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 and European counterparts to ensure that LISA is a success.
How long will the LISA mission last?
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 Earth.
LIGO has already found gravitational waves, why do we need LISA?
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 number of electromagnetic telescopes. Since LISA observes in an entirely separate band from LIGO, it can help answer different questions such as: “How did the massive black holes at the centers of galaxies form and grow?, “How have stars in our Milky Way evolved and died?”, and “Is general relativity the correct description of gravity and black holes?”
How does LISA differ from ground-based gravitational wave interferometers like LIGO, Virgo, and KAGRA?
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. LISA sources will also tend to evolve more slowly, allowing longer observations of each source. The two types of observatories complement one another, just like how different types of electromagnetic observatory (e.g. radio, optical, X-ray, etc.) complement one another.
How did LISA get its name?
It’s an acronym: LISA stands for “Laser Interferometer Space Antenna”.
What type of rocket is currently intended to carry the three satellites into space?
Ariane 6 and/or Vega-C (co-developed by ArianeGroup and Avio) are possible options.