Vanguard 2 was launched from Cape Canaveral, USA, on February 17, 1959 (NASA)

An Earth-orbiting satellite designed to measure the distribution of cloud cover in the diurnal portion of its orbit.

It is the first "meteorological satellite" in the world.

It is a magnesium ball that weighs 10.75 kg and has a diameter of 50.8 cm.

It was launched on February 17, 1959, in an international context characterized by the Cold War, which was a colony between the Western camps, led by the United States of America, and the Eastern camps, led by the Soviet Union.

It was the second successful launch into orbit of the American satellite program (IGY Vanguard), and the first satellite covered by clouds.

Its mission ended on May 8, 1959, and it has an expected total orbital life of 200 to 300 years.

Vanguard goal 2

The goal of the Vanguard 2 launch was to measure the reflection of sunlight from cloud cover and the Earth's surface.

The goal of the program, run by the US Navy, was to launch one or more satellites into Earth's orbit during the International Geophysical Year (IGY).

The International Geophysical Year is a globally coordinated set of research conducted between July 1957 and December 1958, during a period of maximum solar activity, with the aim of better understanding the physical properties of the Earth and the interactions between the Sun and the planet Earth.

The success of the Vanguard 2 experiment prompted the Third World Meteorological Congress, held in Geneva (May 1959), to recognize the importance of meteorological satellites in knowing the general circulation of the atmosphere and thus predicting the weather.

The United States Naval Research Laboratory (NRL) believes that the scientific experiments conducted on the Vanguard satellites, which were inaugurated by the success of the Vanguard 2 mission, led to an increase in scientific knowledge of space and opened the way for more advanced experiments.

Vanguard 2 is the first meteorological satellite designed to measure the distribution of cloud cover in the diurnal part of its orbit (NASA)

Vanguard 2 launch

Vanguard 2 was launched from Cape Canaveral in Florida, USA, on February 17, 1959. The telemetry transmitter was operated for 23 days, but the data on cloud cover was severely deteriorated due to the oscillation of the rotation axis.

The transmitter also operated for 26 days, until March 15, during which 244 major observations were made. After the batteries ran out, the satellite remained visually tracked from Earth to study atmospheric drag and the gravitational field.

The Vanguard 2 mission ended on May 8, 1959, with an expected total orbital life of 200 to 300 years.

Spacecraft and its subsystems

The Vanguard 2 satellite was a magnesium ball weighing 10.75 kilograms and 50.8 centimeters in diameter.

It was gold-plated internally and externally coated with a layer of polished silicon monoxide-coated aluminum of sufficient thickness to ensure thermal control of the devices.

The payload instrument package was mounted in the middle of the sphere, arranged in cylindrical layers, with mercury batteries at the bottom, followed by Minitrack electronics, environmental electronics, telemetry instruments, and experimental electronics.

At the bottom of the beam at the bottom of the ball was the separator, a spring-loaded tube equipped with a timer designed to move the satellite away from the third floor of the launch vehicle once it reaches orbit.

The Vanguard 2 satellite is a magnesium ball weighing 10.75 kilograms and 50.8 centimeters in diameter (NASA)

At the inner top of the ball is a pressure gauge.

The satellite also had two optical telescopes with two photocells mounted on either side of the sphere at a 45-degree angle to the axis of rotation.

As for the antenna, it was formed by bending four metal rods stretched to a spring measuring 76.2 centimeters along the equator of the ball and dropped diagonally outward when deployed.

Radio communication with the satellite was secured by a 1 W, 108.03 MHz remote transmitter, operated by the ground station, and a 10 MHz, 108 MHz transmitter, transmitting a continuous signal for tracking purposes.

Use the command receiver to activate a 50-minute recording device that transmits the telescope experiment data to the remote transmitter.

The satellite was fixed to rotate at 50 revolutions per minute.

Launch vehicle

Vanguard is the design used for both the launch vehicle and the satellite.

The test vehicle consists of three floors (representing floors of 3 missiles).

The first floor was operated by a 28,000-pound GEX-405 system. It contained 152 kilograms of hydrogen peroxide, was 13.4 meters high, 1.14 meters in diameter, and had a mass at launch of about 8,090 kilograms.

The second floor is a liquid engine (AG-10) 5.8 meters high and 0.8 meters in diameter, burning 1,520 kilograms of asymmetric dimethyl hydrazine (UDMH) and white smoke-free nitric acid (Double UIFA) with a tank Helium pressure.

It produced a thrust force of approximately 7,340 pounds (32,600 Newtons), and its mass at launch was approximately 1,990 kilograms. This stage contains a complete guidance and control system.

Grand Central Rocket CO developed a solid-fuel rocket with a thrust of 2,350 pounds (10,400 Newtons) (for a burn duration of 30 seconds) to meet the requirements of the third stage.

The third floor system was 1.5 meters (60 inches) high and 0.8 meters (31.5 inches) in diameter, and the launch mass was 194 kilograms.

The floor's thin (0.076 cm) steel shell contains a front hemispherical dome with a column in the middle to support the satellite and a rear dome in a steel exit nozzle.

3D illustration of the Vanguard 2 satellite (Shutterstock)

The total height of the satellite vehicle was approximately 21.9 meters (72 feet).

The payload capacity was 11.3 kilograms (25 lb) for an Earth orbit of 555 km (345 miles).

The first stage (the first class missile) took 144 seconds to launch, reaching an altitude of 58 kilometers (36 miles), then the second stage (the second class missile) was launched for 120 seconds at an altitude of 480 kilometers (300 miles), and then the third stage was launched to put The satellite is in orbit by a Class III rocket.

International context: the space race

Vanguard 2 was launched in an international context called the Cold War. In 1955, with the United States of America and the Soviet Union manufacturing ballistic missiles used to launch objects into space, the stage was set for national competition.

In separate announcements, both countries announced that they would launch Earth satellites by 1957 or 1958. On July 29, 1955, US President Dwight Eisenhower's press secretary (1890–1969) announced that the United States intended to launch "small satellites orbiting the Earth." From 1 July 1957 to 31 December 1958, Washington's contribution to the International Geophysical Year.

Days after the Sixth Congress of the International Astronautical Federation in Copenhagen (1955), scientist Leonid Sedov spoke to international correspondents at the Soviet embassy and announced his country's intention to launch a satellite in the "near future."

On August 30, 1955, Korolev was able to convince the Soviet Academy of Sciences to establish a committee to launch the Americans into Earth’s orbit, and that was the actual start date of the Space Race.

Vanguard 2 is gold-plated on the inside and externally coated with polished silicon monoxide coated aluminum (NASA)

In this context, two problems were raised regarding the launch of the first meteorological satellite. The first relates to the definition of the airspace of countries in their relationship to satellite orbits, and whether the passage of a satellite over a country 100 kilometers (62 miles) away is interpreted as violating that country’s airspace.

The second is about distinguishing between satellites with scientific objectives and others with security objectives.

To solve the first problem, Eisenhower and his advisors held that the sovereignty of a nation's airspace did not extend beyond the Kerman Line (a line 100 kilometers (62 mi) above the Earth from sea level), and they took advantage of the launches of the International Geophysical Year 1957-1958 to put this principle into law International.

To solve the second problem, or mitigate its severity, the US President had to exclude missiles for military use in launching the Vanguard 2 satellite. Therefore, the Vanguard missile, affiliated with marine research, was chosen.

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