Command and Data Handling (C&DH)
Thermal Control Subsystem (TCS)
Attitude Control Subsystem (ACS)
Reaction Control Subsystem (RCS)
Electrical and Power Subsystem (EPS)
RF Communications (Comm)
Enhanced Thematic Mapper Plus (ETM+)

Landsat 7 was launched on a Delta II-7920-10 from Vandenburg Air Force Base (VAFB) and placed into a 705 km frozen circular orbit. More information about the spacecraft's orbit can be found on the Mission Overview Page .

Landsat 7 is a three-axis stabilized platform carrying a single nadir-pointed instrument, the Enhanced Thematic Mapper Plus (ETM+). S-Band is used for commanding and housekeeping telemetry operations, and X-Band for instrument data downlink. A 378 Gigabit Solid State Recorder can hold 42 minutes of instrument data (approximately 100 images) and 29 hours of housekeeping telemetry concurrently. Power is provided by a single Sun-tracking solar array (1550 watts EOL) and two 50 amp-hour Nickel-Hydrogen batteries. Attitude control is provided through four reaction wheels (pitch, yaw, roll, skewed), three 2-channel gyros, a celestial star sensor, a static Earth sensor, 1750A processor, and torque rods and magnetometers for momentum unloading. Orbit control and backup momentum unloading is provided through a blow-down monopropellant hydrazine system with a single tank containing 270 pounds of hydrazine at launch, associated plumbing, and 12 one pound-thrust jets. Spacecraft weight was approximately 4632 pounds at launch.

More information about the ETM+ instrument can be found on the Science Information Page .

ACS - Coarse Sun Sensor - Inertial Measurement Unit (3 gyros) - Earth Sensor Assembly - Celestial Sensor Assembly - Three Axis Magnetometer (2) - Reaction Wheels (4) - Magnetic Torquer Rods (2)	RCS - Blowdown Hydrazine System  -- Helium pressurized  -- 28 inch dia. Titanium tank  -- 269 lbm of Hydrazine  -- 1 lbf Thrusters (12)	C&DH -1750A processor (2) - 6 Selectable TLM formats - TDM/CCSDS - Solid State Recorder  -- 378 Gb Payload Storage (42 min)  -- 450 Mb H/K Storage (25 hrs)
EPS -Bus Voltage = 28 V ± 2% - Solar Array (1550 watts EOL)  -- Solar Array Drive - 2 NiH, 50-AHr batteries	TCS -Heaters -Thermal Blankets -Radiators	RF - Gimbaled X-band directional antennas (3 Nadir) (Payload data)  -- 150 Mbps/antenna - S-band Omni antennas (1 Nadir, 1 Zenith) (H/K data)  -- 1.216 kbps & 4.864 kbps (R/T)  -- 256 kbps (playback)

Predicted Weight at launch: 4632 lbs

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This page was last updated on May 5, 2003.
You may send e-mail to us at the following address
Tom Cooke at thomas.cooke@gsfc.nasa.gov