NASA Technical Reports Server (NTRS) 20120004207: Summary of 2011 Direct and Nearby Lightning Strikes to Launch Complex 39B, Kennedy Space Center, Florida

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by  NASA Technical Reports Server (NTRS)

31.. InternationClI Conference on
Lightning Protection
2nJ- 7th September 2012 - Vienna, Austria
ICLP 2012
SUMMARY OF 2011 DIRECT AND NEARBY LIGHTNING STRIKES TO
LAUNCH COMPLEX 39B, KENNEDY SPACE CENTER, FLORIDA
C.T. Mata, A.G. Mata
ESC, Kennedy SpaceCenter, Florida, USA.
E-mail: [email protected], angel.g.mata(@,nasa.gov
increase the LC39B lightning instrumentation triggering
ABSTRACT
thresholds and reduce the number of flashes detected to
A Lightning Protection System (LPS) was designed and built those ofinterest only (strikes to either LC39A or LC39B).
at Launch Complex 39B (LC39B), at the Kennedy Space This trigger signal from LC39A to LC39B was left in place
Center (KSC), Florida in 2009. This LPS was instrumented even after Atlantis launched in July 8, 2011. The lightning
with comprehensive meteorological and lightning data
instrumentation system at LC39B helped determine the
acquisition systems that were deployed from late 2010 until
location ofstrikes nearby LC39A during somestorms prior
mid 2011. The first direct strikes to the LPS were recorded in
to launch and even astrikewithin the LC39A perimeterthe
March of2011, when a limited number ofsensors had been
day before launch, preventing a potential launch scrub that
activated. The lightning instrumentation system detected a
total of70 nearbystrokes and 19 direct strokes to the LPS, 2 would have delayed the mission and resulted in additional
of the 19 direct strokes to the LPS had two simultaneous costs.
ground attachment points (in both instances one channel
terminated on the LPS and the other on the nearby ground).
Additionally,there are more unaccounted nearbystrokesseen 2 INSTRUMENTATION OVERVIEWAND SETUP
on video records for which limited data was acquired either
The LC39B LPS and its instrumentation are described in
due to the distance of the stroke or the settings of the data
acquisition system. Instrumentation deployment chronological detail in [I] and [2], respectively. The LPS can be seen as
milestones, a summary of lightning strikes (direct and two independent, but synchronized, data acquisition
nearby), high speed video frames, downconductor currents, systems, Lightning and Weather [3] both running 24/7. In
and dH/dt and dE/dt typicalwaveforms for direct and nearhy general, the LPS consists of a catenary wire system (at
strokesare presented. about 181 meters above ground level) with nine
downconductors connected to ground, supported by three
INTRODUCTION
insulators installed atop three towers in a triangular
The installation of the lightning instrumentation system configuration. Field sensors' signals are digitized and
at Launch Complex 39B (LC39B) started in March 2011 transmitted, via fiber optics, to centralized transient
and was completed in May 2011. The triggering thresholds recorders located in the Pad Termination Connection Room
were adjusted based on previous Camp Blanding testing (PTCR). All the LPS instrumentation, including the
u ing the same instrumentation to detect strikes within the digitizers, transient recorders, and computers, are battery
LC39B perimeter and nearby strikes (close to the pad) as backed up.
predicted dH/dt and dE/dt. During the previous to last
Shuttle Launch (ST -134) the triggering thresholds ofthe 2.1 Lightning Instrumentation
system were reduced in an attempt to detect potential This is an event driven, 100 MS/s sampling system,
lightning strikes at Launch Complex 39A (LC39A), where
which includes six synchronized high-speed video cameras
Endeavor was being prepared to launch. The thresholds
installed atop each ofthe three towers (two per tower) and
were lowered since Endeavour rolled out (March 102011)
until shortly after launch (May 16, 2011). A few storms one remote high-speed video camera installed about five
passed through the area and many images ofnearby strikes kilometers southwest of LC39B (temporarily installed in
were captured with some limited number of waveforms the firing room I of the Launch Control Center (LCe)
with usable data were acquired. ote that the dynamic pending final installation atop the Vehicle Assembly
range of the measurements were not changed so the
Building (VAB». Current sensors installed at ground level
majority ofthe waveforms for nearby strikes had very poor
oneach ofthe ninedownconductorsofthe LPS; four dH/dt,
resolution. Shortly before the roll out of the last Space
3-axis measurement stations; and five dE/dt stations
Shuttlemission(Atlantis, STS-13S, May 312011), atrigger
signal from LC39A was fed into the LC39B lightning composed of two antennas each. The electromagnetic
instrumentation system (June 21, 2011), in an attempt sensors are all installed at ground level with elevations
ranging from 5.9 to 7.4 meters height referred to the North All(9)downconductorsinstrumentation,
American Vertical Datum of 1988 (NAVD88). All these towers 2& 3meteorologicalstationsand2 Mar. 2011
(outof6)hil!hsneedvideocamerasactive
signals are recorded using three synchronized transient
Mar.30Ul&
recorders(HBM GENESIS 16t). Firstandlastnearbylightningstrike Oct. 10'h
recorded
(2011)
The trigger signal for the LC39B LPS instrumentation Mar.3Ilh&
Firstandlastdirectlightningstrike th
system comes from any of the thirty one ground level Aug. 14
recorded
sensors (9 downconductor currents, 12 dH/dt, 10 dE/dt), (20II)
additionally a TTL signal from the LC39A lightning 4(outof6)highspeedcameraandall(12) Apr. 20II
magnetic fieldmeasurementsactive
instrumentationsystem is provided. Aftera qualified trigger
All (6) high speed video cameras and all
is received, the signal of all the ground level sensors is May2011
recorded on a 30 ms time window with 50% pre-trigger (10)electricfieldmeasurementsI active
Meteorological datashownonaTV,
sampling at 100 MS/s. Additionally, the seven high speed
additional triggersignal from LC39Aand
video cameras record up to 455 frames with 312.5us June2011
additional (temporary)highspeedvideo
exposure (up to 142.1ms of video at 3,200fps) with a camerainLCC
resolution of 1280x800, also with 50% pre-trigger. The I (outof2)rainstationsactive Aug. 2011
VAB camera, overlooking both LC39A and LC39B has All (2)rainstationsactive Sep.2011
twice the memory and twice the sampling rate as the
camerasatLC39B, while maintainingtheresolution andthe
acquisition window. This camera is expected to be 4 ACQUIRED DATA, LIGHTNING
operational in February2012.
TheLightningDAQ wasactive from mid-Marchof20II.
2.2 Meteorological Instrumentation
10-------....
This meteorological instrumentation is a 24/7, 1 sample/s,
8.1'------.-..1-1
system, which provides air temperature, relative humidity,
wind direction and wind speed at four different altitudes
(40.2,78.3, 116.4 and 139.3 meters), on each of the four
levels (A, B, C, and D) of the three LC39B lightning
protection towers. Also, the meteorological instrumentation
has two rain gauges (at ground level) that measure rain oStormDays
precipitation and accumulation, adding to a total of 26 .Single-RS
oMultiple-RS
weathersensors(24 distributed amongthe four levelsofthe
threetowers and2atground level).
From March to October20II:
The Meteorological data is displayed on the internal KSC
The Lightning DAQ hastriggeredon 16differentdays
TV system, showing the one-minute running average ofall
a) Direct:The LPS has been struckdirectly by 8
the measurements in addition to the maximum wind gust
lightning flashes (all towers havebeenstruck):
and wind direction over the last minute. Additionally, the
th a. 5 flashes attachedtothetowers
meteorological data will be transmitted to the 45 Weather
Squadron (CCAFS, Florida) to support weather related b. 3 flashes attachedtothe catenarywires or
launchdecisions. downconductors
c. 3single-strokeflashes
3 CHRONOLOGICALMILESTONES
d. 5multi-stroke flashes (max. 8RS; min.
The data acquisition capability ofthe LPS at LC39B has 2RS)
been incrementally increasing after itsconstruction. Table I e. Onlyonemulti-stroke(3RS) flash hadall
shown remarkablemilestones worth noting.
subsequent RS terminatingatthesame
locationasthefirst RS
Table1: LPSchronologicalmilestones.
b) Closenearby(withinthe LC39B perimeterfence):
Time Therehavebeen3nearby lightningstrikeswithin
Action
(year) the LC39B perimeter
ConceptualDesign 2007 a. 1striketotheperimeter fence (multi
Construction 2008-2009
stroke flash, 4 RS)
InstrumentationEnclosurefabrication,
2010
testingandinstallation
DAQinstalled Jan. 2011
All(8)Tower Imeteorologicalstations I From May until July there were some electric field
active Feb. 2011 measurements trOUbleshooting, so, partial (or no) dE/dt
measurementswouldbeavailablefor this period.
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b. 2insidethe perimeter(single-stroke 4.22 NearbyLightningStrokes
flashes)
c) NearbyTheLPS wassubjectto40 nearby(only)
lightning flashes:
a. 2nearbystrikeshappenedsimultaneously
with directstrikes
b. 26single-stroke flashes
c. 14 multi-strokeflashes (max. 6RS; min. 2
RS)
d. Xtriggered by LC39A; Ytriggers by
LC39A with noevidenceoflightning
e. Nearbychannelswith multiple
termination points?
Figure3. NearbystrikesoutheastofTower2ofthe
There have been2lightningstrikes with twosimultaneous LC39Blightning protection system.
groundattachmentpoints(seeFigure 1),tower2and
4.3 Selected High SpeedVideocamera data
nearb (outsidethe LC39B perimeterfence).
5 CONCLUSIONS
After lessthan oneyearofdeployment, thenew lightning
instrumentation system at LC39B has shown significant
improvements over the previous lightning instrumentation
system used at KSC. The instrumentation system has
proven to be reliable and very accurate, acquiring a series
ofastonishing images and set ofwaveforms for typical and
unusual lightning strikes. There is an increased interest to
potentially deploy similar systems throughout KSC and the
Cape Canaveral Air Force Station, in which case there may
be a comprehensive an integrated lightning observation
Figure 1.Striketo Tower2oftheLC39B Lightning system with synchronized lightning instrumentation overan
Protection System with twosimultaneousattachment areaofseveral squaremiles.
points,one toTower2and theotherto the ground
6 REFERENCES
southeastofLC39B,justoutsidethe padfence.
[I] C.T. Mata,V.A. Rakov,"Evaluationoflightningincidenceto
elements ofa complex structure: a Monte Carlo approach,"
4.1 Statistics International Conference on Grounding and Earthing & 3rd
International Conference on Lightning Physics and Effects
4.2 SelectedWaveforms (Ground 2008; 3rd LPE), Florianopolis, Brazil, November
2008
4.2.1 DirectLightningStrokes [2] C.T. Mata, V.A Rakov, T. Bonilla, A.G. Mata, E. Navedo,
G.P. Snyder, "A new comprehensive lightning
instrumentation system for PAD 39B at the Kennedy Space
Center, Florida" International Conference on Lightning
Protection20I0,Cagliari, Italy,September20IO.
[3] CT Mata, A.G. Mata, VA Rakov, "A New Lightning
Instrumentation for Pad 39B at the Kennedy Space Center,
Florida, Oral Presentation, American Meteorological Society
91 Annual Meeting,Seattle,USA,January20II.
Sl
Figure2. DirectlightningstriketoTower2ofthe
LC39Blightningprotectionsystem.
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