37 research outputs found
NASA's Gravitational - Wave Mission Concept Study
With the conclusion of the NASA/ESA partnership on the Laser Interferometer Space Antenna (LISA) Project, NASA initiated a study to explore mission concepts that will accomplish some or all of the LISA science objectives at lower cost. The Gravitational-Wave Mission Concept Study consisted of a public Request for Information (RFI), a Core Team of NASA engineers and scientists, a Community Science Team, a Science Task Force, and an open workshop. The RFI yielded were 12 mission concepts, 3 instrument concepts and 2 technologies. The responses ranged from concepts that eliminated the drag-free test mass of LISA to concepts that replace the test mass with an atom interferometer. The Core Team reviewed the noise budgets and sensitivity curves, the payload and spacecraft designs and requirements, orbits and trajectories and technical readiness and risk. The Science Task Force assessed the science performance by calculating the horizons. the detection rates and the accuracy of astrophysical parameter estimation for massive black hole mergers, stellar-mass compact objects inspiraling into central engines. and close compact binary systems. Three mission concepts have been studied by Team-X, JPL's concurrent design facility. to define a conceptual design evaluate kt,y performance parameters. assess risk and estimate cost and schedule. The Study results are summarized
Das Quantenlimit in der Interferometrie
[no abstract
Gravitational-wave Mission Study
In November 2013, ESA selected the science theme, the "Gravitational Universe," for its third large mission opportunity, known as L3, under its Cosmic Vision Programme. The planned launch date is 2034. ESA is considering a 20% participation by an international partner, and NASA's Astrophysics Division has indicated an interest in participating. We have studied the design consequences of a NASA contribution, evaluated the science benefits and identified the technology requirements for hardware that could be delivered by NASA. The European community proposed a strawman mission concept, called eLISA, having two measurement arms, derived from the well studied LISA (Laser Interferometer Space Antenna) concept. The US community is promoting a mission concept known as SGO Mid (Space-based Gravitational-wave Observatory Mid-sized), a three arm LISA-like concept. If NASA were to partner with ESA, the eLISA concept could be transformed to SGO Mid by the addition of a third arm, augmenting science, reducing risk and reducing non-recurring engineering costs. The characteristics of the mission concepts and the relative science performance of eLISA, SGO Mid and LISA are described. Note that all results are based on models, methods and assumptions used in NASA studie
Real-time phasefront detector for heterodyne interferometers
We present a real-time differential phasefront detector sensitive to better
than 3 mrad rms, which corresponds to a precision of about 500 pm. This
detector performs a spatially resolving measurement of the phasefront of a
heterodyne interferometer, with heterodyne frequencies up to approximately 10
kHz. This instrument was developed as part of the research for the LISA
Technology Package (LTP) interferometer, and will assist in the manufacture of
its flight model. Due to the advantages this instrument offers, it also has
general applications in optical metrology
Space-Based Gravitational-Wave Observatory (SGO) Mission Concept Study
The LISA Mission Concept has been under study for over two decades as a space-based gravitational-wave detector capable of observing astrophysical sources in the 0.0001 to 1 Hz band. The concept has consistently received strong recommendations from various review panels based on the expected science, most recently from the US Astr02010 Decadal Review. Budget constraints have led both the US and European Space agencies to search for lower cost options. We report results from the US effort to explore the tradeoffs between mission cost and science return
Plans for a Next Generation Space-Based Gravitational-Wave Observatory (NGO)
The European Space Agency (ESA) is currently in the process of selecting a mission for the Cosmic Visions Program. A space-based gravitational wave observatory in the low-frequency band (0.0001 - 1 Hz) of the gravitational wave spectrum is one of the leading contenders. This low frequency band has a rich spectrum of astrophysical sources, and the LISA concept has been the key mission to cover this science for over twenty years. Tight budgets have recently forced ESA to consider a reformulation of the LISA mission concept that wi" allow the Cosmic Visions Program to proceed on schedule either with the US as a minority participant, or independently of the US altogether. We report on the status of these reformulation efforts
Breadboard model of the LISA phasemeter
An elegant breadboard model of the LISA phasemeter is currently under
development by a Danish-German consortium. The breadboard is build in the frame
of an ESA technology development activity to demonstrate the feasibility and
readiness of the LISA metrology baseline architecture. This article gives an
overview about the breadboard design and its components, including the
distribution of key functionalities.Comment: 5 pages, 3 figures, published in ASP Conference Series, Vol. 467, 9th
LISA Symposium (2012), pp 271-27
Readout for intersatellite laser interferometry: Measuring low frequency phase fluctuations of HF signals with microradian precision
Precision phase readout of optical beat note signals is one of the core
techniques required for intersatellite laser interferometry. Future space based
gravitational wave detectors like eLISA require such a readout over a wide
range of MHz frequencies, due to orbit induced Doppler shifts, with a precision
in the order of at frequencies between
and . In this paper, we present phase
readout systems, so-called phasemeters, that are able to achieve such
precisions and we discuss various means that have been employed to reduce noise
in the analogue circuit domain and during digitisation. We also discuss the
influence of some non-linear noise sources in the analogue domain of such
phasemeters. And finally, we present the performance that was achieved during
testing of the elegant breadboard model of the LISA phasemeter, that was
developed in the scope of an ESA technology development activity.Comment: submitted to Review of Scientific Instruments on April 30th 201
Data series subtraction with unknown and unmodeled background noise
LISA Pathfinder (LPF), ESA's precursor mission to a gravitational wave
observatory, will measure the degree to which two test-masses can be put into
free-fall, aiming to demonstrate a residual relative acceleration with a power
spectral density (PSD) below 30 fm/s/Hz around 1 mHz. In LPF data
analysis, the measured relative acceleration data series must be fit to other
various measured time series data. This fitting is required in different
experiments, from system identification of the test mass and satellite dynamics
to the subtraction of noise contributions from measured known disturbances. In
all cases, the background noise, described by the PSD of the fit residuals, is
expected to be coloured, requiring that we perform such fits in the frequency
domain. This PSD is unknown {\it a priori}, and a high accuracy estimate of
this residual acceleration noise is an essential output of our analysis. In
this paper we present a fitting method based on Bayesian parameter estimation
with an unknown frequency-dependent background noise. The method uses noise
marginalisation in connection with averaged Welch's periodograms to achieve
unbiased parameter estimation, together with a consistent, non-parametric
estimate of the residual PSD. Additionally, we find that the method is
equivalent to some implementations of iteratively re-weighted least-squares
fitting. We have tested the method both on simulated data of known PSD, and to
analyze differential acceleration from several experiments with the LISA
Pathfinder end-to-end mission simulator.Comment: To appear Phys. Rev. D90 August 201