Deep Space Station Research Articles

Assessment of Callisto Gravity-field Determination Using the Inter-satellite Range-rate Link

China will launch the “Tianwen-IV” mission around 2030, focusing on the orbiting exploration of Jupiter and Callisto, a moon of Jupiter. As part of this ambitious mission, a main satellite will carry another satellite that will be released in the Jupiter system to continue its journey toward Uranus. Considering the current mission planning, we propose an inter-satellite radio-observation mode that differs from the conventional observation mode of tracking from Earth to precisely determine the orbit of the satellites. Given the significance of the Callisto gravity field model in both science objectives and satellite navigation, we have conducted a series of simulation experiments to evaluate the potential of this inter-satellite range-rate data for accurately estimating the Callisto gravity field. The results obtained from the analysis demonstrate that by utilizing 40 days of ground station observations, it is possible to estimate the gravity field model of Callisto up to a degree of 70. Remarkably, when combining these ground station observations with inter-satellite observations, a comparable level of accuracy can be achieved with just 10 days of observations. Furthermore, with reduced inter-satellite observation noise, accuracy improves, enabling estimation up to 80 degrees or higher. Initial inter-satellite distance selection impacts estimation accuracy. These findings serve as a valuable test bed for the future “Tianwen-IV” mission to perform precise orbit determination and gravity field model estimation to reduce reliance on deep space stations.

Period-Multiplying Bifurcations in the Gravitational Field of Asteroids

Periodic orbit families around asteroids serve as potential trajectories for space probes, mining facilities, and deep space stations. Bifurcations of these families provide additional candidate orbits for efficient trajectory design around asteroids. While various bifurcations of periodic orbit families around asteroids have been extensively studied, period-multiplying bifurcations have received less attention. This paper focuses on studying period-multiplying bifurcations of periodic orbit families around asteroids. In particular, orbits with periods of approximately 7 and 17 times that of the rotational period of asteroid 216 Kleopatra were computed. The computation of high-period orbits provides insights into the numerical aspects of simulating long-duration trajectories around asteroids. The previous literature uses single-shooting and multiple-shooting methods to compute bifurcations of periodic orbit families around asteroids. Computational difficulties were encountered while using the shooting methods to obtain period-multiplying bifurcations of periodic orbit families around asteroids. This work used the Legendre–Gauss collocation method to compute period-multiplying bifurcations around asteroids. This study recommends the use of collocation methods to obtain long-duration orbits around asteroids when computational difficulties are encountered while using shooting methods.

A High-Accuracy, High Anti-Noise, Unbiased Frequency Estimator Based on Three CZT Coefficients for Deep Space Exploration Mission.

Deep space exploration navigation requires high accuracy of the Doppler measurement, which is equivalent to a frequency estimation problem. Because of the fence effect and spectrum leakage, the frequency estimation performances, which is based on the FFT spectrum methods, are significantly affected by the signal frequency. In this paper, we propose a novel method that utilizes the mathematical relation of the three Chirp-Z Transform (CZT) coefficients around the peak spectral line. The realization, unbiased performance, and algorithm parameter setting rule of the proposed method are described and analyzed in detail. The Monte Carlo simulation results show that the proposed method has a better anti-noise and unbiased performance compared with some traditional estimator methods. Furthermore, the proposed method is utilized to process the raw data of MEX and Tianwen-1 satellites received by Chinese Deep Space Stations (CDSS). The results show that the Doppler estimation accuracy of MEX and Tianwen-1 are both about 3 millihertz (mHz) in 1-s integration, which is consistent with that of ESA/EVN/CDSN and a little better than that of the Chinese VLBI network (CVN). Generally, this proposed method can be effectively utilized to support Chinese future deep space navigation missions and radio science experiments.

Chinese Deep Space Stations: A brief review [Antenna Applications Corner

To meet the rapidly growing needs of current and future deep space exploration missions, China has developed three deep space stations: Jiamusi and Kashi, (China), and Argentina (South America), for providing continuous telemetry, tracking, and command (TT&C), reliable communication, and precise navigation services. Integrated with state-of-the-art technologies, these three deep space stations are not only powerful for transmission but also extremely sensitive for receiving. Many remarkable innovations and achievements were made during the construction process, including the beam waveguide (BWG), adjustable subreflector, high-power transmitter, cryogenic low-noise amplifier (LNA), antenna-arraying technique, digital baseband receiver, and interferometry. This article briefly reviews the system architecture, general performance, critical system design issues, and contributions made by these Chinese deep space stations (CDSSs) during Chang’e missions.

Foreign space activities in Argentina: Geopolitical imaginaries on the role of China and Europe in the national press (2007–2016)

This article endeavors to understand the construction of a geopolitical imaginary over the People’s Republic of China deep space station on Bajada del Agrio, Province of Neuquén, from the perspective of geopolitics. This paper introduces a comparative perspective: the Chinese space facilities are not a unique case within the borders of this sovereign state: there is a similar space installation called Deep Space Antenna under European Union flag in Malargüe, Province of Mendoza. In order to track the construction of such geopolitical imagination, this article analyzes the discourses offered in newspapers of national circulation in the South American country: Clarín, La Nación, and Página/12 from 2007 to 2016. This work also describes and analyzes domestic and foreign political discourses, and the sources of information the media selects to explain the issues the facilities raise. Argentina is a state of the Global South with an autonomous track of space development. Acquiring technology from a rising power could be disruptive, generating tensions with the core states, which were former exclusive partners and clients.

A Study of the Orbit Determination Ability and Time-Sharing Acquisition Mode for China’s Deep Space Network VLBI Data

According to the interferometric observation data of Jiamusi deep space station and Kashi deep space station of China deep space network during the mission of Chang'E-4 prober, the orbit determination accuracy of real-time data and post-correction data respectively combined with the USB data is analyzed. The difference between the Earth Moon transfer section and the precise orbit is 100 meters, and the difference between the ring moon section and the precise ephemeris is 10 meters. At the same time, the influences of VLBI data weight setting on the orbit accuracy is analyzed. In view of theChina deep space network in subsequent deep space missions such as Chang’E 5, a time-sharing acquisition mode is proposed to reduce the amount of VLBI data. The influence of this mode on orbit accuracy is analyzed by using the measured VLBI data of Chang’E 4 prober. The results show that the real-time data accuracy of China’s deep space network VLBI data has reached the accuracy of post-correction data, which can support the follow-up deep space exploration tasks in China. At the same time, for 2 to 3 hours per day of common viewing time of two stations, in the time-sharing acquisition mode, the total 20 minutes per day data and 1 minute acquisition step can ensure that the orbit accuracy does not decrease.

Similarity based telemetry data recovery for enhancing operating reliability of satellite

Recently, the satellite launching grows rapidly, especially in the commercial aerospace, which produces thousands of in-orbit spacecrafts. The operation and ground management of these satellites is a hotspot issue to ensure the satellites' in-orbit operation reliability. The telemetry data transmission may be delayed by the unstable telemetry link, insufficient ground station sources, interface failures and so on, which exerts a negative influence on the ground management capability and increases the failure risk. Meanwhile, the deep space spacecrafts, space station and Mars exploration expand this transmission delay. Thus, management and intelligent analysis of the telemetry data from Telemetry Ground Station (TGS) gradually become critical for in-orbit satellite operation. To solve above issues, a similarity-based deep learning time series prediction method is proposed to achieve telemetry data recovery. Considering the pseudo-periodic characteristics in telemetry data, this approach extracts similar segments to construct training samples instead of feeding all the observation samples to train the prediction model. As the predicted data is obtained ahead of the actual time-delayed telemetry data, which can provide sufficient analysis time for ground operator to optimize the maintenance strategy. Furthermore, the telemetry prediction data can also guarantee high-complexity digital twin modelling, virtual maintenance and so on. Experimental results with actual satellite telemetry data verify the effectiveness of the proposed method.

Retrieving Doppler Frequency via Local Correlation Method of Segmented Modeling

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.

A Hydrostatic Pressure-Driven Desalination System for Large-Scale Deep Sea Space Station

Compared with the common marine renewable energy sources like solar, wind, and wave energy, etc., the hydraulic pressure stored in the deep seawater can output stable and successive energy flow. Thus, it can be directly coupled with the reverse osmosis (RO) process to supply drinkable mineral water for crews of Deep Sea Space Station (DSSS). We proposed a novel submarine RO desalination system driven by the hydraulic pressure of deep seawater (SHP-RO), composed of a desalination branch to generate fresh water and a back pressure branch to ensure the depth independence of the desalination. The influences of the deep sea environment on the RO were analyzed, based on which the pretreatment of the seawater and the preparation of the drinkable mineral water were studied. The turbine-based energy recovery scheme was investigated in virtue of the CFD simulation on the flow behavior in the different turbine series. It was predicted that, when the DSSS was located at the depth of 1100 m and the operating pressure of the RO process was 6.0 MPa, for a drinkable water production rate of 240 m3/d, the recovered hydraulic pressure energy can achieve 39.22 kW·h, which was enough for driving electricity consumers in the SHP-RO system.

Design and analysis of a direct transfer trajectory from a near rectilinear halo orbit to a low lunar orbit

A near rectilinear halo orbit (NRHO) is regarded as a potential orbit for a future deep space station that can effectively support sustainable crewed lunar exploration missions. In this paper, the L2 southern NRHOs are selected as the research object, and a direct transfer trajectory from an NRHO to a low lunar orbit (LLO) is designed and analyzed. First, based on the circular restricted three-body problem, the characteristics of NRHOs are discussed including geometric behaviour, stability and synodic resonance. Second, optimal direct transfer trajectories are obtained by combining a local gradient optimization with a numerical continuation strategy. A reachable domain calculation model is established. Finally, simulations are carried out to verify the feasibility of the trajectory design method. The relationship between the velocity change and the reachable domain is further analysed through simulation calculations.

A Broadband Digital Spectrometer for the Deep Space Network

The Deep Space Network (DSN) enables NASA to communicate with its spacecraft in deep space. By virtue of its large antennas, the DSN can also be used as a powerful instrument for radio astronomy. Specifically, Deep Space Station (DSS) 43, the 70 m antenna at the Canberra Deep Space Communications Complex (CDSCC) has a K-band radio astronomy system covering a 10 GHz bandwidth at 17 GHz to 27 GHz. This spectral range covers a number of atomic and molecular lines, produced in a rich variety of interstellar gas conditions. Lines include hydrogen radio recombination lines (RRLs), cyclopropenylidene, water masers, and ammonia. A new high-resolution spectrometer was deployed at CDSCC in November 2019 and connected to the K-band downconverter. The spectrometer has a total bandwidth of 16 GHz. Such a large total bandwidth enables, for example, the simultaneous observations of a large number of RRLs, which can be combined together to significantly improve the sensitivity of these observations. The system has two firmware modes: 1) A 65k-pt FFT to provide 32768 spectral channels at 30.5 kHz and 2) A 16k-pt polyphase filterbank (PFB) to provide 8192 spectral channels with 122 kHz resolution. The observation process is designed to maximize autonomy, from the Principle Investigator's inputs to the output data in FITS file format. We present preliminary mapping observations of hydrogen RRLs in Orion KL mapping taken using the new spectrometer.

Preliminarily study of Saturn’s upper atmosphere density by observing Cassini plunging via China’s deep space station

When the Cassini spacecraft finally plunged into the Saturnian atmosphere on 2017 September 15, China’s deep space telescope pointed to Saturn to observe Cassini and study the Saturnian upper neutral atmosphere. In this first Chinese Saturnian radio science experiment, X band Doppler velocity radio science data between the deep space telescope and the Cassini spacecraft were obtained. After removing Saturnian and solar gravity effects, Earth rotation effect, the remaining Saturnian atmosphere drag information was retrieved in the Cassini final plunge progress. Saturn’s upper neutral atmosphere mass density profile is approximately estimated based on atmosphere mass density derived principally by real orbit measurement data. Saturn’s upper neutral atmospheremass density from76 000 km to 1400 km is estimated fromthe orbit measurement data, the mass density results are about from 1.4 × 10−15 kg cm−3 to 2.5 × 10−14 kg cm−3.

Resources for Future Updates of JAXA New Deep Space Station

Resources for Future Updates of JAXA New Deep Space Station

Electron Densities and Nitrogen Abundances in Ionized Gas Derived Using [N ii] Fine-structure and Hydrogen Recombination Lines

Abstract We present a method for deriving the electron density of ionized gas using the ratio of the intensity of the [N ii] 205 μm line to that of hydrogen radio recombination lines (RRLs). We use this method to derive electron densities of 21 velocity components in 11 lines of sight through the Galaxy, including the Galactic center. We observed, at high spectral resolution, the [N ii] 205 μm with the Herschel/HIFI and SOFIA/GREAT instruments and the RRLs with the Green Bank Telescope and the NASA Deep Space Network Deep Space Station 43 (DSS-43) telescope. We find typical electron densities between 8 and 170 cm−3, which are consistent with those derived at low spectral resolution using the [N ii] 205 μm/122 μm ratio with Herschel/PACS on a larger sample of sight lines in the Galactic plane. By matching the electron densities derived from the [N ii] 205 μm/RRL intensity ratio and the [N ii] 122 μm/205 μm intensity ratio, we derive the nitrogen fractional abundance for most of the velocity components. We investigate the dependence of the N/H ratio on galactocentric distance in the inner Galaxy (R gal < 6 kpc), which is inaccessible in optical studies owing to dust extinction. We find that the distribution of nitrogen abundances in the inner Galaxy derived from our data has a slope that is consistent with that found in the outer Galaxy in optical studies. This result is inconsistent with some suggestions of a flatter distribution of the nitrogen abundance in the inner Galaxy.

Transfers from near-rectilinear halo orbits to low-perilune orbits and the Moon’s surface

Near-rectilinear halo orbits (NRHOs) are periodic orbits that belong to the families of halo orbits around the L1/L2 points in a three-body system and have low minimum distances to the smaller primary. NRHOs possess some good dynamical and geometrical properties and are now considered as potential orbits for a near-future crewed deep space station. Recently, intensive investigations have been performed with regard to different aspects of a lunar NRHO mission: Earth-NRHO transfers, station keeping, shadow avoidance, and ground station visibility conditions are deeply studied. At the same time, the important operation of soft lunar landing from the working NRHO is still poorly covered in literature. In this research, we analyze both the direct landing scenario and the option of a transfer from the working NRHO to the intermediate low-perilune orbit (LPO). This kind of orbit can serve as a platform for transport communication between the lunar surface and the working NRHO. Lunar regions attainable after a one-impulse NRHO departure maneuver are identified, and the costs required for the soft landing are analytically estimated based on the classical gravity-turn landing strategy. In the scenario of a two-impulse transfer to the intermediate LPO, a wide range of perilune distances and inclinations is proved to be available. Several resonant NRHOs have been considered as a working orbit: the 4:1 and 9:2 L2 orbits, and the 11:3 L1 orbit. The calculations are performed in a high-fidelity model of motion that includes the JPL's DE430 ephemeris model of the Solar system and solar radiation pressure. The lunar gravitational field is evaluated based on the GRGM1200A spherical harmonic model truncated to degree and order 8.

Lunar Radiometric Measurement Based on Observing China Chang’E-3 Lander with VLBI—First Insight

China Chang’E-3 performed soft landing at the plains of Sinus Iridum on lunar surface on December 14th 2013 successfully; it opened a new window for observing lunar surface with radiometric tracking which many lunar scientific researchers always pursue for. Since July 2014, OCEL (Observing Chang’E-3 Lander with VLBI) project has been conducted jointly by IVS (International VLBI Service of Geodesy and Astrometry) and BACC (Beijing Aerospace Control Center), a global IVS R&D network augmented with two China Deep Space Stations configured for OCEL. This paper presents the current status and preliminary result of the OCEL and mainly focuses on determination of the lander position, which is about 7 meter in height and 14 meter in plane of lunar surface with respect to LRO (Lunar Reconnaissance Orbiter). Based on accuracy analysis, further optimized OCEL sessions will make use of this target-of-opportunity, the Chang’E-3 lunar lander, as long as it is working. With higher accurate radiometric observables, more prospective contribution to earth and lunar science is expected by combining with LLR.

Experimental Study on Water-Lubricated Bearing Material in Deep Sea Space Station

With the deepening of marine development activities, human-related sea-related behavior has gradually moved from shallow sea to deep sea. In this paper, the deep sea environment of the thruster bearing of the deep sea space station is characterized by high pressure, high corrosion, large amount of microorganisms and sediment. The Modified UHMWPE is developed, and the friction under simulated seawater conditions is studied by using different proportions of samples. The experimental results show that the materials developed in this study have lower friction coefficient and better wear resistance than Thordon and Feroform materials, and are very suitable for deep sea environment.

Predictions of space radiation fatality risk for exploration missions

In this paper we describe revisions to the NASA Space Cancer Risk (NSCR) model focusing on updates to probability distribution functions (PDF) representing the uncertainties in the radiation quality factor (QF) model parameters and the dose and dose-rate reduction effectiveness factor (DDREF). We integrate recent heavy ion data on liver, colorectal, intestinal, lung, and Harderian gland tumors with other data from fission neutron experiments into the model analysis. In an earlier work we introduced distinct QFs for leukemia and solid cancer risk predictions, and here we consider liver cancer risks separately because of the higher RBE's reported in mouse experiments compared to other tumors types, and distinct risk factors for liver cancer for astronauts compared to the U.S. population. The revised model is used to make predictions of fatal cancer and circulatory disease risks for 1-year deep space and International Space Station (ISS) missions, and a 940 day Mars mission. We analyzed the contribution of the various model parameter uncertainties to the overall uncertainty, which shows that the uncertainties in relative biological effectiveness (RBE) factors at high LET due to statistical uncertainties and differences across tissue types and mouse strains are the dominant uncertainty. NASA's exposure limits are approached or exceeded for each mission scenario considered. Two main conclusions are made: 1) Reducing the current estimate of about a 3-fold uncertainty to a 2-fold or lower uncertainty will require much more expansive animal carcinogenesis studies in order to reduce statistical uncertainties and understand tissue, sex and genetic variations. 2) Alternative model assumptions such as non-targeted effects, increased tumor lethality and decreased latency at high LET, and non-cancer mortality risks from circulatory diseases could significantly increase risk estimates to several times higher than the NASA limits.

Pulsar Timing at the Deep Space Network

The 70-m DSN’s Deep Space Station antenna 14 (DSS-14) at Goldstone has recently been outfitted with instrumentation to enable pulsar searching and timing operation. Systems capable of similar operations are undergoing installation at DSS-63, and are planned for DSS-43. The Goldstone system is the first of these to become operational with a 640[Formula: see text]MHz bandwidth stretching from 1325–1965[Formula: see text]MHz. Initial results from the pulsar timing pipeline show short-term residuals of [Formula: see text][Formula: see text]ns for pulsar B1937+21. Commissioning observations at DSS-14 to obtain a baseline set of time of arrival (TOA) measurements on several millisecond pulsars (MSPs) are currently underway.

Initial result of the Chinese Deep Space Stations’ coordinates from Chinese domestic VLBI experiments

China’s Lunar Exploration Program (CLEP) prompted the design and construction of the globally distributed Chinese Deep Space Network (CDSN). This network consists of Jiamusi and Kashi stations in China, and Zapala station in Argentina. However, the positions of Jiamusi and Kashi are not accurate enough for future Chinese deep space missions, and geodetic Very Long Baseline Interferometry (VLBI) is the most effective way to determine their positions. Since the CDSN stations are equipped with narrow-band receivers, they cannot participate in current international VLBI sessions in which wide-band frequencies are utilized. Thus a cooperative geodetic program of the CDSN and Chinese VLBI Network (CVN, the VLBI tracking subsystem of the CLEP) was initiated to determine their positions, in which specially designed frequencies can be utilized, and some CVN stations can act as position reference stations owing to their precise positions from long-term international VLBI observations. Primary results have been obtained from the CDSN–CVN combined domestic VLBI experiments from September 28, 2014, through December 10, 2015. The positions of Jiamusi and Kashi are determined to be better than 10-mm precision in the X, Y, and Z directions, which are improved by a factor of approximately 20 over their a priori values.