NASA starshade would enable astronomers to directly image rocky exoworlds

NASA-led researchers propose a hybrid telescope called HOEE, which would use a starshade to directly image rocky exoplanets. The starshade, positioned 175,000 km away in an elliptical orbit, would block starlight to enable optical observations of nearby systems. The device would feature 48 petals and a 50-meter central disk, and could be repositioned with high precision. The team has applied for funding to develop the concept, aiming for a 2027 grant. The starshade would allow ground-based telescopes to observe exoplanets in optical light, which is currently not possible with existing space-based instruments. The concept could detect exoearth within the first minute of observation and help identify chemical signatures of life.

• The starshade would block starlight to reveal exoplanets, which would be billion times fainter than the star itself.
• The hybrid telescope would use an occulter, a starshade with 48 petals and a central disk, to create a perfect shadow over ground-based telescopes.
• The starshade would be repositioned within 6 meters of accuracy using microthrusters powered by hot hydrogen gas.
• The team has applied for Phase B NIAC funding, hoping to receive it by 2027.
• The starshade would allow astronomers to see entire exoplanetary systems and separate planet images from the host star.
• The starshade would enable detection of an exoearth within the first minute of observation and help identify life's chemical signatures.

The concept relies on a long elliptical orbit to match Earth's rotation, using chemical propulsion for station-keeping and solar electric propulsion for retargeting. The starshade would hover directly on the line of sight between the ground telescope and the target star, offering continuous alignment. The design would involve an inflatable structure to keep the total launch mass under 1,500 kg. The starshade would suppress stellar glare before it enters the atmosphere, allowing direct observation of exoplanets. The idea is to look for active stars that flare frequently enough to create auroras on rocky planets orbiting solar-type stars. The project is expected to cost around a billion dollars.

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