Vanguard 3 (Harvard designation: 1959 Eta 1) is a scientific satellite that was launched into Earth orbit by the Vanguard SLV-7 on 18 September 1959, the third successful Vanguard launch out of eleven attempts. Vanguard rocket: Vanguard Satellite Launch Vehicle-7 (SLV-7) was an unused Vanguard TV-4BU (TV-4BU=Test Vehicle-Four BackUp) rocket, updated to the final production Satellite Launch Vehicle (SLV).

Project Vanguard Project Vanguard was a program managed by the United States Navy Naval Research Laboratory (NRL), which intended to launch the first artificial satellite into low Earth orbit using a Vanguard rocket. as the launch vehicle from Cape Canaveral ...

was a program managed by the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

Naval Research Laboratory The United States Naval Research Laboratory (NRL) is the corporate research laboratory for the United States Navy and the United States Marine Corps. It was founded in 1923 and conducts basic scientific research, applied research, technological ...

(NRL), and designed and built by the Glenn L. Martin Company (now

Lockheed-Martin The Lockheed Martin Corporation is an American aerospace, arms, defense, information security, and technology corporation with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is ...

), which intended to launch the first artificial

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioi ...

into

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

using a

Vanguard rocket The Vanguard rocket was intended to be the first launch vehicle the United States would use to place a satellite into orbit. Instead, the Sputnik crisis caused by the surprise launch of Sputnik 1 led the U.S., after the failure of Vanguard TV-3 ...

."The Vanguard Satellite Launching Vehicle — An Engineering Summary" B. Klawans April 1960, 212 pages
Martin Company Engineering Report No 11022, PDF of an optical copy as the

launch vehicle A launch vehicle or carrier rocket is a rocket designed to carry a payload ( spacecraft or satellites) from the Earth's surface to outer space. Most launch vehicles operate from a launch pads, supported by a launch control center and ...

from Cape Canaveral,

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

. Vanguard 3 was an important part of the

Space Race The Space Race was a 20th-century competition between two Cold War rivals, the United States and the Soviet Union, to achieve superior spaceflight capability. It had its origins in the ballistic missile-based nuclear arms race between the t ...

between the U.S. and the

Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...

Previous satellites

Before the 18 September 1959 successful launch of the satellite that became known as Vanguard 3, two other satellites that bore the name "Vanguard 3" were launched, but both launches ended in failures and the satellites did not reach orbit. The failed satellites were: *Vanguard 3A, launched 13 April 1959 on a Vanguard SLV-5 rocket, *Vanguard 3B, launched 22 June 1959 on a Vanguard SLV-6 rocket. The successful satellite that became known as the Vanguard 3 was known as Vanguard 3C before launch.

Spacecraft

The Vanguard 3 satellite was a diameter sphere with a conical boom on top. The lower three-fourths of the sphere was

silicon monoxide Silicon monoxide is the chemical compound with the formula SiO where silicon is present in the oxidation state +2. In the vapour phase, it is a diatomic molecule. It has been detected in stellar objects and has been described as the most common o ...

-coated

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

and the upper fourth and the conical extension were made of

fiberglass Fiberglass (American English) or fibreglass ( Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clo ...

( glass fiber phenolic resin). Mass of the satellite was approximately , the total mass of the orbiting spacecraft with the third stage casing attached was . Power was provided by specially built Yardley Silvercels (AgZn chemical batteries) with non-magnetic lugs, designed to last approximately 3 months. The batteries were held in a pressurized can mounted in the lower two-thirds of the sphere. In its top center, the can also contained a smaller cylinder, which held the electronics for the X-ray, peak memory, temperature measurements, micrometeorite detector, and data encoder, above which was the 30 mW, 108.00

MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...

Minitrack The Minitrack Network was the first U.S. satellite tracking network to become operational, in 1957. It was used to track the flights of Sputnik, Vanguard, Explorer, and other early space efforts. Minitrack was the progenitor of Spacecraft Trackin ...

beacon transmitter. Another cylinder, mounted on top of the pressurized compartment, held the magnetometer instrumentation package, associated electronics, the command receiver and 80 mW, 108.03 MHz transmitter plus electronics providing burst

telemetry Telemetry is the in situ collection of measurements or other data at remote points and their automatic transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Greek roots ''tele'', "remote", an ...

for the magnetometer. A

tape recorder An audio tape recorder, also known as a tape deck, tape player or tape machine or simply a tape recorder, is a sound recording and reproduction device that records and plays back sounds usually using magnetic tape for storage. In its present ...

was used to store data for playback during ground station passes. Four spring loaded aerials extended from the equator of the sphere at 90° intervals. A small

solar cell A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon.

and cadmium sulfide cell were also mounted on the sphere wall near the equator. The magnetometer sensor head was mounted at the end of the conical boom. The sphere was spin-stabilized and had passive thermal control. It had no engines for thrust or

attitude control Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle ...

Launch

Vanguard 3 was launched at 05:20:07

GMT Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London, counted from midnight. At different times in the past, it has been calculated in different ways, including being calculated from noon; as a cons ...

(12:20:07 a.m. EST) on 18 September 1959 from the

Eastern Test Range The Eastern Range (ER) is an American rocket range ( Spaceport) that supports missile and rocket launches from the two major launch heads located at Cape Canaveral Space Force Station and the Kennedy Space Center (KSC), Florida. The range h ...

of the Atlantic Missile Range at Cape Canaveral into a

geocentric orbit A geocentric orbit or Earth orbit involves any object orbiting Earth, such as the Moon or artificial satellites. In 1997, NASA estimated there were approximately 2,465 artificial satellite payloads orbiting Earth and 6,216 pieces of space debri ...

. The satellite was then injected at 05:29:49 GMT into a 33.35°

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

Earth orbit with a

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ell ...

altitude of ,

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ell ...

of , and an

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

of 130.0 minutes. The third stage was purposely left attached to the satellite, in order to produce a long tumble period, to avoid corrections to the magnetometer that would be necessary with a rapidly rotating satellite. Perigee remained on the night side of Earth throughout the mission. All experiments functioned normally and the batteries lasted for 84 days, until 11 December 1959, at which time all communication with the spacecraft ceased. It was still tracked optically (

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observ ...

s) for the atmospheric drag experiment. The objectives of the flight were to measure the

Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic ...

, the solar X-ray radiation and its effects on the Earth's atmosphere, the near-Earth micrometeoroid environment, and the drag effects and density of the upper atmosphere. Instrumentation included a proton magnetometer, X-ray ionization chambers, radio transmitters, and various micrometeoroid detectors. The data obtained provided a comprehensive survey of the Earth's magnetic field over the area covered, defined the lower edge of the Van Allen radiation belt, and provided a count of micrometeoroid impacts. Vanguard 3 has an expected orbital lifetime of roughly 300 years from launch.

Mission objectives

The objectives of the flight were to measure the

, the solar

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

radiation and its effects on the

atmosphere of Earth The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing fo ...

, and the near-Earth micrometeoroid environment.

Instrumentation Instrumentation a collective term for measuring instruments that are used for indicating, measuring and recording physical quantities. The term has its origins in the art and science of scientific instrument-making. Instrumentation can refer to ...

included a

proton magnetometer A proton magnetometer, also known as a proton precession magnetometer (PPM), uses the principle of Earth's field nuclear magnetic resonance (EFNMR) to measure very small variations in the Earth's magnetic field, allowing ferrous objects on land ...

, X-ray ionization chambers, and various micrometeoroid detectors. The spacecraft was a of diameter

sphere. The magnetometer was housed in a

phenolic resin Phenol formaldehyde resins (PF) or phenolic resins (also infrequently called phenoplasts) are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde. Used as the basis for Bakelite, PFs were the first commerc ...

conical tube attached to the sphere. Data transmission stopped on 11 December 1959, after 84 days of operation. The data obtained provided a comprehensive survey of the Earth's magnetic field over the area covered, defined the lower edge of the Van Allen radiation belt, and provided a count of micrometeoroid impacts.

Mission results

Proton Precessional Magnetometer

This experiment had a proton precessional magnetometer to measure the

at altitudes ranging from to and at latitudes between ± 33.4°. The measurements were made on command as the spacecraft passed seven

stations in

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography. Etymology The word ''north ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

and one each in Australia and

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...

. When switched on by command, the polarization coil around the proton sample ( normal hexane) was turned on for 2 seconds followed by a 2 seconds readout of the precession signal. Several readings were taken during each pass over a station. The experiment worked well during its 84 days active life, and approximately 4300 readings were recorded. The experiment is described in J. C. Cain et al., "Measurements of the geomagnetic field by the Vanguard 3 satellite", NASA TN D-1418, Goddard Space Flight Center, Greenbelt, Maryland, 1962, The overall accuracy of the field measurements was approximately 10 nT (gammas).

X-Ray Experiment

The objective of this experiment was to measure the X-ray emission from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

and its effects on the

Atmosphere of Earth The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing fo ...

. The detectors were two identical ionization chambers sensitive to X-ray wavelengths produced in solar flares (2 to 8 Å, or 200 to 800 pm). The ionization chambers were located 120° apart in the equatorial plane of the satellite and received a maximum signal when an ion chamber tube "looked" toward the Sun. The instrumentation were designed to measure the 2 to 8 Å (200 to 800 pm) X-ray flux and record the peak solar flare intensity by means of a peak-reading memory device, during the daylight portion of each orbit. However, due to the overwhelming background radiation of the Van Allen Belts, its sensors were saturated, and no useful information on solar X-rays was gathered.

Micrometeorite Detector

This experiment contained two sealed pressure zones, extending along the interior walls of the satellite, which were designed to record the impact of

micrometeorite A micrometeorite is a micrometeoroid that has survived entry through the Earth's atmosphere. Usually found on Earth's surface, micrometeorites differ from meteorites in that they are smaller in size, more abundant, and different in composition. T ...

s large enough to pierce the satellite shell. These pressure zones were partial vacuums, each at a different pressure, and were protected by 0.66 mm

walls that presented an exposed surface area of 0.162 m², which was 20% of the area of the shell. A puncture in the walls of either zone was detected by a differential pressure gauge mounted between them, and telemetered as a change in the length of one of the telemetry channels. Erosion of the satellite shell through bombardment by

space dust Cosmic dust, also called extraterrestrial dust, star dust or space dust, is dust which exists in outer space, or has fallen on Earth. Most cosmic dust particles measure between a few molecules and 0.1 mm (100 micrometers). Larger particles are c ...

s, and other particles was recorded by three chromium-strip erosion gauges mounted on the satellite surface, and by a photosensitive detector. Electrical resistances of the gauges changed as their surfaces were changed by erosion. The photosensitive detector, a

cadmium sulfide Cadmium sulfide is the inorganic compound with the formula CdS. Cadmium sulfide is a yellow solid.Egon Wiberg, Arnold Frederick Holleman (2001''Inorganic Chemistry'' Elsevier It occurs in nature with two different crystal structures as the rare mi ...

cell protected by an opaque covering of aluminized PET film, also showed a resistance change as the covering was eroded or penetrated. Erosion measurements also were telemetered as channel lengths, which permitted estimates of the erosion rates. Four

barium titanate Barium titanate (BTO) is an inorganic compound with chemical formula BaTiO3. Barium titanate appears white as a powder and is transparent when prepared as large crystals. It is a ferroelectric, pyroelectric, and piezoelectric ceramic material ...

-type

microphone A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and publ ...

s recorded micrometeorite impacts on the satellite's surface. The microphone output was amplified, shaped, and fed into a magnetic counter unit, which provided continuously, in three-decimal digits, the cumulative count of impacts. The unit counted up to 1000 and then reset to zero. The satellite recorded 6600 micrometeorite impacts during 66 days of operation, of which 2800 occurred during a 70 hours interval from 16 to 18 November 1959, almost certainly due to the Earth's annual passage through debris from comet Tempel-Tuttle, which results in the Leonids meteor shower which peaks on the 17 November 1959. No penetrations or fractures were recorded in the sensors of the surface penetration experiment. Because the erosion sensors were not disrupted, no definite results could be drawn from that experiment.

Satellite Drag Atmospheric Density

Because of its symmetrical shape, Vanguard 3 was selected by the experimenters for use in determining upper atmospheric densities as a function of

altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...

season A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's tilted orbit around the Sun. In temperate and ...

, and

solar activity Solar phenomena are natural phenomena which occur within the atmosphere of the Sun. These phenomena take many forms, including solar wind, radio wave flux, solar flares, coronal mass ejections, coronal heating and sunspots. These phenomena are ...

. As the spacecraft continuously orbited, it would lag its predicted positions slightly, accumulating greater and greater delay due to drag of the residual atmosphere. By measuring the rate and timing of orbital shifts, the relevant atmosphere's parameters could be back-calculated knowing the body's drag properties. It was determined that atmospheric pressures, and thus drag and orbital decay, were higher than anticipated, as Earth's upper atmosphere tapered into space gradually. This experiment was very much planned prior to launch. Initial Naval Research Laboratory proposals for

included conical satellite bodies; this eliminated the need for a separate fairing and ejection mechanisms, and their associated weight and failure modes. Radio tracking would gather data and establish a position. Early in the program, optical tracking (with a

Baker-Nunn camera A Schmidt camera, also referred to as the Schmidt telescope, is a catadioptric astrophotographic telescope designed to provide wide fields of view with limited aberrations. The design was invented by Bernhard Schmidt in 1930. Some notable ex ...

network and human spotters) was added. A panel of scientists proposed changing the design to spheres, at least in diameter and hopefully . A sphere would have a constant optical reflection, and constant

coefficient of drag In fluid dynamics, the drag coefficient (commonly denoted as: c_\mathrm, c_x or c_) is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water. It is used in the drag e ...

, based on size alone, while a cone would vary with orientation.

James Van Allen James Alfred Van Allen (September 7, 1914August 9, 2006) was an American space scientist at the University of Iowa. He was instrumental in establishing the field of magnetospheric research in space. The Van Allen radiation belts were named aft ...

proposed a

cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infin ...

, which eventually flew ( Explorer 1). The Project Vanguard finally accepted and 50.8 cm satellites.C. McLaughlin Green, M. Lomask, "Vanguard, A History", Chapter 5, Battle over Vehicle Specifications, NASA SP-4202

Post mission

After the scientific mission ended, Vanguard 3 and two pieces of the upper stage of the rocket used to launch the satellite became derelict

objects Object may refer to: General meanings * Object (philosophy), a thing, being, or concept ** Object (abstract), an object which does not exist at any particular time or place ** Physical object, an identifiable collection of matter * Goal, an ...

. Vanguard 3 remains in orbit. The pieces of the upper stage re-entered the atmosphere on 3 April 2014 and 4 February 2015. As

Vanguard 1 Vanguard 1 (Harvard designation: 1958-Beta 2, COSPAR ID: 1958-005B ) is an American satellite that was the fourth artificial Earth-orbiting satellite to be successfully launched, following Sputnik 1, Sputnik 2, and Explorer 1. It was laun ...

Vanguard 2 Vanguard 2 (or Vanguard 2E before launch) is an Earth-orbiting satellite launched 17 February 1959 at 15:55:02 GMT, aboard a Vanguard SLV-4 rocket as part of the United States Navy's Project Vanguard. The satellite was designed to measure clo ...

, and Vanguard 3 are still orbiting with their drag properties essentially unchanged, they form a baseline data set on the

that is over 60 years old and continuing. Vanguard 3 has an expected lifetime of 300 years.

References

{{Orbital launches in 1959 Spacecraft launched in 1959 Derelict satellites orbiting Earth Project Vanguard