This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: What do you do when the observation you need comes around once a year? Well, preparation is key, but this is the awkward truth about finding another Earth.
When a planet crosses the face of its star, a sliver of starlight passes through its atmosphere on the way to us, and the gases there absorb their own particular colors. Read the spectrum carefully and you can list what the air is made of: oxygen, ozone and water vapor, the things that would make you sit up. For a genuine Earth-type planet orbiting a star like the sun, that signal amounts to roughly 1 part per million.
It's a very faint fingerprint on a very bright light. Astronomers have a standard answer to faint signals: Collect the same measurement repeatedly until the noise averages itself away. It works beautifully for hot Jupiters, which whip around their stars every few days and hand you a fresh transit most weeks.
But an Earth at an Earth-like distance from its star transits once per orbit, and an Earth-like orbit takes a year. Wait a decade and you have 10 attempts. Stacking is no longer the plan because each single transit has to be good enough on its own.
You need to catch enough photons in those few hours, and that means a telescope around 30 meters across (98 feet), in space. JWST's mirror is 6.5 meters (21 feet), it took decades, and it had to unfold itself on arrival in orbit. Jian Ge and colleagues at Shanghai Astronomical Observatory, working with collaborators in China and Spain, have proposed an alternative.
Their concept, Life 2.0, is 900 1-meter telescopes (3.3 feet) flying as a distributed array. Each carries a miniature spectrograph and a very low-noise detector; each observes the transit independently, each is calibrated on its own, and the spectra are combined afterward. The result collects light like a 30-meter aperture (98 feet) without anybody having to build one.
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