Mony a Mickle Maks a Muckle: Minor Body Observations with Optical Telescopes of All Sizes

I review the current capabilities of small, medium and large telescopes in the study of minor bodies of the Solar System (MBOSS), with the goal of identifying those areas where the next generation of Extremely Large Telescopes (ELTs) are required to progress. This also leads to a discussion of the synergies between large and small telescopes. It is clear that the new facilities that will become available in the next decades will allow us to discover smaller and more distant objects (completing size distributions) and to characterise and even resolve larger individual bodies and multiple systems, however we must also recognise that there is still much to be learned from wide surveys that require more time on more telescopes than can ever be available on ELTs. Smaller telescopes are still required to discover and characterise large samples of MBOSS.

💡 Research Summary

The paper provides a comprehensive review of how optical telescopes of varying apertures contribute to the study of minor bodies of the Solar System (MBOSS), ranging from small asteroids and comets to distant trans‑Neptunian objects. It begins by underscoring the scientific importance of MBOSS for understanding planetary formation, dynamical evolution, and impact risk assessment. The author then classifies telescopes into four size categories—small (≤1 m), medium (1–4 m), large (8–10 m), and the forthcoming extremely large telescopes (ELTs, ≥30 m)—and systematically compares their capabilities in terms of limiting magnitude, field of view, spatial resolution, spectral coverage, and operational cost.

Small telescopes, because of their wide fields, low cost, and ease of automation, excel at all‑sky surveys and rapid follow‑up of transient events such as comet outbursts or imminent asteroid impacts. Networks of 0.5–1 m instruments can discover thousands of new objects each year, provide first‑order photometry, rotation periods, and colour indices, and feed candidates to larger facilities. Medium‑aperture telescopes strike a balance between sensitivity and resolution. They enable accurate absolute magnitude determinations, surface albedo estimates, and low‑resolution spectroscopy that reveals bulk composition and volatile activity. Their capability in the near‑infrared opens a window onto the thermal emission of distant, cold bodies.

Large telescopes, despite limited night‑time allocation, deliver high signal‑to‑noise ratios for faint, distant MBOSS. They allow precise colour and spectral measurements, high‑resolution imaging of binary systems, and detailed dynamical studies of multi‑component objects. The paper highlights that large apertures can resolve the components of close binary asteroids, measure mutual orbits, and thus constrain masses and densities.

ELTs represent a paradigm shift. Their unprecedented light‑gathering power and diffraction‑limited resolution (≈10 mas at visible wavelengths) will permit direct imaging of kilometre‑scale bodies at distances of tens of astronomical units, surface mapping of the largest dwarf planets, and high‑resolution spectroscopy capable of detecting subtle mineralogical features and trace organics. ELTs will also enable the study of faint cometary comae and the detection of activity on otherwise inert objects. However, the author cautions that ELTs will be scarce resources with high operational costs, making them unsuitable for large‑scale surveys.

The central thesis is that progress in MBOSS science requires a synergistic, tiered observing strategy. Small telescopes perform the “bread‑and‑butter” work of discovery and statistical sampling; medium and large telescopes conduct the “deep‑dive” characterization; ELTs focus on the most compelling, high‑impact targets that demand the ultimate spatial and spectral resolution. The paper argues that without sustained investment in the lower‑tier facilities, the scientific return of ELTs would be severely limited because the pool of well‑characterized targets would be too small.

In addition to observational strategy, the author stresses the need for robust data pipelines, archiving, and machine‑learning tools to handle the torrent of data from wide‑field surveys and to prioritize ELT follow‑up. International collaboration, shared scheduling, and coordinated campaigns are presented as essential to maximize the scientific yield of the next generation of telescopes.

Finally, the paper outlines specific science cases that ELTs will uniquely address: completing the size‑frequency distribution of MBOSS down to sub‑kilometre scales, probing the surface geology of distant dwarf planets, resolving multiple systems to directly measure masses, and detecting faint volatile signatures on objects at the edge of the Solar System. At the same time, it reiterates that wide‑field, time‑domain surveys conducted by numerous modest‑aperture telescopes remain indispensable for building the statistical foundation upon which these high‑resolution studies will stand.