Abstract. This paper presents a quantitative assessment of the performance of the upcoming LISA Pathfinder geodesic explorer mission. The findings are based on the results of extensive ground testing and simulation campaigns using flight hardware and flight control and operations algorithms. The results show that, for the central experiment of measuring the stray differential acceleration between the LISA test masses, LISA Pathfinder will be able to verify the overall acceleration noise to within a factor two of the LISA requirement at 1 mHz and within a factor 6 at 0.1 mHz. We also discuss the key elements of the physical model of disturbances, coming from LISA Pathfinder and ground measurement, that will guarantee the LISA performance.

We present results from the first directed search for nontensorial gravitational waves. While general relativity allows for tensorial (plus and cross) modes only, a generic metric theory may, in principle, predict waves with up to six different polarizations. This analysis is sensitive to continuous signals of scalar, vector, or tensor polarizations, and does not rely on any specific theory of gravity. After searching data from the first observation run of the advanced LIGO detectors for signals at twice the rotational frequency of 200 known pulsars, we find no evidence of gravitational waves of any polarization. We report the first upper limits for scalar and vector strains, finding values comparable in magnitude to previously published limits for tensor strain. Our results may be translated into constraints on specific alternative theories of gravity.

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LISA Pathfinder, the second of the European Space Agency's Small Missions for Advanced Research in Technology (SMART), is a dedicated technology demonstrator for the joint ESA/NASA Laser Interferometer Space Antenna (LISA) mission. The technologies required for LISA are many and extremely challenging. This coupled with the fact that some flight hardware cannot be fully tested on ground due to Earth-induced noise led to the implementation of the LISA Pathfinder mission to test the critical LISA technologies in a flight environment. LISA Pathfinder essentially mimics one arm of the LISA constellation by shrinking the 5 million kilometre armlength down to a few tens of centimetres, giving up the sensitivity to gravitational waves, but keeping the measurement technology: the distance between the two test masses is measured using a laser interferometric technique similar to one aspect of the LISA interferometry system. The scientific objective of the LISA Pathfinder mission consists then of the first in-flight test of low frequency gravitational wave detection metrology. LISA Pathfinder is due to be launched in 2013 on-board a dedicated small launch vehicle (VEGA). After a series of apogee raising manoeuvres using an expendable propulsion module, LISA Pathfinder will enter a transfer orbit towards the first Sun-Earth Lagrange point (L1). After separation from the propulsion module, the LPF spacecraft will be stabilized using the micro-Newton thrusters, entering a 500 000 km by 800 000 km Lissajous orbit around L1. Science results will be available approximately 2 months after launch.

Preparations for the LISA Pathfinder mission have reached an exciting stage. Tests of the engineering model (EM) of the optical metrology system (OMS) have recently been completed at the Albert Einstein Institute, Hannover, and flight model (FM) tests are now underway. Significantly, they represent the first complete integration and testing of the space-qualified hardware and are the first tests on an optical system level. The results and test procedures of these campaigns will be utilised directly in the ground-based flight hardware tests, and subsequently during in-flight operations. In addition, they allow valuable testing of the data analysis methods using the MATLAB based LTP data analysis (LTPDA) toolbox. This paper presents an overview of the results from the EM test campaign that was successfully completed in December 2009.