Mission Concept for Direct Multipixel Imaging and Spectroscopy of Exoplanets Using the Solar Gravity Lens
Abstract
Delivering a moderately sized optical telescope to the Solar Gravity Lens (≥550 AU from the Sun) enables direct, multipixel (megapixel) imaging and high-resolution spectroscopy of a habitable Earth-like exoplanet situated up to 100 light years. It is possible to achieve an amazing, kilometer-scale resolution on its surface, enough resolve surface features and signs of habitability. While exciting, this opportunity presents immense engineering challenges both from an instrument development and mission, spacecraft design perspective. In this paper we deal with the later issue and propose a mission, spacecraft concept, relying on near-term technologies, capable of delivering a moderately sized optical instrument to the SGL in less than 50 years from launch. Building upon various previous studies (from JPL, APL, KISS, NASA Innovative Advanced Concepts), the mission design relies on a Solar-Thermal Propulsion (STP) based kick stage, used deep in the gravity well of the Sun, allowing the SGL probe to achieve escape velocities in excess of 20 AU/Yr. In comparison the escape velocity of Voyager 1 is approximately 3.7 AU/Yr. To achieve large Delta-Vs at the perihelion, the STP engine concept utilizes heat from proximity to the Sun to heat up the Hydrogen (at 3400k) and expel it at high velocity, delivering an ISP of 1200-1350s. The probe, as designed with help JPL's Team-X, is a RTG based probe with 50 kg of Instruments (mainly the Optical Telescope), totaling to a wet mass of 600 kg. The optical telescope is also used as optical communications terminal for downlinking data to Earth from the SGL. Given the early nature of this study, sensitivity analysis are performed, showing escape velocity contours vs. spacecraft mass, time of flight, launch year and launch vehicle types. Mission trajectories using other more advanced propulsion technologies like Nuclear Electric Propulsion (NEP) are also evaluated and compared to the above STP based baseline. Finally, impact of various space and time constraints from specific SGL exoplanet target, on mission design and mission concept of operations, are also discussed.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E.123A