The Space Interferometry Mission
In this paper we will present selected topics from the SIM science program focusing on some specific astronomical questions to be addressed.
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In this paper we will present selected topics from the SIM science program focusing on some specific astronomical questions to be addressed.
This paper provides an overview of the multidisciplinary integrated modeling methodology for SIM that encompasses the optics, structures, dynamics and control disciplines within a common software environment.
The System Testbed III (STB-3) is the flagship testbed in JPL's Interferometry Technology Program for the Space Interferometry Mission, in which it holds a place as the piece of ground hardware that looks and acts most like the real SIM space system.
The astrometric performance of the Space Interferometry Mission relies on precise measurements of the optical pathlength difference of the starlight through the arms of the interferometers that comprise the SIM instrument, and on precise relative distance between a set of fiducials that define the baselines of the interferometers.
In the course of fulfilling its mandate, the Spectral Calibration Development Unit (SCDU) testbed for SIM-Lite produces copious amounts of raw data. To effectively spend time attempting to understand the science driving the data, the team devised computerized automations to limit the time spent bringing the testbed to a healthy state and commanding it, and instead focus on analyzing the processed results. We developed a multi-layered scripting language that emphasized the scientific experiments we conducted, which drastically shortened our experiment scripts, improved their readability, and all-but-eliminated testbed operator errors. In addition to scientific experiment functions, we also developed a set of automated alignments that bring the testbed up to a well-aligned state with little more than the push of a button. These scripts were written in the scripting language, and in Matlab via an interface library, allowing all members of the team to augment the existing scripting language with complex analysis scripts. To keep track of these results, we created an easily-parseable state log in which we logged both the state of the testbed and relevant metadata. Finally, we designed a distributed processing system that allowed us to farm lengthy analyses to a collection of client computers which reported their results in a central log. Since these logs were parseable, we wrote query scripts that gave us an effortless way to compare results collected under different conditions. This paper serves as a case-study, detailing the motivating requirements for the decisions we made and explaining the implementation process.
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This article is concerned with the discussion of control law design; implementation issues; and the quantification of closed loop performance results obtained in a laboratory experiment.
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SIM-PlanetQuest is a NASA astrophysics mission that is implementing the National Research Counsel's recommended Astrometric Interferometry Mission (AIM) to develop the first, in-space, optical, long-baseline Michelson Stellar Interferometer for performing micro-arcsecond-level astrometry. This level of astrometric precision will enable characterization of planetary systems around nearby stars and enable a number of key investigations in astrophysics including calibration of the cosmological distance scale, stellar and galactic structure and evolution, and dark matter/energy distribution. This paper provides an update on the SIM-PlanetQuest Mission covering the results of the 2005 mission redesign and the recent completion of the last in a series of technology "gates." The SIM-PlanetQuest mission redesign was directed by NASA to recover eroded mass and power margins and to meet specific implementation cost targets. The resulting mission redesign met all redesign objectives with minimal impact to mission science performance. This paper provides the mission redesign objectives and describes the resulting mission and system design including changes in science capability. SIM-PlanetQuest also completed the last of eight major technology development gates that were established in 2001 by NASA, completing the enabling technology development. The technology development program, the last gate, and its significance to the project's flight verification and validation (V&V) approach are briefly described (covered in more detail in a separate paper at this conference). An update on project programmatic status and plans is also provided.
The SIM system testbed III is a full 3-baseline interferometer mounted on a full-scale flexible structure developed at the Jet Propulsion Laboratory under the Interferometry Technology Program.
We developed technique for extracting the phase, visibility and amplitude information as needed for interferometric astrometry with the Space Interferometry Mission.
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We predict the contribution to the on-orbit residual tip-tilt performance due to the reaction wheel disturbance, for different isolater and closed loop optics configurations for the Space Interferometer Mission (SIM).
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