NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header

Radio Science Investigations (RSI)

NSSDCA ID: 2004-006A-11

Mission Name: Rosetta
Principal Investigator:Dr. Martin Paetzold


The Rosetta Orbiter radio science investigations will use the existing radio transmitters and receivers on the orbiter. There are three primary investigations in addition to the routine tracking which takes place for navigation and data return and will be used in conjunction with other experiments. The gravity mapping campaign will use Doppler and range tracking to estimate the mass and gravity field of the comet nucleus. The occultation experiments will study the effects of the innermost coma on radio signals which pass through the coma to Earth before and after occultations of the comet nucleus and will also help determine the morphology of the nucleus. Finally, bistatic radar observations will be used to study the surface of the comet by pointing the high-gain antenna at the nucleus and bouncing the signals off the surface towards Earth, where the forward-reflected signal will reveal properties of the surface such as the roughness and dielectric constant. The primary scientific objectives of the investigations are 1) to determine the mass, bulk density, gravity field, moment of inertia, spin state, orbit, lightshift, and thermal properties of the nucleus; 2) determine the size and shape of the nucleus; 3) determine the dielectric constant and roughness of the surface of the nucleus; 4) Profile the distribution of mm-dm size particles and the plasma content of the coma; 5) aid in determination of the dust and gas flux; and 6) determine asteroid mass and bulk density during flybys.

RSI routine measurements (two-way Doppler and range) are obtained when the spacecraft is tracked for navigation and data return. The routine operational mode is the two-way link mode: S-band uplink at 2.1 GHz and coherent and simultaneous dual-frequency S-band (2.3 GHz) and X-band (8.4 GHz) downlink via the High Gain Antenna (HGA). This takes advantage of the superior stability of the ground station frequency reference source generated by the ground station hydrogen masers. One tracking session will consist of roughly a fourteen-hour pass at the ground station in Perth in 2012/2013. Dual frequency ranging data may be acquired at the beginning and the end of a tracking pass.

Alternate Names

  • RSI
  • Rosetta/RSI
  • urn:esa:psa:context:instrument:ro.rsi

Funding Agency

  • European Space Agency (International)


  • Planetary Science: Small Bodies
  • Planetary Science: Celestial Mechanics

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. Martin PaetzoldPrincipal InvestigatorUniversitat zu

Selected References

  • Paetzold, M., et al., Rosetta Radio Science Investigations (RSI), Space Sci. Rev., 128, 599-627, doi:10.1007/s11214-006-9117-7, 2007.
[] NASA Logo -