Venus Express radio occultation observed by PRIDE

Bocanegra-Bahamón, Tatiana; Calvés, Guifre Molera; Gurvits, L. I.; Cimò, G.; Dirkx, Dominic; Duev, Dmitry A.; Pogrebenko, S. V.; Rosenblatt, P.; Limaye, S. S.; Cui, Lang; Li, P.; Kondo, Tetsuro; Sekido, Mamoru; Mikhailov, Andrey; Kharinov, M. A.; Ипатов, А. В.; Wang, W.; Zheng, Weimin; Ma, Miao; Lovell, J. E. J.; McCallum, Jamie

doi:10.1051/0004-6361/201833160

Cited by 18 publications

(25 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Low signal-to-noise ratio (SNR) or large frequency dynamic range would lead to the phase loss-of-lock on the desired signal [6][7][8]. Specifically, some abrupt changes of frequency would cause the phase loss-of-lock in closedloop tracking measurement mode, for instance, in planetary atmospheric occultation and ring occultation [9,10] an open-loop Doppler measurement is preferable [11][12][13][14][15]. In this case, no real-time signal detection mechanism is typically present; the carrier signal or tone signal of the deep space probe is down converted, digitized, recorded, and analyzed to extract high accuracy open-loop Doppler observables.…”

Section: Introductionmentioning

confidence: 99%

Retrieving Doppler Frequency via Local Correlation Method of Segmented Modeling

et al. 2021

View full text Add to dashboard Cite

The high accuracy radio Doppler frequency is critical for navigating a deep space probe and for planetary radio science experiments. In this paper, we propose a novel method based on the local correlation of segmented modeling to retrieve Doppler frequency by processing an open-loop radio link signal from one single ground station. Simulations are implemented, which prove the validity of this method. Mars Express (MEX) and Tianwen-1 observation experiments were carried out by Chinese Deep Space Stations (CDSS). X-band Doppler frequency observables were retrieved by the proposed method to participate in orbit determination. The results show that the accuracy of velocity residuals of orbit determination in open-loop mode is from 0.043 mm/s to 0.061 mm/s in 1 s integration; the average accuracy of Doppler frequency is about 3.3 mHz in 1 s integration and about 0.73 mHz in 60 s integration. The Doppler accuracy here is better than that of the digital baseband receiver at CDSS. The algorithm is efficient and flexible when the deep space probe is in a high dynamic mode and in low signal to noise ratio (SNR). This will benefit Chinese deep space exploration missions and planetary radio science experiments.

show abstract

Section: Introductionmentioning

confidence: 99%

Retrieving Doppler Frequency via Local Correlation Method of Segmented Modeling

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Lipa and Tyler (1979) proposed a method based on the linearization of the mathematical model that allows involving linear techniques. This method can also be found in recent works on radio occultation experiments (Bocanegra‐Bahamòn et al., 2019). However, this kind of approach enables the propagation of the uncertainty related to the frequency residuals only, neglecting the effects due to the spacecraft trajectory mismodeling.…”

Section: Methodsmentioning

confidence: 92%

A Technique for the Analysis of Radio Occultation Data to Retrieve Atmospheric Properties and Associated Uncertainties

2021

View full text Add to dashboard Cite

A radio occultation experiment consists in the analysis of the perturbations induced by the atmosphere on an electromagnetic signal propagating through it. The most relevant phenomena that affect a radio signal passing through a medium are refraction and absorption. The bending effects on the signal associated with refraction are related to the refractive index of the atmosphere (i.e., its real part), which in turn is linked to the atmospheric mass density, pressure, and temperature. Refraction causes a Doppler frequency shift of the signal traversing the atmosphere. A time series of frequency Doppler shifts is processed to identify the bending effects and, therefore, the atmospheric thermodynamic profiles, that is, a series of values obtained as a function of the radial distance from the center of the planet.Several methodologies have been developed to process radio occultation data. An approach is based on ray-tracing algorithms, and it is well suited for oblate refractive environments, such as Jupiter (Lindal et al., 1981), Saturn (Schinder et al., 2015), and Neptune (Lindal, 1992). Radio occultations of terrestrial planets and icy moons of the Solar System have been processed under the assumption of spherical symmetry of their atmospheres. Fjeldbo et al. (1971) proposed this method to obtain a simplified geometry of the Abstract Among the techniques for atmospheric sounding, radio occultation enables an in depth investigation of vertical profiles from the ionosphere to the troposphere by measuring the radio frequency signal associated to the propagation medium. A precise characterization of the atmospheric layers requires a thorough processing of the raw radio tracking data to estimate the thermodynamic properties of the atmosphere and their related uncertainties. In this work, we present a method to retrieve refractivity, density, pressure, and temperature profiles with the associated uncertainties by analyzing a set of raw radio tracking data occulted by the atmosphere. This technique is also well suited to process two-way Doppler measurements that are not acquired during dedicated occultation campaigns. The NASA mission Mars Reconnaissance Orbiter (MRO) provided a significant amount of radio occultation data that were not planned for atmospheric sounding, but were caused by the spacecraft orbit geometry. Our analysis of one of these occultation profiles with the proposed method allows indicating that MRO occultation datasets provide crucial information regarding Mars' troposphere that can be used as input of general circulation models.Plain Language Summary A solid technique to investigate the structure of a celestial body atmosphere is based on the analysis of the signals induced by the properties of this medium on the spacecraft radio links that pass through the atmosphere during communications with the Earth. A thorough study of these measurements, that is, radio occultation, allows estimating the vertical profiles of atmospheric density, pressure, and temperature. We present here a method to retrieve t...

show abstract

“…In this work, the order of magnitude of the frequency residual uncertainties is estimated to be: 10 −3 Hz for the thermal noise, between 10 −3 and 10 −4 Hz for Earth' ionosphere and troposphere (the DSN provides calibrations to remove the delay caused by the Earth's ionosphere to a precision of approximately 2-5 TECU [24]), 10 −3 Hz for interplanetary plasma, 10 −3 Hz for the spacecraft USO [25,26]. The uncertainty due to the estimated spacecraft trajectory, as well as the one of the residual Earth' ionosphere and troposphere particles after calibration are not quantified herein.…”

Section: Calibrationmentioning

confidence: 99%

Calibration Techniques for Studying Venus and Mars Atmospheres

Gramigna

2020

Aerotec. Missili Spaz.

View full text Add to dashboard Cite

The European Space Agency Venus Express mission (VEX) was sent to Venus in 2005 to unveil the unsolved mysteries regarding its atmosphere, the plasma environment and its temperatures. Radio occultation experiments performed by VeRa radio science instrument probed the planet’s atmosphere by studying the frequency shift on the radio signal sent by the spacecraft to Earth-based ground stations. This study carries out the calibration of the radio frequencies within a radio occultation experiment in order to correct the main sources of error as: thermal noise, spacecraft clock, spacecraft trajectory, and plasma noise. Any uncalibrated effects will bias the retrieval of atmospheric properties. A comparison of the occultation experiments between Venus and Mars is presented, both from the engineering and scientific point of view, through the analysis of Venus Express and Mars Global Surveyor (MGS) occultations data, highlighting stronger calibrations required for VEX, the extreme, hostile, thick Venus’ atmosphere, and a friendly, thin Mars’ atmosphere. This investigation analyzes Venus Express data recorded by the NASA Deep Space Network in 2014, and the results are compatible to previous studies of Venus atmosphere with VEX between 2006 and 2009.

show abstract

Venus Express radio occultation observed by PRIDE

Cited by 18 publications

References 61 publications

Retrieving Doppler Frequency via Local Correlation Method of Segmented Modeling

Retrieving Doppler Frequency via Local Correlation Method of Segmented Modeling

A Technique for the Analysis of Radio Occultation Data to Retrieve Atmospheric Properties and Associated Uncertainties

Calibration Techniques for Studying Venus and Mars Atmospheres

Contact Info

Product

Resources

About