A hollow-waveguide gas correlation radiometer for ultra-precise column measurements of formaldehyde on Mars

摘要

We present preliminary results in the development of a miniaturized gas correlation radiometer that implements a hollow-core optical fiber (hollow-waveguide) gas correlation cell. The substantial reduction in mass and volume of the gas correlation cell makes this technology appropriate for an orbital mission--capable of pinpointing sources of trace gases in the Martian atmosphere. Here, we demonstrate a formaldehyde (H_(2)CO) sensor and report a detection limit equivalent to approx30 ppb in the Martian atmosphere. The relative simplicity of the technique allows it to be expanded to measure a range of atmospheric trace gases of interest on Mars such as methane (CH_(4)), water vapor (H_(2)O), deuterated water vapor (HDO), and methanol (CH_(3)OH). Performance of a formaldehyde instrument in a Mars orbit has been simulated assuming a 3 m long, 1000 (mu)m inner diameter hollow-core fiber gas correlation cell, a 92.8 deg sun-synchronous orbit from 400 km with a horizontal sampling scale of 10 km X 10 km. Initial results indicate that for 1 s of averaging, a detection limit of 1 ppb is possible.