WMAP Mission Specifications

The following tables give the high-level technical specifications for the WMAP instrument and observatory. More details are available by following the linked items in the tables.

WMAP Instrument

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	0.53	0.35	<0.23
Sensitivity (µK, 0.3° x 0.3° pixel)	~35	~35	~35	~35	~35
Radiometer	Differential pseudo-correlation with polarization
Reflectors	Dual Gregorian; 1.4 m x 1.6 m primaries
Thermal	Passive radiative cooling to < 95 K
Structure	Composite / aluminum
Focal plane	3.5° x 3.5° field of view
Pointing accuracy	0.6° control (elevation); 1.8' knowledge

WMAP Observatory

Redundancy	Primarily single string
Lifetime	27 months; fuel limit > 3 years
Mass	840 kg
Orbit	L2 (1-10° Lissajous orbit)
Trajectory	Lunar assist with phasing loops
Communications	2 omnis during phasing loops Medium gain antenna for downlinks after lunar flyby
Uplinks	Once weekly to schedule downlinks
Downlinks	Once daily; Deep Space Network 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	2 star trackers, 2 gyros, coarse & fine Sun sensors, 3 reaction wheels for scanning
Spin rate / Precession rate	0.464 rpm (~2 min per spin) 0.017 rpm (1 hr per precession); 22.5° cone about WMAP-Sun line
Structure	Composite / aluminum
Power	419 W; 3.1 m2 GaAs/Ge array, 22.5° off full Sun 23 A-hr NiH battery; no eclipses
Thermal	Passively cooled with radiators, solar array shades instrument; MLI and gamma-alumina cylinder isolates spacecraft from instrument