The possibility of studying the lunar ionosphere with the SELENE radio science experiment

Imamura, Takeshi; Oyama, K.‐I.; Iwata, T.; Kono, Yusuke; Matsumoto, Koji; Liu, Qinghui; Noda, Hirotomo; Futaana, Yoshifumi; Nabatov, A. S.

doi:10.1186/bf03352803

Cited by 12 publications

(8 citation statements)

References 19 publications

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“…After determining the time span for 4‐way Doppler, we still had room to choose which 2‐way measurement for Rstar or Vstar was carried out. The Vstar 2‐way observation was preferentially chosen when there was a chance for occultation observations using the radio signal from Vstar to detect the lunar ionosphere [ Imamura et al , 2008] or for same‐beam VLBI observations [ Kikuchi et al , 2009]. Some exceptions for the general tracking rule of UDSC were permitted, i.e., tracking of the subsatellites even in so‐called face‐on orbit geometry in which the spacecraft fly over the lunar limb region without occultation.…”

Section: Selene Gravimetrymentioning

confidence: 99%

An improved lunar gravity field model from SELENE and historical tracking data: Revealing the farside gravity features

et al. 2010

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[1] A new spherical harmonic solution of the lunar gravity field to degree and order 100, called SGM100h, has been developed using historical tracking data and 14.2 months of SELENE tracking data (from 20 October 2007 to 26 December 2008 plus 30 January 2009). The latter includes all usable 4-way Doppler data collected which allowed direct observations of the farside gravity field for the first time. The new model successfully reveals farside features in free-air gravity anomalies which are characterized by ring-shaped structures for large impact basins and negative spots for large craters. SGM100h produces a correlation with SELENE-derived topography as high as about 0.9, through degree 70. Comparison between SGM100h and LP100K (one of the pre-SELENE models) shows that the large gravity errors which existed in LP100K are drastically reduced and the asymmetric error distribution between the nearside and the farside almost disappears. The gravity anomaly errors predicted from the error covariance, through degree and order 100, are 26 mGal and 35 mGal for the nearside and the farside, respectively. Owing to the 4-way Doppler measurements the gravity coefficients below degree and order 70 are now determined by real observations with contribution factors larger than 80 percent. With the SELENE farside data coverage, it is possible to estimate the gravity field to degree and order 70 without applying any a priori constraint or regularization. SGM100h can be used for global geophysical interpretation through degree and order 70.

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Section: Selene Gravimetrymentioning

confidence: 99%

An improved lunar gravity field model from SELENE and historical tracking data: Revealing the farside gravity features

et al. 2010

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“…Measurements of the electron density would constrain the ionization sources and plasma removal processes of the circumlunar space even if no electron density enhancements are detected. The Radio Science (RS) experiment on the SELENE (Kaguya) mission addresses this problem with the help of a radio occultation technique [ Imamura et al , 2008, 2010].…”

Section: Introductionmentioning

confidence: 99%

Dual‐spacecraft radio occultation measurement of the electron density near the lunar surface by the SELENE mission

Ando

Imamura

Nabatov³

et al. 2012

J. Geophys. Res.

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[1] During the SELENE (Kaguya) mission the dual-spacecraft radio occultation technique was used to investigate the electron population in the vicinity of the lunar surface. One pair of coherent S-band radio signals from one spacecraft was used to probe the possible electron density enhancement near the Moon, and another signal pair from the other spacecraft measured the solar wind and the terrestrial ionosphere plasma fluctuations, which also exist in the measurement by the former signal pair. The results suggest that any stable ionosphere with densities comparable to the ones observed by the Soviet Luna 19 and 22 missions does not exist near the terminator at high latitudes, although the occurrence of temporal or localized density enhancements cannot be ruled out.Citation: Ando, H., et al. (2012), Dual-spacecraft radio occultation measurement of the electron density near the lunar surface by the SELENE mission,

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“…In the KAGUYA mission, measurements of an electron density profile above the lunar surface were also performed by the radio occultation technique using the spacecraft-Earth link of the OUNA (Vstar) sub-satellite (Imamura et al 2008). As the radio occultation technique is an indirect method for measurement of an electron density profile on the lunar surface, it is necessary to take into account the effects of the Earth's ionosphere as a bias of the measurement quantity.…”

Section: Science On the Plasma Waves And Plasma Physics On The Moonmentioning

confidence: 99%

The Lunar Radar Sounder (LRS) Onboard the KAGUYA (SELENE) Spacecraft

et al. 2010

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The Lunar Radar Sounder (LRS) onboard the KAGUYA (SELENE) spacecraft has successfully performed radar sounder observations of the lunar subsurface structures and passive observations of natural radio and plasma waves from the lunar orbit. After the transfer of the spacecraft into the final lunar orbit and antenna deployment, the operation of LRS started on hours worth of radar sounder data and 8961 hours worth of natural radio and plasma wave data have been obtained. It was revealed through radar sounder observations that there are distinct reflectors at a depth of several hundred meters in the nearside maria, which are inferred to be buried regolith layers covered by a basalt layer with a thickness of several hundred meters. Radar sounder data were obtained not only in the nearside maria but also in other regions such as the farside highland region and polar region. LRS also performed passive observations of natural plasma waves associated with interaction processes between the solar wind plasma and the moon, and the natural waves from the Earth, the sun, and Jupiter. Natural 146 T. Ono et al. radio waves such as auroral kilometric radiation (AKR) with interference patterns caused by the lunar surface reflections, and Jovian hectometric (HOM) emissions were detected. Intense electrostatic plasma waves around 20 kHz were almost always observed at local electron plasma frequency in the solar wind, and the electron density profile, including the lunar wake boundary, was derived along the spacecraft trajectory. Broadband noises below several kHz were frequently observed in the dayside and wake boundary of the moon and it was found that a portion of them consist of bipolar pulses. The datasets obtained by LRS will make contributions for studies on the lunar geology and physical processes of natural radio and plasma wave generation and propagation.

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The possibility of studying the lunar ionosphere with the SELENE radio science experiment

Cited by 12 publications

References 19 publications

An improved lunar gravity field model from SELENE and historical tracking data: Revealing the farside gravity features

An improved lunar gravity field model from SELENE and historical tracking data: Revealing the farside gravity features

Dual‐spacecraft radio occultation measurement of the electron density near the lunar surface by the SELENE mission

The Lunar Radar Sounder (LRS) Onboard the KAGUYA (SELENE) Spacecraft

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