Stand-off molecular composition analysis

Abstract

Composition of distant stars can be explored by observing absorption spectra. Stars produce nearly blackbody radiation that passes through the cloud of vaporized material surrounding the star. Characteristic absorption lines are discernible with a spectrometer, and atomic composition is investigated by comparing spectral observations with known material profiles. Most objects in the solar system-asteroids, comets, planets, moons-are too cold to be interrogated in this manner. Material clouds around cold objects consist primarily of volatiles, so bulk composition cannot be probed. Additionally, low volatile density does not produce discernible absorption lines in the faint signal generated by cold objects. We propose a system for probing the molecular composition of cold solar system targets from a distant vantage. The concept utilizes a directed energy beam to melt and vaporize a spot on a distant target, such as from a spacecraft orbiting the object. With sufficient flux (~10 MW/m 2) on a rocky asteroid, the spot temperature rises rapidly to ~2500 K, and evaporation of all materials on the surface occurs. The melted spot creates a high-temperature blackbody source, and ejected material creates a molecular plume in front of the spot. Bulk composition is investigated by using a spectrometer to view the heated spot through the ejected material. Spatial composition maps could be created by scanning the surface. Applying the beam to a single spot continuously produces a borehole, and shallow sub-surface composition profiling is possible. Initial simulations of absorption profiles with laser heating show great promise for molecular composition analysis.

The 2020 release of the ExoMol database: Molecular line lists for exoplanet and other hot atmospheres

“…Detections in the atmospheres of exoplanets are discussed below. More diverse applications include modelling laser analysis of Solar System objects [40,41] , isotope abundance quantification in stars [42] , search for molecules highly sensitive to the proton-to-electron mass ratio variation [43,44] , models of molecular steering [45,46] , design of THz lasers [47] , design of dark matter detection schemes [48] and the design of novel propulsion systems [49] .…”

The ExoMol database: Molecular line lists for exoplanet and other hot atmospheres

“…In practice these data are also useful for a wide range of other scientific disciplines; examples include studies of the Earth's atmosphere [22,23], hypersonic non-equilibrium [24], analysis of laboratory spectra [25][26][27], measurements of hot reactive gases [28] and the proposed remote analysis of molecular composition using laser oblation [29].…”

Local phase control for a planar array of fiber laser amplifiers

“…Smaller arrays would be useful for missions that deploy to an area near the asteroid, deemed DE-STARLITE. 3,4 An operational DE-STAR or DE-STARLITE would be capable of serving diverse scientific objectives, including spacecraft propulsion 5 , active illumination for asteroid search and orbit refinement 6 , stand-off composition analysis 7 , orbital debris removal and more; multiple uses of the DE-STAR system are depicted in Fig. 1.…”