WATSON: In Situ Organic Detection in Subsurface Ice Using Deep-UV Fluorescence Spectroscopy

Area of Science:

• Astrobiology
• Planetary Science
• Geoscience

Background:

• Terrestrial icy environments preserve organic material and harbor habitable niches for microbial life.
• The cryosphere of other planetary bodies may harbor signs of life.
• Detecting dispersed organic material and microbial cells in ice presents challenges due to heterogeneity and low bulk densities.

Purpose of the Study:

• To introduce the Wireline Analysis Tool for the Subsurface Observation of Northern ice sheets (WATSON) instrument.
• To evaluate WATSON's sensitivity to organic material within a water ice matrix.
• To assess WATSON's capability to detect organic material through varying ice thicknesses.

Main Methods:

• Laboratory experiments were conducted to determine instrument sensitivity and detection limits.
• The Wireline Analysis Tool for the Subsurface Observation of Northern ice sheets (WATSON) was tested for its depth of penetration and detection capabilities in bubbled ice.
• WATSON's scanning system was utilized to map organic and microbial distribution over a defined area.

Main Results:

• The Wireline Analysis Tool for the Subsurface Observation of Northern ice sheets (WATSON) demonstrated a depth of penetration of 10 mm in bubbled ice.
• The instrument achieved a detection limit of fewer than 300 cells.
• WATSON successfully mapped the distribution of organics and microbes over a 75 by 25 mm area.

Conclusions:

• WATSON is a compact deep-UV fluorescence spectrometer designed for nondestructive ice borehole analysis.
• The instrument provides a sensitive fluorescence mapping technique for detecting organics and microbes in icy environments.
• WATSON has potential applications for studying terrestrial glaciers and ice sheets, as well as planetary surfaces like Europa, Enceladus, and Mars.