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Michael Janssen

Photo of Michael Janssen


4800 Oak Grove Drive
M/S 169-506

Pasadena, CA 91109





Member of:

Astrophysics & Space Sciences


Prior to his retirement in 2017, Michael Janssen had nearly fifty years of experience in radio astronomy, specializing in the microwave remote sensing of the Earth and solar system, observational astrophysics and cosmology, and the development and application of microwave instrumentation for astrophysics and remote sensing. In his early years he played leading roles in the development of the world’s first two millimeter-wavelength radio interferometers, and subsequently participated as Co-Investigator or Principal Investigator in a number of space-borne microwave experiments. He was a Co-I and member of the Science Working Group for the Cosmic Background Explorer (COBE) and played a major role in implementing the COBE Differential Microwave Radiometer experiment on COBE, which discovered the origin of structure in the universe. In the same period, he edited and made significant contributions to a book on the microwave remote sensing of atmospheres that is still widely used in the field. He took a temporary time-out in the late 90’s to help with the management of the Earth & Space Sciences Division at JPL, where he worked in several areas to improve the climate for research in the Division and at the Laboratory in general. Recent mission involvement includes participation in the Cassini, Planck, Rosetta and Juno missions. At the time of his retirement, he had active flight involvements including lead for the Cassini RADAR radiometer and PI for the Juno Microwave Radiometer, in orbit around Jupiter since July 2016. He remains active in the ongoing Juno mission and as a collaborator on a new Cassini Data Analysis Program to study Saturn’s atmosphere using archived Cassini data.


  • B.S., Physics, University of California at Berkeley (1963)
  • Ph.D., Atmospheric and Space Sciences, University of California at Berkeley (1972)

Professional Experience

  • Jet Propulsion Laboratory (1972-present)
    • Research Associate (2017-present)
    • Senior Research Scientist (2010-2017)
    • Member Senior Research Scientist Council (2014-2017)
    • Principal Scientist (2002-2010)
    • Assistant Manager, Earth and Space Sciences Division (1997-2002)
    • Acting Manager, Earth and Space Sciences Division (1999)
    • Discipline Program Manager for Astrophysics (1995-1997)
    • Lead Scientist for Astrophysics (1994-1997)
    • Manager, Space Physics and Astrophysics Section (1991-1993)
    • Group Supervisor, Radio/Submillimeter Astronomy (1989-1991)
    • Member of Technical Staff, Earth and Space Sciences Division (1976-1996)
    • Senior Scientist, Earth and Space Sciences Division (1974-1976)
    • National Research Council Resident Research Associate (1972-1974)

Research Interests

  • Microwave remote sensing of the Earth and solar system
  • Observational astrophysics and cosmology
  • Development and application of microwave instrumentation for astrophysics and remote sensing

Selected Awards

  • Fellow, American Association for the Advancement of Science (2017)
  • Edward Stone Award for Outstanding Research Publication (2010)
  • NASA Exceptional Service Medal (2009)
  • Cosmology Prize of the Peter Gruber Foundation: Co-recipient as COBE team member (2006)
  • NASA Exceptional Scientific Achievement Medal for contributions to COBE (1992)
  • Member Phi Beta Kappa
  • National Research Council Postdoctoral Fellowship (1972-1974)

Selected Publications

  1. Janssen, M.A., J.E. Oswald, S.T. Brown, S. Gulkis, S.M. Levin, S.J. Bolton, M.D. Allison, S.K. Atreya, D.Gautier , A.P. Ingersoll, J.I. Lunine, G.S. Orton, T.C. Owen, P.G. Steffes, A. Kitiyakara, J.C Chen, F.W. Maiwald, A.S. Larson, P.J. Pingree, K.A. Lee, R. Redick, R.C. Hughes, G. Bedrossian, D.E. Dawson, W.A. Hatch, D.S. Russel, N.F. Chamberlain, M.S. Zawadski, B. Khayatian, A. Mazer, B.R. Franklin, H.A. Conley, J.G. Kempenaar, M.S. Loo, E.T. Sunada, C.C. Wang, MWR: Microwave Radiometer for the Juno Mission to Jupiter, Space Science Reviews, 213, 139-185, 2017, doi: 10.1007/s11214-017-0349-5.
  2. Janssen, M.A, A. Le Gall, M.J. Malaska, R.M. Lopes, A. Solomonidou, R.D. Lorenz, C.D. Neish, K.L. Mitchell, J. Radebaugh, P.J. Encrenaz, and M. Mastrogiuseppe, Titan’s surface at 2.2-cm wavelength imaged by the Cassini RADAR radiometer: Results and interpretations through the first ten years of observation, Icarus, doi: 10.1016/jicarus.2015.09.027, 2016.
  3. A. Le Gall, M.J. Malaska, R.D. Lorenz, M.A. Janssen, T. Tokano, A.G. Hayes, M. Mastrogiuseppe, J.I. Lunine, G. Veyssière, P. Encrenaz, and O. Karatekin, Composition, seasonal change and bathymetry of Ligeia Mare, Titan, derived from its microwave thermal emission. J. Geophys. Res. Planets, 121, doi:10.1002/2015JE004920., 2016.
  4. Ries, P.A., and M.A. Janssen, A large-scale anomaly in Enceladus’ thermal emission. Icarus 215, 88-102, 2015
  5. Le Gall, A., M.A. Janssen, R.L. Kirk, and R.D. Lorenz, Modeling microwave backscatter and thermal emission from fields of linear dunes: Application to Titan, Icarus 230, 198-207, 2014.
  6. Janssen, M.A., A. Ingersoll, M.D. Allison, S. Gulkis, A. Laraia, K.Baines, S. Edgington, Y. Anderson, K. Kelleher, Saturn’s Thermal Emission at 2.2-cm Wavelength as Imaged by the Cassini Radar Radiometer, Icarus 226, 522-535, 2013.
  7. Janssen, M.A., A. Le Gall and L.C. Wye. Anomalous radar backscatter from Titan's surface? Icarus 212, 321-328, 2011.
  8. Le Gall, A., M.A. Janssen, P. Paillou, R.D. Lorenz, and the Cassini Radar Team, Radar-bright channels on Titan. Icarus 207, 948-958, 2010.
  9. Janssen, M.A. , R.D. Lorenz, R. West, F. Paganelli, R. M. Lopes, R.L. Kirk, C. Elachi, S.D. Wall, W.T.K. Johnson, Y. Anderson, R.A. Boehmer, P. Callahan, Y. Gim, G.A. Hamilton, K.D. Kelleher, L. Roth, B. Stiles, A. Le Gall, and the Cassini Radar Team, Titan's surface at 2.2-cm wavelength imaged by the Cassini RADAR radiometer: calibration and first results, Icarus, 200, 222-239, 2009.
  10. Janssen, M.A., M.D. Hofstadter, S. Gulkis, A.P. Ingersoll, M.Allison, S.J. Bolton, and L.W. Kamp, Microwave Remote Sensing of Jupiter's Atmosphere from an Orbiting Spacecraft, Icarus, 173, 447-453, 2005.
  11. Janssen, M. A., Ruf, C. S., and Keihm, S. J., TOPEX/Poseidon Microwave Radiometer (TMR): II. Antenna Pattern Correction and Brightness Temperature Algorithm, IEEE Trans. Geosci. Remote Sensing 33, 138-146, 1995.
  12. Janssen, M. A., and Lawrence, C. L., Primordial Structure Investigation (PSI): A Low-Cost Space Mission to Image the Intermediate-Scale Cosmic Microwave Background, Astrophys. Lett. and Comm. 32, 289-296, 1995.
  13. Janssen, M.A., editor, Atmospheric Remote Sensing by Microwave Radiometry, Wiley & Sons, New York (1993).
  14. Janssen, M. A. and Gulkis, S., "Mapping the Sky with the COBE Differential Microwave Radiometers", in The Infrared and Submillimeter Sky after COBE, Eds. M. Signore and C. Dupraz, Kluwer Academic Publishers, 391-408 (1992).
  15. Bennett, C. L., Smoot, G. F., Janssen, M. A., Gulkis, S, Kogut, A., Hinshaw, G., Backus, C., Hauser, M. G., Mather, J. C., Rokke, L., Tenorio, L., Wilkinson, D. T., Wright, E. L., Aymon, J., DeAmici, G., Boggess, N. W., Cheng, E. S., Jackson, P. D., Keegstra, P., Kelsall, T., Kummerer, R., Lineweaver, C., Lubin, P. M., Meyer, S. S., Moseley Jr., S. H., Murdock, T. L., Santana, J., Shafer, R. A., Silverberg, R. F., Weiss, R., COBE Differential Microwave Radiometers (DMR): Calibration Techniques, Ap.J. 391, 466-482 (1992).
  16. Smoot, G. F., Bennett, C. L., Kogut, A., Wright, E. L., Aymon, J., Boggess, N. W., Cheng, E. S., De Amici, G., Gulkis, S., Hauser, M. G., Hinshaw, G., Lineweaver, C., Loewenstein K., Jackson, P. D., Janssen, M. A., Kaita, E., Kelsall, T., Keegstra, P., Lubin, P., Mather, J. C., Meyer, S. S., Moseley Jr., S. H., Murdock, T. L., Rokke, L., Silverberg, R. F., Tenorio, L., Weiss, R., and Wilkinson, D. T., Structure in the COBE Differential Microwave Radiometer First-Year Maps, Ap.J. 396, L1-L5 (1992).
  17. Janssen, M. A., A New Instrument for the Determination of Radio Path Delay Due to Atmospheric Water Vapor, IEEE Trans. Geosci. Remote Sensing, GE-23, No. 4, 485-490 (1985).
  18. Janssen, M. A., Bednarczyk, S. M., Gulkis, S., Marlin, H. W. and Smoot, G. F., Pattern Measurements of a Low-Sidelobe Horn Antenna, IEEE Trans. on Antennas and Propagat., AP-28, 759-763 (1979).
  19. Hills, R. B., M. A. Janssen, D. D. Thornton, W. J. Welch, The Hat Creek Millimeter-Wavelength Interferometer, Proc. IEEE, 61, 9, 1278 (1973).
  20. Janssen, M. A., R. Hills, D. D. Thornton, W. J. Welch, Venus: New Microwave Measurements Show No Atmospheric Water Vapor, Science, 179, 994 (1973).