Roman Telescope to Block Starlight in Search for Hidden Worlds Nearby

When scientists attempt to image a planet orbiting a distant star, they face a formidable challenge: the star can be millions or even billions of times brighter than the planet, causing the small world to be lost in its glare.

To address this, NASA’s new Nancy Grace Roman Space Telescope carries a sophisticated instrument called a coronagraph, designed to block most of the star’s light while allowing the fainter light from nearby planets to reach the camera. Scientific American likens the concept to placing a hand in front of the sun to block its glare and see the surroundings more clearly.

However, the technology is far more complex than a simple light-blocking disk.

The instrument employs optical masks and flexible mirrors whose shapes can be adjusted with extreme precision using thousands of micro-actuators to compensate for vibrations and minute distortions in the light.

According to NASA, the technology aims to detect planets that may be up to 100 million times fainter than their host stars, representing an improvement of 100 to 1,000 times over previous space-based coronagraphs.

Finding direct images of Earth-like planets will not be the primary mission of the Roman telescope. The experimental instrument is mainly designed to image large gas giant planets similar to Jupiter, as well as the dust and gas disks from which planetary systems form.

It can also spectrally analyze a portion of the light coming from these planets, providing scientists with preliminary information about the materials present in or around them. The broader goal is to test technologies that NASA may use in the future with more powerful observatories capable of imaging Earth-like planets around Sun-like stars.