The SOLRAD 8,Explorer 30 or SE-A satellite was one of the

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, succeeding t ...

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 ...

(Solar Radiation) program that began in 1960 to provide continuous coverage of solar radiation with a set of standard

photometer A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Most photometers convert light into an electric current using a photoresistor, ph ...

s. SOLRAD 8 was a spin-stabilized satellite oriented with its

spin axis Rotation around a fixed axis is a special case of rotational motion. The fixed-axis hypothesis excludes the possibility of an axis changing its orientation and cannot describe such phenomena as wobbling or precession. According to Euler's rot ...

perpendicular to the sun-satellite line so that the 14 solar X-ray and ultraviolet photometers pointing radially outward from its equatorial belt viewed the sun on each revolution. Data were transmitted in real time by means of an FM / AM the satellite's telemetry system and were recorded by the stations on the

Spacecraft Tracking and Data Acquisition Network The Spacecraft Tracking and Data (Acquisition) Network (STADAN or STDN) was established by NASA in the early 1960s to satisfy the requirement for long-duration, highly available space-to-ground communications. The network was the “follow-on” ...

(STADAN) tracking network.

Eclipse 1966

The satellite observed the solar eclipse on 20 May 1966. This observation may have been the first observation of a

solar eclipse A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of the Earth, totally or partially. Such an alignment occurs during an eclipse season, approximately every six month ...

by an

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 radioisoto ...

Mission

The satellite performed normally, except for the spin system, which failed to maintain 60

rpm Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...

(at spin rates below 10 rpm data reduction became difficult). The spin rate gradually decreased to 4 rpm on 12 September 1966. At that time, ground command succeeded in reactivating spinup to 78 rpm, which exhausted the gas supply. From this point, the spin rate gradually decreased to 10 rpm in August 1967, when data collection was substantially decreased. The satellite performed normally, except for the spin system, which failed to maintain 60 rpm (at spin rates below 10 rpm data reduction became difficult). The spin rate gradually decreased to 4 rpm on September 12, 1966. At that time, ground command succeeded in reactivating spinup to 78 rpm, which exhausted the gas supply. From this point, the spin rate gradually decreased to 10 rpm in August 1967, when data collection was substantially decreased.

Experiment

Solar X-Ray and Ultraviolet Monitor

This experiment was designed to monitor solar X-ray and ultraviolet emissions with a set of standardized detectors so that the data could be compared directly with that produced by other experiments in the SOLRAD series. Eight ion chambers and two

Geiger counter A Geiger counter (also known as a Geiger–Müller counter) is an electronic instrument used for detecting and measuring ionizing radiation. It is widely used in applications such as radiation dosimetry, radiological protection, experimental ph ...

s covering the spectral regions from 0.5 A to 60 A and 1080 A to 1350 A were mounted perpendicular to the satellite spin axis. Analog outputs from the detectors were transmitted continuously on six IRIG telemetry channels. The experiment provided good data for all detectors from 27 November 1965 to 24 August 1967, with the following exceptions: (1) the Lyman-alpha detector and the UV detectors were saturated for normal aspect angles, (2) the core memory failed at launch so that the data were collected in real-time telemetry only, and (3) a gradual decrease in spin rate caused the aspect angle to drift away from normal in the second year of operation.

References

External links