Explorer S-56 was a

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

satellite launched on 4 December 1960, at 21:14

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 ...

as part of the

Explorer program The Explorers program is a NASA exploration program that provides flight opportunities for physics, geophysics, heliophysics, and astrophysics investigations from space. Launched in 1958, Explorer 1 was the first spacecraft of the United Stat ...

. The satellite was composed of a diameter inflatable sphere, and was intended to study the density of the upper atmosphere. The

Scout X-1 Scout X-1 was an American expendable launch system and sounding rocket which was flown seven times between August 1960 and October 1961. Four orbital and three suborbital launches were made, with four of the launches resulting in failures. The ...

rocket used to launch Explorer S-56 failed in flight, and the satellite never reached orbit.

Spacecraft design

The spacecraft consisted of alternating layers of

aluminium foil Aluminium foil (or aluminum foil in North American English; often informally called tin foil) is aluminium prepared in thin metal leaves with a thickness less than ; thinner gauges down to are also commonly used. Standard household foil is typ ...

and

Mylar BoPET (biaxially-oriented polyethylene terephthalate) is a polyester film made from stretched polyethylene terephthalate (PET) and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and a ...

polyester Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include natura ...

film. Uniformly distributed over the aluminium surface were -diameter dots of white paint for thermal control. The sphere was packed in a tube in diameter and long and mounted in the nose of the fourth stage of its

launch vehicle. Upon separation of the fourth stage, the sphere will be inflated by a nitrogen gas bottle, and a separation spring will eject it out into its own orbit. The two hemispheres of aluminium foil will be separated with a gap of Mylar at the spacecraft's equator and will serve as the antenna. A 136

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 ...

, 15 mW beacon will be carried for tracking purposes, the beacon and the SAO

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 exa ...

network will be relied upon for tracking. Power will be supplied by

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.

s and

rechargeable batteries A rechargeable battery, storage battery, or secondary cell (formally a type of energy accumulator), is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to a disposable or prima ...

Launch

Explorer S-56 was launched, at 21:14 GMT on 4 December 1960, from Launch Area 3 at the

Wallops Flight Facility Wallops Flight Facility (WFF) is a rocket launch site on Wallops Island on the Eastern Shore of Virginia, United States, just east of the Delmarva Peninsula and approximately north-northeast of Norfolk. The facility is operated by the Godda ...

(WFF), atop a

launch vehicle with the serial number ST-3. It was the first attempt to place a satellite in orbit using an all-solid propellant launch vehicle and the first orbital attempt made from NASA's Wallops Island facility. It was the first spacecraft launched from

Wallops Island Wallops Island is a island in Accomack County, Virginia, part of the Virginia Barrier Islands that stretch along the eastern seaboard of the United States of America. It is just south of Chincoteague Island, a popular tourist destination. W ...

, but failed to reach orbit due to the second stage not igniting and impacting in the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

, at at east of Wallops Island. It was replaced by the identical

Explorer 9 Explorer 9, known as S-56A before launch, was a NASA satellite which was launched in February 1961 to study the density and composition of the upper thermosphere and lower exosphere. It was a reflight of the failed Explorer S-56 mission, and ...

(1961-004A) spacecraft. The first of six identical

air density The density of air or atmospheric density, denoted '' ρ'', is the mass per unit volume of Earth's atmosphere. Air density, like air pressure, decreases with increasing altitude. It also changes with variation in atmospheric pressure, temperature a ...

research satellites to be launched.

References

{{Reflist, 30em Satellites of the United States Explorers Program

Spacecraft design

Launch

See also

References