P. G. Grant

Publications (8)48.09 Total impact

• Article: Rapid extraction of dust impact tracks from silica aerogel by ultrasonic microblades

  H. A. Ishii, G. A. Graham, A. T. Kearsley, P. G. Grant, C. J. Snead, J. P. Bradley
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  ABSTRACT: Abstract— In January 2006, NASA's Stardust mission will return with its valuable cargo of the first cometary dust particles captured at hypervelocity speeds in silica aerogel collectors and brought back to Earth. Aerogel, a proven capture medium, is also a candidate for future sample return missions and low-Earth orbit (LEO) deployments. Critical to the science return of Stardust as well as future missions that will use aerogel is the ability to efficiently extract impacted particles from collector tiles. Researchers will be eager to obtain Stardust samples as quickly as possible; tools for the rapid extraction of particle impact tracks that require little construction, training, or investment would be an attractive asset. To this end, we have experimented with diamond and steel microblades. Applying ultrasonic frequency oscillations to these microblades via a piezo-driven holder produces rapid, clean cuts in the aerogel with minimal damage to the surrounding collector tile. With this approach, intact impact tracks and associated particles in aerogel fragments with low-roughness cut surfaces have been extracted from aerogel tiles flown on NASA's Orbital Debris Collector (ODC) experiment. The smooth surfaces produced during cutting reduce imaging artifacts during analysis by scanning electron microscopy (SEM). Some tracks have been dissected to expose the main cavity for eventual isolation of individual impact debris particles and further analysis using techniques such as transmission electron microscopy (TEM) and nano-secondary ion mass spectrometry (nanoSIMS).
  Meteoritics & Planetary Science. 01/2010; 40(11):1741 - 1747.
• Article: Scintillating Metal‐Organic Frameworks: A New Class of Radiation Detection Materials

  F. P. Doty, C. A. Bauer, A. J. Skulan, P. G. Grant, M. D. Allendorf
  Advanced Materials 10/2008; 21(1):95 - 101. · 13.88 Impact Factor
• Source

  Available from: Marc Fries

  Article: Comet 81P/Wild 2 under a microscope.

  Don Brownlee, Peter Tsou, Jérôme Aléon, Conel M O'd Alexander, Tohru Araki, Sasa Bajt, Giuseppe A Baratta, Ron Bastien, Phil Bland, Pierre Bleuet, [......], Ian Wright, Hikaru Yabuta, Hajime Yano, Edward D Young, Richard N Zare, Thomas Zega, Karen Ziegler, Laurent Zimmerman, Ernst Zinner, Michael Zolensky
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  ABSTRACT: The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.
  Science 01/2007; 314(5806):1711-6. · 31.20 Impact Factor
• Article: High Resolution Phase Contrast X-ray Imaging of Cosmic Dust Captured in Aerogel

  J  Sheffield-Parker , G A  Graham , S C  Mayo , N  Teslich , P G  Grant , C  Snead , A J  Westphal 
  Microscopy and Microanalysis 07/2005; 11:1396 - 1397. · 3.01 Impact Factor
• Article: Ultrasonic Micro-Blades for the Rapid Extraction of Impact Tracks from Aerogel

  H. A. Ishii, G. A. Graham, A. T. Kearsley, P. G. Grant, C. J. Snead, J. P. Bradley
  [show abstract] [hide abstract]
  ABSTRACT: The science return of NASA's Stardust Mission with its valuable cargo of cometary debris hinges on the ability to efficiently extract particles from silica aerogel collectors. The current method for extracting cosmic dust impact tracks is a mature procedure involving sequential perforation of the aerogel with glass needles on computer controlled micromanipulators. This method is highly successful at removing well-defined aerogel fragments of reasonable optical clarity while causing minimal damage to the surrounding aerogel collector tile. Such a system will be adopted by the JSC Astromaterials Curation Facility in anticipation of Stardust s arrival in early 2006. In addition to Stardust, aerogel is a possible collector for future sample return missions and is used for capture of hypervelocity ejecta in high power laser experiments of interest to LLNL. Researchers will be eager to obtain Stardust samples for study as quickly as possible, and rapid extraction tools requiring little construction, training, or investment would be an attractive asset. To this end, we have experimented with micro-blades for the Stardust impact track extraction process. Our ultimate goal is a rapid extraction system in a clean electron beam environment, such as an SEM or dual-beam FIB, for in situ sample preparation, mounting and analysis.
  02/2005;
• Article: Investigation of ion beam techniques for the analysis and exposure of particles encapsulated by silica aerogel: Applicability for Stardust

  G. A. GRAHAM, P. G. GRANT, R. J. CHATER, A. J. WESTPHAL, A. T. KEARSLEY, C. SNEAD, G. DOMÍNGUEZ, A. L. BUTTERWORTH, D. S. McPHAIL, G. BENCH, J. P. BRADLEY
  [show abstract] [hide abstract]
  ABSTRACT: Abstract— In 2006, the Stardust spacecraft will return to Earth with cometary and perhaps interstellar dust particles embedded in silica aerogel collectors for analysis in terrestrial laboratories. These particles will be the first sample return from a solid planetary body since the Apollo missions. In preparation for the return, analogue particles were implanted into a keystone of silica aerogel that had been extracted from bulk silica aerogel using the optical technique described in Westphal et al. (2004). These particles were subsequently analyzed using analytical techniques associated with the use of a nuclear microprobe. The particles have been analyzed using: a) scanning transmission ion microscopy (STIM) that enables quantitative density imaging; b) proton elastic scattering analysis (PESA) and proton backscattering (PBS) for the detection of light elements including hydrogen; and c) proton-induced X-ray emission (PIXE) for elements with Z > 11. These analytical techniques have enabled us to quantify the composition of the encapsulated particles. A significant observation from the study is the variable column density of the silica aerogel. We also observed organic contamination within the silica aerogel. The implanted particles were then subjected to focused ion beam (FIB) milling using a 30 keV gallium ion beam to ablate silica aerogel in site-specific areas to expose embedded particles. An ion polished flat surface of one of the particles was also prepared using the FIB. Here, we show that ion beam techniques have great potential in assisting with the analysis and exposure of Stardust particles.
  Meteoritics & Planetary Science. 08/2004; 39(9):1461 - 1473.
• Article: Research article - Comet 81P/Wild 2 under a microscope

  D. Brownlee, P. Tsou, J. Aleon, C. M. O. Alexander, T Araki, S. Bajt, G. A. Baratta, R. Bastien, P. Bland, P. Bleuet, [......], I. Wright, H. Yabuta, H Yano, E. D. Young, R N Zare, T. Zega, K. Ziegler, L. Zimmerman, E. Zinner, M. Zolensky
  Science, v.314, 1711-1716 (2006).
• Article: Comet 81P/Wild 2 under a microscope

  D. Brownlee, P. Tsou, J. Aleon, C. M. O. Alexander, T Araki, S. Bajt, G. A. Baratta, R. Bastien, P. Bland, P. Bleuet, [......], I. Wright, H. Yabuta, H Yano, E. D. Young, R N Zare, T. Zega, K. Ziegler, L. Zimmerman, E. Zinner, M. Zolensky
  Science, v.314, 1711-1716 (2006).