Approaches to lowering the cost of large space telescopes

Abstract

New development approaches, including launch vehicles and advances in sensors, computing, and software, have lowered the cost of entry into space, and have enabled a revolution in low-cost, high-risk Small Satellite (SmallSat) missions. To bring about a similar transformation in larger space telescopes, it is necessary to reconsider the full paradigm of space observatories. Here we will review the history of space telescope development and cost drivers, and describe an example conceptual design for a low cost 6.5 m optical telescope to enable new science when operated in space at room temperature. It uses a monolithic primary mirror of borosilicate glass, drawing on lessons and tools from decades of experience with ground-based observatories and instruments, as well as flagship space missions. It takes advantage, as do large launch vehicles, of increased computing power and space-worthy commercial electronics in low-cost active predictive control systems to maintain stability. We will describe an approach that incorporates science and trade study results that address driving requirements such as integration and testing costs, reliability, spacecraft jitter, and wavefront stability in this new risk-tolerant "LargeSat" context.

Analysis of active optics correction for a large honeycomb mirror

“…It starts with a map of M1 surface error, which may come from a thermal model or, for the data presented here, from simulated data that are representative of thermal distortion of M1. 5 For consistency with the simulation of the full active optics system, we use a 231-term Zernike polynomial fit to represent the M1 surface error. We use Zemax to compute the resulting wavefront error in the focal plane.…”

“…The input wavefront errors for this simulation are representative of the errors that might be due to thermal evolution of a spacecraft on orbit. These are a single statistical realization of a hypothetical observatory, 5 and serve as a proof of concept. Future work will more fully explore the sensitivity of the bending modes to different wavefront time series (e.g.…”