Configurable Aperture Space Telescope (CAST)

Space telescopes are valuable scientific assets. The difficulty to access them imposes very expensive testing and components reliability requirements that are critical for mission functionality. We propose to demonstrate a high-performance modular space telescope utilizing NovaWurks’ HiSat interchangeable architecture. The concept enables the construction, repair, and upgrade of an optical space telescope, extending the telescope’s lifetime and enabling multidisciplinary scientific investigations. NovaWurks’ modular architecture extends also to the payload design, enabling back-end instrument switch-outs, repairs, and upgrades. Our specific focus with this CIF is to demonstrate the benefits and performance of a Configurable Aperture Space Telescope, CAST. Specifically, this work proposes to grow the telescope aperture by adding and re-phasing mirror segments and evaluating their optical quality. In this CIF, we also evaluate how the telescope’s performance drives requirements on the HiSat framework.

Starting with TRL 2 (technology concept and/or application formulated) we will aim to reach TLR 3 (analytical and experimental critical function and/or characteristic proof of concept) in Sept 2015 by demonstrating a 2x2 mirror system to validate our optical model and error budget, provide strawman mechanical architecture and structural damping analyses, and derive future satlet-based observatory performance requirements.

CAST merges existing technology (segmented telescope architecture) with emerging technology (smartly interconnected modular spacecraft).

A one-meter visible-wavelength space telescope with 0.1 arcsec spatial resolution can resolve 70 km-sized solar magnetic flares and sunspots, detect 15 m diameter 0.1 albedo Near Earth Objects at 0.10 AU from Earth, resolve Titan and the largest asteroids, map star-formation regions, measure transiting exoplanet atmospheres and monitor AGNs and galaxy dynamics. Such an observatory in Low Earth Orbit would have a 10cm/pixel footprint on Earth. With the retirement of the Hubble Space Telescope (HST) in a few years, access to a visible-wavelength sub-arcsecond imaging platform from space will be in high demand. Its successor, the James Webb Space Telescope (JWST), a 6.5 m, is poised to provide 0.07 arcsec resolution at 2 microns, but it has a fixed instrument complement that is non-changeable. A segmented 1-m in space, providing 7-10x better spatial resolution that can be obtained from the ground, achieves excellent science today. Add the ability to grow the aperture for better sensitivity and this adaptive telescope concept advances numerous NASA science goals. A space-based 1-meter telescope maintains “better than seeing” spatial resolution out to shorter wavelengths, the ultraviolet, which has no ground-based equivalent, and for which, relaxed optical requirements (e.g. 1 arc performance) still provides new science. This is very exciting as there is a lack of a dedicated UV space telescope on NASA’s mission portfolio for the coming decades.

We are exploring enlarging a spherical primary mirror with a spherical seconday mirror with a totally modular approach. The required correcting optics and instrumentation to co-phase and align the segments are required to conform to the modular requirement. 

• How far we can grow the aperture before requiring a change in the secondary mirror 
• What FOV for each primary diameter can be corrected at the diffraction limit.
• Trade Sensitivity vs. FOV for the design suite that shares the same radius of curvature

Mechanically, we will explore limitations and benefits of a hyper-segemented structure.

• Does the structure have complex modes that real-time co-phasing algorithms are not sufficient
• Evaluation of structural stiffness and dampening while maintaining good image quality
• Mass estimate compatibility with satlet architecture