DOCUMENTS: Reference

The path to LISA has involved numerous concepts, proposals, recommendations, and requests for information. Collected here are some of the key documents that have led to the current incarnation of LISA. These reports describe decisions and recommendations made by a wide community of gravitational wave scientists and technlologists, and represent the consensus of much of the space-based gravitational wave detection community. (Note that many of these links lead to external websites where the documents are archived.)

2024 LISA Definition Study Report
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This definition study report, or Red Book, presents a summary of the very large body of work that has been undertaken on the LISA mission over the LISA definition phase.


Unlocking the mHz gravitational wave band is the objective of the LISA (Laser Interferometer Space Antenna) space mission as proposed by the LISA Consortium in 2017. The LISA mission is an international collaboration between ESA, its member states, and NASA. It will consist of three identical spacecraft forming a near equilateral triangle that exchange laser beams over the 2.5x106 km long arms. LISA will use precision laser interferometry to compare separations between test masses that are protected by the spacecraft from non-gravitational disturbances. LISA will coherently measure spacetime strain variations as a function of time, including frequency, phase, and polarization, forming a continuous, all-sky observatory sensitive to all sources simultaneously. LISA’s science objectives cover a wide range of outstanding questions in astrophysics, fundamental physics and cosmology questions such as “What are the fundamental laws of the Universe?” and “How did the Universe originate and of what is it made?”.

2020 Pathways to Discovery in Astronomy and Astrophysics for the 2020s
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This is the final report of the 2020 US Decadal Survey of Astronomy and Astrophysics. (See here for a list of LISA-focused whitepapers submitted to the committee.) The report emphasizes that "NASA should work with the European Space Agency to ensure" that LISA "achieves the full scientific capability envisioned" by the 2010 Decadal Survey report.


This report of the Committee for a Decadal Survey on Astronomy and Astrophysics 2020 (Astro2020) proposes a broad, integrated plan for space- and ground-based astronomy and astrophysics for the decade 2023-2032 It also lays the foundations for further advances in the following decade. This is the seventh in a sequence of decadal survey studies in this field from the National Academies of Sciences, Engineering, and Medicine. This survey examines the program of record, providing advice on the major projects from prior surveys that are yet to be completed. It also lays out priorities for future investments driven by scientific opportunities. The recommendations in this report advance foundational activities that support the people who drive innovation and discovery, and that promote the technologies and tools needed to carry out the science. The report also recommends sustaining activities on a broad range of cost and timescales, as well as activities that enable future visionary projects by maturing them scientifically and technically. Finally, the recommendations set in motion the construction of frontier facilities that will change the view and understanding of the cosmos. The survey is bounded by plausible budget scenarios based on briefings from the sponsoring agencies—the National Aeronautics and Space Administration (NASA), the National Science Foundation (NSF), and the Department of Energy (DOE). Within these bounds, the survey aims high, reflecting this time of great scientific promise and progress, with opportunities to pursue some of the most compelling scientific quests of our times.

2020 Empowering LISA Discovery: NLST Science Support Taskforce Report
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The US NASA LISA Study Team was charged to discuss the kind of data LISA can provide to scientists and the community, and to analyze the impact that various levels of access, latency, and user support have on the ability of the US community to maximize the discovery potential of the ESA-led LISA mission.


The NASA LISA Study Team (NLST) has been tasked by NASA to study how NASA might support US scientists to participate in the scientific exploitation of LISA data, and how US scientists might participate in the science ground segment and access LISA data through public release. At the time of this report, the LISA Project at ESA is in the middle of Phase A, early in formulation. In this document, the NLST has taken the current understanding of these components of the mission and extrapolated to a projected ground segment, data products and data analyses in order to represent what a future LISA user community might experience. Of necessity, those projections are incomplete and speculative, and should not be construed as final or agreed upon by ESA, the LISA Consortium, or NASA.

With that caveat, the report arrived at the following general findings:

  • A broad spectrum of US researchers are expected to want access to LISA data products, and only about half of those are willing to join a Consortium for access.
  • Those researchers will carry out a broad spectrum of research, dependent on the extent of NASA’s support.
  • Pre-cursor science will prepare the community and enhance the research return.
  • The novel nature of the instrument and the data will stimulate many researchers to seek access to deep levels of data. The most demanding science depends on deep access, from pre-launch testing to the earliest phases of the data processing.
  • Prompt, public release of data products, with suitable support, will increase the scientific productivity of the mission through increased participation and diverse thinking.
  • Coordination with electromagnetic observatories, particle detectors and ground-based gravitational-wave interferometers will be essential to the production and scientific utilization of LISA data products, most notably through low-latency alerts.
  • A fuller array of tools, documentation and resources will expedite the research of US scientists.
  • The US research community would benefit from maximal, expeditious access to LISA data products and from participation at all levels of data analysis – from the earliest data products to catalogs.
  • The most pressing activities are: studying and simulating the data analysis process, familiarizing and training non-GW researchers to work with LISA data, cultivating early-career researchers and precursor science, formulating the US LISA ground segment, and engaging in the deepest details of instrument design, analysis and testing to the greatest extent possible.
  • The science productivity of a facility-class mission is greatly enhanced by a full-featured science center and an open access data model. US Science Center could facilitate entry into LISA science by; serving as a portal for the US community to access LISA data products, supporting independent processing pipelines, facilitating astrophysics and fundamental research, providing an interface into the subtleties of the instrument, training new users, and expanding the research community. An early adoption model may be especially important for a novel mission like LISA.
2018 LISA Science Requirements Document
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The SciRD documents the formal science requirements for the LISA mission. Requirements on the mission, spacecraft, instrumentation, and operations are derived from this document. It was developed by the ESA LISA Science Study Team during the first stages of the LISA formulation process.


LISA is a space mission designed to measure gravitational radiation over a broad band at low frequencies, from about 0.1 mHz to 0.1 Hz, a band where the universe is richly populated by strong sources of gravitational waves. It will measure signals from a wide range of different sources that are of strong interest to the astrophysics of black hole and galaxy formation, to tests of general relativity and to cosmology: massive black holes mergers at all redshifts; extreme mass ratio inspirals; the inspiral of stellar-origin black hole binaries; known binary compact stars and stellar remnants; and probably other sources, possibly including relics of the extremely early Universe, which are as yet unknown.

2017 LISA Mission Proposal
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This document proposed LISA as a mission to fulfill the Gravitational Universe science theme, which was previously selected by ESA as the theme for the 3rd large mission in ESA's Cosmic Vision Programme.


Over the coming years, as the sensitivity of ground-based detectors improves, we will see the growth of a rich and productive Gravitational Wave astronomy. New sources with small mass will be discovered in the low redshift Universe. Already the first observation of Gravitational Waves brought a surprise, because the existence of such heavy stellar-origin binary black holes was not widely expected. But the low-frequency window below one Hertz will probably never be accessible from the ground. It is in this window that we expect to observe the heaviest and most diverse objects. Opening a gravitational window on the Universe in the low-frequency regime with the space-based detector LISA will let us go further than any alternative. These low-frequency waves let us peer deep into the formation of the first seed black holes, exploring redshifts larger than z~20 prior to the epoch of cosmic reionisation, and examining systems of black holes with masses ranging from a few M⊙ to 108 M⊙. Exquisite and unprecedented measurements of black hole masses and spins will make it possible to trace the history of black holes across all stages of galaxy evolution, and at the same time test the General-Relativistic nature of black holes through detailed study of the amplitude and phase of the waveforms of Gravitational Wave strain. LISA will be the first ever mission to study the entire Universe with Gravitational Waves.

2016 New Worlds, New Horizons : A Midterm Assessment
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This is a mid-decade assessment of progress in implementing the recommendations of the 2010 US Decadal Survey of Astronomy and Astrophysics. It includes a finding that the US participate as a "strong technical and scientific partner" in an ESA-led LISA mission


New Worlds, New Horizons in Astronomy and Astrophysics (NWNH), the report of the 2010 decadal survey of astronomy and astrophysics, put forward a vision for a decade of transformative exploration at the frontiers of astrophysics. This vision included mapping the first stars and galaxies as they emerge from the collapse of dark matter and cold clumps of hydrogen, finding new worlds in a startlingly diverse population of extrasolar planets, and exploiting the vastness and extreme conditions of the universe to reveal new information about the fundamental laws of nature. NWNH outlined a compelling program for understanding the cosmic order and for opening new fields of inquiry through the discovery areas of gravitational waves, time-domain astronomy, and habitable planets. Many of these discoveries are likely to be enabled by cyber-discovery and the power of mathematics, physics, and imagination. To help realize this vision, NWNH recommended a suite of innovative and powerful facilities, along with balanced, strong support for the scientific community engaged in theory, data analysis, technology development, and measurements with existing and new instrumentation. Already in the first half of the decade, scientists and teams of scientists working with these cutting-edge instruments and with new capabilities in data collection and analysis have made spectacular discoveries that advance the NWNH vision.

2016 Final Report Gravitational Observatory Advisory Team
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This is the final report of an ESA advisory body that considered various options for implementing the Gravitational Universe science theme and produced findings on science capability and technical readiness.


As a result of its meetings, the analysis of requested inputs, and much detailed scientific and technical work by the gravitational wave community, the Gravitational Observatory Advisory Team (GOAT) can report to the ESA Executive in summary as follows:

  • an L3 mission in gravitational waves is technically feasible, with laser interferometry between free-falling test masses as a well-established technical baseline;
  • the scientific potential of a space mission in gravitational wave astronomy is compelling, and made more so by the recent Advanced-LIGO results;
  • the technical and scientific knowledge base now residing in Europe as a result of LISA Pathfinder argues for the timely implementation of a gravitational wave observatory under European leadership.

2016 NASA L3 Study Team Interim Report
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This is an interim report from a NASA study team that considered various technology contributions to an ESA-led gravitational wave mission. A primary finding was that US contribution of payload elements would help provide insight into the final mission design.


The L3 Study Team (L3ST), with support of the Technology Assessment Group (TAG) and the Physics of the Cosmos (PCOS) Program study office, was charged as part of their Phase 1 activities to provide an analysis of potential US hardware contributions to the ESA-led L3 Gravitational Wave mission and an assessment of their consequences on cost, risk, and science return. In this interim report, we provide a preliminary assessment focusing on the major instrument subsystems that the US is best-positioned to provide. We expect and encourage that the establishment of roles and responsibilities will steadily evolve and that further input beyond what is contained in this report will be required.
In addition to our assessment of particular candidate contributions, we highlight the following general findings:

  • The science case for a space-based GW observatory, endorsed by both the 2010 Decadal Survey and ESA’s 2013 Cosmic Visions process, remains compelling. Realizing a mission that fully delivers this science in a timely fashion and with low risk should be the primary objective of US participation in L3.
  • The L3ST concurs with the ESA’s GOAT report that meaningful participation of the US community in the design, development, and operation of L3 will result in a mission that is more technically robust and more scientifically capable.
  • US contribution of central elements of the payload is an effective way to enable meaningful participation and provide impact on, and insight into, the final flight design.
  • The US has strengths in a broad range of technologies relevant to L3. Opportunities should be sought to employ all of these strengths in the partnership regardless of the specific hardware items delivered.

A conclusion of our analysis is that multiple viable options of US participation in L3 exist, each with a different mix of cost, risk, and impact. While it is likely that the US will only contribute a subset of these items to the final partnership, continuing some level of development across the entire portfolio is an effective strategy to reduce overall mission risk as well as provide additional insight to the US science and technology communities.

2013 The Gravitational Universe
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This document proposed the gravitational wave astronomy in the millihertz band (accessible only from space) as a science theme for large-class missions in ESA's Cosmic Visions Programme


The last century has seen enormous progress in our understanding of the Universe. We know the life cycles of stars, the structure of galaxies, the remnants of the big bang, and have a general understanding of how the Universe evolved. We have come remarkably far using electromagnetic radiation as our tool for observing the Universe. However, gravity is the engine behind many of the processes in the Universe, and much of its action is dark. Opening a gravitational window on the Universe will let us go further than any alternative. Gravity has its own messenger: Gravitational waves, ripples in the fabric of spacetime. They travel essentially undisturbed and let us peer deep into the formation of the first seed black holes, exploring redshifts as large as z~20, prior to the epoch of cosmic re-ionisation. Exquisite and unprecedented measurements of black hole masses and spins will make it possible to trace the history of black holes across all stages of galaxy evolution, and at the same time constrain any deviation from the Kerr metric of General Relativity. eLISA will be the first ever mission to study the entire Universe with gravitational waves. eLISA is an all-sky monitor and will offer a wide view of a dynamic cosmos using gravitational waves as new and unique messengers to unveil !e Gravitational Universe. It provides the closest ever view of the early processes at TeV energies, has guaranteed sources in the form of verification binaries in the Milky Way, and can probe the entire Universe, from its smallest scales around singularities and black holes, all the way to cosmological dimensions.

2011 Final Report Gravitational-Wave Mission Concept Study
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This is the final report of a NASA-sponsored analysis team that looked into alternative concepts for addressing LISA science goals after the dissolution of the NASA/ESA LISA project.


The study solicited community input through a Request for Information, a public workshop and an inclusive study process. The study was conducted by a Study Team, consisting of a Core Team of scientists and engineers, a Community Science Team representing the gravitational-wave, astrophysics, and fundamental physics communities, and a Science Task Force — approximately 40 people in all. Three mission concepts and two options were selected for analysis and costing by Team X, the Jet Propulsion Laboratory's (JPL) concurrent design facility.

The concepts studied by Team X were selected to explore the greatest diversity of mission concepts rather than as the 'best' concepts. They included SGO High, identical in design to LISA but with a single-agency cost model; SGO Mid, a LISA-like concept with shorter arms and shorter mission life; LAGRANGE/McKenzie, designed to avoid the drag-free test mass of the LISA design; and OMEGA, a design utilizing six spacecraft in a geocentric orbit that included an option adopting an aggressive schedule and payload design to reduce costs (OMEGA Option 2).

The community input, the Study Team's analyses, and the Team X results are summarized in this document; extensive supporting information is available at the PCOS Web site.

2010 New Worlds, New Horizons : Astro2010 Report
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This is the final report of the 2010 US Decadal Survey of Astronomy and Astrophysics. It includes a recommendation for LISA as the 3rd priority in the Large mission category.


Driven by discoveries, and enabled by leaps in technology and imagination, our understanding of the universe has changed dramatically during the course of the last few decades. The fields of astronomy and astrophysics are making new connections to physics, chemistry, biology, and computer science. Based on a broad and comprehensive survey of scientific opportunities, infrastructure, and organization in a national and international context, New Worlds, New Horizons in Astronomy and Astrophysics outlines a plan for ground- and space- based astronomy and astrophysics for the decade of the 2010s.

2009 LISA : A Response to the Astro2010 RFI for the Particle Astrophysics and Gravitation Panel
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This paper summarized the science case, mission concept, technical readiness, and programmatic status of the NASA/ESA LISA mission for the 2010 US Decadal Survey of Astronomy and Astrophysics.


Gravity dominates the Universe. Gravitational waves are messengers, not from the radiant baryons of stars or gas or dust, but rather from the extreme interactions of compact dark objects, such as black holes of all sizes. They bring detailed information about violent events central to the origin and evolution of galaxies and stars. Though only indirectly observed as yet, gravitational waves will very likely be directly detected in the next decade, opening a whole new spectrum. The millihertz region of that spectrum is expected to have the largest number, the greatest variety and the strongest sources; that rich trove of astrophysical information is only accessible from a space-based detector.