Planetary Imaging in Powers of Ten: A Multiscale, Multipurpose Astrobiological Imager

Contextual, multiscale astrobiological imaging is necessary to discover, map, and image patchy microbial colonization in extreme environments on planetary surfaces. The large difference in scale—several orders of magnitude—between search environment and microorganisms or microbial communities represents a challenge, which to date no single imaging instrument is able to overcome. In support of future planetary reconnaissance missions, we introduce an adapter-based imager, built from an off-the-shelf consumer digital camera, that offers scalable imaging ranging from macroscopic (meters per pixel) to microscopic (micrometers per pixel) imaging, that is, spanning at least 6 orders of magnitude. Magnification in digital cameras is governed by the native resolution of the CCD/CMOS chip of the camera, the distance between camera and object to be imaged (focal length), and the built-in optical and digital zoom. Both telezoom and macro mode alone are usually insufficient for microscopic imaging. Therefore, the focal distance has to be shortened, and the native CCD resolution of the camera has to be increased to attain a microscopic imaging capability. Our adapter-based imager bridges the gap between macroscopic and microscopic imaging, thereby enabling for the first time contextual astrobiological imaging with the same instrument. Real-world applications for astrobiology and planetary geology are discussed, and proof-of-concept imagery taken with our prototype is presented

New Methods of Sample Preparation for Atom Probe Specimens

Magnetite is a common conductive mineral found on Earth and Mars. Disk-shaped precipitates approximately 40 nm in diameter have been shown to have manganese and aluminum concentrations. Atom-probe field-ion microscopy (APFIM) is the only technique that can potentially quantify the composition of these precipitates. APFIM will be used to characterize geological and planetary materials, analyze samples of interest for geomicrobiology; and, for the metrology of nanoscale instrumentation. Prior to APFIM sample preparation was conducted by electropolishing, the method of sharp shards (MSS), or Bosch process (deep reactive ion etching) with focused ion beam (FIB) milling as a final step. However, new methods are required for difficult samples. Many materials are not easily fabricated using electropolishing, MSS, or the Bosch process, FIB milling is slow and expensive, and wet chemistry and the reactive ion etching are typically limited to Si and other semiconductors. APFIM sample preparation using the dicing saw is commonly used to section semiconductor wafers into individual devices following manufacture. The dicing saw is a time-effective method for preparing high aspect ratio posts of poorly conducting materials. Femtosecond laser micromachining is also suitable for preparation of posts. FIB time required is reduced by about a factor of 10 and multi-tip specimens can easily be fabricated using the dicing saw