Future of Astronomy with Small Satellites

Small satellites are revolutionizing the way we access space for commerce and science, including astronomy and planetary science. Yet, like many breakthrough technologies, it has a double-edge.

Earth’s exosphere is set to become increasingly crowded, with tens of thousands of commercial telecommunication satellites planned in the next few years. We need to ensure that technological and socio-economic advancements will not imperil scientific progress and humanity’s access to dark skies.

The historic launch of the first several hundred out of 12,000 planned Starlink satellites heralds the arrival of the era of ultra-large satellite constellations. If it will bring new opportunities or insurmountable challenges to astronomy will probably depend on whether you are conducting your observations in space or from the surface of the Earth.

The Space Academic Network made a case for a small-satellite programme for the United Kingdom to provide access to space, and a route for advancing science and technology; however, funding has not been forthcoming. The search for a killer argument for this widely supported programme continues.

Philanthropic donations are a significant contribution to the betterment of humankind, with a large percentage dedicated to science and education. Affordable small satellites may offer philanthropists the opportunity to give students and underprivileged communities access to small space telescopes.

High-performance scientific satellites are currently the exclusive domain of government-funded agencies. The team behind the Twinkle Space Mission is developing a new class of small and sustainable science satellites that leverages recent innovations in the commercial space sector.

The Colorado Ultraviolet Transit Experiment CubeSat mission aims to observe atmospheric escape from a dozen or more exoplanets by monitoring them in the near-ultraviolet, explains Principal Investigator Kevin France.

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.

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.

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.

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.

CubeSats, a standardized subgroup of small satellites, are a cheap and flexible solution to perform astronomical observations from space that is just starting to be exploited. This Perspective presents an overview of their advantages and of the current and planned projects.

HaloSat, NASA’s first astrophysics-focused CubeSat mission — the size of a small briefcase — will survey the Milky Way’s halo in order to assess its complement of hot baryons, explains Principal Investigator Philip Kaaret.

PolarLight is the first dedicated soft X-ray polarimeter in space since the 1970s and is attempting to reopen this long-awaited window in astronomy, explain Principal Investigator Hua Feng and Ronaldo Bellazzini.

The MICROSCOPE experiment has set the best upper bound to date on the weak equivalence principle, proving Einstein’s postulate with an unprecedented precision, as explained by Principal Investigator Pierre Touboul and team members Manuel Rodrigues and Joel Bergé.

Measurements with a CubeSat gas pixel detector reveal a change in the Crab pulsar polarization after a glitch in the spin period, suggesting that starquakes alter the magnetosphere.

A soft X-ray polarimetry capability has been missing from astronomy since the late 1970s. Here a CubeSat polarimeter named PolarLight has detected the Crab nebula and pulsar in the soft X-ray band, measuring their polarized emission. PolarLight observed a pulsar glitch, with an associated polarization change.

Soft X-ray observations of the southern Galactic sky with the HaloSat CubeSat indicate that the circumgalactic medium (CGM) of the Milky Way has a disk-like profile, with an extended spherical halo. Clumps in the CGM correlate with star-formation activity.