In addition to molecules, it can also help scientists track the weather on these exoplanets. By measuring precise Doppler shifts in these spectral lines, researchers can determine orbital velocities—in other words, how weather is moving on a planet light-years away. Doing so will require a coronagraph to block out the light coming directly from the exoplanet's star, but no coronagraph is perfect and will always let some starlight through. Higher-resolution spectrographs will make it much easier to separate that "noise" from the signal of the light from an actual planet.

This all sounds great in theory, so why haven't we done it already? Simply put, the technology was too big, too heavy and too overcome with noise to be useful. Weight is a critical factor in any telescope, as it directly ties to the cost of the mission. And sensitivity to "dark current" (i.e., electric current caused even when there is no light hitting a sensor) made much of the data older generations of higher-resolution sensors collected useless anyway.

According to Jaffe and his team, though, those problems have largely been solved—at least on the ground. The first is by a new technology called silicon immersion gratings and grisms. These force light to diffract from inside a high-refractive material like silicon, compared with traditional gratings that bounce light off a mirrored surface. This allows engineers to drastically reduce the size (and therefore weight) of the spectrograph and has the added bonus of not requiring any moving parts to adjust mirrors.

The second technological breakthrough is in the area of avalanche photodiode arrays (APAs). These new detectors have near-zero "dark current," and the noise introduced by the sensor itself is less than the signal introduced by a single photon. These baselines make it much more feasible to capture the right kind of light from an exoplanet and ensure it can be differentiated from the starlight of its host star.