Summary: A meter-class telescope with a coronagraph to block solar light, placed in the strong interference region of the solar gravitational lens (SGL), is capable of imaging an exoplanet at a distance of up to 30 parsecs with a few 10 km-scale resolution on its surface.
Original author and publication date: Brian Wang – July 5, 2020
Futurizonte Editor’s Note: We will soon be able to identify islands of the size of Java or Cuba in exoplanets. How soon before we detect cities? And how soon before they detect us?
From the article:
Executive Summary: Innovations and Advanced Concepts Enabled
Direct multipixel imaging of exoplanets requires significant light amplification and very high angular resolution.
With optical telescopes and interferometers, we face the sobering reality: i) to capture even a single-pixel image of an “Earth 2.0” at 30 parsec (pc), a ~90 kilometer (km) telescope aperture is needed (for the wavelength of l = 1 µm); ii) interferometers with telescopes (~30 meter) and baselines (~1 kilometer) will require integration times of ~10,000 years to achieve a signal-to-noise ratio, SNR=7 against the exozodiacal background.
These scenarios involving the classical optical instruments are impractical, giving us no hope to spatially resolve and characterize exolife features.
To overcome these challenges, in a NIAC Phase II study they examined the solar gravitational lens (SGL) as the means to produce direct high-resolution, multipixel images of exoplanets.
The SGL results from the diffraction of light by the solar gravitational field, which acts as a lens by focusing incident light at distances >548 AU behind the sun (Figure 1). The properties of the SGL are remarkable: it offers maximum light amplification of ~100 billion and angular resolution of ~10 billionth of ab arcsec, for l = 1 µm. A probe with a 1-meter telescope in the SGL focal region (SGLF), namely, in its strong interference region, can build an image of an exoplanet at 30 pc [100 light years] with 10-km scale resolution of its surface, which is not possible with any known classical optical instruments. This resolution is sufficient to observe seasonal changes, oceans, continents and surface topography.
They reached and exceeded all objectives set for our Phase II study:
- They developed a new waveoptical approach to study the imaging of exoplanets while treating them as extended, resolved, faint sources at large but finite distances.
- They designed coronagraph and spectrograph instruments needed to work with the SGL.
- They properly accounted for the solar corona brightness.
- They developed deconvolution algorithms and demonstrated the feasibility of high-quality image reconstruction.
- They identified the most effective observing scenarios and integration times.
As a result, they are now able to estimate the SNR for light from realistic sources in the presence of the solar corona. They have proven that multipixel imaging and spectroscopy of exoplanets up to 30 pc [100 light years] are feasible. By doing so, they were able to move the idea of applications of the SGL from a domain of theoretical physics to the practical mainstream of astronomy and astrophysics. Under a Phase II NIAC program, they confirmed the feasibility of the SGL-based technique for direct imaging and spectroscopy of an exoplanet, yielding technology readiness level (TRL) of TRL 3.