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 Planetary Science: People
Joseph Ajello's Picture
Jet Propulsion Laboratory
M/S 183-401
4800 Oak Grove Drive
Pasadena, CA 91109

Joseph Ajello

Dr. Ajello has 40 years of experience in laboratory spectroscopy. He is active in NASA space missions as a co-investigator data analysis of UV observations. He has co-authored 170 publications in the field of UV spectroscopy relevant to atomic and molecular physics, astrophysics of the local ISM and planetary atmospheres. The UV research is directed to the measurement of electron and proton cross sections needed by modelers of spacecraft observations of the Earth, the planets and astrophysical objects or atomic physics theoreticians requiring benchmark cross sections for ab initio calculations. The highlight of the laboratory instrumentation is a 3 meter UV spectrometer with array detectors duplicating the resolution (λ/Δλ) the Hubble Space Telescope. Dr. Ajello has been a co-investigator on the Cassini UVIS, Galileo UVS, Hubble Spacecraft observations of Jupiter and Saturn and FUSE observations of HH objects. In 2011, he wrote a book chapter entitled "UV Molecular Spectroscopy from Electron Impact for Applications to Planetary Atmospheres and Astrophysics".

  • B.S., Physics, Rhodes Colleges, (1962)
  • M.S., Physics, Rensselaer Polytechnic Institute (1964)
  • Ph. D., Astrogeophysics, University of Colorado (1969)

Research Interests
  • UV spectroscopy of planetary atmospheres and interstellar medium
  • laboratory studies of atomic physics collision cross sections for astrophysics
  • auroral physics of the outer planets
  • the interplanetary glow from H(lyman-α) and He(58.4 nm)
  • exobiology life detection by soft x-rays


Cassini-Huygens Icon Cassini-Huygens
The Cassini-Huygens spacecraft is currently exploring the ringed planet, its mysterious moons, the stunning rings and its complex magnetic environment.

Professional Experience
  • Jet Propulsion Laboratory (1971-Present)
    • Senior Research Scientist
    • Principal Investigator:
      • Planetary Atmospheres
      • Astrophysics Research and Analysis
      • Space Physics
      • Air Force Office of Scientific Research
      • Geospace
      • NSF Aeronomy
      • Cassini Data Analysis
    • Co-investigator:
      • Galileo Ultraviolet Spectrometer Team
      • International Solar-and Terrestrial Physics Polar Spacecraft Ultraviolet Imager Team
      • Cassini Ultraviolet Imaging Spectrograph Team
    • Guest Investigator:
      • Pioneer Venus Guest Investigator Program for Interplanetary Ly α
      • Hubble Space Telescope Guest Investigator Program for Studies of the Atmospheres of Jupiter and Io
      • Far Ultraviolet Spectrograph Explorer to study Herbig-Haro objects
      • Ulysses for the Interstellar Wind Studies in H Ly α and He (58.4 nm)
      • Cassini Ultraviolet Imaging Spectrograph studies of Titan atmosphere and Saturn Aurora
    • Experiment Representative to the UV Spectrometer Teams of Voyager and Mariner 9
    • Team Leader Ultraviolet Emission Processes Group
  • Lecturer California Polytechnic State University for Department of Physics

Selected Awards
  • NASA Group Achievement Award Electron Collisions Team (2011)
  • TAP (JPL Technology and Applications) award to the UV Emission Processes Team
  • Ultraviolet Spectrometer NASA Group Achievement awards: Galileo, Voyager and Mariner 9
  • Heinrich Hertz Fellow, University Bonn, Astronomishches Institut, Bonn, Germany.
  • JPL Senior Research Scientist Sabbatical to University of Colorado

Selected Publications
  1. Heays, A., Ajello, J. M., A. Aguilar, B. R. Lewis and S. T. Gibson (2013), High Resolution EUV spectrum of N2 by electron impact, [pdf] Ap. J. Supp., Submitted.
  2. Frisch, P., M. Bzowski, G. Livadiotis, D. McComas, E. Moebius, H. Muelller, W. Pryor, N. Schwadron, J. Sokot, J. Vallerga, J. M. Ajello, "Decades-Long-changes of the interstellar wind through our solar system", Science, 341, 1080 (2013).
  3. Ajello, J.M.,R. West, M., Kristopher Larsen, A. Ian F. Stewart, Larry W. Esposito, William E. McClintock, Gregory M. Holsclaw, E. Todd Bradley, Cassini UVIS Observations of Titan Nightglow Spectra, [pdf] J. Geophys. Res., 117, A12315, doi:10.1029/2012JA017888, (2012).
  4. West, R., Ajello, J.M., Stevens, M. H., D. F. Strobel, D. F. and Gladstone, G. R. (2012), Titan Airglow During Eclipse, [pdf] Geophys. Res. Lett., 39, L18204, doi:10.1029/2012GL053230, 2012.
  5. Ajello, Joseph M., Rao S. Mangina and R. R. Meier, UV Molecular Spectroscopy from Electron-impact for Applications to Planetary Atmospheres and Astrophysics Book chapter 28, published in "Charged Particle and Photon Interactions with Matter" Recent Advances, Applications, and Interfaces-Eds., Y. Hatano, Y. Katsumura, and A. Mozumder, Taylor & Francis, Boca Raton, [pdf] (2011).
  6. Ajello, J. M., Mangina, R., and Strickland, D., Laboratory Studies of UV Emissions from Proton Impact on N2 for Aurora analysis: the Lyman-Birge-Hopfield Band System, [pdf] J. Geophsys. Res., 116, doi:10.1029/2010ja016103 (2011).
  7. Mangina, R. S., Ajello, J. M., West , R. and Diczek, D., (2011), High Resolution Electron Impact Emission Spectra and Cross Sections for N2 from 330-1100 nm, [pdf] Astrophys. J. Supp., 196, 1doi:10.188/0067-0048/196/1/13.
  8. West, R. W., J. M. Ajello, M. H. Stevens, J. S. Evans, and R. S. Mangina, (2011), Airglow emission from Titan during, eclipse, [pdf] Abstracts of Division Planetary Sciences, Pasadena, CA.
  9. Pryor, W., Ajello, J.M. and 20 authors, 'The Auroral Footprint of Enceladus on Saturn', Nature, 472, 331-333, 2011.
  10. Young, J. A., Malone, C. P., Johnson, P. V., Ajello, J. M., Liu, X., and Kanik. Lyman-Birge-Hopfield emissions from electron impact excited N2. [pdf] J. Phys. B: At. Mol. Opt. Phys. 43, doi:10.1088/0953-4075/43/13/135201, (2010).
  11. Malone, C.,P. Johnson, J. McConkey, J. Ajello & I. Kanik, Dissociative excitation of N2O by Electron-impact, J. Phys. B: At. Mol. Phys., 41, doi10.1088/0953-4075/41/9/095201, (2008).
  12. Ajello, J. M., J. Gustin, I. Stewart, K. Larsen, L. Esposito, W. Pryor, W. McClintock, M. H. Stevens, C. P. Malone, and D. Dziczek, Titan Airglow Spectra from Cassini Ultraviolet Imaging Spectrograph (UVIS): FUV Disk Analysis, Geophys. Res. Lett., 35, L06102, doi:10.1029/2007GL032315 (2008).
  13. Pryor, W., P. Gangopadhyay, B. Sandel, T. Forrester, E. Quemerais, E. Moebius, L. Esposito, I. Stewart, B. McClintock, A. Jouchoux, J. Colwell, V. Izmodenov, Y. Malama, K. Tobiska, D. Shemansky, J. Ajello, C. Hansen, M. Bzowski, and P. Frisch, Radiation transport of heliospheric Lyman-alpha from combined Cassini and Voyager data sets, Astron. & Astrophys., 491, 21-28 (2008).
  14. Liu, X., D. E. Shemanksy, C. Malone, P. Johnson, J. M. Ajello, I. Kanik, A. Heays, B. Lewis, S. Gibson and G. Stark, "Experimental and Coupled Channels Investigation of the radiative Properties of the N2 c4′1u+-X1g+ Band System", Ap. J.,113, A02304,doi:10.1029/2007ja012787 (2008).
  15. Aguilar, A., J. M. Ajello, R. S. Mangina, G. K. James, H. Abgrall and E. Roueff, "The Electron Excited Middle UV to Near IR Spectrum of H2: Cross Sections and Transition Probabilities", Ap. J. Supp., 177, 388-407, July (2008).
  16. Ajello, J. M., Aguilar, A., R. S. Mangina, G. K. James, P. Geissler and L. Trafton, "The Middle UV to Near IR Spectrum of Electron Excited SO2", J. Geophys. Res.-Planets, 113, doi:10.1029/2007je002921 (2008).
  17. Ajello, J. M., J. Gustin, I. Stewart, K. Larsen, L. Esposito, W. Pryor, W. McClintock, M. H. Stevens, C. P. Malone, and D. Dziczek, Titan Airglow Spectra from Cassini Ultraviolet Imaging Spectrograph (UVIS): EUV Disk Analysis, Geophys. Res. Lett., 34, L24204, doi:10.1029/2007GL031555 (2008).

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