1 ---- ~---------- ~ /-~- ·. .-,;.. / ' / ,/.. ~~-·I '..:; ~ .. • ~ ... !" .. _. •• I tVi fJ.._Q - ' - ?'1. k.' ' pt; 4 s;;;:;c? . -- .... ~·j~ . ' ; ti?0--'7~' NATIONAL AERONAUTICS AND SPACE ADMINISTRATION .....,... --1---- --- ---- -------~~- -- ~ '+ ' '(NASA-TM-X-628SU) ANALYSIS OF APOLLO 12 N72-73~78 ~ - LIGHTNING INCIDENT h. Godfrey, et al (N.\SA) Feb. 197~ 87 p Unclas ' . CC/99 34130 ! - ----~~--- --- --- ANALYSIS OF APOLLO 12 LIGHTNING INCIDENT ~----- -~ PREPARED BY MARSHALL SPACE FLIGHT CENTER KENNEDY SPACE CENTER ,-- ' MANNED SPACECRAFT CENTER .. '· - ---- --- --- ----·--- --· FEBRUARY 1970 r ---· --- NATIONAL TE~CHNICAL IEJ'IOD4IGID n I ~~cFJCE -IWIBI,YA. ~ !A -----~-- ' -\-dl-,"-''\- ~ ----------- - -- -- ----~- MSC-01540 ANALYSIS OF APOLLO 12 LIGHTNING INCIDENT PREPARED BY Marshall Space Flight Center Kennedy Space Center Manned Spacecraft Center ~ R. Godfrey Manager, Saturn Program Marshall Space Flight Center E. R. Mathews Manager, Apollo Program Kennedy Space Center APPROVED BY Rocco A. Petrone Apollo Director Progr~ NATIONAL AERONAUTICS AND SPACE ADMINISTRATION January 1970 ii TABLE OF CONTENTS Section Page PREFACE iv SUMMARY 1 INI'RODUCTION 2 LIGHTNING PHarOGRAPHS 3 A'IMOSPHERIC ENVIRONMENT . 12 EFFECTS ON SPACE VEHICLE 18 Spacecraft 18 Launch Vehicle 23 Latmch Complex 24 CAUSE OF DISCHARGES . 25 Electrostatic Discharge Theory . . • . 25 Vehicle-Triggered Lightning Theory 26 FLORIDA METEOROLOGICAL CONDITIONS ASSOCIATED WITH ELECTRIFIED CLOUDS • • • • . • • . • • • . . • 29 Effects of Atmospheric Conditions on Launch Window 30 Criteria 31 VEHICLE DESIGN CONSIDERATIONS . 37 Spacecraft 37 Launch Vehicle 42 Launch Complex 44 CONCLUSIOliS • • • • • 48 . . . . . . . . IDRRECTIVE ACTIO!f 50 REFERENCES AND BIBLIOGRAPHY . 51 iii Section Page APPENDIX A -- LIGHTNING AND RELATED INSTRUMENTATION . . . . . A-1 APPENDIX B -- EXPLORATION OF SOME HAZARDS TO NAVAL EQUIPMENT AND OPERATIONS BENEATH ELECTRIFIED CLOUDS B-1 APPENDIX C -- CIRCUIT ANALYSIS C-1 Automatic Abort System Circuit Analysis . C-1 Ordnance Circuit Analysis ...... . C-2 • PREFACE Appreciation is extended to the following personnel for their exper tise and help in the understanding of the Apollo 12 lightning incident at the special December meeting of the American Geophysical Union in San California. Francisco~ Dr. Louis J. Batten Dr. J. D. Robb Institute of Atmospheric Physics Lightning and Transients Research University of Arizona Institute Dr. S. C. Coroniti Dr. J. D. Sartor Panametrics, Inc. Laboratory for Atmospheric Sciences National Center for Atmospheric Research Dr. George A. Dawson Dr. E. L. Schuman Institute of Atmospheric Physics Research Laboratories University of Arizona Environmental Science Services Administration Dr. Hans Dolezalek Dr. William Scott Atmospheric Sciences Program Department of Atmospheric Sciences Office of Naval Research University of Washington Department of the Navy Dr. H. W. Kasemir Dr. Martin A. Uman Research Laboratories Research and Development Center Environmental Science Services Westinghouse Electric Corporation Administration Dr. L. B. Loeb Dr. B. Vonnegut Department of Physics Department of Atmospheric Science University of California, Berkeley State University of New York at Albany Dr. Forrest Mozer Dr. William P. Winn Space Sciences Laboratory Laboratory for Atmospheric University of California, Sciences Berkeley National Center for Atmospheric Research Dr. M. M. Newman Lightning and Transients Research Institute To other participants of this meeting, a special thanks is given for their analytical contributions and consultations which were gracious ly offered during the analysis of the phenomena associated with the light ning incident. Dr. Marx Brook Dr. E. Philip Krider New Mexico Institute of Mining NASA-NRC Resident Research Associate and Technology Manned Spacecraft Center Dr. Arthur A. Few Mr. Charles B. Moore Department of Space Science New Mexico Institute of Mining Rice University and Technology Dr. Donald R. Fitzgerald Dr. Richard E. Orville Air Force Cambridge Research Department of Atmospheric Science Laboratories State University of New York at Albany Dr. G. Freier Dr. E. T. Pierce School of Physics Staff Scientist University of Minnesota Stanford Research Institute y ·-· 1 SUMMARY The Apollo 12 space vehicle was launched on November 14, 1969, at 11:22 a.m. e.s.t. from launch complex 39A at Kennedy Space Center, Florida. At 36.5 seconds and again at 52 seconds, a major electrical distl.lrbance was caused by lightning. As a result, many temporary effects were noted in both the launch vehicle and spacecraft. Some permanent effects were noted in the spacecraft and involved the loss of nine non-essential in strumentation sensors. All noted effects were associated with solid-state circuits, which are the most susceptible to the effects of a discharge. Analysis shows that lightning can be triggered by the presence of the long electrical length created by the space vehicle and its exhaust plume in an electric field which would not otherwise have produced nat ural lightning. Electric fields with sufficient charge for triggered lightning can be expected to contain weather conditions such as the clouds associated with the cold front through which the Apollo 12 vehicle was launched. The possibility that the Apollo vehicle might trigger lightning had not been considered previously. The Apollo space vehicle design is such that a small risk of trig gered lightning is acceptable. In accepting this minimal risk for future flights, launch rule restrictions have been imposed with respect to opera tions in weather conditions associated with potentially hazardous elec tric fields. 2 INTRODUCTION Before the Apollo 12 flight, the only consideration of the effects of lightning on the space vehicle was for the period prior to flight. The methods and procedures used to cope with possible lightning prior to launch have been in existence since the inception of the launch complex. The possibility of the vehicle becoming involved with lightning after lift-off was not a launch consideration, unless natural lightning activ ity was actually present in the launch complex area. This report discusses the significant elements of the lightning in cident during the Apollo 12 launch. The report is addressed to what hap pened and why, and what meteorological conditions could produce lightning with the presence of the launch vehicle. This report also recommends action for minimizing the possibility of creating a similar incident on future Apollo flights. An assessment of the spacecraft and launch vehi cle electrical design to determine the effects of lightning is included. The investigative results represent the combined efforts of the ap propriate personnel at the Manned Spacecraft Center, the Marshall Space Flight Center, and the Kennedy Space Center. The primary contributions to the understanding of the physics associated with the incident and of how to apply the present knowledge of atmospheric electricity to the Apollo Program have been provided by recognized experts in the field. A number of authorities on atmospheric electricity have enthusiastically and voluntarily provided consultation and literature in this area.