Since Apollo 17, scientists have been entertaining the idea to install a gravitational-wave (GW) detector on the Moon. From its first conception, lunar GW detection was recognized to have obvious advantages. Compared to Earth, the Moon is known to be an extremely quiet place, which is key to GW detection. Compared to space where detectors are formed by satellite constellations, lunar detectors can potentially be realized with much longer lifetime and therefore also be extendable and modifiable into a lasting lunar GW detector network. In addition, a lunar GW detector might be our best approach for a first GW detection in the decihertz band opening a most interesting observation band to GW science.
The prospects for lunar science missions have changed profoundly over the last years with the commitment of lead space agencies and private industry to lunar exploration. In 2020, ESA issued a call for science white papers connected to the European Large Logistics Lander, and the Lunar and Planetary Institute published a call for Artemis III science white papers. Together with the 2021 call for white papers for the Biological and Physical Sciences in Space Decadal Survey, science has been moved into the spotlight as an important component of lunar exploration. Efforts have begun to promote a near-term to long-term vision for lunar GW detection [1,2,3]. A first workshop took place in October 2021, https://indico.ego-gw.it/event/263, which attracted many scientists and representatives of space and funding agencies from all around the world. At this point, it is crucial to secure support from space agencies to advance with these projects.
The Moon offers a unique platform for gravitational-wave (GW) detection. It has an extremely quiet geophysical environment and other favorable characteristics for GW observations. Detector concepts have been proposed in 2020, and the enormous opportunities for science call for feasibility studies of these concepts. The goal of the Forum is to discuss the science and technology of lunar GW detectors with leading experts in the field. We want to identify how this new community can move forward highlighting synergies with terrestrial and space-based detectors, and with key facilities for EM astronomy.