NASA Debris Assessment Software (DAS) version 2.0.2 (19 January 2012)
======================================================================

Version 2.0.2 is an incremental bug-fix release for version 2.0.

Installation
-------------------------------------------
Download and run the new DAS 2.0.2 installer.  By default the new 
version will install over (i.e. replace) the previous version; the user 
may change this default.


Changes and fixes in DAS 2.0.2 (2011-12-01)
-------------------------------------------
1. Fixed a logic error in the ORDEM2000-derived routines that produced 
   incorrect collision risk results for missions that began and/or ended 
   in the second half of a given year.  The error was most obvious in 
   missions with short durations.
2. For collision risk assessments, moved the ORDEM sample date to mid-
   year (except for first and last years) to remove debris flux 
   inconsistencies caused by fractional-year-contribution calculations.
3. Fixed a logic error that caused DAS to skip processing collision risk 
   at altitudes above 2000 km.
4. Fixed a formatting error in the ORDEM2000-derived routines that 
   yielded a bad intermediate file, causing the collision risk 
   assessment to crash at high altitudes.
5. Changed orbit propagator time-step to 2 days.  Different modules were 
   using various time-steps, including small steps that could produce 
   singularities in the calculations.
6. Fixed naming and typographical errors in the list of built-in 
   materials used in reentry survivability calculations, and reordered 
   some lines.
   NOTE:  Old (DAS 2.0.1) projects that use the updated materials will 
          need to be updated with the new material names.
      Old material name       New material name
      ----------------------  ----------------------
      Brass- Munthz           Brass- Muntz
      CU/Be (1.9% Beryllium)  Cu/Be (1.9% Beryllium)
      Mag. AZ31               Magnesium AZ31
      Mag. HK31A              Magnesium HK31A
      Niobium (columbium)     Niobium (Columbium)
      Polymide                Polyamide
      Stainless Steel 304L    Steel AISI 304
      Stainless Steel 347L    Steel AISI 347
      Steel 410               Steel AISI 410
      Uzrh                    Uranium Zirconium Hydride
7. Moved to a new software packager/installer (NSIS) compatible with 
   current Microsoft Windows operating systems (both 32- and 64-bit).
8. Removed an unused input ("Retraction Year") from the GUI for 
   assessment of Requirement 4.8-1.
9. Updated the software User's Guide to reflect the new installation/
   removal procedures, and to clearly state the assumptions of the 
   assessment of tethers (Requirement 4.8-1).
10. Included the current solar flux data file, dated 04 April 2012.


Changes and fixes in DAS 2.0.1 (2008-02-05)
-------------------------------------------
1. Fixed a bug that resulted in incorrect rocket body mass and A/M data 
   being transferred from the Mission Editor to the assessment routines 
   for Requirements 4.7-1 and 4.8-1.
2. Fixed a bug in the material properties of Nickel and mp35n which 
   resulted in an incorrect specific heat (Cp) value in one temperature 
   range.