Innovative methods for planetary atmospheric sounding by lasers

This paper presents new methods for planetary atmospheric sounding using different laser sources, direct detection electro-optics systems and passive infrared imaging systems. The proposed methods are suitable for both Earth remote sensing missions and likely future planetary exploration missions performed by using satellites, unmanned flight vehicles, gliders, balloons, roving surface vehicles, or permanent surface installations. The proposed methods offer relative advantages and limitations in different scenarios. All are based on measurements of the laser energy (intensity and spatial distribution) incident on target surfaces of known geometric and reflective characteristics, by means of infrared detectors and/or infrared cameras calibrated for radiance. Various laser sources can be employed with wavelengths from the visible to the far infrared portions of the spectrum, allowing for data correlation and extended sensitivity. Errors affecting the measurements performed using the proposed methods are discussed in the paper and some algorithms are proposed that allow indirect determination of atmospheric chemical species and aerosol particles concentrations for Earth and other planets. These algorithms take into account a variety of linear and non-linear propagation effects. Finally, experimental results are presented relative to some test activities performed on Earth using the proposed techniques. Particularly, data are presented relative to both ground and flight trials performed with laser systems operating in the near infrared (NIR) at λ = 1064 nm and λ = 1550 nm. This includes ground tests performed with 10 Hz and 20 KHz PRF NIR laser systems in a large variety of atmospheric conditions, and flight trials performed with a 10 Hz airborne NIR laser system installed on a TORNADO aircraft, flying up to altitudes of 22,000 ft AGL.