Solrad 9, also known Explorer 37 and Explorer SE-B, was one of the SOLRAD (Solar Radiation) program that began in 1960 to provide continuous coverage of solar radiation with a set of standard photometers.

Launch and operations

Was launched on March 5, 1968 from

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, VA, Norfolk. The facility is operated ...

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, with

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, sect ...

launch vehicle. Solrad 9 was a spin stabilized satellite oriented with its spin axis

perpendicular In geometry, two geometric objects are perpendicular if they intersect at right angles, i.e. at an angle of 90 degrees or π/2 radians. The condition of perpendicularity may be represented graphically using the '' perpendicular symbol'', � ...

to the sun-satellite line so that the 14 solar

X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

and UV photometers pointing radially outward from its

equatorial belt The monsoon trough is a convergence zone between the wind patterns of the southern and northern hemispheres. It is a portion of the Intertropical Convergence Zone in the Western Pacific,Bin WangThe Asian Monsoon.Retrieved 2008-05-03. and is depi ...

viewed the sun with each revolution. Data were simultaneously transmitted via FM/ AM

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'', 'far off', an ...

and recorded in a core memory that read out its contents on command. Individual scientists and institutions were invited to receive and use the data transmitted on the 136 MHz telemetry band on the standard IRIG channels three through eight. In the time that elapsed between the termination of Solrad 8 operations in August 1967 and the orbiting of Solrad 9, solar activity data were obtained using photometers in satellites OSO-4 and OGO-4. Solrad 9 was particularly important among the Solrad series satellites because thanks to the collected data were useful to predict the behavior of the sun during the period of the first crewed missions of the

Apollo Program The Apollo program, also known as Project Apollo, was the United States human spaceflight program led by NASA, which Moon landing, landed the first humans on the Moon in 1969. Apollo followed Project Mercury that put the first Americans in sp ...

, starting from the first,

Apollo 7 Apollo 7 (October 11–22, 1968) was the first crewed flight in NASA's Apollo program, and saw the resumption of human spaceflight by the agency after the fire that had killed the three Apollo 1 astronauts during a launch rehearsal test ...

, it is therefore useful to draw up a mission program to ensure, from this point of view, the safety of

astronaut An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a List of human spaceflight programs, human spaceflight program to serve as a commander or crew member of a spa ...

s. It recorded important data on one of the strongest solar storms that occurred between

Apollo 9 Apollo 9 (March 3–13, 1969) was the third human spaceflight in NASA's Apollo program, which successfully tested systems and procedures critical to landing on the Moon. The three-man crew consisted of Commander James McDivitt, Command Modul ...

and

Apollo 10 Apollo 10 (May 18–26, 1969) was the fourth human spaceflight in the United States' Apollo program and the second to orbit the Moon. NASA, the mission's operator, described it as a "dress rehearsal" for the first Moon landing (Apollo 11, two ...

and which would have produced potentially hazardous (to even fatal) effects to astronauts had then been in space (if the spacecraft were outside the Earth's protective

magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...

) at the time. As of July 1971, it was decided to use the Solrad 10 memory data, put into orbit on the 8th of the same month, and so continued until June 1973, when the Solrad 10 data storage device had a bad operation and

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

began to read data from the memory of Solrad 9. The satellite remained active until February 25, 1974, when the gas reserves useful to maintain control of the facility were over. Once the stability was lost, in fact, the satellite became useless and therefore was turned off. Unlike Solrad 8, its predecessor, Solrad 9 did not remain in orbit and returned to the

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

, disintegrating on November 16, 1990.

References

{{Orbital launches in 1968 1968 in spaceflight Spacecraft launched in 1968 Explorers Program SOLRAD