Researchers suggest how to make space telescopes cheaper and better

The JWST is just the beginning of a new era of space astronomy.
Rizwan Choudhury
The combined Optical Telescope element  Integrated Science instrument module (OTIS) of NASA's James Webb Space Telescope on the High Capacity Rollover Fixture (HCROF) inside Northrop Grumman facility.
The combined Optical Telescope element Integrated Science instrument module (OTIS) of NASA's James Webb Space Telescope on the High Capacity Rollover Fixture (HCROF) inside Northrop Grumman facility.

Source: Northrop Grumman/NASA via Flickr 

The James Webb Space Telescope (JWST) has been a spectacular success so far, revealing new insights into the cosmos with its powerful vision. But the JWST also has a history of cost overruns, delays, and near-cancellations that have raised questions about the feasibility of future space telescopes.

Is there a way to make space telescopes more affordable?

The JWST is just the beginning of a new era of space astronomy. NASA is already working on the next generation of space telescopes, such as the Nancy Grace Roman Space Telescope (formerly WFIRST) and the Habitable Worlds Observatory (formerly LUVOIR), which are expected to launch in 2027 and the late 2030s, respectively.

These space telescopes will likely have hefty price tags. However, a team of researchers believes that there are strategies to reduce the cost of space telescopes. They have published a paper presenting their ideas titled “Approaches to lowering the cost of large space telescopes.” The lead author is Ewan Douglas, an Assistant Professor of Astronomy at the University of Arizona, Steward Observatory. They presented their paper at the SPIE Optics + Photonics 2023 conference in August. 

The economic paradox of space telescopes

The scientific benefits of large space telescopes are undeniable. They offer unparalleled views of the universe that cannot be obtained by any other means. But they also come with a high financial and logistical burden. They can never be cheaper than ground-based telescopes, but ground-based telescopes have limitations that space telescopes can overcome.

No one wants to give up the scientific progress that comes from powerful space telescopes. But it is hard to ignore the criticisms that they are getting too expensive. Detailed in a press release, Douglas and his co-authors have some suggestions on how we can continue to make new discoveries with space telescopes while making the cost more manageable.

The researchers' study centers on a theoretical 6.5-meter optical telescope designed to function in space at ambient temperatures. This dimension is identical to the mirror size of the James Webb Space Telescope. The study outlines how certain technologies have become more affordable and how previously cutting-edge technologies are now readily available. The study also points out that spacecraft like SpaceX's Starship make it possible to launch telescopes with larger primary mirrors without the need for intricate, high-cost mirrors like those in the James Webb telescope.

Leveraging lower technological costs and affordable launch capabilities

The authors note that the cost of ground-based telescopes fell considerably after the 1980s. They argue that advancements in optics, commercial electronics, and the advent of spacecraft like SpaceX's Starship could similarly reduce the costs of space telescopes. This could make large space observatories more financially accessible, falling between the cost projections for space and ground-based observatories.

Today's launch vehicles, like the Ariane 5 that carried the JWST, impose severe size limitations on telescope mirrors, necessitating complex and expensive segmented designs. SpaceX's Starship, however, could accommodate a 6.5-meter monolithic mirror, slashing both costs and complexity.

A new material reality

Unlike the beryllium and gold-coated mirror of JWST, researchers suggest borosilicate glass—a material that's not only cheaper but also offers excellent thermal resistance and malleability. Adaptive optics technology, previously limited to ground-based telescopes, could make this feasible.

Software and spacecraft synergy

As technology evolves, so does the software running these sophisticated telescopes. No longer reliant on niche, costly software, many of today's space missions operate on commercial off-the-shelf electronics and common operating systems—think Linux on the Mars Ingenuity Helicopter.

An orbital change-up

TESS, a space telescope in a 13.7-day period in High Earth Orbit, demonstrates that alternative orbits could lower costs while offering thermal stability and continuous sky coverage. TESS's orbit is expected to last for decades without propulsion, presenting an enticing alternative to the sun-Earth L2 orbit where JWST resides.

Streamlining design processes

Not all cost-saving measures are high-tech. Document management and efficient communication, often overlooked, can make a substantial difference in multi-decade projects requiring collaboration among thousands of skilled individuals.

Douglas and his colleagues aren't merely hypothesizing; some of these innovations have already been implemented in SmallSats, CubeSats, and even the upcoming Nancy Grace Roman Space Telescope.

While this paper offers a tantalizing peek at what the future could hold, it's evident that the road to more cost-effective space telescopes is being paved. The team promises more insights in future papers, particularly concerning the detailed designs and environmental requirements for borosilicate mirrors.

As we continue to look toward the stars, it's imperative to also keep our feet—and budgets—on solid ground. If these researchers have their way, we could be in for an era of astronomical discoveries without the astronomical costs.

The study is also available on arXiv preprint server

Study 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.

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