Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravity Lens Mission (1802.08421v1)

Abstract: The remarkable optical properties of the solar gravitational lens (SGL) include major brightness amplification (~1e11 at wavelength of 1 um) and extreme angular resolution (~1e-10 arcsec) in a narrow field of view. A mission to the SGL carrying a modest telescope and coronagraph opens up a possibility for direct megapixel imaging and high-resolution spectroscopy of a habitable Earth-like exoplanet at a distance of up to 100 light years. The entire image of such a planet is compressed by the SGL into a region with a diameter of ~1.3 km in the vicinity of the focal line. The telescope, acting as a single pixel detector while traversing this region, can build an image of the exoplanet with kilometer-scale resolution of its surface, enough to see its surface features and signs of habitability. We report here on the results of our initial study of a mission to the deep outer regions of our solar system, with the primary mission objective of conducting direct megapixel high-resolution imaging and spectroscopy of a potentially habitable exoplanet by exploiting the remarkable optical properties of the SGL. Our main goal was to investigate what it takes to operate spacecraft at such enormous distances with the needed precision. Specifically, we studied i) how a space mission to the focal region of the SGL may be used to obtain high-resolution direct imaging and spectroscopy of an exoplanet by detecting, tracking, and studying the Einstein ring around the Sun, and ii) how such information could be used to detect signs of life on another planet. Our results indicate that a mission to the SGL with an objective of direct imaging and spectroscopy of a distant exoplanet is challenging, but possible. We composed a list of recommendations on the mission architectures with risk and return tradeoffs and discuss an enabling technology development program.

• The paper introduces a mission concept that uses the solar gravity lens to achieve unprecedented multipixel imaging and spectroscopy of exoplanets.
• It details advanced techniques like rotational deconvolution to mitigate image blurring from gravitational lensing.
• The study addresses engineering challenges in propulsion, navigation, and adaptive control for spacecraft operating beyond 600 AU.

Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravity Lens Mission

The exploration of exoplanets has garnered interest in recent years, especially regarding the direct imaging and spectroscopic analysis of potentially habitable worlds. The paper "Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravity Lens Mission," under the auspices of the NASA Innovative Advanced Concepts (NIAC) program, elaborates on a sophisticated mission concept that leverages the remarkable optical properties of the Solar Gravity Lens (SGL) for observing distant exoplanets.

Optical Principles and Feasibility

The SGL functions as a powerful natural telescope that can theoretically enable the direct imaging of exoplanets at impressive resolutions. The amplification of brightness (~10^11) and fine angular resolution (~0.1 nas) posited by the SGL make it feasible to observe exoplanets up to 100 light years away. The SGL compresses the complete image of an exoplanet into a region with a diameter of approximately 1.3 km, allowing kilometer-scale resolution imagery that can detect surface features, potentially including signs of habitability.

Mission Architecture and Instrumentation

The paper details several mission architectures aimed at achieving these ambitious goals, involving either a single spacecraft or clusters of smaller spacecraft, operating at heliocentric distances beyond 600 AU. The use of a one-meter telescope equipped with a coronagraph is suggested to reduce the interference from solar light, ensuring clearer imaging by the SGL.

Imaging and Deconvolution Techniques

Crucial to the success of the mission is the imaging process, which must contend with the significant image blurring inherent in gravitational lensing. The authors discuss direct and rotational deconvolution methodologies to extract high-resolution images from the data. Rotational deconvolution can provide pixel resolution across planetary surfaces by leveraging planetary motion and changes in light patterns.

Practical and Technical Challenges

The paper acknowledges the significant engineering challenges involved in such a mission. These include achieving the needed propulsion and long-term navigation for spacecraft operating at immense distances, capturing data over extended periods, and integrating this information for coherent image reconstruction. Additionally, the influence of solar corona and the Sun's motion within the solar system's barycentric reference frame are considered, necessitating sophisticated adaptive control and navigation systems.

Prospective Technologies and Outcome

The authors conclude that while challenging, the mission is feasible using currently available high-TRL technologies. By exploiting the SGL, this mission could hypothetically achieve extensive multipixel resolutions of exoplanets much sooner than conventional methods could. This mission is poised not only for mapping uncharted exoplanets but also represents a substantial progression in remote sensing capabilities, offering profound implications for future astrophysical inquiries and the search for extraterrestrial intelligence.

Future Developments

The research proposes a need for continued development in propulsion systems, spacecraft autonomy, and advanced imaging techniques. A successful mission would greatly expand our understanding of exoplanet environments and potentially habitable worlds, providing unprecedented insight decades before other technologies could achieve similar results. Conclusively, the mission advances the technological envelope for interstellar exploration and heralds a leap in our cosmic observational scale.