reached orbit, President Eisenhower presented the ambassador of Brazil with an accurate map of his forest-shrouded country. NASA’s imaging experts had kludged it together by combining dozens of satellite images into a countrywide composite.
Later the six Transit Navigation Satellites and the two dozen or so satellites in the GPS constellation made surveying considerably more accurate, convenient, and cost-effective. GPS-derived sub-centimeter accuracies soon became possible using the precise timing measurements made available by the GPS satellites and their international competitors. Positioning errors were dramatically reduced compared with most conventional surveying techniques. In part, this became possible because ground-based and space-based hardware units and new software modules were soon providing accurate and reliable positioning corrections.
Professional surveyors measure, map, and analyze relatively large portions of the Earth’s surface. Armed with precision instruments, they define and record accurate land contours and property boundaries. And they pinpoint the spatial locations of natural landmarks and man-made structures. Surveying has, for many centuries, been an essential element of civilized human existence. But it’s practical, everyday importance is sometimes overlooked.
Hopefully, this brief article will help bring the fundamental importance of pre-cision surveying back into sharp focus.
Seal Beach, California
The recent abort, and eventual successful launch, of the Space-X mission to resupply the space station is one of many bumps in the road to commercial space. One should not expect the road to be smooth, or that replacing a Russian supply system with over a half century and almost 1,000 missions in its heritage […]
The recent abort, and eventual successful launch, of the Space-X mission to resupply the space station is one of many bumps in the road to commercial space. One should not expect the road to be smooth, or that replacing a Russian supply system with over a half century and almost 1,000 missions in its heritage will be easy. While we all hope that the commercial efforts of such companies as Space-X and Orbital Science Corporation will succeed, we also know many problems will arise.
According to Ed Keith, an ATI teacher of rocket and missile design and technology, the NASA commercial space road is a major step in the right direction. On the other hand, he sees many bumps along that same road. Historically, American launch vehicles have been developed and operated with large government budgets. New commercial ventures have an incentive to do the same type of missions at much lower cost. This means that some short cuts are made, some new risks are accepted, and new ways of doing business are employed.
In Mr. Keith’s three day class on Fundamentals of Rockets and Missiles, the questions of commercial versus government design standards are compared. The apparent effect is that a commercial rocket DDT&E (Design, Development, Test & Evaluation) effort, like the Space-X Falcon, should cost about one-fifth of what a government DDT&E program costs for a comparable sized rocket. This cost difference is documented in some cost models or Cost Estimation Relationships (CER). These same cost models fail to explain why any but commercials should be chosen. Mr. Keith’s explanation is that the shortcuts have one major impact; lower initial reliability. Indeed, the first three launch attempts of the Space-X Falcon-1 launch vehicles all failed. Since then, there have been two successful launches of the Falcon-1 and three successful launches of the much larger Falcon-9. Commercial space ventures have the opportunity to take calculated risk short cuts that government programs are mandated to avoid, and the business incentive to make wiser trade-offs and choices.
This does not mean that the road to commercial space will be smooth from here on in. A more realistic expectation is for the road to be bumpy. Space-X has had five successful launches in a row, but their proven historical reliability is five successes in eight tries, or 62.5% reliability. The best we can say regarding the Falcon-9 rocket is that we can be confident it is at least 75% reliable at this time. If, or when, a Falcon-9 rocket fails in the future, it should be considered a bump on the way to commercial space, not a failure of this new way of doing business.
Even this latest successful launch cannot be counted as a victory for commercial space until the Dragon Space Capsule successfully docks with the Space Station. While the launch is the most risky six minutes of the mission, Space-X still must get the craft safely to a docking port with all the cargo intact. The difficulty and risks of rendezvous and docking of a spacecraft to the Space Station should not be underestimated.
There will always be critics of commercial space who will look for negative occurrences to undermine commercial style ventures. There is also a high probability that a number of future commercial space missions will include embarrassing failures. The criteria for success in commercial space should not be whether the road is bumpy with occasional failures. The success criteria should be whether access to space is better, faster and cheaper using commercial methods and incentives than is practical with the type of government bureaucratic methods and incentives that have dominated the final frontier for the past half century.
Dr. Tom Logsdon teaches Orbital Mechanics and Global Positioning Satellite technology classes for ATI. His colleague, Edward L Keith, teaches Fundamentals of Rockets and Missiles, Space Mission Analysis and Design and other rocket related classes for ATI. These instructors are available to reporters who need more information. Contact ATI at 410-956-8805.
The shuttle transportation was, by any reasonable standard, one of the most complicated engineering projects in the long history of science and technology. But, as it was implemented, it never made much economic sense. In part, this disappointing outcome, came about because its payload was too big and heavy to achieve reliable and cost-effective operation. […]
The shuttle transportation was, by any reasonable standard, one of the most complicated engineering projects in the long history of science and technology. But, as it was implemented, it never made much economic sense. In part, this disappointing outcome, came about because its payload was too big and heavy to achieve reliable and cost-effective operation.
Why was the shuttle payload so big and heavy?
The shuttle payload was originally baselined at 65,000 pounds. It never actually carried that much weight: the heaviest payload it ever flew into space was around 50,000 ponds. But, as a practical matter, even that lighter payload was much too heavy. Military users insisted on heavy-life capabilities because they wanted to use the shuttle transportation system to launch their big, heavy spy satellites into space.
In my view, a 15,000-pound payload weight would have been a more practical selection. With a correspondingly lighter orbiter, those troublesome thermal tiles would have been unnecessary. And the booster could have been towed (using Kevlar cables) from the shuttle landing strip at Cape Canaveral by 747 airplanes up to a 40,000-foot attitude with a release velocity of about 600 miles per hour.
Unmanned cargo missions using the amazingly inexpensive Russian Soyuz booster – or an American equivalent – could have carried heavy components into low-altitude earth orbits at much more affordable prices.
As Figure 1 indicates, the Russians offered to sell the Americans Soyuz missions with 15,400-pound payloads for $12 million each. On such a mission, the delivery cost for each pound of payload would have been only $780, or about 1/6th the comparable cost of the American Delta II booster. In my opinion, we should have bought 1000 Soyuz boosters. Instead, we put severe restrictions on the use for boosting American satellites into space.
In my view we lost a golden opportunity. But, actually, chemical rockets – Soyuz, Delta II, the shuttle transportation system – are the problem, not the solution. So what is the alternative?
Satellites Without Rockets
As I have often told my students in my “Launch and Orbital Mechanics” short courses: “There is nothing wrong with the space program that the elimination of chemical rockets wouldn’t cure.” Chemical rockets are dirty, dangerous, fragile, unreliable, and horribly expensive.
A simple mathematic derivation shows that a typical multistage rocket of modern design wastes about 97-percent of its energy accelerating propellants it’s going to burn later. If cars were similarly inefficient, few people would want to own one.
Is there a better way to launch payload into space? In my 4-day short courses on “Launch and Orbital Mechanics”, held at key locations around the country, I list and discuss 30 alternatives to chemical rockets. These include solar electric propulsion, laser-powered rockets, maglev boosters, nuclear powered rockets, tethered satellites, and skyhooks (space elevators). These alternatives, implemented in the proper combination, could revolutionize the way future generations conduct large-scale operations and do business in space.
What If the Space Shuttle Engineers Had Designed My Car?
Many times, over the years, I have taught at Vandenberg Air Force Base in California where satellites are launched into near polar orbits. Vandenberg is 175 miles from my home in Seal Beach, California. It is one of the few short-course locations I drive to in my car. Mostly I fly to the various locations where the courses are offered.
A few years ago, I was driving back home from Vandenberg Air Force Base when an interesting question occurred to me: “What would my car be like if the engineers who designed the space shuttle orbiter had designed it?
When I got back to Seal Beach, I kludged together Figure 2. Study its contents to see how incredibly inefficient the shuttle transportation system turned out to be. Notice, for example, that only 1 percent of the lift-off weight of the shuttle transportation system is useful payload that ends up being left in space. If my car had been designed with similar payload-carrying capabilities, it would be able to deliver only one 21-pound briefcase to Vandenberg or any other destination 175 miles away.
Expendable rockets are not much more efficient. On a typical mission only about 2.5 to 3.0 percent of their lift-off weight is useful payload. Isn’t it becoming abundantly clear why there’s nothing wrong with the space program that the elimination of chemical rockets wouldn’t cure?”
It was the middle of March, but still the ground was covered with fresh snow and the wind swept in over the north pasture and swirled around the gangling apparatus. He flipped up his rough collar against the wind, but it was hopeless; even fastening all the snaps on his galoshes and buttoning the bottom […]
It was the middle of March, but still the ground was covered with fresh snow and the wind swept in over the north pasture and swirled around the gangling apparatus. He flipped up his rough collar against the wind, but it was hopeless; even fastening all the snaps on his galoshes and buttoning the bottom button of his topcoat would not have kept out the chilly Massachusetts wind. He glanced out at the hazy horizon and then up at the launch apparatus hoping he had thought of everything. The test conditions were far from ideal. The cold air could crack the nozzle and even if it got aloft the wind could drive his awkward little vehicle into the ground before burnout. But it was pointless to consider the risks now, he was committed. The launch would take place today.
He posed for a quick photograph and then, crouched behind a wooden lean-to, he cautiously pointed a blowtorch in the direction of the ungainly framework. In an instant, the tiny rocket hurled itself 41 feet into the air and within 2.5 seconds the terrifying roar was over.
It was 1926, Charles Lindbergh had not yet made his transatlantic flight, and yet Dr. Robert Goddard stood over the remains of his tiny rocket, smoldering and unimpressive in the snow, and dreamed of rocket flights to the moon and beyond.
There would be other launches far more impressive. Forty years later, television newsman Walter Cronkite would desperately brace himself against the windows of his trailer as they rattled from the blast of a rocket 3 miles away; but here today in Aunt Effie’s cabbage patch, the world’s first liquid-fueled rocket had been flight tested.
On July 2, 1982, during the final day of their mission, astronauts Ken Mattingly and Henry Hartsfield, riding the space shuttle Columbia, flew uncomfortably close to a spent Russian Intercosmos rocket high above the northwester coast of Australia. By coincidence, that same region of space had experienced an earlier encounter with orbiting space debris when […]
On July 2, 1982, during the final day of their mission, astronauts Ken Mattingly and Henry Hartsfield, riding the space shuttle Columbia, flew uncomfortably close to a spent Russian Intercosmos rocket high above the northwester coast of Australia. By coincidence, that same region of space had experienced an earlier encounter with orbiting space debris when America’s Skylab crashed in the outback in 1979. Astronauts Mattingly and Hartsfield were warned in advance, but they could not catch a glimpse of the big Intercosmos rocket as it whizzed by their spacecraft at 7000 mi/h.
Six months later, Russia’s Cosmos 1402 abruptly slammed into the earth. Like its sister ship Cosmos 954, it was a spy satellite — powered by a nuclear reactor fueled with radioactive uranium. But, unlike its sister ship, Cosmos 954 crashed to earth on the sovereign territory of an innocent nation. In 1978, when Cosmos954 fell in northern Canada, the Canadian government spent $6million cleaning up the mess. Later, with some resistance, the Soviet Union reimbursed Canada for half that amount.
Military engineers track approximately 7000 objects in space as big as a soccer ball or bigger. A few hundred of them are functioning satellites. The rest are a varied lot: spent rockets, protective shrouds, clamps, fasteners, jagged fragments from space vehicle explosions, even an astronaut’s silver glove. In addition to the 7000 objects of trackable size, tens of thousands of smaller ones are presently swarming around our planet.
These orbiting fragments are hazardous, but not to the people living on the ground below. On the average, human beings occupy the surface of the earth, only 17 tiny bodies per square mile. The Skylab was among the largest reentry bodies ever to plunge through the atmosphere, but scientific calculations indicated that the probability of any specific individual being hit by Skylab debris was only about 1 in 200 billion.
Actually, no calculations at all are needed to demonstrate that the probability of being bashed by orbital space debris is extremely small. More than 1500 large, hypervelocity meteorites are known to have plunged through the atmosphere and hit the earth — roughly 8 per year for the past 200 years. Many of them shattered into smaller fragments on reentry, but not one single human being’s death certificate reads “death by meteorite.” And yet, if we go back far enough into the dim shadows of history, we may find at least one reliable reference to human injury and death caused by falling meteorites. It is buried in the bible’s book of Joshua, in a passage describing how terrified soldiers fleeing from battle were killed by “stones falling from heaven.”
“Houston, we have a problem.” “Say again, Apollo 13.” “We have a problem.” It was a problem all right! Seconds before, a violent explosion had ripped through the Apollo Service Module, knocking out two of its three fuel cells and dumping the astronauts’ precious oxygen supplies into black space. At first they managed to remain […]
“Houston, we have a problem.”
“Say again, Apollo 13.”
“We have a problem.”
It was a problem all right! Seconds before, a violent explosion had ripped through the Apollo Service Module, knocking out two of its three fuel cells and dumping the astronauts’ precious oxygen supplies into black space. At first they managed to remain fairly calm, but as their crippled spacecraft hurtled on toward the moon, a fresh crisis suddenly unfolded: The lithium hydroxide canisters in the LEM (Lunar Excursion Module) and the Service Module turned out to be noninterchangeable, and as a result, the air the astronauts were breathing was rapidly becoming polluted. Fortunately, they were able to patch together a workable connection to the canisters in the Service Module, thus making them usable in their overcrowded “lifeboat” LEM. During the next few years other astronauts successfully achieved a number of other spectacular spaceborne repairs, thus proving that astronauts were definitely not merely along for the ride of “Spam in a can” as a cynical journalist once wryly observed. When the micrometeoroid shield was ripped off the main body of the Skylab, for instance, the astronauts erected a big cooling parasol to shield themselves from the burning rays of the sun. On the next mission, astronauts Jack R. Lousma and Owen K. Garriott remodeled the Skylab’s parasol sunshade by erecting two 55-foot metal poles to form a large A-frame tent over their freshly occupied home in space. Other Skylab astronauts repaired an ailing battery, retrieved exposed film from the Apollo telescope mount, and removed and replaced several gyroscopes used in stabilizing their wobbling craft. These complicated tasks were all performed in full space suits outside the protective envelope of the Skylab modules.
The retrieval and redeployment of the Solar Max satellite — which was filmed with IMAX cameras operated by other space shuttle astronauts — provides another powerful illustration of the skill and dexterity of humans in space.Ì Space-age robots have also performed in a similarly impressive manner. For instance, when the television camera mounted on the elbow of the shuttle’s 50-foot robot arm sent back pictures of a big chunk of ice growing on the outside of the waste-water vent on the shuttle orbiter, the Canadian robot arm helped the astronauts execute a clever solution. Rather than risk possible damage to the shuttle’s delicate heat shield, should chunks of the ice break loose during reentry the astronauts were instructed to use the robot arm like a big, heavy trip hammer to knock the ice loose.
On another mission, the robot arm was ready to release the Earth Radiation Budget Satellite into the blackness of space. Unfortunately, during deployment, its solar arrays got stuck in an awkward position so the astronauts used the robot arm to shake the satellite vigorously. Then they held it up to the warming rays of the sun so its solar array could unfold.
Researchers and technicians at Oceanroutes in Palo Alto, California, earn their daily bread using three different types of satellites for finding safe and efficient trajectories for large oceangoing vessels. Each optimum route takes into account real-time weather conditions, the physical characteristics of the ship, and the wishes of the ship’s master — who is given […]
Researchers and technicians at Oceanroutes in Palo Alto, California, earn their daily bread using three different types of satellites for finding safe and efficient trajectories for large oceangoing vessels. Each optimum route takes into account real-time weather conditions, the physical characteristics of the ship, and the wishes of the ship’s master — who is given an updated trajectory twice each day. The Navstar constellation provides accurate positioning information that is relayed from the ship to Palo Alto through INMARSAT satellites. Weather satellites from various countries furnish the necessary meteorological reports. Sitting in their comfortable offices in Palo Alto and in several other cities around the globe, Oceanroute’s engineers work with more than a thousand ships in a routine month. Each recommended route is custom designed for that particular ship “on that specific voyage, with the given cargo load, status of trim and draft, with the ship’s own distinctive speed and sea-handling characteristics.”
The computer program emphasizes emerging weather, but it also takes into account currents, fog, choke points, navigational hazards, and sea ice in northern regions. Some cargoes, such as fruit and oil, are temperature-sensitive; others, such as automobiles and heavy machinery, may shift under heavy waves. Still others have time-critical deliveries. The Oceanroute’s program successfully takes these and numerous other factors into account whenever it makes its routing recommendations.
The cost of the service for a typical voyage is $800, a fee that is repaid 30 to 40 times over by shortened travel times and more efficient maritime operations. In 43,000 crossings aided by Oceanroute’s computers, travel times have been reduced an average of four hours in the Atlantic and eight hours in the Pacific. Operating a large oceangoing vessel can cost as much as $1,000 per hour, so time savings alone can translate into enormous reductions in cost. Other expenses are also reduced. When Oceanroute’s services were not yet available, the cost of repairing weather-damaged ships ran from $32,000 to $53,000 in an average year. Today, for some companies, these costs have plummeted to only about $6,000. Cargo damage has also declined. One international auto dealer told a team of Oceanroute’s researchers that his cargo damage claims had dropped by over $500,000 per year.
The rockets that hurl the Navstar satellites into orbit are direct descendents of the highly destructive Chinese “fire arrows” built and launched by Chinese military engineers 750 years ago. The earliest Chinese rockets were slender tubes stuffed with gunpowder and fastened to long flat sticks that jutted out behind the rocket to promote stable flight. […]
The rockets that hurl the Navstar satellites into orbit are direct descendents of the highly destructive Chinese “fire arrows” built and launched by Chinese military engineers 750 years ago. The earliest Chinese rockets were slender tubes stuffed with gunpowder and fastened to long flat sticks that jutted out behind the rocket to promote stable flight. In 1232 they were launched in large quantities on the outskirts of Peking, when special Chinese rocket brigades successfully pushed back Mongol cavalrymen. And, in 1249, they were used with great effect by the Moors in their military campaign along the Iberian Peninsula.
Near the beginning of the nineteenth century, Englishman William Congreve concocted superior powder blends and moved the stabilizing stick to the center of the rocket for improved accuracy. In 1807 the British blasted Copenhagen with 25,000 Congreve rockets. nine years later, when they bombarded Fort McHenry , they inadvertently provided “the rocket’s red glare,” which helped inspire America’s National Anthem.
In 1903 a lonely Russian schoolteacher, Konstantin Tsiolkovsky , correctly concluded that rockets fueled with liquid hydrogen and liquid oxygen would be considerably more efficient than the simpler solid-fueled rockets then in use. He also devised a concept for stacking rockets one atop the other to yield the enormous speeds necessary for successful interplanetary travel.
Twenty-three years later Dr. Robert Goddard knelt on the frozen ground in his Aunt Effie’s cabbage patch at Auburn, Massachusetts, and casually used a blowtorch to ignite the world’s first liquid-fueled rocket. Goddard is today revered for his expansive expertise, but during his lifetime his contemporaries criticized him unmercifully because he had once dared to mention the possibility of sending a small flash powder to impact the moon. Years later, when one of his liquid-fueled rockets reached its design altitude of 2,000 feet, a banner headline wryly commented: “Moon Rocket Misses Target by 237,799 Miles!”
The rockets built by the Goddard team were all handcrafted machines, but Germany’s rocketeers , working under the direction of Werner von Braun, constructed liquid-fueled rockets in mass-¼production quantities. When World War II fizzled to a halt, many of the German scientists came to Los Alamos to help American’s military and space-age rocketeers .
In 1961, when President Kennedy courageously announced that the United States would conquer the moon, America’s rocketeers had not yet orbited a single astronaut. The Saturn V moon rocket they later developed for the mission, was the pinnacle of the rocket maker’s art. But it was expendable; NASA’s space shuttle is a “reusable” booster. It delivers payloads weighing as much as 50,000 pounds and brings others back to earth for refurbishment and repair, gently landing — as TV Newsman Edwin Newman once observed: “like a butterfly with sore feet.”
Watching an Apple Falling from a Tree In 1665, Isaac Newton left Cambridge University and returned to his hometown of Woolsthorpe to escape the worst ravages of the Black Plague. Safely back among familiar surroundings, he made landmark discoveries that have provided us with precisely the keys we needed to conquer space. Although the young […]
Watching an Apple Falling from a Tree
In 1665, Isaac Newton left Cambridge University and returned to his hometown of Woolsthorpe to escape the worst ravages of the Black Plague. Safely back among familiar surroundings, he made landmark discoveries that have provided us with precisely the keys we needed to conquer space.
Although the young Newton had reportedly been a mediocre student in the early grades, his powerful intelligence asserted itself even before he reached his teenage years. When he was still a tow-headed youngster, for instance, he managed to construct a charming little windmill backed up by one mouse-power so it could go on turning when the wind refused to blow. Later, he made a paper kite rigged to carry a small lantern high above the British countryside. The people of Woolsthorpe had never before seen flickering lights floating across the nighttime sky, so the young Isaac may have been responsible for some of the earliest sightings of UFOs.
At the age of 23, while relaxing on his mother’s farm, Isaac Newton, by his own account, saw an apple falling from a tree. That simple incident caused him to wonder why apples always tumble down. That apple tumbled down toward the ground while the pale August moon continued to sail contentedly overhead. Soon he theorized that the force of gravity tugged on apple and moon falls off systematically with increasing altitude in the same way a light beam dissipates as we move farther away from its source. Double the distance and its intensity falls of by a factor of 4.
Thus, by Newton’s reckoning, the force of gravity pulling on the moon should be about 1/3000th as strong as the gravity we experience at the surface of the earth. In 1 minute, he soon calculated a falling apple would be pulled downward about 10 miles, but the moon would fall toward the earth only about 16 ft. During that same 1-minute interval, the moon’s orbital velocity also carried it sideways 38 miles. Consequently, its horizontal and vertical motion combine to bring it back onto the same gently curving circular path over and over again.
Isaac Newton figured out how gravity works because of a fortunate encounter with his mother’s favorite apple tree. Armed with only his inverse square law of gravitation, three deceptively simple laws of motion, and one of the most powerful intellects that ever pondered anything, Newton quietly set about to unravel the hidden secrets of the universe.
Using Wounded Dogs to Navigate Ships on the High Seas Finding the latitude of a sailing ship can be surprisingly easy: sight the elevation of the Pole Star above the local horizon. Finding longitude turns out to be quite a bit harder because, as the earth rotates, the stars sweep across the sky 15 degree […]
Using Wounded Dogs to Navigate Ships on the High Seas
Finding the latitude of a sailing ship can be surprisingly easy: sight the elevation of the Pole Star above the local horizon. Finding longitude turns out to be quite a bit harder because, as the earth rotates, the stars sweep across the sky 15 degree every hour. A one second timing error thus translates into a 0.25 nautical mile error in position. How is it possible to measure time on board a ship at sea with sufficient accuracy to make two-dimensional a practical enterprise?
One 18th century innovator, whose name has long since been forgotten, advocated the use of a special patent medicine said to involve some rather extraordinary properties. Unlike other popular nostrums of the day, the Power of Sympathy, as its inventor, Sir Klenm Digby, called it, was applied not to the wound but to the weapon that inflicted it. The World of Mathematics, a book published by Simon and Schuster, describes how this magical remedy was to be employed as an aid to maritime navigation.
Before sailing, every ship should be furnished with a wounded dog. A reliable observer on shore, equipped with a reliable clock and a bandage from the dog’s wound, would do the rest. very hour on the dot, he would immerse the dog’s bandage in a solution of the Power of Sympathy and the dog on shipboard would yelp the hour.
As far as we know, this intriguing method of navigation was never actually tested under realistic field conditions, so we have no convincing evidence that it would have worked as advertised.