Key Takeaways:

  1. American astronomers widely support using advanced rockets like SpaceX’s Starship for NASA’s future observatories to overcome mass and volume constraints.
  2. Large-scale rockets like Starship offer increased payload capacity at reduced costs, potentially revolutionizing space exploration.
  3. The National Academies’ Astro2020 survey highlights the need for large telescopes on large launchers, aligning with NASA’s plans for future observatories.
  4. Utilizing rockets such as Starship or New Glenn could lead to streamlined telescope designs, cost reductions, and possibly expedited mission timelines.
  5. Despite uncertainties, the transformative potential of new launchers like Starship and New Glenn signals a paradigm shift in space mission capabilities.
This slide from a presentation by Lee Feinberg, an engineer at NASA’s Goddard Space Flight Center, shows concepts for a space telescope fitting inside the volumes of a SpaceX Starship rocket and a Blue Origin New Glenn rocket.

A consensus exists among prominent American astronomers regarding the utilization of groundbreaking lift capabilities provided by large-scale new rockets such as SpaceX’s Starship for NASA’s forthcoming generation of significant observatories.

For instance, deploying a successor to the James Webb Space Telescope (JWST) via Starship could liberate the mission from cumbersome mass and volume limitations, which typically escalate complexity and expenses, as outlined by a trio of astronomers during a recent session with the National Academies’ Committee on Astronomy and Astrophysics.

“The increased mass and volume capabilities, at reduced costs, expand the range of design possibilities,” stated Charles Lawrence, NASA’s Jet Propulsion Laboratory’s chief scientist for astronomy and physics. “We aim to capitalize on this opportunity.”

Lawrence’s presentation focused on the influence of large, new launch vehicles on future astronomy ventures. He delivered the presentation last week, alongside Martin Elvis, an astronomer at the Harvard-Smithsonian Center for Astrophysics, and Sara Seager, an astrophysicist and planetary scientist at MIT. The three authors also penned a paper earlier this year in Physics Today, exploring this subject.

The Starship’s ability to transport over 100 metric tons into space, at a significantly reduced cost per kilogram compared to existing rockets, is well-documented to revolutionize the broader space industry. With a diameter of 9 meters (of which 8 meters could accommodate payload), the Starship nearly doubles the payload volume of any existing rocket.

Astronomers are increasingly considering the integration of rockets like the Starship or Blue Origin’s New Glenn, boasting a slightly smaller 7-meter payload fairing, to launch the next era of large space telescopes.

Large Telescopes on Large Launchers

In 2021, the National Academies issued a comprehensive review of the top priorities in astronomy and astrophysics for the US scientific community. Known as Astro2020, this survey outlined a roadmap for NASA to dedicate much of the 2020s to developing technologies and designs for the subsequent series of “great observatories,” following Hubble, Chandra, James Webb, and the Roman Space Telescope slated for launch in 2027.

NASA’s policy aligns with the recommendations of the scientific community. The plan envisages commencing development of these new telescopes around the end of the decade. The first proposed is the Habitable Worlds Observatory, a large telescope comparable in size to Webb, featuring a primary mirror approximately 6 meters (20 feet) in diameter and equipped with a coronagraph or a starshade to block starlight, facilitating direct observations of exoplanets. This capability is absent in Webb.

The Habitable Worlds Observatory, capable of detecting light across infrared, visible, and ultraviolet wavelengths, would focus on studying Earth-like exoplanets to identify those with conditions conducive to life. Subsequently, NASA plans to launch equally ambitious far-infrared and X-ray telescopes to explore the formation of stars, black holes, and galaxies, as recommended by scientists in 2021.

These ambitious multibillion-dollar missions are not scheduled for launch until the 2040s. This timeline is considered challenging, as highlighted by Elvis and his colleagues in their paper published earlier this year. “A newly qualified PhD today will be nearing retirement by the time the first observatory is launched.”

NASA lacks the necessary budget to accelerate the launches, and the new telescopes require advancements in optics, detectors, and materials to be feasible.

The advent of large, new rockets could potentially alleviate some of these technological challenges, scientists suggest. This could lead to streamlined designs, cost reductions, and possibly expedited development and construction of the next great observatories. Perhaps the launch timeline need not extend into the 2040s, considering the initial estimate from the National Academies indicating an $11 billion cost for the Habitable Worlds Observatory.

“Designs are heavily influenced by launch vehicle constraints in terms of volume and mass available for the desired orbit, inevitably leading to increased complexity and costs,” Elvis explained.

Elvis recommends that engineers reevaluate their assumptions about the rockets available for launching these new telescopes into space in the coming years.

“We propose studies of all three Astro2020 flagships, their payloads, and spacecraft within this new Starship paradigm or any large launcher paradigm to capitalize on the expanded design space,” Elvis stated last week.

“The primary questions revolve around the feasibility of the significant cost savings we’ve outlined and whether Astro2020 can be expedited as a result,” he added.

Constraints of Rocket Capacity

To illustrate the limitations imposed by a rocket’s capacity, let’s revisit the James Webb Space Telescope. Webb had to fit within the roughly 5-meter-diameter payload fairing of an Ariane 5 rocket, which boasted the largest payload envelope among available launch vehicles during Webb’s initial design phase. Consequently, the telescope’s 18 individual primary mirror segments had to fold, and engineers devised a five-layer sunshade, resembling a tennis court in size, made of lightweight but efficient insulation to shield the telescope from the Sun’s heat and light. All these measures were necessary to ensure Webb’s compatibility with its rocket during its 2021 launch.

With a larger rocket like Starship or New Glenn, future telescopes could utilize a monolithic mirror, eliminating the need for segmented mirrors. While there are scientific arguments favoring segmented mirrors for certain applications, the verdict remains undecided. Moreover, instead of requiring a complex deployable sunshade prone to failure, engineers could attach a larger rigid sunshade encompassing the entire telescope.

The James Webb Space Telescope unfolded origami-style over the course of several weeks, transforming itself from launch configuration into a fully deployed observatory.

Launching a telescope atop a substantial rocket like the Starship could result in thicker and heavier mirrors, thus simplifying their manufacturing and polishing processes, according to scientists. With a heavier rocket, spacecraft designers could incorporate larger solar panels to enhance power generation. This surplus power could facilitate the use of more economical electronics with increased redundancy, as per Elvis.

Lee Feinberg, the optics manager for Webb and a co-chair of the technical assessment group examining the Habitable Worlds Observatory, stressed the crucial lesson learnt from the JWST regarding the necessity of comprehensively understanding rockets beforehand. Flexibility remains paramount, especially considering the considerable timeframe involved in mission planning.

The uncertainty surrounding future rocket developments is evident. For the Roman Space Telescope’s upcoming launch, NASA initially anticipated a selection of rockets. However, unforeseen delays with emerging rockets such as United Launch Alliance’s Vulcan and Blue Origin’s New Glenn led to SpaceX securing the contract for a Falcon Heavy launch.

Feinberg emphasized the necessity of adaptability in rocket choices during recent discussions with SpaceX and Blue Origin. While New Glenn and Starship exhibit promise, other options like NASA’s Space Launch System are deemed prohibitively expensive.

Considering Starship’s broader diameter, studies indicate its potential suitability for various telescope designs, including those proposed for the Habitable Worlds Observatory. Feinberg underscored Starship’s adaptability during a recent meeting.

Despite Starship and New Glenn’s pending orbital debut and requisite flights, SpaceX and Blue Origin have ample time to establish their rockets’ reliability before NASA entrusts them with flagship missions.

Seager highlighted the importance of evaluating Starship’s track record before its potential deployment for NASA missions. Although pricing for Starship or New Glenn launches in the 2030s or 2040s remains uncertain, they are anticipated to represent a fraction of the overall mission cost.

Launching telescopes towards the L2 Lagrange point necessitates refueling Starship in orbit. NASA’s optics experts express concerns regarding potential contamination of a telescope’s mirrors during the refueling process. Moreover, telescopes awaiting refueling in low-Earth orbit may be exposed to temperature fluctuations, posing a risk of damage.

Understanding these challenges will be imperative in the years ahead. While SpaceX is expected to provide insights as they refine their processes, uncertainties remain. On the New Glenn front, there is optimism regarding its capability to reach the L2 point.

Feinberg envisions Starship accommodating mirrors as large as 10 to 12 meters wide, enabling NASA to pursue even more ambitious space telescope designs. New Glenn’s capacity is estimated to be around 8 meters. Larger mirrors enhance a telescope’s collecting area, improving its ability to detect fainter celestial objects.

Elvis emphasized the transformative impact of these launchers on space mission design and cost considerations. The advent of Starship and New Glenn heralds a paradigm shift in space exploration capabilities.

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