Only seven years after U.S. President John F. Kennedy announced the U.S. would send humans to the moon within a decade, the mighty Saturn V, the largest machine to ever fly, rose majestically off the ground on November 9, 1967, on an unmanned test flight. Two years later, Kennedy's dream was fulfilled, with one small step on the lunar surface, in the greatest technical achievement in human history.
The success of the Apollo Moon Program lay largely in a massive brute force effort, where the government funded roughly 400,000 people from across the entire U.S. to ensure the Americans beat the Russians to the moon. Considering they were building an enormous system that was entirely new from the ground up, on a ridiculously short timescale, it is amazing the rockets performed as well as they did.
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Because of the tight timetable, the first flight, known as Apollo 4, was an "all up" test, where the entire rocket was flown with everything in place. This is risky, because the assorted parts of the rocket were built in different parts of the country and had never operated together as a single unit. Remarkably, the first flight was a total success.
Apollo 8 is often considered the most daring mission because it was the first time human beings left the gravitational pull of the Earth and committed themselves to another heavenly body. It was also the first time humanity saw itself as a single living entity with the famous "Earthrise" picture taken from the moon.
Of course, those conditions don't exist today. The NASA workforce is one-tenth of what it used to be and funds are limited. The last 45 years have been spent building space shuttles and the International Space Station, which is why we don't have the technology to take people back to the moon.
Another giant rocket that will rival the Saturn V, called the SLS, is under construction, which could take astronauts beyond the moon, possibly to Mars. But it is tremendously expensive and behind schedule, with its first flight now pushed back to 2020.
The other contender is the Falcon 9 Heavy, being built by the private corporation SpaceX. It is scheduled to fly within the next few months, but a recent test of new engines resulted in an explosion, and the company's founder, billionaire Elon Musk, says there is a good chance the rocket will not make it on the first try.
The sample of lunar dust used in the study were brought back by Apollo 17 astronauts in the last crewed mission to the Moon in 1972. This dust contains tiny crystals that formed billions of years ago. These crystals are a telltale sign of when the Moon must have formed.
This atom-by-atom analysis, conducted using instruments at Northwestern University, showed how many of the atoms inside the zircon crystals had undergone radioactive decay. When an atom has an unstable configuration of protons and neutrons in its nucleus, it undergoes decay, shedding some of these protons and neutrons and transforming into different elements. For instance, uranium decays into lead. Scientists have established how long it takes this process to occur, and by looking at the proportion of different uranium and lead atoms (called isotopes) present in a sample, they can tell how old it is.
This study was contributed to by Jennika Greer at the University of Glasgow, B. Zhang at the University of California, Los Angeles, D. Isheim, and D.N. Seidman at Northwestern University, A. Bouvier at Bayreuth University, and Philipp Heck at the Field Museum.
The history of the Chinese New Year festival can be traced back to about 3,500 years ago. Chinese New Year has evolved over a long period of time and its customs have undergone a long developmental process.
The date of the Chinese New Year is determined by the lunar calendar. The holiday falls on the second new moon after the winter solstice on December 21. Each year the New Year in China falls on a different date than on the Gregorian calendar. The dates usually range sometime between January 21 and February 20.
Even though it is winter, the Chinese New Year is popularly known as the Spring Festival in China. Because it starts from the Beginning of Spring (the first of the twenty-four terms in coordination with the changes of Nature), it marks the end of winter and the beginning of spring.
The prosperity of economies and cultures during the Tang, Song, and Qing dynasties accelerated the development of the Spring Festival. The customs during the festival became similar to those of modern times.
Nowadays, many traditional activities are disappearing but new trends have been generated. CCTV (China Central Television) Spring Festival Gala, shopping online, WeChat red envelopes, and overseas travel make Chinese New Year more interesting and colorful.
In 1969, astronauts of Apollo 11 were the first to set foot on the moon and to study the lunar surface. Over the next several Apollo missions, ending in 1972, they brought back moon rocks for scientific research to unlock mysteries of the universe.
Scientists knew the rocks contained clues to the origins of the solar system as well as minerals that could be of interest for advancing space travel beyond the moon. But back then, in-depth analysis was hindered because of a low inventory of rock samples and a lack of advanced research technology.
Neutrons are ideally suited to studying the chemical composition of the Apollo moon rocks: They can pass through almost any material, but light elements such as hydrogen will block or deflect them upon contact.
Using the MARS instrument, which specializes in creating radiographic images similar to clinical x-rays, Needham loaded the samples into containers stationed on a rotating platform that allows measurements to be taken of the rocks in 360 degrees. Regions where hydrogen atoms are likely to be found are highlighted within the rocks as the neutron beam passes through the sample.
In the neutron images, the hydrogen atoms show up as brightly colored spots in contrast to the rest of the sample. The more difficult it is for a neutron to pass through an element, the brighter that element will appear, creating a color scale that corresponds to different elements. The 360-degree measurements can then be used to create 3D models of the rocks that can in turn be compared with results from other research techniques, such as x-rays and electron microscopy.
The Earth formed over 4.6 billion years ago out of a mixture of dust and gas around the young sun. It grew larger thanks to countless collisions between dust particles, asteroids, and other growing planets, including one last giant impact that threw enough rock, gas, and dust into space to form the moon.
Understanding how the Earth and moon formed is important for piecing together the history of the solar system and answering questions like how long planets take to form, what planets are made of, and what makes a planet suitable for life. This also guides planetary scientists in their search for other habitable (or inhabited!) worlds in our solar system and beyond!
Using these measurements, and simulations of the physics of dust and planetesimal collisions, planetary scientists and astronomers have established that the dust-to-protoplanet process takes tens of millions of years.
Samples of rock from the moon, brought to Earth by lunar meteorites and the Apollo moon landings, can be used to understand the history of the Moon and its relationship to the Earth through the chemistry of their minerals.
The first big clue about where the moon came from comes from oxygen. Oxygen, like many other elements, is able to exist in multiple forms, known as isotopes. Different types of meteorites coming from the asteroids left over in the solar system after planet formation have different proportions of each of these oxygen isotopes. So, by measuring the oxygen isotopes of a given planet, planetary scientists can calculate the different types of asteroid that collided to form the planet. Lunar samples have a very similar oxygen isotope makeup to the Earth.
Some scientists believe that the oxygen isotopes are because the object that hit Earth was made up of the same mixture of meteorites as the Earth itself, potentially suggesting that the impactor planet formed close by in the solar system.
Other scientists propose that after the impact all of the oxygen was able to move around in the hot vapor surrounding the Earth and moon, mixing up all the different oxygen isotopes and erasing any original differences between the Earth and Theia.
Both of these pieces of evidence are hard to explain without a giant impact. An impact origin for the moon provides the high temperatures needed to explain the lack of potassium, zinc, and sodium on the moon, and also an opportunity for lots of mixing between the proto-Earth and the material that would become the moon. But when did this impact take place?
By the time of the moon-forming impact, the Earth was already separated into these rock and metal layers. However, the intense force and heat of the impact re-melted the proto-Earth, re-mixing the separated rock and metal. After this mixing, the Earth was still hot enough for separation to occur again and form new rock and metal layers - this is the key to dating when the moon formed!
After the moon-forming impact, Earth was a very different planet from the world we see today! Where the present-day Earth has oceans covering much of its surface, the early Earth was covered in a magma ocean - a layer of molten rock hundreds of miles deep that was melted by the energy released during the collision. Any water present would only exist as water vapor in the atmosphere.
Some planetary scientists believe that plate tectonics is essential for a planet to develop life. This is because the repeated production and destruction of crust by plate tectonics both releases carbon dioxide to the atmosphere and removes it, helping keep temperatures on Earth similar (and comfortable for microbes, fish, and humans!) over billions of years.
Whether a planet has plate tectonics is much more complicated than just having a solid surface, though, and might also depend on the types and amount of different asteroids, planetesimals, and protoplanets that the Earth is made of because of the way different chemicals and minerals can change how planet interiors behave over billions of years. 152ee80cbc
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