Disadvantages

sun

BRIGHT. UNAMBIGUOUS. LOW POWER AND WEIGHT.' USUALLT MUST BE KNOWN 'ORSOLAR CELLS AMO EQUIPMENT PROTECTION

MAY NOT BE VISIBLE DURING PARTS OF ORBIT ' AROUND LARGE CENTRAL BODY; 1/2-DEG ANGULAR DIAMETER (VIEWEDFROM EARTHI LIMITS ACCURACY TO -1 ARC MINUTE

earth, OR OTHER CENTRAL BODY

ALWAYS AVAILABLE FOR NEARBY SPACECRAFT. BRIGHT; LARGELY UNAMBIGUOUS (MAY BE MOON INTERFERENCE): NECESSARY FOR MANY TYPES OF SENSOR AND ANTENNA COVERAGE. ANALYSIS RELATIVELY EASY

TYPICALLY REQUIRE S SCAN MOTION TD SENS HORIZON. SENSORS MUST BE PROTECTED FROM SUN: RESOLUTION LIMITED TO - 0 1 OEG BECAUSE OF HORIZON DEFINITION;ORBIT AND ATTITUDE STRONGLY COUPLED

MAGNETIC F te ID I

ECONOMICAL. LOW POWER REQUIREMENTS: CRAFT

POOR RESOLUTION f> O.SDEGI; GOOD ONLY NEAR EARTH-LIMITED BY FIELD STRENGTH AND MODELING ACCURACY; ORBIT AND ATTITUDE STRONGLY COUPLED. SPACECRAFT MUSI BE MAGNETICALLY CLE AN (OR INFLIGHT CALIBRATION REQUIRE DL SENSITIVE TOBIASES

STARS ONCLUOINO DISTANT PLANETS)

HIGH ACCURACY (- to-3 BEG). AVAILABLE ANY. WHERE in 8«v; ESSENTIALLY ORBIT INDEPENDENT. EXCEPT FOR VELOCITY ABERRATtON

SENSORS HEAVY. COMPLEX. AND EXPENSIVE: .IDENTIFICATION OF STARS FOR MULTIPLE TARGET SENSORS IS COMPLE X AND TIME CONSUMING:SENSORS NEED PROTECTION FROM SIM. DOUBLE AND MULTIPLE STARS CAUSE PROBLEMS. USUALLY REQUIRE SECOND ATTITUDE SYSTEM FOR INITIAL ATTITUDE ESTIMATES

inert!AL SPACE (GYROscopes; ACCELEROMETCRS)

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