The MAVEN Radio Occultation Science Experiment (ROSE)
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The MAVEN Radio Occultation Science Experiment (ROSE) Paul Withers1 · M. Felici2 · M. Mendillo1 · L. Moore2 · C. Narvaez2 · M.F. Vogt2 · K. Oudrhiri3 · D. Kahan3 · B.M. Jakosky4
Received: 10 December 2019 / Accepted: 11 May 2020 © Springer Nature B.V. 2020
Abstract The Radio Occultation Science Experiment (ROSE) is part of the scientific payload of the Mars Atmosphere Volatile EvolutioN (MAVEN) spacecraft. Here we motivate the science objectives of the MAVEN ROSE investigation, which are (1) to determine the vertical structure of plasma in the ionosphere and (2) to identify the density, altitude, and width of the ionospheric density peak. MAVEN ROSE achieves these science objectives by performing two-way X-band radio occultations. Data are acquired ingress and egress opportunities using the high-gain antenna and a carrier-only signal. They are also acquired on ingress opportunities using the low-gain antenna with telemetry on the signal. Raw data are processed to yield vertical profiles of the electron density in the ionosphere of Mars with an accuracy on the order of 109 m−3 , a vertical resolution on the order of 1 km, and a vertical range on the order of 100–500 km. Data products are archived at the NASA Planetary Data System. In order to ensure the reproducibility of the results of the MAVEN ROSE investigation, software programs to determine MAVEN ROSE electron density profiles from time series of frequency residuals accompany this article. Furthermore, here we examine what the MAVEN ROSE observations reveal about the behavior of the ionosphere of Mars. Peak density, peak altitude, and total electron content mostly display the expected trends with solar zenith angle. However, deviations from those trends are present. Peak density at fixed dayside solar zenith angle can vary by 30% and M1 layer density at fixed solar zenith angle can vary even more. Solar irradiance variations are the most likely cause of these variations. Peak altitude at fixed dayside solar zenith angle This is a Special Communication, linked to the Topical Volume on ‘The Mars Atmosphere and Volatile Evolution (MAVEN) Mission’ published in Space Science Reviews (https://link.springer.com/journal/11214/195/1)
B P. Withers
[email protected]
1
Department of Astronomy/Center for Space Physics, Boston University, Boston, MA, USA
2
Center for Space Physics, Boston University, Boston, MA, USA
3
NASA Jet Propulsion Laboratory, Pasadena, CA, USA
4
Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO, USA
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can vary by 20 km or more. Thermospheric responses to lower atmospheric dust events are the most likely cause of these variations. Several instances of unusual ionospheric features are present in the dayside electron density profiles. A layer with density 3 × 1010 m−3 that appears to occur at 60 km altitude may be a horizontally-confined region of larger density that actually occurs at higher altitudes. Significant changes in density over short vertical distances aroun
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