My Science School

Itokawa is the first asteroid from which samples were brought to Earth for analysis. This feat was achieved by Japanese space probe Hayabusa which touched down on the asteroid in November 2005 and returned to Earth in June 2010.

Hayabusa's close-up observations of the asteroid and the subsequent analysis of its dust in labs on Earth support the conclusion that Itokawa is part of what remains from a much larger object that was shattered by a collision. The dust also confirms that S-type (this refers to the asteroid's color spectrum) asteroids like Itokawa, which are the most common type of asteroid in the inner main belt, are the source of the most common kind of meteorite found on Earth: the ordinary chondrite.

Scientists think Itokawa is not solid, but rather is a rubble pile, an agglomeration of rocks loosely held together by their mutual gravity. Few craters are visible, presumably because any impact energetic enough to create a crater shakes rocks loose and they fill the hole.

One sign that the asteroid was once part of a much larger object is that many of the captured dust particles show signs of having slowly cooled after forming deep inside a rocky object at a temperature of some 1,500 degrees Fahrenheit (800 degrees Celsius). For this to have occurred, the diameter of the rocky object would have to have been greater than 20 km (12 miles), whereas Itokawa's longest dimension is only 0.5 km (0.3 miles).

Another clue is that the largest boulder found on Itokawa is about 50 m (160 feet) across, which is believed to be too big to have been ejected by the impact that created the asteroid's largest crater. Scientists think the rock is a fragment of whatever cataclysmic event resulted in Itokawa's current construction.

Writing in the journal Science, Hayabusa's science team described the asteroid's shape as resembling a sea otter, with one distinct part designated as the head and the other, larger part designated as the body. One of the scenarios that the team cited as most likely to explain this is that after Itokawa's parent body was shattered, the slight mutual gravity of the fragments brought them together into two or more rubble piles, and two of these piles eventually bumped gently into each other and stuck together. Another possibility is that Itokawa was originally one rubble pile, and a large impact temporarily broke off a chunk of it until gravity brought it back and the two parts became reattached.

Itokawa's orbit around the sun crosses those of both Earth and Mars.

Credit : NASA Science 

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On October 4th 1957, Russia launched the first manmade satellite into space. It was known as Sputnik-1. The satellite was a sphere 56cm (22in) in diameter and weighed 83.6kg (1851b).

The spacecraft obtained data pertaining to the density of the upper layers of the atmosphere and the propagation of radio signals in the ionosphere. The instruments and electric power sources were housed in a sealed capsule and included transmitters operated at 20.005 and 40.002 MHz (about 15 and 7.5 m in wavelength), the emissions taking place in alternating groups of 0.3 s in duration. The downlink telemetry included data on temperatures inside and on the surface of the sphere.

Since the sphere was filled with nitrogen under pressure, Sputnik 1 provided the first opportunity for meteoroid detection (no such events were reported), since losses in internal pressure due to meteoroid penetration of the outer surface would have been evident in the temperature data. The satellite transmitters operated for three weeks, until the on-board chemical batteries failed, and were monitored with intense interest around the world. The orbit of the then inactive satellite was later observed optically to decay 92 days after launch (January 4, 1958) after having completed about 1400 orbits of the Earth over a cumulative distance traveled of 70 million kilometers. The orbital apogee declined from 947 km after launch to 600 km by Dec. 9th.

The Sputnik 1 rocket booster also reached Earth orbit and was visible from the ground at night as a first magnitude object, while the small but highly polished sphere, barely visible at sixth magnitude, was more difficult to follow optically. Several replicas of the Sputnik 1 satellite can be seen at museums in Russia and another is on display in the Smithsonian National Air and Space Museum in Washington, D.C.

Credit : NASA

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US astronaut Alan Shepherd, the commander of Apollo 14, played the first golf shot on the Moon in 1971.

When America's first man in space was assigned to be commander of Apollo 14, he saw an opportunity to create the 1971 equivalent of a viral moment. So, before his trip to the Moon, he commissioned a custom 6-iron head that he could attach to the end of a lunar sampling tool in lieu of a regular golf club.

Then, as his time on the lunar surface came to an end, he stood in front of a TV camera with his makeshift club and two golf balls. After a few one-armed swings that mainly moved regolith, he shanked his first ball into a crater. He made better contact with the second ball, though. And as it sailed out of the camera’s view, he remarked, "Miles and miles and miles."

Of course, he didn't mean that literally. But in the Moon's airless environment with just one-sixth the gravity of Earth, Shepard later estimated that his modest pitch shot carried the ball about 200 yards (600 feet).

However, image specialist Andy Saunders recently analyzed archival stills taken by the astronauts with their Hasselblad cameras, as well as video from the lunar ascent module as it lifted off from the surface. Saunders managed to identify not only Shepard’s golf balls, but also his footprints from his stance and his divots. By comparing these to more recent satellite images from NASA’s Lunar Reconnaissance Orbiter, Saunders was able to measure the distance on Shepard's second shot. The result? A rather tame 40 yards (120 feet).

Still, that's not bad for a one-handed bunker shot taken while wearing a bulky spacesuit in weak gravity. Plus, it served as one of the Apollo program's most memorable moments. When asked about the shot at a post-flight Congressional hearing, Shepard quipped, "I did this since I am patriotic and concerned about the security of the nation."

Credit : Astronomy.

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An airship is a sausage-shaped balloon filled with a lighter-than-air gas that makes it float. The early airships could carry passengers across the Atlantic, but they were slow and dangerous because they were filled with hydrogen gas which burns easily. Modern airships are filled with safe helium gas, but they are still slow.

The first successful airship was constructed by Henri Giffard of France in 1852. Giffard built a 160-kilogram (350-pound) steam engine capable of developing 3 horsepower, sufficient to turn a large propeller at 110 revolutions per minute. To carry the engine weight, he filled a bag 44 metres (144 feet) long with hydrogen and, ascending from the Paris Hippodrome, flew at a speed of 10 km (6 miles) per hour to cover a distance of about 30 km (20 miles).

In 1872 a German engineer, Paul Haenlein, first used an internal-combustion engine for flight in an airship that used lifting gas from the bag as fuel. In 1883 Albert and Gaston Tissandier of France became the first to successfully power an airship using an electric motor. The first rigid airship, with a hull of aluminum sheeting, was built in Germany in 1897. Alberto Santos-Dumont, a Brazilian living in Paris, set a number of records in a series of 14 nonrigid gasoline-powered airships that he built from 1898 to 1905.

The most-successful operator of rigid airships was Ferdinand, count von Zeppelin, of Germany, who completed his first airship, the LZ-1, in 1900. This technically sophisticated craft, 128 metres (420 feet) long and 11.6 metres (38 feet) in diameter, had an aluminum frame of 24 longitudinal girders set within 16 transverse rings and was powered by two 16-horsepower engines; it attained speeds approaching 32 km (20 miles) per hour. Zeppelin continued improving his designs through World War I, when many of his airships (called zeppelins) were used to bomb Paris and London. Airships were also used by the Allies during the war, chiefly for antisubmarine patrol.

In the 1920s and ’30s, airship construction continued in Europe and the United States. A British dirigible, the R-34, made a round-trip transatlantic crossing in July 1919. In 1926 an Italian semirigid airship was successfully used by Roald Amundsen, Lincoln Ellsworth, and General Umberto Nobile to explore the North Pole. In 1928 the Graf Zeppelin was completed by Zeppelin’s successor, Hugo Eckener, in Germany. Before it was decommissioned nine years later, it made 590 flights, including 144 ocean crossings. In 1936 Germany inaugurated a regular transatlantic passenger service with the dirigible Hindenburg.

Despite these achievements, airships were virtually abandoned in the late 1930s because of their cost, their slow speed, and their intrinsic vulnerability to stormy weather. In addition, a succession of disasters—the best known probably being the explosion of the hydrogen-filled Hindenburg in 1937—coupled with advances in heavier-than-air craft in the 1930s and ’40s made dirigibles commercially obsolete for most applications.

Credit : Britannica 

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It is an aircraft that can land and take off from water. The underside of the plane is shaped like a boat. Each wing has a float underneath to keep the plane balanced in the water. Some, called amphibians, have wheels and can be used on land or on water.

Ascending into common use during the First World War, flying boats rapidly grew in both scale and capability during the Interwar period, during which time numerous operators found commercial success with the type. Flying boats were some of the largest aircraft of the first half of the 20th century, exceeded in size only by bombers developed during the Second World War. Their advantage lay in using water instead of expensive land-based runways, making them the basis for international airlines in the interwar period. They were also commonly used as maritime patrol aircraft and air-sea rescue, particularly during times of conflict. Flying boats such as the PBY Catalina and Short Sunderland played key roles in both the Pacific Theater and the Atlantic of the Second World War.

The popularity of flying boats gradually trailed off during the Cold War era, partially because of the investments in airports during the conflict that eased the introduction of larger, and faster, land-based airliners. Despite being largely overshadowed, limited use of the type continued with some operators, such as in the case of the Shin Meiwa US-1A and the Martin JRM Mars. In the 21st century, flying boats maintain a few niche uses, such as dropping water on forest fires, air transport around archipelagos, and access to undeveloped areas. Many modern seaplane variants, whether float or flying boat types, are convertible amphibious aircraft where either landing gear or flotation modes may be used to land and take off.

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The Russian major Yuri Alexeyevitch Gagarin became the first man to fly in space on April 12th 1961. His spaceship Vostock orbited the Earth for 108 minutes before returning.

He was killed at the age of 34 in 1968 when the MIG-15 jet trainer he was flying crashed.

The first cooperative human space flight project between the United States and the Soviet Union took place in 1975. The Apollo-Soyuz Test Project was designed to test the compatibility of rendezvous and docking systems for American and Soviet spacecraft and to open the way for future joint manned flights.

Since 1993, the U.S. and Russia have worked together on a number of other space flight projects. The Space Shuttle began visiting the Russian Mir space station in 1994, and in 1995 Norm Thagard became the first U.S. astronaut to take up residency on Mir. Seven U.S. astronauts served with their Russian counterparts aboard the orbiting Mir laboratory from 1995 to 1998. The experience gained from the Mir cooperative effort, as well as lessons learned, paved the way for the International Space Station.

In-orbit construction on the Station began in November 1998, and it has been staffed non-stop with international crews since November 2000. The first Station crew, made up of U.S. commander Bill Shepherd and cosmonauts Yuri Gidzenko and Sergei Krikalev, was launched on board a Russian Soyuz spacecraft. The crew returned to Earth on the Space Shuttle Discovery in March 2001.

Credit :  NASA

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