POST2 version 3.1.7D dated March 02, 2016 is available for distribution and is for government use only.
2006 NASA Software of the Year Runner-Up
POST2 version 1.1.8D is still available for distribution and is for government use only.
Contact Scott Striepe for more information.
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Ascent, Click for larger Image
Separation (Multiple Vehicles)
Separation, Click for larger Image
Orbital Transfer, Click for larger Image
Orbital Transfer
Atmosphere Entry, Click for larger Image Atmosphere Entry
Multibody Terminal Descent, Click for larger Image Multibody Terminal Descent
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Shuttle Image
Space Shuttle
Hyper-X, Click for larger Image Hyper-X
MER, Click for larger Image Mars Exploration Rover
Odyssey, Click for larger Image
Mars Odyssey
Star Dust, Click for larger Image
Enhancement and modification of the code is available, contact Scott Striepe to discuss funding options.

POST2 Title Image

Latest Version: POST2 version 3.1.7D dated March 02, 2016

Version 3.1.1D of the Program to Optimize Simulated Trajectories II (POST2) is now available. This version has several upgrades and improvements based on feedback from users and assessment by developers. Over time, computational resource changes have resulted in adjustments needed in POST2 to better utilize current computer hardware capabilities and maintain compatibility with newer operating systems. The software was modified to support a 64-bit architecture as well as adjusted the structures to be only C-based and thus removing the reliance on aligning C and FORTRAN structures, often a significant issue in the previously released version.

Several other enhancements have been included in this release. All tables are automatically "cloned" when a new vehicle is created from another (previously these tables had to be input again to reset the independent variable to the new vehicle). A milestone can be read by POST2 on any platform independent of the platform's binary byte ordering (Endianess) used to create it. Critical program variables, such as event criteria, event trigger values, event derivatives, print block output and virtually all mnemonic data in the program may now be integers. Vehicle attitude can be initialized using three new quaternion options (inertial to body, body to G-frame, and inertial to navigation frame). Additive table biases are now available to augment the previous table multiplier capability. Other changes are noted in the updated user's manual.

The Program to Optimize Simulated Trajectories II (POST2) is a generalized point mass, discrete parameter targeting and optimization program. POST2 provides the capability to target and optimize point mass trajectories for multiple powered or unpowered vehicles near an arbitrary rotating, oblate planet. POST2 has been used successfully to solve a wide variety of atmospheric ascent and entry problems, as well as exatmospheric orbital transfer problems. The generality of the program is evidenced by its multiple phase simulation capability which features generalized planet and vehicle models. This flexible simulation capability is augmented by an efficient discrete parameter optimization capability that includes equality and inequality constraints. POST2 supports NASA’s Strategic Goal to expand the frontiers of knowledge, capability, and opportunity in space by directly contributing to expanding our human and robotic presence into the solar system and to the surface of Mars as well as other planetary bodies. Read more ...

POST2 was developed from the original POST software starting in 1995. POST development began in the early 1970’s in partnership with the Martin Marietta Co. as a space shuttle simulation program. Throughout the years, many models and capabilities have been added to POST; the program has been significantly improved with additional capabilities added in the area of vehicle modeling, trajectory simulation, and targeting and optimization. Three and Six degree-of-freedom (3- and 6-DOF) versions of POST that can optimize and target ascent, entry, and orbital trajectories have been available since the early 1980's. POST has become an industry standard trajectory simulation and optimization tool that has been transferred to hundreds of organizations in government, industry, and academia. Read more...

*To check the status of your POST2 request,
please contact Software Release Office.*

POST2 has been compiled and run on the following operating system: SGI, SUN, PC-Linux, PC-WINDOWS, MAC OSX, and HP-UX.
For current information, please contact Scott Striepe.

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Last Updated: 9/08/2016