MAP Instrument Description

Frequencies (GHz)	22	30	40	60	90
Wavelengths (mm)	13.6	10.0	7.5	5.0	3.3
# of channels	4	4	8	8	16
Resolution (FWHM, degrees)	0.93	0.68	0.47	0.35	0.21
Sensitivity (uK, 0.3x0.3 pixel)	35	35	35	35	35
Radiometer	Differential pseudo-correlation with polarization
Reflectors	Dual Gregorian; 1.6 m x 1.4 m primaries
Thermal	Passive radiative cooling to < 95 K
Structure	Composite / Aluminum
Focal plane	3.5 x 3.5 degree field of view
Pointing	0.6 degree absolute (elevation); 1.8' knowledge

MAP Observatory Description

Redundancy	Primarily single string
Lifetime	27 months; fuel limit > 3 yrs
Mass	800 kg
Orbit	L2 (1-10 degree Lissajous orbit)
Trajectory	Lunar assist with phasing loops
Communications	2 omnis during phasing loops Medium gain antenna for downlinks after lunar fly-by
Uplinks	Once weekly to schedule downlinks
Downlinks	Once daily; DSN always in view
Downlink data rate from L2	667 kbps to 70 m dish; 16 min/day
Propulsion	Blow-down hydrazine with 8 thrusters
Attitude control	Star tracker, Sun sensors, 3 reaction wheels for scanning Gyro interpolates star tracker data
Spin rate / Precession rate	0.464 rpm (~2 min per spin) 0.017 rpm (1 hr per precession); 22.5 degree cone about anti-Sun line
Structure	Composite / Aluminum
Power	400 W; 3.1 m2 GaAs/Ge array 22.5 degrees off full Sun 23 A-hr NiH battery; no eclipses
Thermal	Solar array shades instrument MLI and gamma-alumina cylinder isolates spacecraft from instrument

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