Detecting an Earth-like planet presents a significant challenge due to the fact that the planet is about 10 billion times dimmer than its parent star. This means that the faint light reflected from the planet is extremely difficult to collect, as it is overshadowed by the brightness of the star. To address this issue, it is essential to block nearly all of the star’s light in order to effectively capture the light emitted by the planet.
One method for blocking the starlight is through the use of a coronagraph. However, even with this technology, the telescope’s optics must be carefully controlled to prevent any instability that could lead to leakage of starlight. Factors such as misalignment between mirrors or changes in the mirror’s shape can result in glare that obscures the planet, making it even more challenging to detect.
In order to successfully detect an Earth-like planet using a coronagraph, precise control of both the telescope and the instrument’s optical quality, or wavefront, is necessary. This level of precision must reach an extraordinary level, on the order of 10s of picometers (pm), which is approximately the size of a hydrogen atom. Achieving this level of control is critical in order to be able to effectively capture the faint light emitted by an Earth-like planet.