Perspectives

The concepts and development milestones of the two Chinese space-based gravitational wave observatories, TianQin and Taiji, are introduced. Considering their similar goals and operation window with LISA, possible collaborations among them are discussed.

The Mars Subsurface Water Ice Mapping (SWIM) project aims at determining the regions where near-surface ice is most likely to be present, according to the combination of all the available datasets. Focusing on the northern mid-latitudes, they identify in particular Deuteronilus Mensae and Arcadia Planitia as promising sites.

The commercial development of small satellites provides a unique opportunity to the astronomical community to overcome terrestrial limitations such as geography, atmosphere and planetary motion at a fraction of the cost of traditional space-based astronomy missions.

Recently, nanosatellite capabilities, driven by commercial and scientific innovation, have led to the development of high-performance satellite payloads and subsystems. This article reflects on the history, current state and future of the field.

In the context of near-Earth space becoming increasingly privatized and crowded due to the launch of satellite constellations, space must be viewed as an ancestral global commons that contains the heritage and future of humanity’s scientific and cultural practices.

The number of small satellites has grown hugely in the past decade, from tens of satellites per year in the mid-2010s to a projection of tens of thousands in orbit by the mid-2020s. This presents both problems and opportunities for observational astronomy. Small satellites offer complementary cost-effective capabilities to both ground-based astronomy and larger space missions. Compared with ground-based astronomy, these advantages are not just in the accessibility of wavelength ranges where the Earth’s atmosphere is opaque, but also in stable, high-precision photometry, long-term monitoring and improved areal coverage. Astronomy has a long history of new observational parameter spaces leading to major discoveries. Here we discuss the potential for small satellites to explore new parameter spaces in astrophysics, drawing on examples from current and proposed missions, and spanning a wide range of science goals from binary stars, exoplanets and Solar System science to the early Universe and fundamental physics.

Australian astronomers generate more greenhouse emissions than the average Australian citizen, thereby exacerbating the climate crisis. By quantifying contributions from different activities such as supercomputing and air travel, as presented here, astronomers can focus on reducing emissions by changing their practices in the most critical areas.

Extreme blazars emitting teraelectronvolt photons are ideal targets to study particle acceleration processes. The growing number of such sources has been critical for γ-ray cosmology, studying intergalactic magnetic fields and putting constraints on exotic physics.

This Perspective highlights the science opportunities and the vast discovery space of simultaneous observations from the LISA and Athena observatories, which would be missed if they were operated in different epochs .

Volcanic and tectonic global maps of the inner planets and the Moon allow conclusions about the long-term volcanic behaviour of terrestrial planets and hint at the most promising extrasolar planets to look for active, radiogenically driven volcanism.

Years of dedicated efforts to tackle gender inequality in Europe show positive trends, but equality has not yet been achieved. This Perspective reports on the most recent initiatives in science and technology, with a special focus on the field of astronomy.

PhD bridge programmes provide an asset-based model to improve access and inclusion for students from underrepresented groups. Several well-known PhD bridge programmes in the United States are described and lessons learned from their experiences are discussed.

An overview of the nationwide programmes that are making an impact on diversity, culture and climate in Australia is presented, along with the most promising and innovative initiatives in Australian universities and institutions.

The convoluted challenges that stifle equity in academia can be understood in terms of dynamical systems descriptions of conflict developed in the social sciences, explaining the persistence of exclusive cultures and the inadequacy of simple fixes.

Measurements from Cassini’s Grand Finale, when the spacecraft flew between Saturn and its rings, have been used to claim that the rings are much younger than the planet itself. However, this interpretation does not solve all of the inconsistencies, and the question of the age of Saturn’s rings is still open.

‘Oumuamua is the first interstellar interloper observed in our Solar System and studied in some detail. This Perspective reviews the data acquired during its visit and discusses its origin and properties, concluding that there is no basis to the theory of an artificial ‘Oumuamua.

The future of Solar System exploration lies in the subsurface of rocky bodies, including planets. Robots provide a relatively cost-effective and safe method of probing the subsurface; this Perspective summarizes recent efforts in robotic drilling and regolith-sampling methods, concluding with a summary of China’s future space exploration plans.

KAGRA is a new gravitational wave detector being built in Japan. Unlike LIGO/Virgo, it will operate at cryogenic temperatures with sapphire mirrors. KAGRA will help improve the localization of gravitational wave detections and determination of the source parameters.

Examining and comparing many of the definitions of a black hole, it is concluded that the profusion of different definitions is a virtue that makes the investigation of black holes possible and fruitful in many different kinds of problems.

The sunspot number time series is an essential tool to determine the secular variations of solar activity, but particular care must be taken to handle and present incomplete temporal coverage. The authors present the current state of research and propose a new way to visualize long-term solar activity data.