 | |
| Names | SolarMax SMM |
|---|---|
| Mission type | Heliophysics |
| Operator | NASA |
| COSPAR ID | 1980-014A |
| SATCATno. | 11703 |
| Website | hao.ucar.edu |
| Mission duration | 9 years, 9 months, 18 days |
| Spacecraft properties | |
| Bus | Multimission Modular Spacecraft |
| Manufacturer | Fairchild Industries |
| Launch mass | 2,315 kg (5,104 lb) |
| Dimensions | 4 × 2.3 m (13.1 × 7.5 ft) |
| Start of mission | |
| Launch date | 14 February 1980, 15:57:00 UTC |
| Rocket | Delta 3910 D-151 |
| Launch site | Cape CanaveralLC-17A |
| End of mission | |
| Disposal | Deorbited |
| Decay date | 2 December 1989 |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Low Earth |
| Eccentricity | 0.00029 |
| Perigee altitude | 508.0 km (315.7 mi) |
| Apogee altitude | 512.0 km (318.1 mi) |
| Inclination | 28.5 degrees |
| Period | 94.80 minutes |
| Mean motion | 15.19 |
| Epoch | 14 February 1980, 15:57:00 UTC |
TheSolar Maximum Missionsatellite (orSolarMax) was designed to investigateSolar phenomena, particularlysolar flares. It was launched on February 14, 1980. The SMM was the first satellite based on theMultimission Modular Spacecraft bus manufactured by Fairchild Industries, a platform which was later used forLandsat 4 andLandsat 5[1] as well as theUpper Atmosphere Research Satellite.
After anattitude control failure in November 1980 it was put in standby mode until April 1984 when it was repaired by a Shuttle mission.
The Solar Maximum Mission ended on December 2, 1989, when the spacecraftre-entered the atmosphere and burned up over the Indian Ocean.[2]
| Name | Target | Principal Investigator |
|---|---|---|
| Coronagraph/Polarimeter: 446.5–658.3 nm, 1.5- 6 sq.solar radiifov, 6.4 arcsec res. | Solar corona, prominences, and flares | House, Lewis L.,High Altitude Observatory |
| Ultraviolet Spectrometer and polarimeter 175.0–360.0 nm raster imager, 0.004 nm sp.res. | Solar UV,Earth'satmosphere | Tandberg-Hanssen, Einar A.,NASAMarshall Space Flight Center |
| Soft X-ray Polychromator: raster imager, crystal spectrom. in parts of 0.14–2.25 nm | Solar flares, active solar regions | Acton, Loren W.,Lockheed Palo Alto, Culhane, JUniversity College, London, Leonard, Gabriel, Alan-Henri,Rutherford Appleton Laboratory |
| Hard X-ray Imaging Spectrometer:fov 6.4 arcmin, 8 or 32 arcsec res, 3.5–30 keV | Solar active regions and flares | de Jager, Cornelis,University of Utrecht |
| Hard X-ray Burst Spectrometer: CsI(Na), 15 energy channels covering 20–260 keV | Solar flares and active regions | Frost, Kenneth J.,NASA Goddard Space Flight Center |
| Gamma-ray Spectrometer: NaI(T1),0.01-100 MeV in 476 channels, 16.4 s per spectrum | solar gamma-rays | Chupp, Edward L,University of New Hampshire |
| Active Cavity Radiometer Irradiance Monitor: 0.001-1000 micrometer solar flux | solar irradiance | Willson, Richard C,NASA Jet Propulsion Laboratory |
The white-light coronagraph/polarimeter (C/P) took coronal images for about six months from March 1980 before suffering an electronics failure in September that prevented operation.[2]
In November 1980, the second of four fuses in SMM'sattitude control system failed, causing it to rely on itsmagnetorquers in order to maintain attitude. In this mode, only three of the seven instruments on board were usable, as the others required the satellite to be accurately pointed at the Sun. The use of the satellite's magnetorquers prevented the satellite from being used in a stable position and caused it to "wobble" around its nominally sun-pointed attitude.[3] SMM was left in standby mode for 3 years.[2]
The first orbiting, uncrewed satellite to be repaired in space, SMM was notable in that its useful life compared with similarspacecraft was significantly increased by the direct intervention of a crewed space mission. DuringSTS-41-C in April 1984, theSpace ShuttleChallenger rendezvoused with the SMM, astronautsJames van Hoften andGeorge Nelson attempted to use theManned Maneuvering Unit to capture the satellite and to bring it into the orbiter's payload bay for repairs and servicing. The plan was to use an astronaut-piloted Maneuvering Unit to grapple the satellite with the Trunnion Pin Attachment Device (TPAD) mounted between the hand controllers of the Maneuvering Unit, null its rotation rates, and allow the Shuttle to bring it into the Shuttle's payload bay for stowage. Three attempts to grapple the satellite using the TPAD failed. The TPAD jaws could not lock onto Solar Max because of an obstructing grommet on the satellite not included in its blueprints.
This led to an improvised plan which nearly ended the satellite's mission. The improvisation had the astronaut use his hands to grab hold of a solar array and null the rotation with a push from the Maneuvering Unit's thrusters. Instead, this attempt induced higher rates and in multiple axes; the satellite was tumbling out of control and quickly losing battery life. SMM Operations Control Center engineers shut down all non-essential satellite subsystems and with a bit of luck were able to recover the satellite minutes before total failure. The ground support engineers then stabilized the satellite and nulled its rotation rates for capture with theShuttle's robotic arm. This proved to be a much better plan. The satellite had been fitted with one of the arm'sgrapple fixtures so that the robotic arm was able to capture and maneuver it into the shuttle's payload bay for repairs.[3]
During the mission, the SMM's entire attitude control system module and the electronics module for the coronagraph/polarimeter instrument were replaced, and a gas cover was installed over the X-ray polychromator.[3] Their successful work added five more years to the lifespan of the satellite. The mission was depicted in the 1985IMAX movieThe Dream Is Alive.
10 comets were discovered in images from the SMM, all of which are members of theKreutz sungrazer group.[4]Robert M. MacQueen estimated that the comets seen by SMM havenuclei no greater than 16 m (52 ft) in radius.[5]
| Designation | Alternate | Observation date | Discoverer | Ref |
|---|---|---|---|---|
| C/1987 T2 (SMM-1) | - | 1987-Oct-05 | O. C. St. Cyr | [6] |
| C/1987 U4 (SMM-2) | - | 1987-Oct-17 | O. C. St. Cyr | [7] |
| C/1988 M1 (SMM-3) | 1988l | 1988-Jun-27 | O. C. St. Cyr | [8] |
| C/1988 Q1 (SMM-4) | 1988m | 1988-Aug-21 | D. Kobe C. Waugh | [9] |
| C/1988 T1 (SMM-5) | 1988n | 1988-Oct-11 | O.C. St. Cyr | [10][11] |
| C/1988 U1 (SMM-7) | 1988q | 1988-Oct-24 | A. L. Stanger | [12][13] |
| C/1988 W1 (SMM-6) | 1988p | 1988-Nov-18 | O.C. St. Cyr | [14][15] |
| C/1989 L1 (SMM-8) | 1989m | 1989-Jun-02 | O.C. St. Cyr D. L. Kobe | [16][17] |
| C/1989 N3 (SMM-9) | 1989q | 1989-Jul-08 | O.C. St. Cyr | [18][19] |
| C/1989 S1 (SMM-10) | 1989x | 1989-Sep-28 | O.C. St. Cyr | [20][21] |
Significantly, the SMM's ACRIM instrument package showed that contrary to expectations, the Sun is actually brighter during thesunspot cycle maximum (when the greatest number of dark 'sunspots' appear). This is because sunspots are surrounded by bright features calledfaculae, which more than cancel the darkening effect of the sunspot.
The major scientific findings from the SMM are presented in several review articles in a monograph.[22]
SMM's orbit slowly decayed due to atmospheric drag taking it down into denser regions. TheMarch 1989 geomagnetic storm was reported to have led to SMM dropping half a kilometre at the start of the storm and 5 kilometres over the whole period.[23] The satellite eventually lost attitude control on November 17, 1989, and re-entry and burn-up occurred on December 2, 1989, over the Indian Ocean.[2]
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