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Planetary Sciences

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Radio Science
Radio Science

JPL radio science researchers participate in many NASA deep space missions. They contribute to developing engineering requirements consistent with the scientific objectives for each spacecraft and ground elements of radio science instruments; participate in instrument design and development; acquire science data; and participate in analysis and interpretation.

Radio links between spacecraft and Earth are utilized to examine changes in the characteristics of electromagnetic waves such as the phase/frequency, amplitude, radio spectrum, or polarization to investigate many aspects of planetary science, space physics and fundamental physics. Radio Science investigations include:

Saturn's rings with radio signal extinction
A profile of the rings of Saturn from radio occultations at three wavelengths (three radios on-board the Cassini spacecraft at different frequencies) S-band (red), X-band (green) and Ka-band (blue). The signal extinction is shown from which the optical thickness and particle size distribution are inferred. The profile is superimposed on an image of the rings generated from radio occultation data (credit: E. A. Marouf, SJSU).

Recent Opportunities and Discoveries

Mars gravity field
A gravity map of Mars generated from radio tracking techniques shows variations resulting from surface and subsurface density variations (credit A.S. Konopliv, JPL).
Since 1995, radio science has had a significant role in subsequent missions and is credited with the following additional accomplishments:
  • First detection of Martian core and bulk seasonal CO2 deposition at poles (Mars Pathfinder)
  • Vastly improved gravity field of Mars, with determination of Love number and correlation with topography (Mars Global Surveyor (MGS), Odyssey, Mars Reconnaissance Orbiter (MRO), and Mars Express)
  • First detection of planetary gravity field variations other than Earth (MGS)
  • First determination of the mass of Phobos (MGS)
  • First non-spherical gravity field of an asteroid (NEAR mission to Eros)
  • High accuracy profiling of Martian atmospheric structure from radio occultations (MGS)
  • Detection of ionospheres on the Galilean Satellites (Galileo)
  • Jovian deep atmospheric wind speeds and ammonia concentration (Galileo Probe)
  • State-of-the art tests of General Relativity and search for gravitational waves (Cassini)
  • Improved gravity field of Mercury (MESSENGER)
  • Measurement of Mars upper atmospheric density from spacecraft drag (several orbiters)
  • Surface characteristics of Venus, Earth’s Moon, Mars and Titan from bistatic radar experiments
  • Detection of meteor layers in ionospheres of Mars and Venus (Mars Express, Venus Express) Modeling the mass distribution in the interiors of the large moons of Jupiter (Galileo)
  • Height profile of winds on Titan with the Doppler Wind Experiment (Huygens)
  • High resolution gravitational field of the Earth via spacecraft-to-spacecraft links (GRACE)
  • Gravitational field of Saturn and its large satellites (Cassini)
  • Atmospheric Structure of Saturn and its large satellites (Cassini)
  • Profiling of internal dynamics and of particle size distribution within Saturn’s rings (Cassini)
  • Characterization of the lunar interior from crust to core with the GRAIL mission
  • Characterization of the interior structure of asteroid Vesta with gravity measurements with the Dawn mission


Kamal Oudrhiri – Technical Contact
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