Direct imaging of planetary systems around other stars to detect and characterize Earth-like planets that could sustain life requires telescopes that are larger and more stable than any previous telescope.
Because an Earth-like planet is 10 billion times fainter than its star, it is necessary to block nearly all of the star’s light before we can see the planet. The resulting glare will “hide” the planet. To detect an Earth-like planet with a coronagraph requires a telescope whose optical quality is stable to better than 10 picometers per 10 minutes – which is about 1 million times smaller than the width of a human hair.
According to NASA Predictive Thermal Control (PTC) project lead, Philip Stahl (MSFC/ST10), “Picometers are very small, and measuring telescope stability to picometer levels is virtually impossible. Therefore, to predict on-orbit performance we perform STOP analysis – we model a telescope’s Structural Thermal Optical Performance based on its measurable physical properties.”
The PTC project team at NASA’s Marshall Space Flight Center (MSFC) has demonstrated technology to enable ultra-stable thermal control in large space telescopes. MSFC and its industrial partner L3Harris of Rochester, NY designed, built, and integrated a 25-zone active thermal control system with a 1.5-meter Ultra-Low Expansion (ULE©) glass mirror. Since 2011, NASA’s Astrophysics Division has invested in mechanical and thermal technology to design, build and control ultra-stable telescopes. Technologies developed by PTC and its precursor study – Advanced Mirror Technology Development (AMTD) – are under consideration for the Roman Space Telescope as well as several potential future missions.
To read the complete article, go to: https://science.nasa.gov/technology/technology-highlights/controlling-the-temperature-of-telescope-mirrors-to-search-for-earth-like-planets.