The on-line interactive systems of the National Space Science Data Center (NSSDC) are examined. The worldwide computer network connections that allow access to NSSDC users are outlined. The services offered by the NSSDC new technology on-line systems are presented, including the IUE request system, Total Ozone Mapping Spectrometer (TOMS) data, and data sets on astrophysics, atmospheric science, land sciences, and space plasma physics. Plans for future increases in the NSSDC data holdings are considered

Green, James L.

English

NASA Technical Reports Server

N60-2S  3
The New Space and Earth
Science Information Systems
at NASA's Archive
JAMES L. GREEN*
The National Space Science Data Center (NSSDC), established in 1967, serves as a long-
term archive and distribution center for data obtained on NASA space science flight
investigations and provides a variety of services to enhance the overall scientific return
from NAS/gs initial investment in these missions. NASA science data at the NSSDC cover
the disciplines of astrophysics, Earth science, planetary physics, and space plasma physics.
Over 6,000 gigabytes of digital data (125,000 magnetic tapes) and 91 miUion feet of film
products from NASA science missions have been acquired by the NSSDC since it was
established in 1967 _.To handle the requests for both digital and film products, the NSSDC
has a variety of computer systems, both interactive and batch; dedicated photo laboratory
facilities; large online database management machines; and optical mass storage devices.
It also manages NAS_s largest computer-to-computer wide area network.
Based on current agreements concerning furore NASA missions, the NSSDC data holdings
will increase dramatically, nearly doubling every 2 years, reaching nearly 40D00 gigabytes
by 1995. Innovative ways of managing the information about such large volumes of data
and implementation of large mass storage systems are necessary to provide users with better
archive access while the NSSDC effectively manages the ever-increasing volumes of data
that are coming into the archive a.
With the ease of electronic access dramatically increasing over the last few years, the
NSSDC has created a major new thrust by developing online computer information systems
accessible to remote users 24 hours a day. Currently, not all the information about the
NSSDC archive is accessible to remote users, and less than 2 percent of the NSSDC's
total digital data archive is online 3, but these systems are already a major achievement in
providing rapid access to NASA-acquired science data that is unprecedented in archive data
management.
*Directall correspondence to: James L Green, NASAGoddard Space Flight Center,Code 6302, Greenbelt,
Maryland 20771.
Government Information Quarterly, Volume 7, Number 2, pages 141-147.
ISSN: 0740-624X.
https://ntrs.nasa.gov/search.jsp?R=19900019127 2020-03-19T21:44:58+00:00Z
142 GOVERNMENT INFORMATION QUARTERLY Vol. 7/No. 2/'1990
This article focusses on the new NSSDC online interactive systems that are used exten-
sively over international computer networks. These systems are typical of how NSSDC
is responding to user demands for rapid access to archived data.
WORLDWIDE NETWORK CONNECTIONS
Many computer network connections have been made to provide remote access to the
NSSDC by all its diverse users. Figure 1 shows a breakdown of the major network connec-
tions by communication protocol. The Bitnet connection supports only mail communica-
tion among many universities in the United States and NSSDC. Selected science computer
network nodes worldwide and the general public primarily use the X.25 international packet
networks to gain access to the data center. There are two major wide-area NASA networks
that are used extensively by NSSDC: The Space Physics Analysis Network (SPAN)4 and
the NASA Science Network (NSN). SPAN contains more than 2,800 nodes in the United
States and is internetworked with more than 10,000 nodes in the United States, Europe,
Canada, and Japan (through other networks such as HEPNET). SPAN is managed by
NSSDC and used exclusively by space and Earth scientists working primarily on NASA-
related missions and projects.
BITNET
I
• NSN
• NSFNET NSSDC • SPAN
• ARPANET • EUROPEAN SPAN
HEPNET
• MANY OTHERS : EUROPEAN HEPNET
I • MANY OTHERS
X.25 (INTERNATIONAL)
• GTE/TELENET
• TRANSPAC
• DATEXP
• DATAPAC
• MANY OTHERS
Figure I. The wide-area networkaccess to the NSSDC. NSSDC manages the SPAN computer
network, which supports many connections to other wide-area DECnet networks such as
HEPNET. Another major NASA network is the NSN, which provides TCP/IP connectivity to many
other computer networks and the NSSDC. The Bitnet connection supports only mail
communication between many universities in the United States and NSSDC. Selected science
nodes throughout the world, in addition to the general public, use the X.25 international
packet networks primarily to gain access to the data center.
NSN (which uses the TCP/IP protocol) is internetworked with other wide-area networks,
such as ARPANET and the NSFnet, and can reach many thousands of computers, pri-
marily at universities. In general, these wide-area networks are of relatively low speed
but are providing a tremendously valuable service for remote users to gain access to NASA
computer resources and to communicate with fellow researchers across the country.
The New Spaceand EarthScienceInformation 143
The bulk of the wide-area network traffic is for informational purposes such as remote
logon and mail; however, data transfer (in limited amount) is also supported. The wide-
area networks provide the pathways for remote users to access the NSSDC facilities at any
time, day or night 5.
"NEW TECHNOLOGY" DATA AND INFORMATION SYSTEMS
The NSSDC is responding to an ever-increasing number of user requests by putting more
of the data and information about the data in its archive online for direct user access. With
the ease of electronic access dramatically increasing over the last few years, the NSSDC's
new online computer information systems can now be accessible to remote users 24 hours
a day. This allows the NSSDC to "remain open" past normal working hours, providing
scientists and students the ability to "browse" through the online information to look for
an important data set.
The new online data and information systems currently operational at the NSSDC are
shown in Table 1. These systems have been a tremendous success, handling more than 2,500
accesses by remote users annually and growing rapidly. The systems shown in Table 1 pro-
vide a variety of services, depending on the desires of the community of scientists they
serve. The online systems provide information about data holdings, with several levels of
complexity. For instance, the Master Directory (MD) contains a high-level overview of
data held in the NSSDC and at a number of other NASA centers, established U.S. science
research institutions, and other U.S. government agencies such as the National
Oceanographic and Atmospheric Administration (NOAA) and the U.S. Geological Survey
(USGS). The MD, therefore, is the first reference system to point to where the data are
held e. More detailed information about data holdings, such as the processing history, quality,
time resolution, etc., must be found in the other data systems, such as NASA Climate Data
System (NCDS), to which the MD will refer a user.
The online information systems MD, personnel data base, Total Ozone Mapping Spec-
trometer (TOMS) data, Solar Wind data (OMNI), and the International Ultraviolet Ex-
plorer (1UE) request system are all accessible from one computer account called the NSSDC
Online Data and Information System (NODIS). The interactive traffic to the NODIS account
over the last year is shown in Figure 2. Since 1987, many new systems have been added
to the NODIS account. Figure 2 shows the tremendous popularity of the NODIS system,
with the average user accessing NODIS more than twice a month.
Another important example of the ready access to the data in the NSSDC archive is the
IUE Interactive Request System. This system allows scientists to order observations taken
by the 1UE spacecraft.
The IUE Interactive Request System became operational in November 1987 through the
NODIS account. The request system 7 consists of a large online mass storage device, menu-
driven interactive information access software, a high-speed local-area network connec-
ting the online storage with the interactive front ends, and the wide-area networks access
to the system.
Rapid access to selected data has been frequently requested by scientists. Since it is not
known ahead of time what sections of any one data set will be requested, the NSSDC loaded
all the IUE data into the NASA Space and Earth Science Computer Center's IBM 3850
Mass Store in order to better accommodate the large user demand through faster request
144 GOVERNMENT INFORMATION QUARTERLY Vol. 7/No. 2/1990
Table 1. NSSDC New Technology Online Systems.
SCIENCE DISCIPLINE SERVICE INFORMATION DATA*
All
Astrophysics
Atmospheric Science
Land Sciences
Space Plasma Physics
General
Master Directory X
IUE Request System
ROSAT Information Management System
Astronomy Catalog System
STARCAT with SIMBAD access
NASA Climate Data System
Ozone TOMS Data
Crustal Dynamics
Pilot Land Data System
Central Online Data Directory
Omni Solar Wind Data System
Plasma and Field Models
Coordinated Data Analysis Workshop
SPAN-Network Information Center
Personnel database
X Xt
X
X X
X X
X X
X X
X X
X
X
X X
X Xtt
X X
NOTES:
* Only partial data sets are available
t All available data is on line
tl" Only software is being distributed
and delivery response. It is important to note that the NSSDC typically manages its archive
offline. Storing all the IUE data online was done with full IUE Project cooperation to gain
valuable experience with highly requested online data sets. The IUE data that are currently
online consist of over 70,000 unique star images and spectra and total approximately 90
gigabytes in volume.
The IUE interactive request system software runs on the NSSDC VAX computers, which
allow for a remote SPAN user to log on and order IUE data from the electronic IUE Merged
Observer Log.
Once the exact data segment requested has been identified, the NSSDC request coordinator
networks the IUE data from the Mass Store system. For requesters desiring a small number
of spectra, the NSSDC request coordinator can network the data through SPAN to the target
computer of the requesting individual within approximately 24 hours or create a magnetic
tape to be mailed. Requests for IUE data sent on magnetic tape are handled easily by this
system. Requests for IUE data also come to the NSSDC through letters and phone calls
(not all users are on computer networks).
The New Spaceand EarthScience Information 145
Figure 3 shows the yearly number of IUE images requested by individuals from 1979
to 1989. NSSDC also sends large amounts of IUE data to other archives; these requests
are not included in this figure. The solid colored bars in Figure 3 show the number of
images sent out on magnetic tape to individual requestors; the size of the cross-hatched
bar represents the average monthly number of IUE images that have been networked to
remote users using SPAN. From 1979 to nearly the end of 1987 the only service the NSSDC
offered was an offline service in which a tape copy of the data was produced and sent to
the requester. The bar graph also shows the yearly number of IUE images requested in
1988 and 1989.
1200
1000 I
80O
600i
400 ,
o /
Jan- Feb Mar Apr
89
May June July Aug Sept Oct Nov Dec Jan-
90
[] CZCS
[] IUE
[] Canop
[] Model
[] Requ
[] OMNI
[] NIMB
[] PIMS
IIM:)
Figure 2. Interactive traffic from remote users, accessing several key NSSDC systems.
Using the NODIS System, number of sessions (open circles) and users (filled-in points)
is plotted against time. The dramatic increase seen after April 1989 results from several
Information Systems becoming operational. It is important to note that the average
number of accesses by scientists is more than twice per month.
Figure 3 also shows the dramatic increase in the amount of IUE data requested in 1988
and 1989, reaching approximately 3500 images and spectra a year. The computer networks
were used to deliver, about 38 percent of the data, in 1988, and 60 percent of the data
in 1989, while the remainder, are satisfied by sending magnetic tapes. Currently, the trend
in the use of the IUE Interactive Request System, as well as all the other systems shown
in Table 1, continues to climb.
The networked IUE images satisfied requests from many scientists at 15 institutions in
the United States, Europe, and Canada (locations serviced by SPAN). In addition, care
is taken to use SPAN for networking of the IUE data at times of non-peak network usage.
Tests are currently under way in which some IUE data are compressed before being
146 GOVERNMENTINFORMATIONQUARTERLYVol. 7/1'4o.2/1990
networked to the user's remote computer and are then decompressed, therefore reducing
the communication load on the wide-area network.
4000
35O0
3000
E 2500
_'_ 2000
E
1000
Z
500
0
1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989
Year
Tape Images
SPAN Images
Figure 3. Number of IUE images requested (per year) since the archive was opened
in 1979. Although the IUE Interactive Request System became operational in November
1987, it was not until January 1988 that remote users routinely accessed the new in-
teractive system. The huge increase in the number of images distributed in 1988 and
1989 can be attributed to the better service that is now provided electronically. The
cross-hatched bar in 1988 shows that nearly 40 percent of all images requested are
delivered over computer networks. In 1989 it was 60 percent.
The request results for 1.988and 1989 (Figure 3) clearly show that the tremendous increase
in requested data results from the convenience the interactive request system provides to
the user. The following factors are a major part of the user convenience provided by the
IUE Interactive Request System:
* immediate ordering of needed spectra/images;
• rapid turnaround providing the desired data while the scientists are interested;
• data loaded to the target system (no tape handling);
• data arriving in the desired format; and
• no need to send replacement tape to the NSSDC (currently the SPAN and NSN net-
works are a "free" service to users).
The New Space and Earth Science Information 147
The IUE example is typical of all the interactive data and information systems that allow
NSSDC to disseminate as much information as possible in a timely manner.
FUTURE INFORMATION SYSTEM ACTIVITIES
Based on current agreements concerning future NASA missions, the NSSDC data holdings
will increase dramatically, approximately doubling every 2 years, reaching nearly 40,000
gigabytes by 1995. This is a staggering amount of data. Within the next year, the Hubble
Space Telescope (HST) will be launched and will produce approximately 2,500 gigabytes
(2.5 terabytes) of data per year. HST is a new type of mission for NASA; it is being designed
as a "nearly permanent" observatory in space (lasting at least 15 years) and is one of NASA's
several Great Observatories in space. Because of the huge amounts of data and the impor-
tance of the mission to the astrophysics community, the Space Telescope Institute in
Baltimore, Md., has been created to be responsible for the science mission management
and data archiving for the HST. It plans to make all HST data readily available through
an online data archive.
The ability to electronically access and query the contents of a remote archive is of tremen-
dous importance, greatly facilitating research in the space and Earth science fields. These
online information systems must continue to grow in capability and complexity in order
to accommodate the huge data volumes NSSDS expects to manage in the near future. It
is clear, from examples like the Master Directory and IUE Interactive Request System,
that online interactive information and data retrieval systems do provide a better service
to the science research community than the offline letter requests for highly requested data
sets.
Through the new online information systems, the NSSDC is striving to support active
archive research on the individual scientist level at any time of day or night convenient
to the researcher. The NSSDC will continue to aggressively pursue the "electronification"
of its information about data and, to the extent reasonable, its archived data 8. Much of the
new data coming into NSSDC will be managed by the online interactive systems, but much
more work remains to be done with the existing archived data.
NOTES AND REFERENCES
1. Jmlaes L. Green, "NSSDC Data Holdings: Scope, Complexity, and Future Requirements," in Proceedings
of the Workshop on Geophysical lnformatics, Viniti Publishing House, Moscow, 1990.
2. Joseph King, "Mass Storage Technologies for NASA's Future Data Environment," in Proceedings of the
Workshop on Geophysical lnformatics, Viniti Publishing House, Moscow, 1990.
3. James L. Green, "The NSSDC Information Systems: Status and Plans," in Proceedings of the Workshop
on Geophysical lnformatics, Viniti Publishing House, Moscow, 1990.
4. James L. Green, "The Space Physics Analysis Network," Computer Physics Communications, 49 (1988):
205-213.
5. James L. Green, "NSSDC Applications for Computer Networking," in Proceedings of the Workshop on
Geophysical lnformatics, Viniti Publishing House, Moscow, 1990.
6. Joseph King, "Data Finding in a Distributed International Environment," in Proceedings of the Workshop
on Geophysical Informatics, Viniti Publishing House, Moscow, 1990.
Z Charleen M. Perry, "The National Space Science Data Center and International Ultraviolet Explorer:
1978#Present, "' in Decade of UVAstronomy with the IUE Satellite, ESA Special Publication (ESA SP-281)
Vol. 2: 357-360, June 1988.
8. James L. Green (editor), The National Space Science Data Center: Users Guide, NSSDC Technical Publica-
tion, (January 1989).



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