scholarly journals Science operation plan of Phobos and Deimos from the MMX spacecraft

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Tomoki Nakamura ◽  
Hitoshi Ikeda ◽  
Toru Kouyama ◽  
Hiromu Nakagawa ◽  
Hiroki Kusano ◽  
...  
Keyword(s):  
Equatorial Plane ◽  
Three Dimensional ◽  
Landing Site ◽  
Satellite Orbit ◽  
Satellite Orbits ◽  
Polar Regions ◽  
Sample Collection ◽  
Resonant Orbits ◽  
Science Operations ◽  
Moon Exploration

AbstractThe science operations of the spacecraft and remote sensing instruments for the Martian Moon eXploration (MMX) mission are discussed by the mission operation working team. In this paper, we describe the Phobos observations during the first 1.5 years of the spacecraft’s stay around Mars, and the Deimos observations before leaving the Martian system. In the Phobos observation, the spacecraft will be placed in low-altitude quasi-satellite orbits on the equatorial plane of Phobos and will make high-resolution topographic and spectroscopic observations of the Phobos surface from five different altitudes orbits. The spacecraft will also attempt to observe polar regions of Phobos from a three-dimensional quasi-satellite orbit moving out of the equatorial plane of Phobos. From these observations, we will constrain the origin of Phobos and Deimos and select places for landing site candidates for sample collection. For the Deimos observations, the spacecraft will be injected into two resonant orbits and will perform many flybys to observe the surface of Deimos over as large an area as possible. Graphical Abstract

scholarly journals Science Operation Plan of Phobos and Deimos From the MMX Spacecraft

2021 ◽  
Author(s):  
Tomoki Nakamura ◽  
Hitoshi Ikeda ◽  
Toru Kouyama ◽  
Hiromu Nakagawa ◽  
Hiroki Kusano ◽  
...  
Keyword(s):  
Equatorial Plane ◽  
Three Dimensional ◽  
Landing Site ◽  
Satellite Orbit ◽  
Satellite Orbits ◽  
Polar Regions ◽  
Sample Collection ◽  
Resonant Orbits ◽  
Exploration Mission ◽  
Moon Exploration

Abstract The science operations of the spacecraft and remote sensing instruments for the MMX (Martian Moon eXploration) mission are discussed by the mission operation working team. In this paper, we describe the Phobos observations during the first 1.5 years of the spacecraft's stay around Mars, and the Deimos observations before leaving the Martian system. In the Phobos observation, the spacecraft will be placed in low-altitude quasi-satellite orbits on the equatorial plane of Phobos and will make high-resolution topographic and spectroscopic observations of the Phobos surface from five different altitudes orbits. The spacecraft will also attempt to observe polar regions of Phobos from a three-dimensional quasi-satellite orbit moving out of the equatorial plane of Phobos. From these observations, we will constrain the origin of Phobos and Deimos and select places for landing site candidates for sample collection. For the Deimos observations, the spacecraft will be injected into two resonant orbits and will perform many flybys to observe the surface of Deimos over as large an area as possible. (166 words)

ROBOTS for MOON EXPLORATION

2021 ◽  
Author(s):  
Maxim Litvak ◽  
Igor Mitrofanov ◽  
Lev Zelenyi ◽  
Vladislav Tretyakov ◽  
Tatiana Kozlova ◽  
...  
Keyword(s):  
Lunar Regolith ◽  
Landing Site ◽  
Isotopic Analysis ◽  
Lunar Soil ◽  
Soil Samples ◽  
Robotic Arm ◽  
Successful Implementation ◽  
Polar Regions ◽  
Sample Collection ◽  
Water Ice

<p>Russian lunar program includes several landing missions of Luna-25, Luna-27, Luna-28 which should be implemented step by step to explore mineralogical, chemical, and isotopic compositions of the lunar polar regolith, search for volatile compounds, deliver soil samples to the Earth and prepare future manned expeditions to Moon.</p><p>The successful implementation of these missions requires employing of excavation and drilling of lunar regolith to the different depths with extraction of soil samples for the farther analysis (in situ or sample return).The first mission in row Luna-25 will be launched in October 2021 and landed at the area located north of Boguslawsky crater. This lander is equipped with the Lunar Manipulation Complex (LMC) – the robotic arm that should excavate lunar regolith (down to 5 – 25 cm) and deliver sample of lunar soil to the analytical instrumentation for the elemental and isotopic analysis. The robotic arm is already passed through the validation, functional and calibration tests in lunar-like conditions (low pressures and low temperatures) to imitate interaction with lunar soil simulant enriched with different content of water.</p><p>The Luna – 27 and Luna – 28 will be landed at southern polar regions (landing site selection is in progress). They will be equipped with Deep Drill Systems (DDS) to take samples of polar regolith enriched with water ice and other volatiles from 1-2 m depths. The DDS for Luna-27 , as part of the PROSPECT suit, shall be contributed by ESA. The DDS for Luna – 28 (the sample polar return mission) is being developed by Space Research Institute.In this presentation we report the results of ground tests with LMC units and DDS prototype.In addition to DDS, it is expected that Luna – 28 will carry a small sized lunokhod (~100 kg) to support sample collection and proceed with geological survey program (up to 30 km around the landing site per one year). The lunokhod will study elemental/isotopic/mineral composition of lunar regolith along rover traverse to estimate accessibility of lunar resources (first of all, water ice as a source of hydrogen and oxygen) applicable for potential industry utilization and support of manned expeditions. </p><p>The Russian lunar program assumes synergy of robotic and manned missions. Beyond Luna -25,27,28, it is expected that the next lunar missions will deliver to Moon surface heavy lunokhod, which will prepare the landing of the manned mission.  Finally, as part of testing program for manned lander (without cosmonauts), it is proposed to deliver multifunctional robotic equipment to support  the following arrival of cosmonauts. </p>

scholarly journals Comparisons of CODE and CNES/CLS GPS satellite bias products and applications in Sentinel-3 satellite precise orbit determination

GPS Solutions ◽  
2021 ◽  
Vol 25 (4) ◽  
Author(s):  
Bingbing Duan ◽  
Urs Hugentobler
Keyword(s):  
Linear Combination ◽  
Orbit Determination ◽  
Fractional Part ◽  
Precise Orbit Determination ◽  
Satellite Orbit ◽  
Satellite Orbits ◽  
Satellite Clock ◽  
Analysis Center ◽  
Wide Lane ◽  
Total Difference

AbstractTo resolve undifferenced GNSS phase ambiguities, dedicated satellite products are needed, such as satellite orbits, clock offsets and biases. The International GNSS Service CNES/CLS analysis center provides satellite (HMW) Hatch-Melbourne-Wübbena bias and dedicated satellite clock products (including satellite phase bias), while the CODE analysis center provides satellite OSB (observable-specific-bias) and integer clock products. The CNES/CLS GPS satellite HMW bias products are determined by the Hatch-Melbourne-Wübbena (HMW) linear combination and aggregate both code (C1W, C2W) and phase (L1W, L2W) biases. By forming the HMW linear combination of CODE OSB corrections on the same signals, we compare CODE satellite HMW biases to those from CNES/CLS. The fractional part of GPS satellite HMW biases from both analysis centers are very close to each other, with a mean Root-Mean-Square (RMS) of differences of 0.01 wide-lane cycles. A direct comparison of satellite narrow-lane biases is not easily possible since satellite narrow-lane biases are correlated with satellite orbit and clock products, as well as with integer wide-lane ambiguities. Moreover, CNES/CLS provides no satellite narrow-lane biases but incorporates them into satellite clock offsets. Therefore, we compute differences of GPS satellite orbits, clock offsets, integer wide-lane ambiguities and narrow-lane biases (only for CODE products) between CODE and CNES/CLS products. The total difference of these terms for each satellite represents the difference of the narrow-lane bias by subtracting certain integer narrow-lane cycles. We call this total difference “narrow-lane” bias difference. We find that 3% of the narrow-lane biases from these two analysis centers during the experimental time period have differences larger than 0.05 narrow-lane cycles. In fact, this is mainly caused by one Block IIA satellite since satellite clock offsets of the IIA satellite cannot be well determined during eclipsing seasons. To show the application of both types of GPS products, we apply them for Sentinel-3 satellite orbit determination. The wide-lane fixing rates using both products are more than 98%, while the narrow-lane fixing rates are more than 95%. Ambiguity-fixed Sentinel-3 satellite orbits show clear improvement over float solutions. RMS of 6-h orbit overlaps improves by about a factor of two. Also, we observe similar improvements by comparing our Sentinel-3 orbit solutions to the external combined products. Standard deviation value of Satellite Laser Ranging residuals is reduced by more than 10% for Sentinel-3A and more than 15% for Sentinel-3B satellite by fixing ambiguities to integer values.

scholarly journals Modeling and Performance Evaluation of Precise Positioning and Time-Frequency Transfer with Galileo Five-Frequency Observations

2021 ◽  
Vol 13 (15) ◽  
pp. 2972
Author(s):  
Wei Xu ◽  
Wen-Bin Shen ◽  
Cheng-Hui Cai ◽  
Li-Hong Li ◽  
Lei Wang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Satellite Orbit ◽  
Average Frequency ◽  
Satellite System ◽  
Observation Data ◽  
Navigation Satellite ◽  
Dual Frequency ◽  
Time Frequency ◽  
Combination Model ◽  
Frequency Transfer

The present Global Navigation Satellite System (GNSS) can provide at least double-frequency observations, and especially the Galileo Navigation Satellite System (Galileo) can provide five-frequency observations for all constellation satellites. In this contribution, precision point positioning (PPP) models with Galileo E1, E5a, E5b, E5 and E6 frequency observations are established, including a dual-frequency (DF) ionospheric-free (IF) combination model, triple-frequency (TF) IF combination model, quad-frequency (QF) IF combination model, four five-frequency (FF) IF com-bination models and an FF uncombined (UC) model. The observation data of five stations for seven days are selected from the multi-GNSS experiment (MGEX) network, forming four time-frequency links ranging from 454.6 km to 5991.2 km. The positioning and time-frequency transfer performances of Galileo multi-frequency PPP are compared and evaluated using GBM (which denotes precise satellite orbit and clock bias products provided by Geo Forschung Zentrum (GFZ)), WUM (which denotes precise satellite orbit and clock bias products provided by Wuhan University (WHU)) and GRG (which denotes precise satellite orbit and clock bias products provided by the Centre National d’Etudes Spatiales (CNES)) precise products. The results show that the performances of the DF, TF, QF and FF PPP models are basically the same, the frequency stabilities of most links can reach sub10−16 level at 120,000 s, and the average three-dimensional (3D) root mean square (RMS) of position and average frequency stability (120,000 s) can reach 1.82 cm and 1.18 × 10−15, respectively. The differences of 3D RMS among all models are within 0.17 cm, and the differences in frequency stabilities (in 120,000 s) among all models are within 0.08 × 10−15. Using the GRG precise product, the solution performance is slightly better than that of the GBM or WUM precise product, the average 3D RMS values obtained using the WUM and GRG precise products are 1.85 cm and 1.77 cm, respectively, and the average frequency stabilities at 120,000 s can reach 1.13 × 10−15 and 1.06 × 10−15, respectively.

scholarly journals Review of progress in gathering, distributing and using satellite data for activities within COST 238 (PRIME)

1996 ◽  
Vol 39 (4) ◽  
Author(s):  
I. Kutiev ◽  
S. Stankov
Keyword(s):  
Satellite Data ◽  
Satellite Orbit ◽  
Testing Procedure ◽  
Satellite Orbits ◽  
Neutral Atmosphere ◽  
Recombination Rates ◽  
F Region ◽  
Field Lines ◽  
The Given ◽  
To Receive

Recent progress in using the satellite data for various PRIME purposes is briefly presented. The satellite data base is already in operation and contains data of local plasma and neutral atmosphere parameters taken from several ionospheric satellites. A method of tracing the locally measured parameters along the magnetic field lines down to hmF2 is developed using a theoretical F-region code. This method is applied to receive f0F2sat needed to test monthly median and instantaneous mapping methods. In order to reduce the uncertainties arising from the unknown photoionization and recombination rates, f0F2 is calibrated at one point on the satellite orbit with a Vertical Incident (VI) f0F2 and their ratio is then assumed constant along the whole satellite track over the PRIME area. The testing procedure for monthly median maps traces the measured plasma density down to a basic height of 400 km, where individual f0F2sat values are accumulated in every time/subarea bin within the given month, then their median is calibrated with the available medians from the VI ionosonde network. From all available satellite orbits over the PRIME area, 35 of them were found to pass over two VI ionosonde stations. The second station in these orbits was used to check the calculated f0F2sat with the measured VI f0F2. The standard deviation was found to be only 0.15 MHz.

scholarly journals A short geostatistical study of the three-dimensional spatial structure of fumonisins in stored maize

2010 ◽  
Vol 3 (1) ◽  
pp. 95-103 ◽  
Author(s):  
M. Rivas Casado ◽  
D. Parsons ◽  
N. Magan ◽  
R. Weightman ◽  
P. Battilani ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Spatial Structure ◽  
Spatial Correlation ◽  
Three Dimensional ◽  
Sample Collection ◽  
Data Set ◽  
Research Areas ◽  
Geostatistical Approach ◽  
Sampling Protocols ◽  
Current Sample

The heterogeneous three-dimensional spatial distribution of mycotoxins has proven to be one of the main limitations for the design of effective sampling protocols. Current sample collection protocols for mycotoxins have been designed to estimate the mean concentration and fail to characterise the spatial distribution of the mycotoxin concentration due to the aggregation of the incremental samples. Geostatistical techniques have been successfully applied to overcome similar problems in many research areas. However, little work has been developed on the use of geostatistics for the design of sampling protocols for mycotoxins. This paper focuses on the analysis of the two and three-dimensional spatial structure of fumonisins B1 (FB1) and B2 (FB2) in maize in a bulk store using a geostatistical approach and on how results help determine the number and location of incremental samples to be collected. The spatial correlation between FB1 and FB2, as well as between the number of kernels infected and the level of contamination was investigated. For this purpose, a bed of maize was sampled at different depths to generate a unique three-dimensional data set of FB1 and FB2. The analysis found no clear evidence of spatial structure in either the two-dimensional or three-dimensional analyses. The number of Fusarium infected kernels was not a good indicator for the prediction of fumonisin concentration and there was no spatial correlation between the concentrations of the two fumonisins.

scholarly journals Age- and sex-related changes of the volume of maxillary sinuses quantified via cone beam computed tomography

2021 ◽  
Vol 10 (14) ◽  
pp. e312101422220
Author(s):  
Lucas Eigi Borges Tanaka ◽  
Ademir Franco ◽  
Rafael Ferreira Abib ◽  
Luiz Roberto Coutinho Manhães-Junior ◽  
Sergio Lucio Pereira de Castro Lopes
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Three Dimensional ◽  
Specific Treatment ◽  
Cone Beam ◽  
Patient Specific ◽  
Sample Collection ◽  
Left And Right ◽  
Age And Sex ◽  
Maxillary Sinuses

Anatomical studies found in cone beam computed tomography (CBCT) an optimal resource for the three-dimensional (3D) assessment of the head and neck. When it comes to the maxillary sinuses, CBCT enables a life-size reliable volumetric analysis. This study aimed to assess the age and sex-related changes of the maxillary sinuses using volumetric CBCT analysis. The sample consisted of CBCT scans of 112 male (n = 57) and female (n = 55) individuals (224 maxillary sinuses) distributed in 5 age categories: 20 |— 30, 31 |— 40, 41 |— 50, 51 |— 60 and > 60 years. Image acquisition was accomplished with the i-CAT Next Generation device set with voxel size of 0.25 mm and field of view that included the maxillary sinuses (retrospective sample collection from an existing database). Image segmentation was performed in itk-SNAP (www.itksnap.org) software. The volume (mm3) of the segmented sinuses was quantified and compared pairwise based on side (left and right), sex (male and female) and age (five groups). Differences between left and right sides volume were not statistically significant (p > 0.05). The mean volume of maxillary sinuses in males was 22% higher than females (p = 0.0001). Volumetric differences were not statistically significant between age categories for males and females (p > 0.05). The discriminant power of sinuses’ volume may support customized and patient-specific treatment planning based on sex.

Disputes over satellite orbits will increase

2021 ◽  
Keyword(s):  
Satellite Orbit ◽  
Satellite Orbits ◽  
Content Type

Headline INTERNATIONAL: Satellite orbit disputes will increase

An Advanced Receiver Autonomous Integrity Monitoring (ARAIM) Ground Monitor Design to Estimate Satellite Orbits and Clocks

2020 ◽  
Vol 73 (5) ◽  
pp. 1087-1105
Author(s):  
Yawei Zhai ◽  
Jaymin Patel ◽  
Xingqun Zhan ◽  
Mathieu Joerger ◽  
Boris Pervan
Keyword(s):  
Measurement Errors ◽  
Satellite Orbit ◽  
Global Navigation Satellite Systems ◽  
Estimation Accuracy ◽  
Satellite Orbits ◽  
Integrity Monitoring ◽  
Satellite Systems ◽  
Receiver Autonomous Integrity Monitoring ◽  
The Impact ◽  
Advanced Receiver

This paper describes a method to determine global navigation satellite systems (GNSS) satellite orbits and clocks for advanced receiver autonomous integrity monitoring (ARAIM). The orbit and clock estimates will be used as a reference truth to monitor signal-in-space integrity parameters of the ARAIM integrity support message (ISM). Unlike publicly available orbit and clock products, which aim to maximise estimation accuracy, a straightforward and transparent approach is employed to facilitate integrity evaluation. The proposed monitor is comprised of a worldwide network of sparsely distributed reference stations and will employ parametric satellite orbit models. Two separate analyses, covariance analysis and model fidelity evaluation, are carried out to assess the impact of measurement errors and orbit model uncertainty on the estimated orbits and clocks, respectively. The results indicate that a standard deviation of 30 cm can be achieved for the estimated orbit/clock error, which is adequate for ISM validation.

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