The groundbreaking discovery of gravitational waves (GW) by the Laser Interferometer Gravitational-wave Observatory (LIGO) in 2015 marked a turning point in the field of astronomy. These ripples in spacetime, resulting from the merger of massive objects, had been predicted by Einstein’s theory of general relativity a century earlier. Looking ahead, the advancement of this field will be significantly propelled by the introduction of next-generation observatories such as the Laser Interferometer Space Antenna (LISA).

With its enhanced sensitivity, LISA will enable astronomers to trace GW events back to their origins and utilize them to investigate the inner workings of exotic objects and the laws of physics. The European Space Agency (ESA), as part of its Voyage 2050 planning cycle, is currently considering mission themes that could be realized by 2050, including the realm of GW astronomy.

In a recent publication, researchers from the ESA’s Mission Analysis Section and the University of Glasgow presented an innovative concept building upon LISA, known as LISAmax. According to their findings, this observatory has the potential to improve GW sensitivity by two orders of magnitude.

The research was spearheaded by Dr. Waldemar Martens, a theoretical physicist and Mission Analyst at the ESA’s European Space Operations Center (ESOC) in Darmstadt, Germany. Dr. Martens collaborated with Michael Khan, an aerospace engineer and astrophysicist, also serving as a Mission Analyst at ESOC, and Dr. Jean-Baptiste Bayle, an astronomy and astrophysics research fellow at the University of Glasgow.

Since the initial detection of GW events by LIGO scientists, subsequent refinements have expanded the types of events that can be detected. Collaborations between observatories like the Virgo Observatory in Italy and the Kamioka Gravitational Wave Detector (KAGRA) in Japan, along with LIGO, have led to the formation of the Ligo-Virgo-KAGRA (LVK) Collaboration. Through these combined efforts and technological upgrades, the number of detected events has multiplied, with some even being traced back to their sources.

To date, astronomers have identified GW events resulting from the mergers of binary black holes (BBHs) and binary neutron stars (kilonova events). However, it is theorized that there are many other potential sources of GW, and studying these events could significantly advance our understanding of the Universe.

Dr. Martens explains, “Among those are primordial gravitational waves that were produced during processes a fraction of a second after the Big Bang. We hope that LISA can detect those, but it is not clear yet. That’s one of the reasons why detectors with higher sensitivity and/or different frequency bands are considered for Voyage 2050.”

Voyage 2050 represents the latest planning cycle within the ESA’s scientific program. As the foundation and principal “mandatory program” of the European Space Agency, all member states contribute to the selection of science goals, proposals, and funding through unanimous decision. These cycles establish long-term funding horizons, enabling member states to plan their priorities well in advance and providing the European scientific community with a clear vision of research areas worthy of investment and development.

Since the 1980s, the program has followed cycles of approximately 20 years, aligning with the timeframe required to prepare ambitious space missions. The initial planning cycle, Horizon 2000, launched in 1984 and resulted in missions like the Solar and Heliospheric Observatory (SOHO), Cluster, Rosetta, XMM-Newton, and Herschel. Subsequently, the Cosmic Vision cycle commenced in 2005, encompassing missions between 2015 and 2025, such as the recently launched JUpiter ICy moons Explorer (JUICE)

By Impact Lab