16 résultats pour "launch"

• ROCKETS AND LAUNCH VEHICLES

  direction is balanced by an equal force in the opposite direction. This principle is well shown by the backward movement, or recoil, of a cannon when it fires a cannonball. The English genius Isaac Newton first stated the reaction principle as his third law of motion: "to every action there is an equal and opposite reaction." Rockets are often called reaction engines. 2.Solid propellants The fuel and oxidizer in a rocket are called its propellants, because when they burn they produce the gas...

• Artificial Satellite - astronomy.

  The first stage of a multistage rocket consists of rocket engines that provide a huge amount of force, or thrust. The first stage lifts the entire launch vehicle—with itsload of fuel, the rocket body, and the satellite—off the launch pad and into the first part of the flight. After its engines use all their fuel, the first stage portion of therocket separates from the rest of the launch vehicle and falls to Earth. The second stage then ignites, providing the energy necessary to lift the satellit...

• Apollo Program - astronomy.

  Moon’s orbit; rendezvousing and docking with the CSM; and finally, setting a course home to Earth. On return to Earth, the spacecraft was slowed by drag from Earth’satmosphere and by parachutes (just before splashdown), before landing in the ocean. The transit time to and from the Moon was approximately three days each way.Depending on the specific mission, the time in lunar orbit ranged from less than one day for Apollo 8 to over six days for the final three missions, and the time on thelunar s...

• Apollo Program - U.

  Moon’s orbit; rendezvousing and docking with the CSM; and finally, setting a course home to Earth. On return to Earth, the spacecraft was slowed by drag from Earth’satmosphere and by parachutes (just before splashdown), before landing in the ocean. The transit time to and from the Moon was approximately three days each way.Depending on the specific mission, the time in lunar orbit ranged from less than one day for Apollo 8 to over six days for the final three missions, and the time on thelunar s...

• Space Shuttle - astronomy.

  The two SRBs, with their combined thrust of some 26 million newtons (about 5.8 million lb), provide most of the power for the first two minutes of flight. The SRBs takethe space shuttle to an altitude of 45 km (28 mi) and a speed of 4,973 km/h (3,094 mph) before they separate and fall back into the ocean to be retrieved,refurbished, and prepared for another flight. After the boosters fall away, the three main engines continue to provide thrust. These engines are clustered at the rear end of the...

• Space Exploration - astronomy.

  to produce 250,000 newtons (56,000 lb) of thrust. The Germans launched thousands of V-2s carrying explosives against targets in Britain and The Netherlands. Whilethey did not prove to be an effective weapon, V-2s did become the first human-made objects to reach altitudes above 80 km (50 mi)—the height at which outer spaceis considered to begin—before falling back to Earth. The V-2 inaugurated the era of modern rocketry. A2 Early Artificial Satellites During the years following World War II, the...

• Rocket.

  the vacuum of space, however, demonstrated that this belief was not true. In fact, rockets produce more thrust in the vacuum of space than on Earth. Air pressure andfriction with the air reduce a rocket’s thrust by about 10 percent on Earth as compared to the rocket’s performance in space. B Thrust and Efficiency Thrust is a measurement of the force of a rocket, or the amount of “push” exerted backward to move a rocket forward. Thrusts vary greatly from rocket to rocket.Engineers measure thrust...

• Rocket - astronomy.

  the vacuum of space, however, demonstrated that this belief was not true. In fact, rockets produce more thrust in the vacuum of space than on Earth. Air pressure andfriction with the air reduce a rocket’s thrust by about 10 percent on Earth as compared to the rocket’s performance in space. B Thrust and Efficiency Thrust is a measurement of the force of a rocket, or the amount of “push” exerted backward to move a rocket forward. Thrusts vary greatly from rocket to rocket.Engineers measure thrust...

• NASA - astronomy.

  Challenger shuttle after launch in 1986 and the Columbia shuttle during reentry in 2003, killing both crews. Investigations traced the accidents to design flaws and tomanagement problems. Both accidents led to design and procedure changes, and to a temporary stoppage of shuttle flights. Following the Columbia disaster, NASA alsoannounced plans to retire the shuttle in 2010, after completion of the International Space Station (ISS), a human orbital research facility. The Constellation program is...

• Moon - astronomy.

  B Volcanic Features Maria, domes, rilles, and a few craters display indisputable characteristics of volcanic origin. Maria are plains of dark-colored rock that cover approximately 40 percent ofthe Moon's visible hemisphere. The maria formed when molten rock erupted onto the surface and solidified between 3.16 billion and 3.96 billion years ago. This rockresembles terrestrial basalt, a volcanic rock type widely distributed on Earth, but the rock that formed the maria has a higher iron content an...

• Vietnam War.

  rigged, since about 150,000 more people voted in Saigon than were registered. Diem then deposed Bao Dai, who had been the only other candidate, and declaredSouth Vietnam to be an independent nation called the Republic of Vietnam (RVN), with himself as president and Saigon as its capital. Vietnamese Communists and manynon-Communist Vietnamese nationalists saw the creation of the RVN as an effort by the United States to interfere with the independence promised at Geneva. III THE BEGINNING OF THE...

• Vietnam War - History.

  rigged, since about 150,000 more people voted in Saigon than were registered. Diem then deposed Bao Dai, who had been the only other candidate, and declaredSouth Vietnam to be an independent nation called the Republic of Vietnam (RVN), with himself as president and Saigon as its capital. Vietnamese Communists and manynon-Communist Vietnamese nationalists saw the creation of the RVN as an effort by the United States to interfere with the independence promised at Geneva. III THE BEGINNING OF THE...

• Vietnam War - U.

  rigged, since about 150,000 more people voted in Saigon than were registered. Diem then deposed Bao Dai, who had been the only other candidate, and declaredSouth Vietnam to be an independent nation called the Republic of Vietnam (RVN), with himself as president and Saigon as its capital. Vietnamese Communists and manynon-Communist Vietnamese nationalists saw the creation of the RVN as an effort by the United States to interfere with the independence promised at Geneva. III THE BEGINNING OF THE...

• Adolf Hitler I INTRODUCTION Adolf Hitler (1889-1945), German political and military leader and one of the 20th century's most powerful dictators.

  A Economic Collapse At the end of World War I, the Allies (those countries who had fought against Germany) had demanded that Germany pay reparations—that is, payments for wardamages. The government refused to pay all that was demanded by the Allies. When Germany failed to pay enough, France and Belgium occupied the coal mines in theRuhr industrial area in west central Germany in January 1923. In protest, the German government halted all reparation payments and called for passive resistance by a...

• Adolf Hitler.

  A Economic Collapse At the end of World War I, the Allies (those countries who had fought against Germany) had demanded that Germany pay reparations—that is, payments for wardamages. The government refused to pay all that was demanded by the Allies. When Germany failed to pay enough, France and Belgium occupied the coal mines in theRuhr industrial area in west central Germany in January 1923. In protest, the German government halted all reparation payments and called for passive resistance by a...

• Adolf Hitler .

  A Economic Collapse At the end of World War I, the Allies (those countries who had fought against Germany) had demanded that Germany pay reparations—that is, payments for wardamages. The government refused to pay all that was demanded by the Allies. When Germany failed to pay enough, France and Belgium occupied the coal mines in theRuhr industrial area in west central Germany in January 1923. In protest, the German government halted all reparation payments and called for passive resistance by a...