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The LISA Consortium is a large international collaboration that combines the resources and expertise from scientists in many countries all over the world. Together with ESA and NASA, the LISA Consortium is working to bring the LISA Mission to […]
The gravitational waves that LISA is designed to observe have typical timescales of hours. So long as the distance between the satellites is smoothly changing over these time scales, the gravitational waves can be observed as an additional modulation on top of this smooth change. Each satellite is in an independent Keplerian orbit around the Sun with the plane of the triangle inclined at 60 degrees to the plane of the ecliptic. Over the course of the mission, the nominal 2.5 million kilometer distance between each satellite will vary by hundreds of thousands of kilometers. LISA will be able to […]
No. Both ground motion and time variations in familiar Newtonian gravity from spurious mass motions on the Earth prevent observations below about 1 Hz on the ground. It is necessary to make measurements in space in order to observe many of the important astrophysical sources throughout the […]
Gravitational waves are ripples in the fabric of space-time generated by some of the most powerful astrophysical events – such as collisions of black holes and exploding stars. Gravitational waves travel at the speed of light through the universe. They allow us to explore the dark side of the […]
If you are a professional researcher, you may want to join the LISA Consortium. In the US, you should check out NASA’s Gravitational Wave Science Interest Group (GWSIG) https://pcos.gsfc.nasa.gov/sigs/gwsig.php. If you are a student, you may consider applying for an internship at a NASA center involved with LISA […]
LISA is led by the European Space Agency (ESA), which in 2017 selected LISA for study as a large-class mission in the Cosmic Visions Programme. LISA was Adopted as a project by ESA’s Science Program Council in January 2024. Partnering with ESA are NASA and a collection of European National space agencies. NASA will provide three critical hardware elements for LISA: lasers, telescopes, and charge management devices. In addition, NASA is developing a science ground segment to process the LISA telemetry and produce scientific data products for public consumption. NASA scientists, engineers, and managers are working closely with the ESA […]
The LISA mission is designed for 4 years of nominal science operations, with a potential extended mission of up to 6 years. In addition to wear-and-tear of the spacecraft and its instruments, limitations to LISA’s lifetime come from the amount of propellant available to perform the drag-free flight of the spacecraft around the test masses, the long-term stability of the orbits that form the constellation, and communications difficulties associated with increasing distance between the consteallation and […]
LISA’s data and telemetry requirements are relatively modest when compared to many other astrophysics missions. While the precise details are being developed as part of the mission formulaiton process, the rough numbers are known. During normal operations, only one of the three LISA spacecraft will be in contact with the ground. In addition to transmitting its own data, the spacecraft will serve as a relay for data from the other two spacecraft, which will share data over a dedicated inter-constellation link. This is efficient because the separation between spacecraft (2.5Mkm) is roughly 20x smaller than the distance to Earth (approximately […]
Interferometry is a technique that uses the interference of waves to make precise measurements. The wavelength of the interfering waves acts like the tick marks on a ruler for measuring distance. Optical interferometers can make very precise measurements because the wavelength of the light waves they use is small — around one micron for instruments like LIGO and LISA. A fundamental limitation of interferometry is that precision of the measurement is limited by the stability of the waves used in the interferometer. For an optical interferometer, if the wavelength of the light fluctuates, a spurious signal will be generated that […]
The orbits of the LISA spacecraft are set up in such a way that the constellation maintains a nearly perfect equilateral triangular shape that is inclined by roughly 60 deg with respect to the ecliptic plane. Once each spacecraft is inserted into its predetermined orbit, tracking from the ground will be used to precisely locate them and determine their relative positions. The spacecraft will then undergo a “constellation acquisition” procedure which begins with one spacecraft turning on its laser while its partner spacecraft scans the sky. At some point during the scan, an acquisition sensor on the partner spacecraft will […]
Since gravitational waves are the stretching of spacetime itself, they have the interesting property that the measured displacement between two reference objects scales with the original separation between those objects. In other words, if there is more spacetime to stretch, the total stretch is larger. LISA’s arms are roughly a million times longer than LIGO’s, which means that a gravitational wave of the same amplitude will produce displacements that are roughly a million times larger in LISA. The total displacement is still small, on the order of picometers (one picometer = one trillionth of a meter) but is well within […]
The gravitational waves that LISA is designed to observe have typical timescales of hours. So long as the distance between the satellites is smoothly changing over these time scales, the gravitational waves can be observed as an additional modulation on top of this smooth change. Each satellite is in an independent Keplerian orbit around the Sun with the plane of the triangle inclined at 60 degrees to the plane of the ecliptic. Over the course of the mission, the nominal 2.5 million kilometer distance between each satellite will vary by hundreds of thousands of kilometers. LISA will be able to […]
Gravitational wave science is about much more than just verifying the existence of the waves themselves. Long before LIGO made its first detection in 2015, the consensus amongst most physicists was that gravitational waves were real. The real power of gravitational waves is as a new tool for understanding our Universe. The early results from LIGO have already demonstrated this potential by uncovering what appears to be a new population of heavy black holes as well as determining the origin of heavy elements in the Universe through observations of a neutron star merger that was also observed by a large […]
LISA is an all-sky instrument, with the sensitivity to gravitational waves only weakly depending on the location of the source in the sky. Localization of individual sources comes from two main effects. The first is the motion of the LISA constellation around the Sun, which introduces shifts in both frequency (Doppler effect) and amplitude (sweeping the LISA sensitivity pattern across the sky). These shifts encode information about the sky position of the source in the waveform that LISA observes. Since most LISA sources are observed for months or years, there is sufficient modulation to provide localization. The second effect is […]
At any one moment, LISA will be sensing gravitational waves from millions of individual sources. The vast majority of these will be binary systems of compact objects in the Milky Way, but signals will also be received from extragalactic sources such as the mergers of massive black holes. Each of these signals has a distinct waveform that depends on the astrophysical properties of the source (masses, spins, orientations, positions, etc.). Thanks to extensive work in theory and modeling, we have very good templates for these sources which we can compare to the LISA data and extract individual signals using a […]
Gravitational wave interferometers all operate on the same physical principle that gravitational waves can be observed by measuring the proper distance between freely-falling objects using beams of light. However LISA will operate in a very different regime to ground-based observatories. LISA’s million-kilometer-scale arm lengths are optimized to observe gravitational waves with milliHertz frequencies. These low-frequency gravitational waves don’t influence detector like LIGO very much since they are optimized to detect frequencies in the tens to hundreds of Hertz. In general, LISA will observe systems with larger masses and increased separations in comparison to those observed by LIGO, Virgo, and KAGRA. […]
The Gravitational Universe is a new window in astronomy. Powerful sources of gravitational waves are being used to probe a universe that cannot be explored by other means. Significant advances in astronomy have been made by looking at the Universe using electromagnetic radiation as a probe. But with gravitational waves, we can also study the dark universe, analogous to listening for objects that do not produce light. LISA will enable us to explore the dark universe through gravitational […]
The gravitational waves that LISA will discover include ultra-compact binaries in our Galaxy, supermassive black hole mergers, and extreme mass ratio inspirals, among other possibilities. LISA will be the first to explore gravitational waves in the frequency range of 0.1 milliHertz to 0.1 […]
Since gravitational waves are the stretching of spacetime itself, they have the interesting property that the measured displacement between two reference objects scales with the original separation between those objects. In other words, if there is more spacetime to stretch, the total stretch is larger. LISA’s arms are roughly a million times longer than LIGO’s, which means that a gravitational wave of the same amplitude will produce displacements that are roughly a million times larger in LISA. The total displacement is still small, on the order of picometers (one picometer = one trillionth of a meter) but is well within […]
Key features of LISA are interferometric measurement of distances, million-km long baselines, drag free spacecraft based on inertial sensors, and the familiar “cartwheel”-orbits. Unique are the free-falling test masses inside each spacecraft. The test masses will be undisturbed by forces other than gravitation. A new technology, the so-called “drag-free” operation, allows the spacecraft to follow the test masses, all the while shielding the test masses from spurious […]