NASA Starshade Would Enable Astronomers To Directly Image Rocky Exoworlds

A NASA-led team is developing a hybrid telescope called the Hybrid Observatory for Earth-like Exoplanets (HOEE), which would use a starshade to block out the light from a parent star, enabling direct imaging of rocky exoplanets. The starshade, positioned 175,000 km away in an elliptical Earth orbit, would be used with the European Southern Observatory's Extremely Large Telescope, scheduled to begin scientific observations in northern Chile by late 2030. The starshade would create an artificial eclipse to allow ground-based observers to see reflected light from exoplanets. The team has applied for Phase B NIAC funding, hoping to receive it by 2027. The starshade would feature 48 petals, each 24.5 m long, and a 50-m-diameter central disk, and could be repositioned within six meters of accuracy using microthrusters powered by hot hydrogen gas. The concept relies on a long elliptical astro-stationary orbit to match Earth’s rotation, using chemical propulsion for station-keeping and solar electric propulsion for retargeting. HOEE would suppress stellar glare before it enters the atmosphere, enabling sharper images and the detection of exoearth within the first minute of observation. The starshade would also allow astronomers to distinguish planet images from other earth-sized planets and the host star. The idea is that the starshade would efficiently collapse into a standard launch vehicle’s payload, keeping the total launch mass under 1,500 kg. Airapetian believes the project would cost around a billion dollars.

• The starshade would block out the parent star's light to enable directly imaged optical observations of nearby solar systems and rocky exoplanets.
• The starshade would create an artificial eclipse to occult the parent star’s light, allowing ground-based observers to receive reflected light from the exoplanet.
• The starshade would be positioned 175,000 km away in an elliptical Earth orbit and could be repositioned within six meters of accuracy using microthrusters powered by hot hydrogen gas.
• HOEE would suppress stellar glare before it enters the atmosphere, enabling sharper images and the detection of exoearth within the first minute of observation.
• The starshade would allow astronomers to distinguish planet images from other earth-sized planets and the host star.
• The concept relies on a long elliptical astro-stationary orbit to match Earth’s rotation, using chemical propulsion for station-keeping and solar electric propulsion for retargeting.
• HOEE would also enable a definitive path to identifying the chemical signatures of life.
• Airapetian wants to find active stars that are flaring frequently enough to create extrasolar auroras on rocky planets orbiting solar-type F, G, and K stars.
• The starshade would hover directly on the line of sight between the ground telescope and the target star, offering continuous fine alignment on the celestial target.
• The starshade would be capable of being repositioned within six meters of accuracy using microthrusters powered by hot hydrogen gas.
• The starshade would efficiently collapse into a standard launch vehicle’s payload, keeping the total launch mass under 1,500 kg.
• Airapetian believes the project would cost around a billion dollars.

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