Further Reentry Analysis

0100-EX-PL-2012 Text Documents

Planet Labs Inc

2012-07-17ELS_127618

Cosmogia  Tech  Note   Satellite  Reentry  Survivability  Analysis       Prepared  By:  James  Mason     The   Dove   1,   2,   3   and   4   Orbital   Debris   Assessment   Reports   include   an   analysis   using   NASA's   DAS   2.0   software   of   the   risk   of   casualties   on   the   ground   due   to   atmospheric   reentry.   While   the   risk   of   casualties   was   always   found   to   be   compliant   with   NASA-­‐STD-­‐8719.14,   DAS   did   suggest   a   small   probability   that   our   optical   tube   assembly   (OTA)   would   reach   the   ground.   We   therefore   chose   to   perform   higher   fidelity   analysis  to  better  quantify  this  risk.  Very  few  analysis  tools  exist  to  model  the  physics  of  reentry,  so  we   chose  to  work  with  the  NASA   Debris  Program  Office   who  maintains  The  Object  Reentry  Survival  Analysis   Tool  (ORSAT).  From  the  ORSAT  website:     "The   ORSAT   code   uses   integrated   trajectory,   atmospheric,   aerodynamic,   aerothermodynamic,   and   thermal/ablation   models   to   perform   a   complete   satellite   or   launch   vehicle   upper   stage   component  analysis  in  determining  the  impact  risk"  More  details  on  ORSAT's  methodology  and   capabilities  can  be  found  online  (http://www.orbitaldebris.jsc.nasa.gov/reentry/orsat.html).   Typically   this   tool   is   only   used   after   DAS   has   deemed   re-­‐entry   risks   as   non-­‐compliant,   however   we   requested  that  ORSAT  be  used  for  our  Invar  OTA.  The  dimensions  and  a  drawing  of  the  tube  assembly   were  provided  to  Nicholas  Johnson  of  the  debris  office  and  he  confirmed,  via  email:     From: Johnson, Nicholas L. (JSC-KX111) <nicholas.l.johnson@nasa.gov> Date: Tue, Jul 10, 2012 at 8:32 AM Subject: RE: ORSAT/SCARAB To: James Mason <james@cosmogia.com> Mr.  Mason,   We  have  assessed  the  survivability  of  both  the  Invar  tube  and  its  end  plate.    We  determine  with  high   confidence  that  both  elements  will  in  fact  demise,  i.e.,  not  reach  the  surface  of  the  Earth  following  reentry.   Let  me  know  if  we  can  be  of  any  further  assistance.   Best  regards,   Nicholas  L.  Johnson NASA Upon  asking  for  further  details  of  the  analysis  results,  Mr.  Johnson  instructed  us  to  refer  any  questions   to  him  and  the  NASA  Debris  Program  Office.   Contact   Nicholas  L.  Johnson   Chief  Scientist,  Orbital  Debris   Email:  Email:  nicholas.l.johnson@nasa.gov   Fax:  281-­‐483-­‐5276  


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Document Modified: 0630-11-06 00:00:00
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