TDRSS antenna 
Thematic 
Multi-níssión Mapper Mae specteet 
modular canner 
spacecraft 
Figure l.--Landsat-4 will use the multi-mission modular spacecraft 
to carry the multispectral scanner (MSS) and the thematic mapper 
(TM) with antennas for communication with tracking and data re- 
lay satellite system (TDRSS) and the global positioning system 
(GPS) 
There are no on-board tape recorders for either the MSS or the TM. 
the two sensors can record data independently or simultaneously. When within 
range of a ground station equipped to receive it, data can be transmitted di- 
rectly--MSS data on S-band at 15 megabits/second and TM data on X-band at 
85 megabits/second. At all other times, data will be relayed to TDRSS and from 
there to the ground station at White Sands. After some preliminary processing, 
it will then be sent by domestic communication satellite (DOMSAT) to the image 
processing facility at Goddard Space Flight Center (GSFC) for product genera- 
tion. 
In operation, 
The MSS data is compatible with the network of foreign Landsat receiving stations 
and NASA is providing ground tape recorders at the ground stations in Brazil, 
Sweden, Japan, Australia, Thailand, and India to assure that coverage is obtained 
from certain high priority areas. These tapes are shipped to GSFC for processing. 
GSFC transmits high density digital tape data (HDDT) via DOMSAT to the EROS Data 
Center (EDC) at Sioux Falls, South Dakota. EDC produces both film and computer 
compatible tapes (CCTs) for distribution to users. The MSS ground processing 
System at GSFC is capable of processing about 200 scenes/day. In the first 
quarter of 1983, the National Oceanic and Atmospheric Agency (NOAA) will assume 
responsibility for command and control of the spacecraft and distribution of MSS 
data. 
The first few scenes of TM data clearly demonstrated the utility of the additional 
spectral bands and the increased spatial resolution. Initially the TM will be 
operated as a NASA experimental sensor. TM data will be transmitted on X-band 
directly to the ground station at GSFC until TDRSS is operational. No foreign 
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