C.Johnson

Catherine Louise Johnson
Professor
Planetary geophysics
Office: EOS-South 355   Phone: 604-827-3480
Contact: 
Personal Website: http://www.eos.ubc.ca/~cjohnson/

Research Interests

MESSENGER Mission Updates (in reverse chronological order)

  1. October:  MESSENGER presentations at GSA and DPS Meetings.
  2. September 30th:  Science Magazine articles (7):  first publications with orbit data
  3. March 29th:  First Image of Mercury from Orbit!: 
  4. March 18th:  MESSENGER in Orbit!

I.  Mercury

I am a Participating Scientist on the MESSENGER mission to Mercury and am a member ofr the Geophysics and Atmosphere & Magnetopshere science teams.  On March 18 00:45 UTC (March 17, 5:45pm PDT) NASA's MESSENGER spacecraft successfully went into orbit around the innermost planet, after over 6 years of travel. MESSENGER Mission Web Page. Collaborators:

  1. PhD. Student: Reka Moldovan
  2. Postdoc:  Andreas Ritzer
  3. Former MSc student Hideharu Uno and former postdoc P. Surdas Mohit.
  4. Many on the MESSENGER team, in particular Michael Purucker, GSFC.

II.  Lunar Geophysics

Lunar Seismicity: Understanding both the origin of lunar quakes observed in the Apollo Passive Seismic Experiment data, and in what these quakes tell us about the internal structure of the Moon. Collaborators:

  1. Ph D. Student Jean-Francois Blanchette Guertin
  2. Postdoc:  Pascal Audet (Miller Fellow, UC Berkeley)
  3. Former PhD. student:  Renee Weber (now at Marshall Space Flight Center)

Lunar Magnetism:  Determining if and when the moon might have had a core dynamo.  In particular I am interested in understanding the origin of strong mangetizations measured in some Apollo samples (notably in samples with ages in the 3.9 - 3.6 Ga range), and the origin of crustal magnetic anomalies observed globally by the Lunar Prospector Magnetometer and Electron Reflectometer. Collaborators:

  1. Postdoc Kristin Lawrence (Planetary Science Institute, Tucson)
  2. John Tarduno (University of Rochester)

Impact Craters: Characterizing the topography of complex craters using new high resolution altimetry data returned by the Lunar Reconnaissance Orbiter Prospector Mission. Collaborators:

  1. Undergraduate Student:  Jessica Kalynn
  2. Gordon Ozinski (U. Western Ontario) & Olivier Barnouin (Applied Physics Laboratory)

IV:  Evolution of Mars' Magnetic Field and Atmosphere

Understanding how long Mars could have retained an early atmosphere either with or without the presence of a global magnetic field. Collaborators:

  1. Postdoc Kristin Lawrence (Planetary Science Institute, Tucson)
  2. Carol Paty (Georgia Tech), Steve Brecht (Bay Area Research Corp.) & Steve Ledvina (Space Sciences Lab, UC Berkeley)

V:  Long-term Geomagnetic Field Behavior

A long-standing question in geomagnetism has been whether spatial variations in the physical and chemical properties of the lowermost mantle affect outer core dynamics in a way that has an observable surface expression.  For example, there has been ongoing debate as to whether the magnetic field in the Pacific region is anomalous since the paleomagnetic work of Allan Cox and colleagues in the 1970s. My research in this area includes field work, laboratory measurements, data assimilation from the literature, and the development and application inversion techniques and statistical approaches to model the time-averaged field and its temporal variations.  Collaborators:

  1. Cathy Constable & Lisa Tauxe (Scripps Institution of Oceanography)
  2. Julien Aubert (IPGP, France)
  3. John Tarduno (University of Rochester)

 

Selected Publications