The Scaling Relationship Between Telescope Cost and Aperture Size for Very Large Telescopes

TL;DR

This paper analyzes historical cost data of ground-based telescopes to understand how costs scale with aperture size, revealing different relationships before and after 1980, and discussing implications for future large telescope projects.

Contribution

It identifies the changing power-law relationships between telescope cost and aperture size over time and discusses the economic implications for future telescope designs.

Findings

Pre-1980 costs scaled as aperture^2.8

Post-1980 costs scaled as aperture^2.5

Multi-mirror telescopes show cost savings and deviate from traditional scaling laws

Abstract

Cost data for ground-based telescopes of the last century are analyzed for trends in the relationship between aperture size and cost. We find that for apertures built prior to 1980, costs scaled as aperture size to the 2.8 power, which is consistent with the previous finding of Meinel (1978). After 1980, `traditional' monolithic mirror telescope costs have scaled as aperture to the 2.5 power. The large multiple mirror telescopes built or in construction during this time period (Keck, LBT, GTC) appear to deviate from this relationship with significant cost savings as a result, although it is unclear what power law such structures follow. We discuss the implications of the current cost-aperture size data on the proposed large telescope projects of the next ten to twenty years. Structures that naturally tend towards the 2.0 power in the cost-aperture relationship will be the favorable choice for future extremely large apertures; our expectation is that space-based structures will ultimately gain economic advantage over ground-based ones.