Perspectives in 2020

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 .