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 NASAs 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 1970s 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...