SOLRAD (SOLar RADiation) 4B was a
solar X-ray,
ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
, and electronic surveillance satellite. Developed by the
United States Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
's
United States 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 ...
, it was the fifth in both the
SOLRAD
SOLRAD (short for "SOLar RADiation," sometimes presented as "SOLRAD") was an American series of satellites sponsored by the US Navy in a program to continuously monitor the Sun. SOLRAD was the Naval Research Laboratory's first post-Vanguard satelli ...
and the
GRAB (Galactic Radiation And Background) programs.
This satellite was the only SOLRAD to be launched from
Vandenberg Air Force Base Vandenberg may refer to:
* Vandenberg (surname), including a list of people with the name
* USS General Harry Taylor (AP-145), USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in K ...
, to be launched via
Scout
Scout may refer to:
Youth movement
*Scout (Scouting), a child, usually 10–18 years of age, participating in the worldwide Scouting movement
**Scouts (The Scout Association), section for 10-14 year olds in the United Kingdom
**Scouts BSA, sectio ...
rocket, and to be launched unaccompanied by any other satellites. Launched on 26 April 1962, a fourth stage failure resulted in payload impact at 225 nautical miles of the downrange. SOLRAD 4B was the last of the SOLRAD/GRAB missions, future SOLRADs being launched with the
National Reconnaissance Office
The National Reconnaissance Office (NRO) is a member of the United States Intelligence Community and an agency of the United States Department of Defense which designs, builds, launches, and operates the reconnaissance satellites of the U.S. f ...
's (NRO) next-generation
POPPY
A poppy is a flowering plant in the subfamily Papaveroideae of the family Papaveraceae. Poppies are herbaceous plants, often grown for their colourful flowers. One species of poppy, ''Papaver somniferum'', is the source of the narcotic drug opi ...
satellites.
Background
The
United States Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
's
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) established itself as a player early in 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 tw ...
with the development and management of
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 ...
(1956–1959),
[ ] America's first satellite program. After Vanguard, the Navy's next major goal was to use the observational high ground of Earth's orbit to survey Soviet
radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
locations and
frequencies
Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...
. This first space surveillance project was called "GRAB", later expanded into the more innocuous
backronym
A backronym is an acronym formed from an already existing word by expanding its letters into the words of a phrase. Backronyms may be invented with either serious or humorous intent, or they may be a type of false etymology or folk etymology. The ...
, Galactic Radiation and Background.
As American space launches were not classified until late 1961,
a cover mission sharing the
satellite bus
A satellite bus (or spacecraft bus) is the main body and structural component of a satellite or spacecraft, in which the payload and all scientific instruments are held.
Bus-derived satellites are opposed to specially produced satellites. Bus-d ...
was desired to conceal GRAB's electronic surveillance mission from its intended targets.
The field of solar astronomy provided such cover. Since the invention of the rocket, astronomers had wanted to fly instruments above the atmosphere to get a better look at 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 ...
. The Earth's atmosphere blocks large sections of sunlight's
electromagnetic spectrum
The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies.
The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from ...
, making it impossible to study the Sun's X-ray and ultraviolet output from the ground. Without this critical information, it was difficult to model the Sun's internal processes, which in turn inhibited stellar astronomy in general.
[ ] On a more practical level, it was believed that solar flares directly affected the Earth's
thermosphere
The thermosphere is the layer in the Earth's atmosphere directly above the mesosphere and below the exosphere. Within this layer of the atmosphere, ultraviolet radiation causes photoionization/photodissociation of molecules, creating ions; the ...
, disrupting
radio communications
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmit ...
. The U.S. Navy wanted to know when its communications were going to become unreliable or compromised.
Sounding rockets
A sounding rocket or rocketsonde, sometimes called a research rocket or a suborbital rocket, is an instrument-carrying rocket designed to take measurements and perform scientific experiments during its sub-orbital flight. The rockets are used to ...
had shown that solar output was unpredictable and fluctuated rapidly. A long-term, real-time observation platform above the Earth's atmosphere – in other words, a
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 radioisotope ...
– was required to properly chart the Sun's radiation, determine its effects on the
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 ...
, and correlate it with ground-based observations of the Sun in other wavelengths of light.
Thus, the SOLRAD project was conceived to address several NRL goals at once:
* to make the first long-term continuous observations of the Sun in ultraviolet and X-ray light, and to correlate these measurements with ground-based observations.
[
* to evaluate the level of hazard posed by ultraviolet and X-ray radiation.]
* to better understand the effect of solar activity (including solar flares
A solar flare is an intense localized eruption of electromagnetic radiation in the Sun's atmosphere. Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections, solar particle events, and other solar phe ...
) on radio communications.[ ][ ]
* to cheaply and efficiently produce a satellite for the GRAB surveillance mission by using a proven design.
* to obscure the GRAB mission under a scientific cover.
SOLRAD 4B had two successful predecessors in SOLRAD 1
SOLRAD (SOLar RADiation) 1 is the public designation for SOLRAD/GRAB 1, a combination science and surveillance satellite launched into orbit on 22 June 1960. It was the first satellite to successfully observe solar X-rays, the first to conduct ...
and SOLRAD 3
SOLRAD (SOLar RADiation) 3 was a solar X-ray satellite, the third in the SOLRAD program. Developed by the United States Navy's Naval Research Laboratory (USNRL), it shared satellite space with and provided cover for the Navy's GRAB 2 (Galac ...
, both of which made significant contributions to the understanding of ultraviolet and X-ray astronomy in the previous two years,[ and which returned an abundance of intelligence on Soviet air defense radar installations.] SOLRAD 4B's immediate predecessor, SOLRAD 4, failed to make it to orbit on 26 January 1962, due to a faulty booster.
Spacecraft
SOLRAD 4B was a functional duplicate of SOLRAD 4: roughly spherical, modeled on the Vanguard
The vanguard (also called the advance guard) is the leading part of an advancing military formation. It has a number of functions, including seeking out the enemy and securing ground in advance of the main force.
History
The vanguard derives fr ...
satellite (which also had been developed by the 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 ...
). The satellite included both scientific SOLRAD and electronic surveillance GRAB packages within the same body. Mass of 25 kg, the fifth in the SOLRAD series was more heavily instrumented than prior SOLRADS. Instead of one X-ray photometer, like SOLRAD 1
SOLRAD (SOLar RADiation) 1 is the public designation for SOLRAD/GRAB 1, a combination science and surveillance satellite launched into orbit on 22 June 1960. It was the first satellite to successfully observe solar X-rays, the first to conduct ...
and SOLRAD 2
SOLRAD (SOLar RADiation) 2 was the public designation for a combination surveillance and solar X-rays and ultraviolet scientific satellite, the second in the SOLRAD program developed by the United States Navy's Naval Research Laboratory. The ...
, or two, like SOLRAD 3
SOLRAD (SOLar RADiation) 3 was a solar X-ray satellite, the third in the SOLRAD program. Developed by the United States Navy's Naval Research Laboratory (USNRL), it shared satellite space with and provided cover for the Navy's GRAB 2 (Galac ...
, it carried four X-ray photometers, allowing it to detect more intense and higher energy X-rays. Three of the photometers were shielded against Van Allen radiation belts (which could spoil results) by magnet
A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, ...
s, as had been done on earlier missions. The fourth was protected by a beryllium
Beryllium is a chemical element with the symbol Be and atomic number 4. It is a steel-gray, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form mi ...
shield. It was hoped that SOLRAD 4B would not only conduct basic research into solar X-ray astronomy, but also determine the hazard hard X-rays posed to astronaut
An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member aboard a spacecraft. Although generally r ...
s and 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 radioisotope ...
s.
Another point of difference between SOLRAD 4B and SOLRAD 1 to 3 was its four Lyman-alpha
The Lyman-alpha line, typically denoted by Ly-α, is a spectral line of hydrogen (or, more generally, of any one-electron atom) in the Lyman series. It is emitted when the atomic electron transitions from an ''n'' = 2 orbital to the gr ...
detectors.[ Used for measuring ultraviolet radiation, two such detectors had been included on SOLRAD 1 and SOLRAD 2 to determine the impact of solar ultraviolet on radio reception.] None had been measured, and the detectors had been deleted from SOLRAD 3. They were reinstated on SOLRAD 4 and SOLRAD 4B not for solar study, but for night-time measurement to see if ambient Lyman-alpha radiation constituted a threat to astronaut
An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member aboard a spacecraft. Although generally r ...
s and 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 radioisotope ...
s.[
]
Mission
On 26 April 1962 at 10:49 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 ...
, Scout X-2
Scout X-2 was an American expendable launch system and sounding rocket which was flown twice in 1962. It was a four-stage rocket, based on the earlier Scout X-1, uprated first and third stages. It was a member of the Scout family of rockets.
T ...
#111 blasted off from Vandenberg Air Force Base Western Test Range. A lack of attitude gas in the Scout's 4th stage caused the payload to crash at 225 nautical miles downrange.
Legacy
SOLRAD 4B was the final flight of the SOLRAD/GRAB series. A subsequent SOLRAD/GRAB mission ("SOLRAD 5") was cancelled and the satellite intended for the mission was ultimately donated to the National Air and Space Museum
The National Air and Space Museum of the Smithsonian Institution, also called the Air and Space Museum, is a museum in Washington, D.C., in the United States.
Established in 1946 as the National Air Museum, it opened its main building on the Nat ...
in 2002.[
In 1962, all U.S. overhead reconnaissance projects were consolidated under the ]National Reconnaissance Office
The National Reconnaissance Office (NRO) is a member of the United States Intelligence Community and an agency of the United States Department of Defense which designs, builds, launches, and operates the reconnaissance satellites of the U.S. f ...
(NRO), which elected to continue and expand the GRAB mission starting July 1962[ ] with a next-generation set of satellites, code-named POPPY
A poppy is a flowering plant in the subfamily Papaveroideae of the family Papaveraceae. Poppies are herbaceous plants, often grown for their colourful flowers. One species of poppy, ''Papaver somniferum'', is the source of the narcotic drug opi ...
. With the initiation of POPPY, SOLRAD experiments would no longer be carried on electronic spy satellites; rather, they would now get their own satellites, launched alongside POPPY missions to provide some measure of mission cover. Starting with SOLRAD 8, launched in November 1965, the final five SOLRAD satellites were scientific satellites launched singly, three of which were also given NASA 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 ...
numbers. The last in this final series of SOLRAD satellites flew in 1976. In all, there were thirteen operational satellites in the SOLRAD series. The GRAB program was declassified in 1998.[
]
See also
* General information on the SOLRAD project
* General information on the GRAB project
References
{{Orbital launches in 1962
1962 in spaceflight
Spacecraft launched in 1962
Satellites of the United States