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Ionospheric Thermospheric Mesospheric (ITM) Data Evaluation Panel

FINAL REPORT / June 6, 1994

Members and Meetings



1.1 Data Census
1.2 Data Evaluation

2.1 Review the Draft Assessment/Prioritization Guidelines
2.2 Review and Prioritize the List of Restoration Candidate Projects
2.3 Identify Data Sets not Currently Archived
2.4 Review and Prioritize the List of NSSDC-Held Data Sets for NSSDC's Institutional Restoration Activity.
2.5 NARA-Related Request


ITM Data Evaluation Panel - Final Report

Executive Summary

The panel recognizes that in a healthy program, which approaches optimum efficiency in the production of scientific understanding, about 5% of the budget must be devoted to data system design and operations, and data restoration efforts. In future programs the system must be designed to reduce the burden associated with preservation of data following the execution phase of a mission. However, it also remains our objective to make presently inaccessible or deteriorating data sets accessible to the data system that we anticipate constructing. In attempting to establish some priority for restoration and archival efforts, both the state of deterioration of the data and their usefulness to the community must be considered. The availability of geophysical parameters derivable from the data will be of maximum benefit to the largest segment of the community. It is therefore recommended that as much effort be placed into the derivation of such parameters from the data as to their restoration.

In seeking to construct a model by which data restoration efforts should be selected and executed, the panel recommends that proposals for such efforts be accompanied by a sound scientific rationale for the undertaking and a description of the geophysical information to be extracted from the newly restored data. In many cases it may be appropriate to support a pilot program in which the closed-ended task is demonstrated.

In surveying the candidate restoration efforts reviewed by the ITM panel we find that restoration of analog wave data from the ISIS spacecraft would serve as a model by which future efforts could be conducted. In this case the ITM panel recommends that the production of topside F region parameters like peak concentration and scale height would be an integral part of the exercise of converting analog topside ionograms to digital form and subsequent storage to magnetic media.

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Since the first satellites were launched in the late fifties, NASA and the other space agencies have flown a large number of space science missions. The science data collected by these satellite instruments and the scientific knowledge gained from these data constitute the most important investment return for the tax-paying public. Many of these data sets are essential and irreplaceable assets for long-term studies of global change in our solar-terrestrial environment. Media deterioriation and storage limitation have put several of these data sets in imminent danger of being lost permanently.

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1.1 Data Census

In 1990 the General Accounting Office (GAO) criticized NASA for poor data accountability in two GAO reports (IMTEC-90-1: NASA Is Not Properly Safeguarding Valuable Data From Past Missions; IMTEC-90-3: NASA Is Not Properly Archiving All Potentially Valuable Data). Following these reports and the earlier recommendation of the Committee on Data Management and Computation (Selected Issues in Space Science Data Management and Computation, CODMAC, National Research Council, NationalAcademy Press, Washington, D.C., 1988), NASA's Office of Space Science and Application (OSSA) began a major data survey in 1990. The key questions were, What data are where ? and What is their state? The effort was led by the two main NASA archives, the National Space Science Data Center (NSSDC) and the Jet Propulsion Laboratory (JPL). Results of their two-phase approach are summarized in two reports: Margret Johnson, NASA Data Census - Phase 1 Report, JPL, March 1990; Joseph H. King, Report on Phase Two of 1990 OSSA Data Census, NSSDC/WDC-A-R&S Report 91-23, October 1991). Phase one was primarily oriented toward data held at Goddard Space Flight Center, including NSSDC, and at JPL. The final report identifies 294 data sets from 72 spacecraft, including more than 100 very low-level (telemetry-type) data products. In phase two survey packages were sent to 213 scientists (mostly Principal Investigators, PIs) involved in 549 inactive satellite experiments and 106 active experiments. Of the 549 inactive investigations, 167 involved no more archive-desirable data, 37 had more potentially archive-desirable data, while for the remaining 345 there was no response. Starting with the 37 not-yet-archived data sets, NASA-HQ's Space Physics Division (SPD) began compiling a list of data restoration candidate projects. Additional data sets were identified by a 1992 SPD survey of more than 250 space scientists.

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1.2 Data Evaluation

Recognizing the need for community advice and support in identifying, assessing, and prioritizing data restoration projects, the SPD initiated the formation of Data Evaluation Panels in the Spring of 1992. Four panels were established representing the four science branches of SPD: Solar, Magnetospheric, Cosmic and Heliospheric, and ITM. Panel tasks and methods to accomplish these tasks were discussed in several meetings of the panel chairs (or their representatives) with Jim Willett (SPD) and Joe King (NSSDC), resulting in the following panel instructions:

  1. Review the draft assessment/prioritization guidelines. These guidelines were developed by a special sub-committee (on data screening) of the Space Physics Data System (SPDS) Steering Committee.

  2. Review and prioritize the list of restoration candidate projects. The list is based on the 1990 Data Census, on the 1992 SPD Data Survey, and on restoration proposals submitted directly to Jim Willett or the panel chairs. Each panel primarily focuses on its discipline- specific subset but can also comment on data sets that are of interest across disciplines.

  3. Identify data sets not currently archived that hold sufficient scientific potential that follow-up contacts are warranted. NSSDC provided each panel with listings of data sets in the three categories: active, inactive/known status, inactive/unknown status. The "status unknown" listings (see the ITM listing in Appendix B) identify investigations for which, despite various efforts, it is still unknown whether all important data have been archived. The panels are asked to identify those investigations on this list that may hold important unarchived data whose future accessibility would be of great interest to the science community.

  4. Review and prioritize a list of NSSDC-held data sets for NSSDC's institutional restoration activity. NSSDC is restoring data sets from old low-BPI (mostly 7-track) magnetic tapes to 6250-BPI tapes and 3489 tape cartridges (in pairs, backing each other up). A discipline-specific list of mostly large-volume data sets was generated by NSSDC for each panel asking their review and advice on priority.

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The ITM Panel was formed in July of 1992 and met in April of 1993 and in January of 1994 (see page for details). A report on the ITM Panel activities was presented at the SPDS Community Workshop in June 1993 at Rice University in Houston, Texas.

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2.1 Review the Draft Assessment/Prioritization Guidelines

The SPDS Sub-Committee on Data Screening had developed a list of 12 evaluation criteria and a step-by-step guide to the evaluation process (see Appendix A). In a more or less joint effort the panel chairs/representatives established a scorecard based on the earlier SPDS recommendations. As shown in Appendix A, the scorecard contains 25 evaluation criteria pertaining to the scientific value, the technical status and management aspects of the data restoration project. Thesuggested rating ranges from 0 (worst) to 10 (best).

Evaluation of the "scientific value" criteria is the responsibility of the Data Evaluation Panels, the "technical status" criteria are best rated by the proposal provider, and the "management aspects" criteria by the SPD coordinator. This approach is based on the evaluation process suggested by the SPDS committee, but it is much clearer in defining responsibilities and the required steps.

The ITM panel viewed the scorecard approach as quite helpful in prioritizing the data restoration projects. As an enhancement it was suggested to add an overall rating in each of the three categories.

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2.2 Review and Prioritize the List of Restoration Candidate Projects.

The following data restoration proposals were evaluated by the ITM Panel (the name of the requester is given in parentheses):

  1. Digitizing Topside Sounder Ionograms from Alouette 1,2 and ISIS 1,2 (D. Bilitza, Hughes STX)
  2. Restoring Airglow data from OGO 1 to 4 (R.R. Meier, NPL)
  3. Obtain Plasma Parameter from PV-ORPA (W.C. Knudsen, Knudsen Inc., CA)
  4. Archive Visible Airglow Data from AE-C, D, E (P. Hays, U. Michigan)
  5. Rescue data from ISIS telemetry tapes (R. Benson, GSFC)
  6. Convert All-Sky Auroral Conjugate Data to Digital Format (H.C. Stenbaek-Nielsen, U. Alaska Fairbanks)
  7. Save Ion Mass Spectrometer Rocket Data (D. Hunton, AF/PL)
  8. ERBS, Nimbus 7, SAGE, Aerosol Data (McCormick)
  9. Rescue of Prognoz 7,8, and 10 satellite Data (A. Etemadi, U. College London)
  10. ISO Spacelab 1 Data (S.T. Wu, U. Alabama Huntsville)

Discussions centered primarily on three questions:

The scientific value question: Are the data unique? Irreplaceable? Superseded by newer data? Is there still un-mined science? Would there be multiple uses and users for the restored data?

The urgency question: How immediate is the threat of losing the data and/or metadata/expertise? Are there low-cost solutions to extend the deadline to a later date?

The feasibility question: Is it doable? Is the proposed approach the right one? Do the required metadata and expertise still exist?

A reoccuring topic was the more general question at what level data should be archived: raw telemetry, reduced data products, value-added science data. It was noted that NSSDC primarily archives higher level data sets, but that for the more recent ITM missions (AE-C, D, E, DE-1, -2) telemetry will be also archived. Archiving the full, well-documented telemetry data set makes it possible to reprocess science data at a later date when improved data analysis algorithms and techniques are available.

The following sections describe and discuss the 10 data restoration proposals that were received by the ITM Data Evaluation Panel. The overall PRIORITY RATING is based on the scorecard ratings that were established by the panel.

2.2.1. Digitizing Topside Sounder Ionograms from Alouette 1,2 and ISIS 1,2

These swept frequency ionograms exist in analog form on over 12,500 reels of microfilm. Only a few percent of these have been reduced to electron density profiles, and these are stored on over 300 7-track tapes. Hardware and software developed for the new, automated ionosondes (digisondes) by B. Reinisch and his colleagues at the University of Massachussetts at Lowell could be applied to scale and reduce the ionograms. This proposal was withdrawn in favor of the second ISIS proposal, since the use of the ISIS telemetry tapes as proposed in restoration project 2.2.5 would clearly provide a much better way of obtaining digitized topside ionograms

. PRIORITY RATING: withdrawn

CONTACT: D. Bilitza, HSTX/GSFC, (301) 441-4193

2.2.2. Restoring OGO 1-4 Lyman-Alpha and UV Airglow Data

At present NSSDC has 50 books of stripcharts from OGO-4 Lyman-Alpha and UV Airglow, "poorly documented". No digital data are listed in NSSDC's Master Catalog. The panel finds it unlikely that this data source would be heavily used. It is old, the calibration would be uncertain, and the type of data is now (or soon will be) available from other sources (e.g., RAIDS, UARS). Only restoration of the Lyman-Alpha part would be worth pursuing, because of its relevance for long-term studies.


CONTACT: R.R. Meier, NRL, (202) 767-2773

2.2.3. Obtain Plasma Parameter from PV-ORPA
W.C. Knudsen, the PV-ORPA PI is in the process of submitting the data to he Planetary Data System (PDS).


CONTACT: W.C. Knudsen, Knudsen Geoph. Res. Inc., CA, (408) 354-2923

2.2.4. Visible Airglow Data from AE-C, D, E and DE-2

Higher level data products from these experiments are already archived at NSSDC. Recently NSSDC acquired also the AE-C, -D, and -E telemetry and plans to obtain the DE telemetry as well. Archiving of intermediate data products would have to be accompanied with software and documentation for the many kinds of retrieval and inversions that are necessary for a scientific interpretation of these data. Data of this type needs to be handled carefully, since the line-integrals have to be converted to "volumetric measurements" using an inversion technique. Since a data display and analysis system exists at the University of Michigan Ann Arbor, it was recommended that this system should be considered for inclusion in the evolving SPDS.

PRIORITY RATING: Top priority for inclusion of the DE/AE graphical system in SPDS

CONTACT: VAE Data: P. Hays, U. Michigan, (313) 764-7220 Graphical System: T. Killeen, U. Michigan, currently at GSFC

2.2.5. Rescue Data from ISIS Telemetry Tapes and Convert from Analog to Digital Format.

About 100,000 original ISIS 1, 2 telemetry tapes are in danger of being lost permanently, since storage at the Public Archives of Canada can no longer be supported. It is proposed to use "still" existing equipment to read the analog and digital data and to transfer the data to a modern storage media in a digital format. The contents of 150 ISIS telemetry tapes would fit onto one helical-scan tape. The GSFC/Code 500 Tape Testing Facility hastested two sample tapes and found them in good condition. A Statement of Work for this project is included in Appendix C of this report. The panel assigned highest priority to the restoration and digitization of this unique topside data set. The ISIS observations cover more than a solar cycle from 1969 onward. Only about 20% of the telemetry tapes have been processed to produce topside ionograms on microfilm (more than 10 000 reels) and only a few percent are available in digital form. The panel recommends a pilot project with a few hundred tapes selected over the whole mission period. The project should also explore the possibility of using the automatic scaling and conversion software that has been developed for the ground-based ionosonde; this procedure would allow topside electron density profiles to be automatically produced from the ionograms.


CONTACT: R. Benson, GSFC, (301) 286-4037

2.2.6. Convert All-Sky Auroral Conjugate Data to Digital Format

During the period 1967 through 1971, the U. Alaska in cooperation with Los Alamos conducted a series of conjugate auroral flights using two USAF KC-135 jet aircraft flying out of Anchorage, Alaska and Christchurch, New Zealand. Great efforts were made to ensure conjugancy of the two aircraft at all times (using GSFC 12/86 or 10/68 magnetic field model). A total of 18 flights were made for about 60 hours of auroral observations. Primary data are black-and-white all-sky film images taken by a 160-degree field of view lens at 12 frames per minute (about 80,000 images). Resolution is less than 1 km in the central region of the image. First step: Convert all images to a high resolution digital format and transfer all navigation logs to a computer data base. The panel felt that this restoration proposal should be also assessed by the Magnetospheric Panel. The information was forwarded to the Magnetospheric Panel Chair.


CONTACT: H.C. Stenbaek-Nielsen, U. Alaska Fairb. (617) 353-2631

2.2.7. Save Ion Mass Spectrometer Rocket Data

These are data from two dozen rocket flights of R. Narcisi's Ion Mass Spectrometer and Langmuir probes on some of the flights (mid 60 to mid 80). The original strip charts and hand-written tables are at present stored in 8 to 10 boxes at the Air Force Phillips Laboratory in Bedford, Massachusetts. This is a unique set of ion composition data that will not be reproduced. The ITM panel recommends that the feasibility of archiving these unique data be assessed. Don Hunton (PL) suggested that a $5K to $10K effort would be sufficient to save the still accessible part of this data set. A graduate student could, under his supervision, go through the boxes, catalog and document the flight results, and cross-reference with existing publications. He believes that the information required for interpreting the analog stripcharts is already lost. Therefore the effort would concentrate on higher level data products (plots) and the final result could be a report cataloging still existing information about instrumentation and results for all flights.


CONTACT: D. Hunton, AF/PL, (617) 377-4057

2.2.8. ERBS, Nimbus 7, SAGE, Aerosol Data (McCormick)

This is not really an ITM data resource. It belongs to the Earth Sciences Division.

2.2.9. Rescue of Prognoz 7,8, and 10 satellite Data (A. Etemadi, Imperial College London,
Dr. Ata Etemadi and Prof. Oleg Vaisberg (IKI) propose to transfer the data from magnetic tapes to CD-ROM. This involves magnetosheath, solar wind, and bow shock plasma data for the years 1978 (Prognoz 7), 1981 (Prognoz 8), and 1985 (Prognoz 10) with a 2-min time resolution and also Venus plasma and magnetic field data from the Venera 9 and 10 orbiters (1975-76). The proposal was forwarded to the Magnetospheric and Cosmic & Heliospheric Data Evaluation Panels.

2.2.10. ISO Spacelab 1 Data (S.T. Wu, U. Alabama Huntsville)

In his letter to Jim Willett, S.T. Wu notes that the Center for Space Plasma and Aeronomic Research (CSPAR) at the University of Alabama in Huntsville would be a good candidate for inclusion in the Space Physics Data System (SPDS). Their data holdings include besides others data from the Spacelab 1 Imaging Spectrometric Observatory (ISO) and most likely also from the recent ISO flight as part of the Atlas-1 Space Shuttle payload. This proposal had been submitted to the Solar Data Evaluation Panel. It was not included in the present ITM review process. It should be considered by the SPDS ITM discipline team during a future data evaluation cycle.

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2.3 Identify Data Sets not Currently Archived.

Several archive-desirable data sets were identified by the panel:

A systematic assessment of the NSSDC-provided list of inactive/status unknown investigations, however, was not attempted during this review cycle. This task remains to be taken on by the SPDS/ITM team.

Following the lead of the Magnetospheric Panel the ITM Panel participated in efforts to solicit community help in identifying important space physics data that are not yet archived. An AGU/EOS article by the Magnetospheric Panel chair was expanded to include information about all panels and their activities (H. Waite, Rescuing Aging Space Physics Data Sets, American Geophysical Union, EOS Transactions 74, #38, 436, September 21, 1993). The article is reproduced in Appendix D. With help from NSSDC, ITM data listings were prepared and posted on NSSDC's Anonymous FTP site for community review. An example page is shown in Appendix E.

The following satellite experiments were identified by the ITM Panel as having produced important data sets that should be archived.

2.3.1. ESRO-4 Mass Spectrometer and Plasma Measurements.
Al Hedin informed the other panel members that he had in his possession a magnetic tape with all the reduced ESRO-4 mass spectrometer data. He had received this tape some time ago from the PI, Von Zahn (Germany). Von Zahn was contacted by the panel chair, and he agreed to archive the data tape with NSSDC. Data from the Positive-Ion Spectrometer (Raitt, PI) are archived at NSSDC on three magnetic tapes. For the three remaining experiments no data have been archived at NSSDC: Auroral Particle Spectrometer (Hultqvist, PI), Solar Particle Spectrometer (De Jaeger, PI), Solar Particle Spectrometer (Luest, PI).

NEXT ACTION: Contact PIs (only Hultqvist is still active) to get more information for next prioritization cycle.

2.3.2. OGO-6 Visible Optical Data.

Three OGO-6 experiments measured the visible airglow: Airglow and Auroral Emissions, 69-051A-11, 6300 & 3914 ; Line Shape of the 6300 Airglow Emission, 69-051A-14; Sodium Airglow Photometer, 69-051A-26, 5890 & 5896. Blamont (CNES, France) was the PI for the first two and the CoI for the last one. Currently, there are no data from any of these experiments archived at NSSDC.

NEXT ACTION: Contact Blamont to get more background information for next prioritization cycle.

2.3.3. SETA-1 and -2 Atmospheric Density Data

This involves a number of classified Air Force satellites. Of particular interest are the accelerometer data and the orbital decay data. Since these missions were flown more than 10 years ago it was felt that the panel should undertake a new effort to request de-classification of this important data set. This was discussed with Frank Marcos, the principal contact at Phillips Laboratory, who indicated that an official letter from the Panel could help the de-classification process. A letterwas drafted and sent to Marcos.

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2.4 Review and Prioritize the List of NSSDC-Held Data Sets for NSSDC's Institutional Restoration Activity.

The list of NSSDC-held ITM data sets that are potential candidates for NSSDC's restoration program is shown at the end of this section. Since most of these data sets date back to the late sixties and early seventies, additional information about the investigations and data was required for a balanced assessment of these data sets. All necessary information was obtained from NSSDC's Master Catalog (NMC).

The priority assignments given by the panel distinguish between high, medium, and low priority for the restoration candidates. It was also discussed whether any of the data sets should be marked as "restoration not desirable", but there was no agreement on any specific data set.


January 20 1994

Ratings of the ITM panel are indicated in the rightmost colum using the following criteria:

A - Recommended for restoration; high priority.

B - Recommended for restoration; medium priority.

C - Recommended for restoration; low priority.

Volume information indicates the number of magnetic tapes (DD) or restored magnetictapes (DR).

  Spacecraft, Investigation, PI                         NSSDC-Id,
   Data Set Name, Contact,                  Volume         Date(YYMM)         Rating

  ARIEL 3, RF CAPACITANCE PROBE, Sayers                 67-042A-06 
   PLASMA FREQUENCY VALUES, TAPE, Sayers    DD/ 53         6705-6804    -06A	C

  ARIEL 4,LANGMUIR PROBE, Foster                        71-109A-01
   LANGMUIR PROBE DATA, TAPE, Foster        DD/476         7112-7312    -01A    C

  ARIEL 4,VLF/ELF PROPAGATION, Kaiser                   71-109A-03 
   VLF/ELFPROPAG. DATA, TAPE, Foster        DD/476         7312-7312    -03A    C

  AEROS 2, RETARDING POT ANALYZER, Spenner              74-055A-02
   RPA PLASMA MEASURMNT, TAPE, Rawer        DD/5           7407-7509	-02A    A

  ISIS 1,SPHER. ELECTRO. ANALYZER, Sagaly               69-009A-08
   ION TEMP AND DENSITY, TAPE, Sagalyn      DD/4           6901-6911    -08B    A     

  ISIS 2,RETARD. POTEN. ANALYZER,, Maier                71-024A-08
   ION TEMP, CONC OF H,HE,0, Maier          DD/2           7301-7711    -08D    A

  INJUN 5,VLF RECEIVER,30CPS-16KC, Gurnett              68-066B-02
   VLF SIGNAL STRENGTH, TAPE, Brechwal      DD/949         6808-7005    -02A    B

  INJUN 5,SPHERIC.RET.POT.ANAL, Sagalyn                 68-066B-04
   RET. POT. AN. DATA, TAPE, Brechwald      DD/949         6808-7005    -04A    B

  OGO 4,AIRGLOW PHOTOMETER, Reed                        67-073A-12
    AIRGLOW EMISSION INTENSITIES,TAPE, Reed DD/9           6708-6801    -12C    C
    ZONAL AVERAGES, TAPE, Zanner            DD/1           6707-6812	-12K    C
    CALIBRATION DATA, TAPE, Zanner          DD/4           6707-6812    -12M    C
    DIRECTORY DATA, TAPE, Zanner            DD/9           6707-6811    -12N    C
    PHOTOMETER OUTPUT, TAPE, Zanner         DD/11          6708-6801    -12O
                                            DR/2           6708-6801    -12O
    SEC. BY SEC. AIRGLOW DATA, TAPE, Zanner DD/46          6707-6810    -12P
                                            DR/12          6707-6810    -12P
    SYNOPTIC AIRGLOW DATA, TAPE, Zanner     DD/6           6708-6801    -12Q    C

  OGO 5,UV AIRGLOW,1304A AND 1216A, Barth               68-014A-21
   AIRGLOW INTENSITIES (1304A,1216A),Thomas DD/456        6803-7206     -21A    B

  OGO 6,UV PHOTOMTR.1304A+1216A, Barth                  69-051A-13
   AIRGLOW DATA (1304A,1216A), TAPE, Sparks DD/110        6906-700      -13A    A

The following data sets are only of secondary interest to ITM and should be assessed by the responsible data panels (OSO - solar; PIONEER - planetary, PDS)

  OSO 5,ZODIACAL LGT+TERRS.AIRGLOW                      69-006A-07
   ZODIACAL LGT + AIRGLOW, MAG TAPE, Ney    DD/78          6901-7007    -07C

  PIONEER 10,UV PHOTOMETER,200-800A                     72-012A-06
    EUV EDR PHOTON EMISSION DATA, Askew     DD/48          7203-8912    -06A

  PIONEER 11,UV PHOTOMETER,200-800A                     73-019A-06 
   EUV EDR PHOTON EMISSION DATA, Askew      DD/55          7304-891     -06A

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2.5 NARA-Related Request

The National Archives and Records Administration (NARA) started an effort in 1993 to Study the Long-Term Retention of Selected Scientific and Technical Records of the Federal Government. Of the five panels involved in this effort, one is related to Space Science Data. This panel, chaired by Chris Russell (UCLA), had asked the ITM Data Evaluation Panel to identify ITM data sets that are well documented and could be used as test examples for the NARA study.

From:	NCF::BILITZA      "Dieter Bilitza, 301-441-4193"  8-FEB-1994 
To:	SMTP%""
Subj:	ITM Recommendations for NARA study concerning longterm 
retention of scientific data

Dear Prof. Russell,

During the last meeting of our Ionospheric Thermospheric Mesospheric 
(ITM) Data Evaluation Panel on January 12th, Rhiki Sharma 
(NASA-HQ/SAIC) informed us about the activities of the "Space Science Panel 
for the Study on the Long-Term Retention of Selected Scientific and Technical
Records of the Federal Government". He also kindly forwarded your 
requestfor a recommendation from our Panel concerning ITM data set(s) that 
could be used as test example for this study. After discussing a number of
potential candidates the ITM Panel decided to suggest the following 
data sets:

(A) AE-C, -D, -E combined data set

AE-C, 12/16/73 - 12/12/78, 68 degrees, 1973/74: 150 km - 4000 km, 
	1975/76: 300 km, 1977/78: 400 km
AE-D, 10/6/75 - 1/29/76, 90 degrees, 150 km - 4000 km 
AE-E, 11/20/75 - 6/10/81, 20 degrees, 1975/77: 150 km - 3000 km

The three Atmosphere Explorer satellites, operating in complementary 
orbits from the mid-seventies to the early eighties, carried a full 
set of instruments for probing the terrestrial thermosphere and ionosphere 
(14 to 16 instruments; almost identical payload). The data set 
established by these satellites has led to a better understanding of
the thermospheric/ionospheric processes and will serve as the prime
insitu database for years to come. [Into the Thermosphere * The 
Atmosphere Explorers, NASA SP-490, 1987]

The AE-C, -D, and -E data are archived at NSSDC on 134 merged mission 
tapes using the project-specific Unified Abstract (UA) format. 
Recently NSSDC restored the 134 9-track/1600 bpi tapes onto 12 9-track/6250 bpi 
tapes and 3480 tape cartridges. 

(B) An early, if not the first, ITM satellite data set

Vanguard 1, 3/17/58, 650 km - 4010 km, 34 degrees
The satellite carried a radio beacon (PI unknown) but no data were
archived at NSSDC. Atmospheric densities were deduced from the orbital 
drag (Jacchia). Jacchia's results are archived at NSSDC on microfiche.
Please let us know if you would require more detail about these data
sets. Please, also, acknowledge receipt of this message.

Best Regards,

Dieter Bilitza,
ITM Panel Chair  

From:	SMTP%""  9-FEB-1994 04:16:08.55
Subj:	Re:  ITM Recommendations for NARA study concerning longterm 
of scientific data

Thank you. We agree with you on the suitability of this dataset but
we chose others for which we had more recent experience to give as
examples in our report which has been submitted to the executive 
committee. Bill Kurth whom you copied is our representative on the 
executive committee and he may wish to act on your suggestion but
it is now out of my hands. 

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The ITM Data Evaluation Panel feels strongly that one of the most important legacies of the large number of space missions, performed with considerable effort and at great expense, is the quantity of data that were collected, and that maintaining these data in usable condition for future use is imperative. Many of these sets are in immediate danger of being lost, and action is necessary as soon as possible to save them. The NASA-HQ (SMI/SPD) Data Restoration Initiative is a step in the right direction and the ITM Panel unanimously endorses this activity and strongly supports continuation of this effort. During the meetings of April 29, 1993 and January 12, 1994 the ITM Data Evaluation Panel discussed several data restoration candidate projects and decided to make the following recommendations. All of these items were considered to be of top priority for ITM action:

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April 29, 1993, at GSFC, Greenbelt

January 12, 1994, at Hughes STX, Greenbelt

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