Most of the more than 2000exoplanets we’ve discovered thus far were spotted using the transit method. That means we observed slight drops in light from their parent stars as the planets passed in front. This is a fairly effective way to detect planets, but it offers little or no data on what their atmospheres are like, or even if they have atmospheres. Since we believe some sort of atmosphere to be essential for complex life, this is an important question. So do we have to wait for the next generation of super-telescopes? Maybe not.
There are some powerful telescopes set to come online in the next few years that could help us study the atmosphere of exoplanets. For example, the James Webb Space Telescope will launch in 2018 with an array of exoplanet-detection instruments. It’s also a hugely expensive project with costs nearing $10 billion. According to a team of European scientists, it might not be as hard as we thought to study exoplanet atmospheres. The Twinkle project aims to launch a small satellite with a total mission cost of about £50 million ($79 million).
According to mission scientists, the Twinkle satellite would reside in low-Earth orbit and use a small mirror just 50 centimeters in diameter to observe the infrared signature from exoplanets up to several hundred light years away. This really is a tiny satellite compared to what we’ve been using to study the universe. Hubble’s primary mirror is 8 feet across and the Webb telescope will have a gigantic segmented mirror 21 feet across.
The Twinkle satellite won’t be ideal for detecting Earth-like atmospheres, but it could be good enough to study so-called “hothouse” worlds. Those are planets that orbit very close to their stars. These planets would have very strong infrared signatures that could be studied in detail with the modest mirror aboard the proposed Twinkle satellite. For example, the nearby exoplanet 55 Cancri e has a surface temperature of 3,700 degrees Fahrenheit. The infrared readings from such a planet could allow Twinkle to reconstruct molecular composition and weather.
Whether or not Twinkle becomes a reality depends on funding.A previous version of Twinkle was proposed to the ESA, but wasn’t chosen for launch. This one slims down the budget by using off-the-shelf components and low-Earth orbit rather than delivery to Lagrangian point L2. $79 million is cheap for a space mission, so it’s plausible that one or more organizations will be interested in making it happen. It could take as little as 3-4 years to launch Twinkle, the team says.