(MDP), data evaluation and quality control, transmission of both image and inventory data to EDC, 
and EDC processing of data received into final user products. These steps are illustrated in Figure 2, 
The relative complexity of this figure compared to Figure 1 illustrates that the nature of the ground 
system had to be changed significantly to accomodate this mode of operations. Furthermore, the 
roles of GSFC and EDC were altered. In the early film production days all responsibility for final 
archival product generation resided at GSFC. In the HDT era the role of GSFC became one of 
providing HDT products to EDC for their use in the generation of both film and CCT. Processing 
HDT required that both facilities upgrade their ground systems. Early in unit testing at both sites it 
was discovered that some confusion could result due to final product anomalies and their origin, 
Therefore, a concerted effort was made to increase the frequency of meetings between technical 
personnel from the two sites to upgrade the dialog, understand system limitations, and increase 
production yields. This interface was successful in the timely production of MSS data for customers 
but had several residual problems traced back to the production systems in use at the time (2). 
3.0 THE NOAA PRODUCTION ERA (1982-1986) 
3.1 LANDSAT 4/5 MSS 
The introduction of a new series of satellites, the Landsat 4/5 series, led NASA to construct a new 
ground processing system. This system treats MSS data in a similiar fashion as was done for 
Landsats 2 and 3 in that image data on HDT are preprocessed at GSFC and transmitted to EDC for 
archive and user product generation. The significant difference here is that the current system is 
designed around a standard Digital Equipment Corporation VAX 11/780 computer rather than 
through the merger of multiple hardware and software elements from a variety of different vendors. 
This operational system was transitioned to NOAA in 1983 and is able to generate over 200 MSS 
scenes each day of production. Its production flow is illustrated in Figure 3. Reference to this 
figure illustrates that the order for data is passed from EDC to GSFC through a file or tape called the 
Archival Request Order Tape (AROT). Requests on this tape are used both for new acquisitions and 
for the production of products not yet in the archive. Processing information is used to define a 
workorder. When data are received at GSFC they are processed on the MSS Image Processing 
System (MIPS). This system produces partially processed MSS data (HDT-AT that contain MSS 
scenes that have been radiometrically corrected - geometric correction data are appended). The 
Goddard High density Inventory Tape (GHIT) is produced after quality evaluations have been 
completed. HDT data are transmitted from GSFC to EDC via Domsat. GHIT data are sent to EDC 
using DECNET. The EDC system has remained unchanged for Landsats 4/5 MSS. They receive 
the partially processed data, process it to an archive film data base, generate user film products, and 
produce user requested CCT's in a band sequential format. This mode of production at EDC is 
consistent with the production of Landsat 2 and 3 data. 
With this production system over 90% of the data captured are routinely preprocessed at GSFC and 
sent to EDC within 48 hours of receipt. This represents an improvement in volume and turnaround 
time when compared to the first HDT based system. 
3.2 THEMATIC MAPPER IMAGE PRODUCTION 
The Thematic Mapper (TM) was conceived by NASA as a second generation instrument relative to 
the MSS. As such it was principally designed to observe vegetation cover and provide a better 
measure of crop acreages in regions or countries with small fields. To aid in this assessment a 30 
meter spatial resolution was adopted and there was some sharpening of the spectral bands. 
Complete details of the evolution of instrument, spacecraft, and ground system are presented in the 
review by Salomonson and Mannheimer (3). 
Early TM image evaluations using data acquired from Landsat 4 were designed to characterize 
sensor response and verify the utility of TM for special applications. These studies were carried out 
by principal investigators funded by the NASA Landsat science office. Most principal investigators 
performed digital analyses using single scene data acquired over predetermined areas of the Earth's 
surface. Scientific results for each scene were categorized using different radiometric and geometric 
analysis methodologies. These results have been published (4,5). 
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