NASA Technical Reports Server (NTRS) 20120006561: Eclipse-Free-Time Assessment Tool for IRIS

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by  NASA Technical Reports Server (NTRS)

of candidate IRIS spacecraft mission or- culate air vehicle stability in a variety of
Data Distribution System bits in an accurate and timely fashion. critical flight conditions. The code is
(DDS) and Solar Dynamic The software is a suite of Fortran subrou- based on fundamental, non-linear equa-
Observatory Ground Station tines and data files organized as a “com- tions of motion and is able to translate
(SDOGS) Integration Manager putational” engine that is used to accu- results into a qualitative, graphical scale
The DDS SDOGS Integration Manager rately predict the long-term orbit useful to the non-expert.
(DSIM) provides translation between na- evolution of IRIS mission orbits while MASCOT was created to provide the
tive control and status formats for systems searching for Earth shadow conditions. conceptual aircraft designer accurate
within DDS and SDOGS, and the ASIST The core algorithms of this software predictions of air vehicle stability and
(Advanced Spacecraft Integration and product have been used to solve a variety control characteristics. The code takes
System Test) control environment of unique orbital mechanics and target- as input mass property data in the form
in the SDO MOC (Solar Dynamics Obser- ing problems. Past applications include of an inertia tensor, aerodynamic load-
vatory Mission Operations Center). lunar shadow requirements for Chan- ing data, and propulsion (i.e. thrust)
This system was created in response for dra, perigee decay of geosynchronous loading data. Using fundamental non-
a need to centralize remote monitor and transfer orbits due to third-body point- linear equations of motion, MASCOT
control of SDO Ground Station equip- mass perturbations, and prediction of or- then calculates vehicle trim and static
ments using ASIST control environment bital lifetime and decay of Earth satellites. stability data for the desired flight condi-
in SDO MOC, and to have configurable This work was done by David Eagle of a.i. tion(s). Available flight conditions in-
table definition for equipment. It pro- solutions Inc. for Kennedy Space Center. For ad- clude six horizontal and six landing rota-
vides translation of status and monitoring ditional information, contact David Eagle at tion conditions with varying options for
information from the native systems into [phone]. KSC-13519 engine out, crosswind, and sideslip, plus
ASIST-readable format to display on three take-off rotation conditions. Re-
pages in the MOC. sults are displayed through a unique
The manager is lightweight, user graphical interface developed to pro-
friendly, and efficient. It allows data trend- Automated and vide the non-stability and control expert
ing, correlation, and storing. It allows Manual Rocket Crater conceptual design engineer a qualitative
using ASIST as common interface for re- Measurement Software scale indicating whether the vehicle has
mote monitor and control of heteroge- An update has been performed to soft- acceptable, marginal, or unacceptable
neous equipments. It also provides fail- ware designed to do very rapid automated static stability characteristics. If desired,
over capability to back up machines. measurements of craters created in sandy the user can also examine the detailed,
This work was done by Kim Pham and substrates by rocket exhaust on liftoff. quantitative results.
Thomas Bialas of Goddard Space Flight Center. The previous software was optimized for This work was done by Sean P. Kenny of
Further information is contained in a TSP pristine lab geometry and lighting condi- Langley Research Center and Luis Crespo of the
(see page 1).GSC-16020-1 tions. This software has been enhanced to National Institute of Aerospace. Further infor-
include a section for manual measure- mation is contained in a TSP (see page 1).
ments of crater parameters; namely, LAR-17483-1
crater depth, crater full width at half max,
Eclipse-Free-Time Assess- and estimated crater volume. The tools
ment Tool for IRIS provide a very rapid method to measure
IRIS_EFT is a scientific simulation that these manual parameters to ease the bur- Patched Conic
can be used to perform an Eclipse-Free- den of analyzing large data sets. Trajectory Code
Time (EFT) assessment of IRIS (Infrared This software allows for rapid quantiza- PatCon code was developed to help
Imaging Surveyor) mission orbits. EFT is tion of the rocket crater parameters where mission designers run trade studies on
defined to be those time intervals longer automated methods may not work. The launch and arrival times for any given
than one day during which the IRIS progress of spreadsheet data is continuously planet. Initially developed in Fortran, the
spacecraft is not in the Earth’s shadow. saved so that data is never lost, and data can required inputs included launch date, ar-
Program IRIS_EFT implements a special be copied to clipboards and pasted to other rival date, and other orbital parameters
perturbation of orbital motion to numeri- software for analysis. The volume estimation of the launch planet and arrival planets at
cally integrate Cowell’s form of the system of a crater is based on the central max depth the given dates. These parameters in-
of differential equations. Shadow condi- axis line, and the polygonal shape of the clude the position of the planets, the ec-
tions are predicted by embedding this in- crater is integrated around that axis. centricity, semi-major axes, argument of
tegrator within Brent’s method for find- This work was done by Philip Metzger of periapsis, ascending node, and inclina-
ing the root of a nonlinear equation. The Kennedy Space Center and Christopher Immer tion of the planets. With these inputs, a
IRIS_EFT software models the effects of of ASRC Aerospace Corp. Further information patched conic approximation is used to
the following types of orbit perturbations is contained in a TSP (see page 1).KSC-13386 determine the trajectory.
on the long-term evolution and shadow The patched conic approximation di-
characteristics of IRIS mission orbits: vides the planetary mission into three
(cid:129) Non-spherical Earth gravity, parts: (1) the departure phase, in which
(cid:129) Atmospheric drag, MATLAB Stability and the two relevant bodies are Earth and the
(cid:129) Point-mass gravity of the Sun, and Control Toolbox Trim and spacecraft, and where the trajectory is a
(cid:129) Point-mass gravity of the Moon. Static Stability Module departure hyperbola with Earth at the
The objective of this effort was to create MATLAB Stability and Control focus; (2) the cruise phase, in which the
an in-house computer program that Toolbox (MASCOT) utilizes geometric, two bodies are the Sun and the spacecraft,
would perform eclipse-free-time analysis aerodynamic, and inertial inputs to cal- and where the trajectory is a transfer el-
18 NASA Tech Briefs, January 2012