This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Finding an Earth-like world beyond the solar system is the holy grail of exoplanet research, and the field has seen remarkable technological advances in detecting and studying exoplanets since the first confirmed exoplanet around a sun-like star was discovered in 1995. These advances include ground- and space-based telescopes, notably the James Webb Space Telescope.
Although astronomers have already directly imaged some exoplanets, directly imaging Earth-like planets around sun-like stars remains a major technological challenge, primarily because these planets are extremely faint compared with their host stars and appear very close to them in the sky. But a proposed mission called the Habitable Worlds Observatory (HWO) could advance progress toward not only observing but directly imaging Earth-like exoplanets. While HWO has been in the works for about 10 years now, it's still not slated to launch until sometime in the 2040s.
In the meantime, researchers are developing new engineering concepts for this highly anticipated telescope. These concepts were discussed in a June 2026 study published in the Journal of Astronomical Telescopes, Instruments, and Systems and hold the potential to continue HWO's development well in advance of its launch. For the study, the researchers introduced engineering concepts called Exploratory Analytic Cases (EACs) designed to balance the demands of the science goals with the engineering needs.
The purpose of this study was to discuss the first three of five EACs regarding HWO's architecture design, focusing on telescope type, size and whether an on- or off-axis design is needed. The telescope size includes the mirror diameter in meters, and the type of telescope includes the mirror and aperture design, with the study focusing on inscribed, circumscribed, round and outer diameter. For example, inscribed includes the inner baseline measurement while circumscribed includes the measured outer region that holds a set of mirrors.
A round mirror is how it sounds, while an outer diameter mirror denotes the maximum edge-to-edge measurement. The difference between on-axis and off-axis design is that the former has all of the components within the field of view of incoming light, obstructing a portion of the view, while the latter has all of its components outside the field of view, resulting in an unobstructed view. For the EACs, the researchers designed EAC1 as having a 6-m inscribed / 7.2-m circumscribed, off-axis design; EAC2 with a 6-m round, off-axis design; and EAC3 having an 8-m outer diameter, on-axis design.
In the end, the researchers favored the off-axis design to allow greater light-gathering operations, along with focusing on a larger aperture size to enable greater light-collecting area. Another design consideration the researchers recommended was temperature properties, which influence light-collecting and overall telescope operations. This is especially relevant to the coronagraph instrument (CI), which blocks out the star's glare, enabling the direct imaging of orbiting exoplanets.
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