The laser interferometer space antenna (LISA) mission uses laser interferometry to detect and observe gravitational waves from astrophysical sources. Modelling of LISA ultimately needs to forecast and interrelate the behaviour of the science input, structure, optics, control systems and many other factors that affect the performance of the flight hardware. These models include high precision STOP (structural-thermal-optical) analyses. In addition, self-gravity analyses of the spacecraft, based on the structural-thermal modelling results, are required for each analysis cycle to understand the gravitational interaction between the spacecraft components. The complete analysis cycle is called STOP-G. Several aspects of this analysis require unprecedented precision due to LISA's challenging design requirements. We present here a modelling approach designed to minimize analysis errors, particularly those that enter when mapping results from one modelling step to the next. Central to the approach is the use of a single model topology for all phases of the STOP-G analysis cycle. The feasibility of this approach was verified using a simplified model of the LISA spacecraft.

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The Laser Interferometer Space Antenna (LISA) mission, a space-based gravitational wave detector, uses laser metrology to measure distance fluctuations between proof masses aboard three sciencecraft. The total acceleration disturbance to each proof mass is required to be below 3 × 10−15 m s−2 Hz−1/2 at 0.1 mHz. Self-gravity noise due to sciencecraft distortion and motion is expected to be a significant contributor to the acceleration noise budget. To minimize these effects, the gravitational field at each proof mass must be kept as small, flat and constant as possible. It is estimated that the static (non-fluctuating) self-gravity acceleration must be kept below 5 × 10−10 m s−2 with a gradient below 3 × 10−8 s−2 in order to meet the required noise levels. Most likely it will not be possible to directly verify that the LISA sciencecraft meets these requirements by measurements; they must be verified by models. The LISA integrated modelling team developed a new self-gravity tool that calculates the gravitational forces and moments on the proof masses to aid in the design and verification of the LISA sciencecraft. We present here an overview of the tool and the latest self-gravity results calculated using the current baseline design of LISA.

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A new formula for the limiting force to be used in dual control vibration testing is explored by use of a simple but general-purpose example. The results of the force formula are compared with the exact solution and found to be in excellent agreement. Extrapolation from random vibration to sine sweep testing is included.