Studies of Gravitational-Wave Mission Concepts

Welcome to this informal wiki, dedicated to the development of a space-based gravitational-wave observatory in the tradition of LISA.

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ESA Study

After the ESA/NASA partnership ended in mid-March 2011, ESA established an effort to re-formulate an all-European mission for the Cosmic Visions L1 opportunity. However, they generously offered to consider low-level NASA participation at a later date. To facilitate that participation, ESA Headquarters invited NASA Headquarters to name a U.S. representative on the re-created European Science Working Group. NASA Headquarters named Tuck Stebbins (Goddard Space Flight Center) as that representative.

Information and useful links from the ESA reformulation effort appear here. Note that the science team and ESA have not settled on a name or acronym for the new mission concept. In the material below and elsewhere on the web, you will see it referred to as NGO (New Gravitational-Wave Observatory) or EuLISA (European LISA) or ELISA or New LISA or similar trial names.

The re-formulation has encompassed several activities:

  • In the first three months, a small core team has cooked up and assessed possible design options.
  • A science performance assessment team is evaluating the science performance of mission configurations.
  • The Concurrent Design Facility at ESTEC in Noordwijk, NL performed a engineering and cost analysis of an NGO baseline during June and July 2011.
  • A Science Working Group meets regularly and reviews and decides on mission concept choices, science performance assessments, engineering analyses, and strategy options.
  • ESA's industrial contractor (Astrium) is developing a baseline design. This involves exploring architecture choices, performing design trade studies and evaluating overall feasibility.

The links below to further information are organized around these activities:

Core Team

ESA Science Performance Assessment Team

Concurrent Design Facility Study

ESA Science Working Group

ESA Industrial Study

The schedule for the ESA reformulation study is

Tuck Stebbins, 23 Sep. '11

As of November 2011, the ESA L1 Downselect schedule is currently under re-consideration. The Science Programme Committee, the guiding body for the science programme, will establish a new schedule at their regular February 2012 meeting. The SPC is considering a proposal by the Executive to downselect to a final concept in a single step at a special meeting in the April/May 2012 timeframe, with a ratifying vote at their regular June 2012 meeting.

Tuck Stebbins, 7 Dec. '11

Statement from the new European LISA science team (7/29/2011)

New Developments in Space-based Gravitational Wave Astronomy. For almost two decades now, ESA and NASA have studied the LISA mission for the observation of low-frequency gravitational waves as an equally shared partnership of the two agencies.

ESA has recently changed the guidelines for large (“L-class”) missions in the Cosmic Vision framework to require European-only funding, because NASA was financially unable to proceed on the timescale of the launch of the first L-class mission ('L1') in ESA's Cosmic Vision Programme. A search for a European-led variant of LISA that could be launched by 2022 was begun.

After studying several configurations, a new baseline for transfer, orbit and layout has been identified that will be refined in the coming month with the help of European industry. The new baseline employs less costly orbits, and simplifies the design of LISA by reducing the distance between the satellites and employing four rather than six laser links. This considerably reduces the mass and cost, while retaining much of the original science, in part because of new approaches to data analysis.

The European Science Team and a Science Task Force, composed of members of the gravitational wave and astrophysics communities in both Europe and the US, have assessed the scientific validity of the new LISA baseline for the fields of physics, astrophysics and cosmology and have shown that the new configuration should detect thousands of galactic binaries, tens of (super)massive black hole mergers out to a redshift of z=10 and tens of extreme mass ratio inspirals out to a redshift of 1.5 during its two year mission. The investigation of fundamental physics and cosmology tests will continue over the next few months, until we have a finalized mission proposal by the fall of 2011. The preliminary results of this investigation are looking promising.

This announcement is not an official statement of ESA or NASA.

Karsten Danzmann, formerly co-chair of the LISA International Science Team

NASA Study

NASA Study Overview

With the end of the joint NASA/ESA project, the Astrophysics Division at NASA Headquarters redirected the gravitational-wave effort in the U.S. toward two goals. One was to support the NGO study - in part through the NASA representative on the NGO Science Working Team, but also through engineering and scientific activities. The other was to develop new concepts for a future NASA-led mission, in the event that NGO did not go forward.

The LISA Project team at Goddard and JPL has provided support to the NGO study through orbital analyses, trajectory analyses, design input, etc. Members of the LISA Project team have contributed to the ESA Core Team, ESA Science Performance Assessment Team, the Concurrent Design Facility Study, the ESA Science Working Group and the ESA Industrial Study. Several in the U.S. science community have been making important contributions to the ESA Science Performance Assessment Team and the writing of the Yellow Book.

The effort to develop new concepts for a future NASA-led mission has also proceeded. While no specific concept has been selected, the NASA core team - made up of members of the LISA Project team at JPL and GSFC - has chosen to refer to that future mission as the Space-Based Gravitational-Wave Observatory (SGO) for convenience.

Ongoing technology development work in micronewton thrusters, phasemeters, telescopes, and lasers has also been refocused to respond to both NGO and SGO.

NASA work on both NGO and SGO are managed by the Physics of the Cosmos (PCOS) Progam Office. This Program Office at Goddard provides program implementation support to the Astrophysics Division at NASA Headquarters. The PCOS Program web site has information about the Program, the PhysPAG, the TechSAG and instructions for subscribing to News and Announcements.

NASA RFI Response Preparation

The full text of the request for information was posted on the NASA research opportunities web page GW RFI (select “Solicitations” then “Open Solicitations” then “NNH11ZDA019L”).

Responses were due on November 10, 2011, and can be found on the PCOS webpage. The RFI response coordination webpage was here.

For further information on this RFI contact the NASA HQ PCOS program officers, Jaya Bajpayee, PCOS Program Executive, at, and Rita Sambruna, PCOS Program Scientist, at Please check for the most up to date information on the program.

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