other species. Many other conclusions drawn from these data are often of dubious validity [@2014PNAS..11112601B].

Moreover, observed primary transit spectrophotometry is often either featureless within observational uncertainties or shows only a rise in transit depth at blue wavelengths, indicating the presence of clouds or hazes that intercept the stellar light. A few major chemical features have been clearly detected$-$mainly the sodium and potassium lines at 0.59 $\mu m$ and 0.77 $\mu m$, respectively, along with the 1.4-$\mu m$ water feature. The rise in transit depth observed at short wavelengths is consistent with Mie scattering by micron-size haze particles; with very little mass, a trace species at a high altitude ($<0.01$ bar) can produce a rising transit spectrum at short wavelengths [@2016Natur.529...59S].

The upcoming [*James Webb Space Telescope (JWST)*]{}, to be launched by the end of 2018, will offer an enormous advantage in spectroscopic observation of exoplanets over existing platforms such as [*HST*]{} and the [*Spitzer Space Telescope*]{}. It possesses a much larger collecting area (diameter 6.5 meters, as opposed to 2.4 meters for [*HST*]{}), and it will be able to observe spectra panchromatically from 0.6 $\mu m$ to 28.3 $\mu m$. It will also observe continuously, without interruption by Earth 