satellite

The first fictional depiction of a satellite being launched into orbit is a short story by Edward Everett Hale, The Brick Moon. The story is serialized in The Atlantic Monthly, starting in 1869.The idea surfaces again in Jules Verne's The Begum's Millions (1879).

In 1903 Konstantin Tsiolkovsky (1857–1935) published The Exploration of Cosmic Space by Means of Reaction Devices (in Russian: Исследование мировых пространств реактивными приборами), which is the first academic treatise on the use of rocketry to launch spacecraft. He calculated the orbital speed required for a minimal orbit around the Earth at 8 km/s, and that a multi stage rocket fueled by liquid propellants could be used to achieve this. He proposed the use of liquid hydrogen and liquid oxygen, though other combinations can be used.

History of artificial satellites:

The first artificial satellite was Sputnik 1, launched by the Soviet Union on 4 October 1957, and initiating the Soviet Sputnik program, with Sergei Korolev as chief designer and Kerim Kerimov as his assistant. This in turn triggered the Space Race between the Soviet Union and the United States.Sputnik 1 helped to identify the density of high atmospheric layers through measurement of its orbital change and provided data on radio-signal distribution in the ionosphere. Because the satellite's body was filled with pressurized nitrogen, Sputnik 1 also provided the first opportunity for meteoroid detection, as a loss of internal pressure due to meteoroid penetration of the outer surface would have been evident in the temperature data sent back to Earth.

Weapons

History

Prehistoric weapons

An array of Neolithic artifacts, including bracelets, axe heads, chisels, and polishing tools.

Very simple weapon use has been seen in some communities of chimpanzees, leading to speculation that early hominids may have first used weapons five million years ago, but these would probably have been wooden clubs, spears and unshaped stones none of which would leave an unambiguous record.

The earliest unambiguous examples of weapons are:

• Eight wooden throwing spears, the Schöninger Speere, which have been dated as 400,000 years ago.
• By 250,000 years ago wooden spears were made with fire hardened points.
• From 80,000 years ago humans began to make complex stone blades, which were used as spear points.
• Bows and arrows may have been used by 60,000 years ago^.
• The oldest known javelins date to around 42,000 BC.
• Wooden throwing darts have been in use since the middle paleolithic.
• The oldest atlatl (a spear-throwing weapon) dates back to 27,000 years ago.
• Throwing sticks are also one of the earliest type of weapon.

Ancient world weapons

A four wheeled ballista drawn by armored cataphract horses, c. 400.

Ancient weapons were initially simply improvements of the late neolithic versions, but then significant improvement in materials and techniques created a series of revolutions in military technology.

• The use of metal, first copper from about 3,300 BC, followed shortly by bronze led to the Bronze Age sword and other similar weapons.
• The domestication of the horse and the invention of the spoked wheel by the Andronovo culture led to the light, horse drawn chariot. Chariots for use in battle were important in this era. The earliest spoke wheeled chariots date to ca. 2000 BC and their usage peaked around 1300 BC (see Battle of Kadesh), then declined, ceasing to have military importance by the 4th century BC
• Cavalry developed once horses were bred to support the weight of a man.
• Iron ore is much more common that the copper and tin required for bronze, so although the early Iron Age sword was not necessarily superior to their bronze predecessors, once iron working developed around 1200 BC in the ancient Near East, and India and much later 800 BC in Europe iron began to be used widely in weapons.
• Aggressive, militaristic empires.
• Professional armies.
• Siege weapons such as the battering ram, siege hook, catapult and ballista and Chinese repeating crossbow.
• advanced fighting ships.