NASA study proposes optical interferometry to map exoplanet continents

A NASA NIAC study led by Paul Stankus of Brookhaven Science Associates outlines a method to image continents on Earth-like exoplanets using formation-flying optical interferometers. Two spacecraft 100 km apart would suppress starlight by a factor of 10^10 and combine planet light to achieve ~1 microarcsecond resolution, enough to resolve surface features at 10 parsecs. European projects like LIFE and VLTI upgrades are pursuing complementary approaches.

Bottom line — Stankus's NIAC Phase I study gives a concrete architecture for exoplanet cartography, with lab tests underway at Brookhaven.

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• The design uses 'dynamic hierarchical nulling' to separate starlight from planet light, preserving the star's beam as a phase reference, per NASA's project page.
• A 100 km baseline at 500 nm yields ~1 µas resolution, enough for a handful of resolution elements across an Earth-sized planet at 10 pc, according to NextBigFuture.
• The concept can scale to longer baselines and more collectors, moving toward Antoine Labeyrie's hypertelescope idea of a flotilla of small mirrors spanning hundreds of kilometres, NextBigFuture notes.
• The European LIFE mission (led by ETH Zurich) uses five spacecraft as a mid-infrared nulling interferometer to characterize atmospheres of terrestrial exoplanets, per Wikipedia.
• A separate study proposes adding a fifth telescope to the Very Large Telescope Interferometer (VLTI) in Chile to directly image exo-Earths in reflected starlight within this decade, Universe Today reports.
• Photon collection remains the binding constraint: integration times may stretch to weeks per target, and space-qualified optical paths must maintain nanometre stability, according to Beyond Tomorrow.
• The study was published July 22, 2026, and is part of NASA's NIAC 2026 selections, with bench demonstrations of photonic nulling stages expected through 2027, per Beyond Tomorrow.

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