3.2 Mission Operations 
NASCOM includes the circuits, switching, and 
terminal facilities, arranged in a global system 
to provide operational telecommunications sup 
port for all NASA projects. NASCOM will provide 
the data transport path between the White Sands 
facilities, CDOS facilities, and the EOSDIS ele 
ments that require operational support. These 
include the EOS Mission Operations Center 
(EMOC), Instrument Control Centers (ICCs), and 
IDPGFs. The PSCN provides "non-operational" 
network support to NASA projects, and will be 
utilized for network links to scientific users 
of EOSDIS and to users and archives of other 
agencies. 
Operating elements of the CDOS include the Data 
Interface Facility (DIF), the Data Handling 
Centers (DHCs), and the Platform Support Center 
(PSC). The DIF will be responsible for receiv 
ing data from the NASA platforms via the TDRSS 
ground terminals and also for uplinking commands 
as received from the PSC. The DHCs will receive 
data from the DIF and routinely perform level 
zero and ancillary data processing. Level zero 
data will be forwarded to the IDPGFs for further 
science processing while engineering and quick- 
look data will be routed to the ICCs for engi 
neering assessment and health and safety moni 
toring. Ancillary data (attitude, orbit, house 
keeping, etc.) will be stored and made available 
to users as required. The PSC will routinely 
obtain a conflict-free scheduling plan for oper 
ation of the EOS instruments from the EMOC, ver 
ify the availability of necessary platform re 
sources, and coordinate with the Space Network 
Control Center for TDRSS scheduling and command 
uplinks via the DIF. 
The EOS Mission Operations Center (EMOC) will be 
the mission control center for EOS activities 
and will be located at GSFC. As the project 
control center, the EMOC will have full respon 
sibility for mission planning and schedule im 
plementation, monitoring the execution of the 
payload portions of the approved schedule, com 
mand review, and coordination with the PSC and 
ICCs. It will be responsible for coordinating 
the planning and scheduling inputs from the ICCs 
and forwarding them to the PSC. - This planning 
function includes allocation of platform re 
sources in accordance with the overall mission 
science plan developed by the IWG, planning for 
TDRSS, and coordination with the international 
partners who have payloads on NASA platforms, or 
for NASA payloads on foreign platforms. 
The Instrument Control Centers are responsible 
for payload health, safety, and commanding. 
Current plans are for the majority of the ICCs 
to be collocated with the EMOC at GSFC. The re 
mainder will be located at JPL. The ICCs will 
be responsible for monitoring the health and 
safety of their instruments, generating and 
checking commands, and providing planning inputs 
to the EMOC. Each instrument Principal 
Investigator (PI) and research facility instru 
ment Team Leader (TL) will be provided with an 
Instrument Support Terminal (1ST), located at 
their home institution, with which to interface 
with the ICCs. The PI/TL is responsible for 
defining the operational scenario for the in 
strument, for assessing the instrument's ongoing 
performance, and for providing direction to the 
ICC for generation of command loads. The 1ST 
will enable the PI/TL to access remotely any in 
formation available to the ICC, and will support 
analysis of instrument performance and the gen 
eration, test, and communication to the ICC of 
operational scenario requests. 
3.3 Science Data Processing and Archiving 
Science processing of standard data products 
takes place in the IDPGFs using algorithms fur 
nished by the EOS investigators and integrated 
on the IDPGF processing facilities. Closely as 
sociated with the IDPGFs will be the DADS in 
which the processed data will be stored and ac 
cessed upon demand for further processing or for 
distribution to users. The IDPGF and DADS 
facilities comprise the EOSDIS active archives 
(located within the DAACs). The term "active" 
implies that these archives will be the foci for 
intensive scientist interactions with the data, 
especially during periods shortly after instal 
lation of new or upgraded processing algorithms 
when validation and quality control activities 
are particularly important. All EOS investiga 
tors will have electronic network access to the 
active archives through common workstation in 
terfaces and network connections installed at 
their local SCFs. The SCFs will be the sites 
for local quality control of data, generation of 
specialized data products, analysis of EOS data, 
and further development of algorithms and models 
using EOS data. For interdisciplinary investi 
gators working with large-scale global models 
EOS-dedicated supercomputing facilities will be 
made available as required. 
Current plans are to distribute the EOSDIS 
active archives to a limited number of sites at 
which the responsible institutions can provide 
the long-term commitment, satellite data pro 
cessing experience, and science involvement nec 
essary to support the EOS mission. These active 
archives will be networked together as nodes of 
a "virtual" system operating under EOSDIS man 
agement control, with common standards, inter 
faces, and protocols. All users, including non- 
EOS investigators, will be able to obtain com 
plete mission planning and scheduling informa 
tion and information on all data products in the 
EOSDIS archives through the Information 
Management System (IMS). This facility may be 
centralized or distributed in physical implemen 
tation but in either case will provide users 
with the option of a single EOSDIS interface at 
which all information concerning the EOS mission 
may be obtained. The IMS will thus provide 
access to all directories, inventories, browse 
data, documentation, and ordering information 
concerning archived data and products. It is 
particularly important that for each data prod 
uct accessed or ordered the user be able to 
assess the quality of the data, its processing 
history, and its resultant utility for the 
intended investigation, and that the data be de 
livered in a timely manner, with complete docu 
mentation, and on convenient media and format. 
4 OPERATIONS 
4.1 Data Acquisition and Processing 
Data from EOS instruments will be acquired ac 
cording to priorities set by the EOS 
Investigator Working Group (IWG), the EOS 
Program Office, and the Earth Observations 
International Coordination Working Group (E0- 
ICWG). These priorities will be those used by 
EOSDIS in its day to day operations. Long-term 
and short-term operations plans will be devel 
oped which will have some built-in flexibility 
for handling targets of opportunity and other 
short time turnaround requests as scheduling 
priorities and resources allow. All acquired 
data from instruments on the NASA platforms will 
be transmitted to ground via TDRSS. For the 
currently selected instruments, the total com 
bined time-averaged data rate for all NASA polar 
platforms and attached payloads is approximately 
60 Mbps. Thus, including data packaging over 
head and taking into account the TDRSS zone of 
exclusion, the provision of one equivalent TDRSS 
300 Mbps channel will provide adequate margin 
for EOS requirements. 
All NASA instrument data will be processed by 
EOSDIS at least to level one (calibrated instru