Autonomous optical navigation for interplanetary exploration based on information of earth-moon

The image elements of earth-center and moon-center are obtained by processing the images of earthand moon, these image elements in combination with the inertial attitude information and the moon ephemerisare utilized to obtain the probe initial position relative to earth, and the Levenberg-Marquardt algorithm is usedto determine the accurate probe position relative to earth, and the probe orbit relative to earth is estimated by u-sing the extended Kalman filter. The autonomous optical navigation algorithm is validated using the digital simu-lation.

Autonomous relative optical navigation based on unified modeling of external systematic errors

To solve the problem that external systematic errors of the optical camera cannot be fully estimated due to limited computing resources,a unified dimensionality reduction representation method for the external systematic errors of the optical camera is proposed,and autonomous relative optical navigation is realized.The camera translational and misalignment errors are converted into a three-dimensional rotation error,whose differential model can be established through specific attitude control and appropriate assumption.Then,the rotation error and the relative motion state are jointly estimated in an augmented Kalman filter framework.Compared with the traditional method that estimates the camera translational and misalignment errors,the proposed method reduces the computational complexity in that the estimated state dimension is reduced.Furthermore,as demonstrated by numerical simulation,the estimation accuracy is improved significantly.

UPF based autonomous navigation scheme for deep space probe

The autonomous "celestial navigation scheme" for deep space probe departing from the earth and the autonomous "optical navigation scheme" for encountering object celestial body are presented. Then, aiming at the conditions that large initial estimation errors and non-Gaussian distribution of state or measurement errors may exist in orbit determination process of the two phases, UPF (unscented particle filter) is introduced into the navigation schemes. By tackling nonlinear and non-Gaussian problems, UPF overcomes the accuracy influence brought by the traditional EKF (extended Kalman filter), UKF (unscented Kalman filter), and PF (particle filter) schemes in approximate treatment to nonlinear and non-Gaussian state model and measurement model. The numerical simulations demonstrate the feasibility and higher accuracy of the UPF navigation scheme.

Optimal crater landmark selection based on optical navigation performance factors for planetary landing

Planetary craters are natural navigation landmarks that widely exist and are easily observed.Optical navigation based on crater landmarks has become an important autonomous navigation method for planetary landing.Due to the increase in observed crater landmarks and the limitation of onboard computation,the selection of good crater landmarks has gradually become a research hotspot in the field of landmark-based optical navigation.This paper designs a fast crater landmark selection method,which not only considers the configuration observability of crater subsets but also focuses on the influence on navigation performance arising from the measurement uncertainty and the matching confidence of craters,which is different from other landmark selection methods.The factor of measurement uncertainty,which is anisotropic,correlated and nonidentically distributed,is quantified and integrated into selection based on crater pairing detection and localization error evaluation.In addition,the concept of the crater matching confidence factor is introduced,which reflects the possibility of 2D projection measurements corresponding to 3D positions.Combined with the configuration observability factor,the crater landmark selection indicator is formed.Finally,the effectiveness of the proposed method is verified by Monte Carlo simulations.

The deep-space multi-object orbit determination system and its application to Hayabusa2’s asteroid proximity operations

The deep-space multi-object orbit determination system(DMOODS)and its application in the asteroid proximity operation of the Hayabusa2 mission are described.DMOODS was developed by the Japan Aerospace Exploration Agency(JAXA)for the primary purpose of determining the trajectory of deep-space spacecraft for JAXA’s planetary missions.The weighted least-squares batch filter is used for the orbit estimator of DMOODS.The orbit estimator supports more than 10 data types,some of which are used for relative trajectory measurements between multiple space objects including natural satellites and small bodies.This system consists of a set of computer programs running on Linux-based consumer PCs on the ground,which are used for orbit determination and the generation of radiometric tracking data,such as delta differential one-way ranging and doppler tracking data.During the asteroid proximity phase of Hayabusa2,this system played an essential role in operations that had very strict navigation requirements or operations in which few optical data were obtained owing to special constraints on the spacecraft attitude or distance from the asteroid.One example is orbit determination during the solar conjunction phase,in which the navigation accuracy is degraded by the effect of the solar corona.The large range bias caused by the solar corona was accurately estimated with DMOODS by combining light detection and ranging(LIDAR)and ranging measurements in the superior solar conjunction phase of Hayabusa2.For the orbiting operations of target markers and the MINERVA-II2 rover,the simultaneous estimation of six trajectories of four artificial objects and a natural object was made by DMOODS.This type of simultaneous orbit determination of multi-artificial objects in deep-space has never been accomplished before.

Rendezvous to asteroid with highly uncertain ephemeris: Hayabusa2’s Ryugu-approach operation result

This paper describes the guidance and navigation technique used by Hayabusa2 for the asteroid rendezvous operation to reach Ryugu.The operation results,including the achieved guidance and navigation performance,are also summarized.Multiple assessment and navigation teams worked closely to provide reliable navigation solutions with a short solution delivery cycle.Although the uncertainty of the Ryugu’s ephemeris was considerable before Hayabusa2’s arrival,a combination of radiometric-optical hybrid navigation and a stochastic-constrained optimum guidance method was able to achieve an accuracy of less than 100 m and 1 cm/s,and the arrival was precisely timed.

Simultaneous estimation of spacecraft position and asteroid diameter during final approach of Hayabusa2 to Ryugu

This paper presents the optical navigation results of the asteroid explorer Hayabusa2 during the final rendezvous approach phase with the asteroid Ryugu.The orbit determination of Hayabusa2 during the cruising phase uses a triangulation-based method that estimates the probe and asteroid orbits using the directions from which they are observed.Conversely,the asteroid size is available as optical information just prior to arrival.The size information allows us to estimate the relative distance between the probe and the asteroid with high accuracy,that is strongly related to the success or failure of the rendezvous.In this study,the relative distance and asteroid size in real space are simultaneously estimated in real time by focusing on the rate of change of the asteroid size observed in sequential images.The real-time estimation results coincided with those of precise analyses performed after arrival.

Advancing theranostics with tumor-targeting peptides for precision otolaryngology

Worldwide, about 600,000 head and neck squamous cell carcinoma (HNSCC) are de-tected annually, many of which involve high risk human papilloma virus (HPV). Surgery is the primary and desired first treatment option. Following surgery, the existence of cancer cells at the surgical margin is strongly associated with eventual recurrence of cancer and a poor outcome. Despite improved surgical methods (robotics, microsurgery, endoscopic/laparo-scopic, and external imaging), surgeons rely only on their vision and touch to locate tumors during surgery. Diagnostic imaging systems like computed tomography (CT), magnetic reso-nance imaging (MRI), single-photon emission computed tomography (SPECT) and positron-emission tomography (PET) are too large, slow and costly to use efficiently during most sur-geries and, ultrasound imaging, while fast and portable, is not cancer specific. This purpose of this article is to review the fundamental technologies that will radically advance Precision Otolaryngology practices to the benefit of patients with HNSCC. In particular, this article will address the potential for tumor-targeting peptides to enable more precise diagnostic imaging while simultaneously advancing new therapeutic paradigms for next generation image-guided surgery, tumor-specific chemotherapeutic delivery and tumor-selective targeted radiotherapy (i.e., theranostic).

Hayabusa2’s station-keeping operation in the proximity of the asteroid Ryugu

The Japanese interplanetary probe Hayabusa2 was launched on December 3,2014 and the probe arrived at the vicinity of asteroid 162173 Ryugu on June 27,2018.During its 1.4 years of asteroid proximity phase,the probe successfully accomplished numbers of record-breaking achievements including two touchdowns and one artificial cratering experiment,which are highly expected to have secured surface and subsurface samples from the asteroid inside its sample container for the first time in history.The Hayabusa2 spacecraft was designed not to orbit but to hover above the asteroid along the sub Earth line.This orbital and geometrical configuration allows the spacecraft to utilize its high-gain antennas for telecommunication with the ground station on Earth while pointing its scientific observation and navigation sensors at the asteroid.This paper focuses on the regular station-keeping operation of Hayabusa2,which is called“home position”(HP)-keeping operation.First,together with the spacecraft design,an operation scheme called HP navigation(HPNAV),which includes a daily trajectory control and scientific observations as regular activities,is introduced.Following the description on the guidance,navigation,and control design as well as the framework of optical and radiometric navigation,the results of the HP-keeping operation including trajectory estimation and delta-V planning during the entire asteroid proximity phase are summarized and evaluated as a first report.Consequently,this paper states that the HP.keeping operation in the framework of HPNAV had succeeded without critical incidents,and the number of trajectory control delta-V was planned fficiently throughout the period.