AGU Press Releases and Images

December 2003

FOR IMMEDIATE RELEASE

A new LASER instrument for in-situ measurements on Mars

San Francisco - Scientists at the School of Ocean and Earth Science and Technology have proposed a LASER instrument that could measure in-situ rock age and geochemistry on Mars. The laser desorption (LD) resonance ionization (RI) mass spectrometer (MS) would be capable of measuring the geochemical and isotopic composition of surface rocks to provide insight into the formation and evolution of the Martian crust and mantle.

The prototype instrument (called LDRIMS) will use a new type of multi-bounce time of flight mass spectrometer integrated with existing lasers to collect both rubidium-strontium (Rb-Sr) and neodymium-samarium (Nd-Sm) isotopic ages.

The instrument uses the laser to produce the atoms required for dating, and then sends those atoms to the mass spectrometer to measure the resulting isotopes. The instrument will have two different operating modes, "RI" and "LD". The "RI" mode can be used to selectively ionize and precisely measure the abundance of Rb-Sr isotopes to obtain igneous rock ages within < ±250 Ma. The "LD" mode can collect all desorbed ions, thereby providing high precision (part per thousand or better) elemental measurements of the composition of the surface.

Other important features of this instrument include its small mass (<10 kg in weight), low power consumption (< 50 Watts of power), and small size (it will fit into a box the size of two desk drawers).

"This instrument could be used for Mars or the Moon or any solid surface planetary body in the Solar System," says Scott Anderson, Principal Investigator of this study. "It is important because we will be able to do the geochemistry really well, but also obtain a date from the surface using multiple geochronometers with minimal sample handling".

The proposed LDRIMS could be used on the 2009 Mars Science Laboratory (MSL), Scout and landed missions, and for any rocky body in the solar system, and hence is important for the Discovery and New Frontier Programs.

For more information, contact F. Scott Anderson, anderson@higp.hawaii.edu (808) 956-6887, cell (818) 687-9471

Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822 United States

PDF version of this press release

LASER RIMS instrument

A. A small sample is placed in the instrument. The surface can be cleaned if necessary using LASER ablation, based on a laser like that used for the proposed 2009 MSL LIBS experiment. After cleaning, the laser is again fired to produce a cloud of atoms, including the targeted Rb-Sr or Nd-Sm atoms. Measuring the isotopes of these atoms with a mass spectrometer is tricky due to isobaric interferences from other atoms with similar masses.

B. The atom cloud is illuminated by lasers (labeled TDL above) tuned to ionize only one element (for example, either Rb or Sr), removing all isobaric interferences, and allowing the isotopes to be measured without using a heavy high sensitivity mass spectrometer.

C. The ionized atoms are then drawn into the mass spectrometer using electrostatic fields. We will use a new type of mass spectrometer capable of moderately high resolution in a compact shape. This new development measures the flight time of ions down a flight tube. Heavier ions take longer to travel down the tube, and hence can be identified; longer tubes provide more resolution. Our innovation will be to use a small tube, but by allowing the ions to bounce multiple times in tube, create a larger virtual tube length, and thus higher resolution.

(Image by F. Scott Anderson, HIGP/SOEST)

For more information, contact Tara Hicks.

Last Updated Wed December 3, 2003. Maintained by Tara Hicks.

(c) Copyright 2003. SOEST Outreach Office. All rights reserved.