SMM
Solar Maximum Mission

The Solar Maximum Mission (SMM) was intended primarily to study solar flares and related phenomena. Launched during a period of maximum solar activity, SMM observed more than 12,000 flares and over 1,200 coronal mass ejections during its 10 year lifetime. SMM provided measurements of total solar radiative output, transistion region magnetic field strengths, storage and release of flare energy, particle accelerations, the formation of hot plasma, and coronal mass ejection. The payload also observed the short-wavelength and coronal manifestations of flares. Observations from SMM were coordinated with in situ measurements of flare particle emissions made by the ISEE 3 satellite. SMM was the first satellite to be retrieved, repaired and redeployed in orbit. In 1984, the STS-41C Shuttle crew restored the spacecraft's malfunctioning attitude control system and replaced a failed electronics box for the coronagraph/polarimeter. SMM collected data until November 24, 1989, and re-entered on December 2, 1989.

Spacecraft
The solar payload instruments and the sun-sensor system were contained in the instrument module occupying the top 2.3 meters of the craft. The Multimission Modular Spacecraft (MMS), below the instrument module, contained the systems for attitude control, power, communication, and data handling. Two fixed solar panels, located between the instrument module and the MMS supplied 1500-3000W. The fine-pointing Sun-sensor system had a precision of 1 arcsec along all 3 axes.

Payload
Active Cavity Radiometer Irradiance Monitor (ACRIM) - measured total solar irradiance. Gamma Ray Spectrometer (GRS) - studied the composition of solar and interstellar gamma ray emissions. Hard X-ray Burst Spectrometer (HXRBS) - studied hard X-ray spectra of solar flares in 15 energy channels between 20-260 keV. soft X-ray Polychtomator (XRP) - monited soft X-ray emissions. Hard X-ray Imaging Spectrometer (HXIS) - Ultraviolet Spectrometer and Polarimeter (UVSP) - a raster imager providing 0.04 A sp. res. Coronograph/Polarimeter - studied the faint solar corona between 2 and 5 solar radii with a 6.4 arcsec resolution.

Country of Origin	United States
Customer/User	NASA
Manufacturer(s)	Fairchild
Size	4 meters long
Orbit	512 km x 508 km; incl.= 28.5 deg
Related Sites	SMM at GSFC SMM Data

Launch Facts

Name	Int'l Desig.	Date	Site	Vehicle	Orbit	Mass(kg)
Notes
SMM	1980-014A	2/14/80	ESMC	Delta 3910	LEO	2315
Solar Maximum Mission; solar observatory; repaired 4/9/84 by STS-41C in orbit