Introduction

The concept of aperture synthesis is not limited to radio astronomy; it can also be applied to optical telescopes, albeit with significant challenges. This article explores the feasibility of building a large optical telescope through aperture synthesis, drawing parallels with the successful implementations in radio astronomy.

Aperture Synthesis in Radio Astronomy

The idea of aperture synthesis originated in radio astronomy, where it has been successfully utilized to create virtual telescopes with much larger apertures than those of individual radio telescopes. This technique involves combining signals from multiple antennas to achieve resolving power equivalent to a single antenna of the array’s maximum size, known as the baseline.

Limitations for Optical Interferometry

While aperture synthesis can be applied to optical telescopes, the challenges are significantly greater. The accuracy required for optical interferometry is stringent, as the position and alignment of each telescope must be precise to within 1/4 wave of light, which is 150 nm for visible light. This level of precision is much more difficult to achieve compared to radio astronomy, where an accuracy of a meter or so down to a few millimeters is acceptable.

Technological Challenges

For optical interferometry, the synchronization and coordination of telescopes spread over vast distances, such as across the solar system, present a significant technological hurdle. Using laser rangefinders can help calibrate pointing and synchronize observations for smaller distances, but for interplanetary distances, no feasible method currently exists to accurately measure and reposition telescopes to coordinate observations.

Another proposed solution is the use of a "solar system GPS" to fix positions accurately. However, achieving the necessary mm accuracy across billions of kilometers remains a stretch, making this approach highly challenging.

Possible Solutions for Optical Telescopes

Despite these challenges, there is still hope for implementing aperture synthesis in optical telescopes. One potential approach is to use a flock of smaller aperture telescopes spread throughout the solar system. By synchronizing themselves, these telescopes can present an image far more resolute than any current optical telescope, such as the Hubble or Webb.

Scalability and Synchronization

The scalability and synchronization of these telescopes would be critical. The miniaturization of telescopes and advancements in telecommunications could make it feasible to deploy a network of telescopes across the solar system. Laser communication systems and advanced signal processing techniques could be employed to ensure the synchronization of data from these distributed telescopes.

A flock of smaller aperture telescopes could be strategically placed at various points in the solar system, including planets, moons, and other celestial bodies. Each telescope would capture its own data and then transmit it back to a central processing hub for synthesis into a cohesive, ultra-high-resolution image.

Conclusion

While the concept of building a large optical telescope with aperture synthesis is theoretically possible, the current technological limitations pose significant challenges. However, advancements in technology and innovative solutions, such as the use of smaller, distributed telescopes, may pave the way for realizing this ambitious goal. Further research and development are necessary to overcome the hurdles and make aperture synthesis a reality in the field of optical astronomy.