Announcements

NASA's LISA Study Team welcomes new membership

10/23/2019

The NASA LISA Study Team welcomes seven new members to it's ranks! For information about the current NLST membership and alumni who have stepped down, please consult the Study Team Roster.

Call for Nominations to Augment the NASA LISA Study Team
Due: October 11, 2019

09/19/2019

NASA welcomes nominations, including self-nominations, for new members of the NASA LISA Study Team (deadline: October 11, 2019). We particularly encourage people of diverse backgrounds, skills, career stages, and viewpoints to apply. See the full text of the call and application instructions for more information.

Newly discovered binary system will be a strong LISA source

08/09/2019

Astronomers using the Zwicky Transient Facility (ZTF) have announced the discovery of ZTFJ1539+5027, a pair of white dwarfs that orbit one another roughly every seven minutes. This system will be a strong LISA source, detecable after roughly one week of observing and with a total signal-to-noise ratio of nearly 200 in a four-year LISA mission.

First Results from GRACE-FO's Laser Interferometer

07/19/2019

The first results from the Laser Ranging Instrument (LRI) on the Gravity Recovery and Climate Experiment Follow On (GRACE-FO) mission were published in Physical Review Letters on July 19th, 2019. The GRACE-FO mission maps the Earth's gravity field by precisely tracking the relative positions of a pair of spacecraft that orbit the Earth. The LRI makes these measurements using heterodyne laser interferometry, the same technique that will be used for LISA. These first results from LRI demonstrate nanometer-level precision over the 220km range between the GRACE-FO satellites.

Event Horizon Telescope makes first image of a black hole

04/10/2019

The Event Horizon Telescope project, an international effort to link radio telescopes across Earth to build a planet-sized telescope with superb angular resolution has made the first image of a black hole. The image is of gas surrounding a black hole of nearly six billion solar masses in the galaxy M87. LISA will measure the mergers of massive black holes which are the ancestors of these supermassive black holes.

Ground-based gravitational wave observatories begin 3rd observing run

04/01/2019

O3, the third observing run of the advanced ground-based gravitational wave detectors has begun after the LIGO and Virgo teams have spent over a year upgrading their instruments to improved sensitivities. O3 is expected to last for a full year with increased event rates. O3 will also feature low-latency, public alerts which will enable follow-up of gravitational wave events by a variety of astronomical facilities.

Ground-based detectors release combined catalog from first two observing runs

12/01/2018

The LIGO Scientific Collaboration has released the results from their first two observing runs which includes four new black hole mergers in addition to the six previously-announced black hole mergers and the one neutron star merger. Details can be found on LIGO's O1/O2 catalog page.

LISA Data Challenge

7/11/2018

The first data set for the LISA Data Challenge has been released by the LISA Consortium. If you'd like to try your hand at extracting gravitational wave sources from simulated LISA data, you can download tools and data at the Data Challenge Website. The deadline for entries to this first challenge will be near the end of 2018.

TOP

Why LISA? ...Gravitational Waves.

What are Gravitational Waves?

This movie shows a simulation of the merger of two black holes and the resulting emission of gravitational radiation. The very fabric of space and time is distorted by massive objects, which is shown here by the colored fields. The outer sheets (red) correspond directly to outgoing gravitational radiation, which was recently detected by the NSF's LIGO observatories. Credit: NASA/C. Henze

Gravitational waves were first theorized by Albert Einstein. They are created during events such as supermassive black hole mergers, or collisions between two black holes that are billion times bigger than our Sun. These collisions are so powerful that they create distortions in spacetime, known as gravitational waves.

Gravitational waves detectable by the LISA mission could also come from other distant systems including smaller stellar mass black holes orbiting supermassive black holes, known as Extreme Mass Ratio Inspirals (EMRIs).

What do Gravitational Waves tell us?

There are many astrophysical phenomena that are either very dim or completely invisible in any form of light that astronomy has relied on for 400 years. Gravitational waves are a powerful new probe of the Universe that uses gravity instead of light to take measure of dynamical astrophysical phenomena. Studying gravitational waves gives enormous potential for discovering the parts of the universe that are invisible by other means, such as black holes, the Big Bang, and other, as yet unknown, objects. LISA will complement our knowledge about the beginning, evolution and structure of our universe.



Why do we need to go to space?

A space-based configuration allows for an extremely large detector to study regions of the gravitational wave spectrum that are inaccessible from Earth.

gravitational wave spectrum
Click Image to Zoom. There are promising detection techniques across the entire gravitational wave spectrum, which is populated by a broad range of astrophysical sources. The spectrum in the region probed by LISA is one of the most interesting, populated by a rich diversity in astrophysical phenomena of interest to astronomers and astrophysicists.

A Different Frequency Range from Different Objects

The gravitational wave spectrum covers a broad span of frequencies. LISA operates in the low frequency range, between 0.1 mHz and 1 Hz (compared to LIGO's frequency of 10 Hz to 1000 Hz). The difference means that the waves LISA is looking for have a much longer wavelength, corresponding to objects in much wider orbits and potentially much heavier than those that LIGO is searching for, opening up the detection realm to a wider range of gravitational wave sources.

LISA has three spacecraft that form an equilateral triangle in space where the sides of the triangle, also called LISA's "arms", extend about a million miles. Therefore, from space, LISA can avoid the noise from Earth and access regions of the spectrum that are inaccessible from Earth due to these extremely long arms. The gravitational wave sources that LISA would discover include ultra-compact binaries in our Galaxy, supermassive black hole mergers, and extreme mass ratio inspirals, among other exotic possibilities.

The Entire Spectrum

We aim to study the entire gravitational wave spectrum, covering a range of gravitational wave sources using experiments on



WHAT is LISA?

LISA is a space-based gravitational wave detector constructed of three spacecraft separated by millions of miles.

LISA's enormous detector size and orbit, trailing behind the Earth as it orbits the Sun, are illustrated here. Credit: AEI/Milde Marketing

LISA's Size and Precision are Out of this World

LISA consists of three spacecraft that are separated by millions of miles and trailing tens of millions of miles, more than one hundred times the distance to the Moon, behind the Earth as we orbit the Sun. These three spacecraft relay laser beams back and forth between the different spacecraft and the signals are combined to search for gravitational wave signatures that come from distortions of spacetime. We need a giant detector bigger than the size of Earth to catch gravitational waves from orbiting black holes hundreds of millions of times more massive than our sun. NASA is a major collaborator in the European Space Agency (ESA)-led mission, which is scheduled to launch in the early 2030s and we are getting ready for it now!


How does LISA Detect Gravitational Waves?

Gravitational wave events will cause the three LISA spacecraft to shift slightly with respect to each other.

LISA laser beam
Click Image To Zoom. LISA will observe a passing gravitational wave directly by measuring the tiny changes in distance between freely falling proof masses inside spacecraft with its high precision measurement system. Credit: AEI/MM/exozet

Catching Waves

A bit like the objects moving on the surface of a pond produce ripples and waves, massive objects moving in space distort the fabric of spacetime and produce gravitational waves. Some of these gravitational wave events will cause the three LISA spacecraft to shift slightly with respect to each other, as they "ride the gravitational waves", to produce a characteristic pattern in the combined laser beam signal that depends on the location and physical properties of the source.

LISA is Extremely High Precision

These signals are extremely small and require a very sensitive instrument to detect. For example, LISA aims to measure relative shifts in position that are less than the diameter of a helium nucleus over a distance of a million miles, or in technical terms: a strain of 1 part in 1020 at frequencies of about a millihertz.

The LISA Pathfinder Mission was a proof-of-concept mission to test and prove the technology needed for LISA's success.


What is LISA Pathfinder?

LISA Pathfinder Mission was a proof-of-concept mission for LISA.

lisa pathfinder artists impression
Click Image to Zoom. LISA Pathfinder operated from a vantage point in space about 1.5 million km from Earth towards the Sun, orbiting the first Sun-Earth Lagrangian point, L1. Credit: ESA - C.Carreau

LISA Pathfinder Exceeded Expectations

LISA Pathfinder was launched on December 3, 2015 as a proof-of-concept that tests that the noise characteristics of free-floating test masses within the spacecraft are small enough compared to an expected gravitational wave signal. Completing its mission in July, 2017, LISA Pathfinder has shown that the low noise levels surpassed the original requirements, demonstrating that key technology for LISA is well underway.


lisa pathfinder characteristics
View/Download: 1500px Full Screen | 3508px Full Screen

This plot shows the primary result from LISA Pathfinder's year and a half of science operations. The plot shows the measured level of imperfection from pure free-fall of the two gold-platinum test masses. The solid and hatched shaded areas show the designed level of performance for LISA Pathfinder and LISA respectively. The blue trace shows the preliminary result from Pathfinder, which was obtained just two months after science operations began. The red trace shows the final result, obtained in February 2017 after the instrument was tuned to improve performance. These measurements demonstrate that the technology developed for Pathfinder can be used as the basis for LISA's detection of gravitational waves.
Credit: ESA/LISA Pathfinder Collaboration.

Related Articles

What is LIGO?

LIGO is a ground-based observatory that first detected gravitational waves.

LIGO Detections
Click Image to Zoom. With their first few detections, LIGO and VIRGO have made significant contributions to our understanding of black holes and neutron stars. This graphic shows the masses for black holes detected through electromagnetic observations (purple); the black holes measured by gravitational-wave observations (blue); neutron stars measured with electromagnetic observations (yellow); and the masses of the neutron stars that merged in an event called GW170817, which were detected in gravitational waves (orange). The remnant of GW170817 is unclassified, and labeled as a question mark. Details/Credit: LIGO-Virgo/Frank Elavsky/Northwestern University.

Opening the Gravitational Wave Window

On September 14, 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO), a ground-based gravitational wave observatory, made history by detecting the first gravitational waves from the merger of two stellar mass black holes. Since then, LIGO and its European counterpart VIRGO, have announced the detection of several additional black hole systems as well as a neutron star merger which also produced light detected by dozens of telescopes on ground and in space. This represents nothing less than the birth of an entirely new field of astronomy.

aerial view of LIGO
Click Image to Zoom. The LIGO Laboratory operates two detector sites, one near Hanford in eastern Washington, and another near Livingston, Louisiana. This photo shows the Livingston detector site. Credit: LIGO/Caltech

Ground Based vs Space Based

As LIGO, VIRGO, and other ground-based detectors increase their sensitivity, the number and quality of black hole and neutron star merger events observed will increase. New kinds of events, such as nearby supernovae, may be detected as well. However, there are some gravitational wave sources that are not detectable by even the most advanced ground-based detectors. Gravitational Waves at very low frequencies have wavelengths larger than the Earth itself. Deploying an antenna large enough to efficiently detect them requires going to space. LISA's three spacecraft will create an equilateral triangle in space and the paths between each pair of spacecraft, referred to as LISA's arms, will extend millions of miles. By measuring distance changes in these arms caused by passing gravitational waves, LISA will be able to measure their amplitude, direction and polarization. Astronomers will use this information to learn about the sources in this previously-unexplored region of the gravitational wave spectrum.



Who's Involved?

Led by ESA, the project is a collaboration of ESA, NASA, and the global scientific community.

ESA and NASA logos

The European Space Agency (ESA) is leading the LISA mission. Together with NASA and an international consortium of scientists, the project brings together global expertise in gravitational wave detection.

What is NASA's Role?

NASA supports both ESA and the LISA Consortium as a collaborative partner providing science and engineering expertise, technology development, and interface with the U.S. research community. This includes development of enabling technologies, systems engineering support, prototyping of ground segment and data analysis infrastructure, and research in LISA-related astrophysics.

NASA is directly supporting the development of five key technologies for possible contribution to the ESA-led LISA mission. LISA Telescope and laser systems are being developed at the Goddard Space Flight Center; a phase measurement system and precision micropropulsion system are being developed at the Jet Propulsion Laboratory; and a Charge Management System is being developed by the University of Florida under an award from NASA. The NASA LISA Study Office is coordinating this suite of development activities and managing interfaces with European partners.

How to Get Involved

neutron star merger simulation of gravitational waves
Click Image to Zoom. Numerical simulation of the gravitational waves emitted during the merger of two neutron stars into a black hole. Credit: Max Planck Institute for Gravitational Physics. More Info

For Scientists


Education and Outreach Resources

Links to gravitational wave education resources for teachers and students.


Citizen Science Projects