Space exploration and exploitation depend on the development of on-orbit robotic capabilities for tasks such as servicing of satellites, removing of orbital debris, or construction and maintenance of orbital assets. Manipulation and capture of objects on-orbit are key enablers for these capabilities. This survey addresses fundamental aspects of manipulation and capture, such as the dynamics of space manipulator systems (SMS), i.e., satellites equipped with manipulators, the contact dynamics between manipulator grippers/payloads and targets, and the methods for identifying properties of SMSs and their targets. Also, it presents recent work of sensing pose and system states, of motion planning for capturing a target, and of feedback control methods for SMS during motion or interaction tasks. Finally, the paper reviews major ground testing testbeds for capture operations, and several notable missions and technologies developed for capture of targets on-orbit. In fact, although several missions for on-orbit target capture using a SMS have been demonstrated so far, such as JAXA’s ETS-VII ( Oda, 1999 ; Yoshida, 2003 ), DARPA’s Orbital Express ( Whelan et al., 2000 ), and China’s Aolong-1 ( Space Flight, 2016 ), robotic capture of a tumbling satellite has not been attempted yet. The SMS for future on-orbit servicing missions will be operated from ground or autonomously, depending on mission constraints, requirements, and the level of technology readiness. However, they tend to be computationally expensive; hence, methods for increasing the speed of computation are still needed. Free-Flying Space Manipulator Systems To increase SMS mobility and perform larger end-effector displacements ( Papadopoulos and Dubowsky, 1991b ; Lampariello et al., 2003 ; Lampariello, R., 2013 ) or/and limit the contact force disturbances during docking operations ( Shibli et al., 2005 ; Flores-abad et al., 2014a ), the SMS must operate in the free-flying mode. In this mode, the spacecraft can be transferred and oriented arbitrarily in space. Contact dynamics simulations for practical cases with stiff contact materials and complex contact geometries (e.g., manipulator capturing or spacecraft docking) usually are very inefficient because of the required large number of iterative computations and very small numerical integration step size (for numerical stability). Many studies have been devoted to improving efficiency of computational contact models. Mazhar et al. (2015) presented a solution method to simulate the multibody systems with frictional contact. The presented method reduced the required time by one or two orders of magnitude. Sensing of Pose and State Motion State Estimation Robust relative navigation systems are critical for many current and near-future lunar or space exploration missions to support rendezvous, proximity operations and docking for both crewed and uncrewed vehicles. Reliable relative pose information in full 6-DoF is required during approach and docking of a visiting vehicle with the ISS. It is deemed that the safety of the controlled spacecraft during such proximity maneuvers critically depends on the performance and robustness of the relative navigation systems. The Rendezvous and Docking assembly principle have different drawbacks, including high risk of collision, high requirement for the GNC system and large fuel consumption ( She et al., 2020 ). To accomplish the task with space robots, the free-floating dynamics is typically omitted, since the parts to be assembled and the robotic arm which assembles them, are both hosted on the same spacecraft. Examples of robotic assembly planning for this specific task can be found in She et al. (2020) and Martinez-Moritz et al. (2021) . The motion planning task was divided in the latter into a global and a local layer. Wertz and Bell (2003) gave an overview of hardware and software technologies (sensors and actuators) required for autonomous rendezvous and docking of two spacecraft started at a remote distance. The terminal phase of the Demonstration of Autonomous Rendezvous Technology (DART) mission that includes proximity maneuvers for rendezvous to a cooperative spacecraft under an advanced video guidance sensor is described in Ruth and Tracy (2004) . Adaptive control law for spacecraft rendezvous and docking under measurement uncertainty such as aggregation of sensor calibration parameter, systematic bias, or some stochastic disturbances was proposed in Singla and Junkins (2006) and Aghili and Su (2016) . The development and experimental validation of adaptive visual servoing for on-orbit servicing was presented in Aghili (2012) ; see Figure 3 . The vision guidance problem for the shortest time was cast into the optimal control framework pertaining to two sequentially occurring maneuvers in the pre-grasping and post-capturing phases ( Aghili, 2013 ). An emulation of zero-g translational motion can be achieved by an air-bearing table on which a spacecraft translates on a flat surface perpendicular to the gravity direction while being floated on a cushion of compressed air with almost no resistance. This technique has been used for testing various space systems such as formation flying ( Choset and Kortenkamp, 1999 ), free-flying space robots ( Yoshida, 2003 ), orbital rendezvous and docking ( Matunaga et al., 2000 ; Aghili Northrop Grumman’s MEV and MRV Orbital ATK (now part of Northrop Grumman) has developed the Mission Extension Vehicle (MEV) missions in the past few years. They were the first OOS missions developed by a private company purely for commercialization. MEV-1 was launched in October 2019 and completed its historic docking with the Intelsat 901 spacecraft on February 25, 2020. This marked the very first time two commercial satellites docked in orbit. IS-901 resumed communications services on April 2, 2020. MEV-2 was launched and successfully docked with the Intelsat 10-02 (IS-10-02) on April 12, 2021 ( Grumman, 2021 ).

Balance-URSONet: A Real-Time Efficient Pose Spacecraft Estimation Network The high-precision attitude estimation technique for non-cooperative targets in space, based on monocular cameras, has important application value in missions such as space debris removal, autonomous rendezvous and docking, and on-orbit services. However, due to the inherent missing information problem of monocular vision systems and the high complexity of target geometry, existing monocular pose estimation methods find it difficult to realize an effective balance between accuracy and computational efficiency. Current solutions commonly adopt deep neural network architectures to improve estimation accuracy; but, this method is often accompanied by the problems of a dramatic expansion of the number of model parameters and a significant increase in computational complexity, which limits its deployment and real-time inference capabilities in real spatial tasks.

Relative Dynamics and Modern Control Strategies for Rendezvous in Libration Point Orbits Deep space missions are recently gaining increasing interest from space agencies and industry, their maximum exponent being the establishment of a permanent station in cis-lunar orbit within this decade. To that end, autonomous rendezvous and docking in multi-body dynamical environments have been defined as crucial technologies to expand and maintain human space activities beyond near Earth orbit. Based on analytical and numerical formulations of the relative dynamics in the Circular Restricted Three Body Problem (CR3BP), a family of optimal, linear and nonlinear, continuous and impulsive, guidance and control techniques are developed for the design of end-to-end rendezvous trajectories between co-orbiting spacecraft in this multi-body dynamical environment. To this end, several modern control techniques are effectively designed and adapted to this problem, with particular emphasis on the design of low cost rendezvous manoeuvres.

Radio links are also used during rendezvous and docking procedures and for audio and video communication between crew members, flight controllers and The International Space Station (ISS) is a space station in low Earth orbit (LEO). It is the product of the International Space Station program and is operated by five partner space agencies: NASA (United States), Roscosmos (Russia), ESA (Europe), JAXA (Japan), and CSA (Canada). It is the first space station built, maintained and crewed through international cooperation and the largest human space Ru… Similar cases are also seen in other parts of the structure. Key to box background colors: Pressurised component, accessible by the crew without using spacesuits Docking/berthing port, pressurized when a visiting spacecraft is present Airlock, to move people or material between pressurized and unpressurized environment Unpressurised station superstructure Unpressurised component Temporarily defunct or non-commissioned component Former, no longer installed component Future, not yet installed component === Pressurised modules === ==== Zarya ==== Zarya (Russian: Заря, lit. It was taken outside and installed on the ERA aft facing base point on Nauka during the VKD-55 spacewalk. ==== Robotic arms and cargo cranes ==== The Integrated Truss Structure (ITS) serves as a base for the station's primary remote manipulator system, the Mobile Servicing System (MSS), which is composed of three main components: Canadarm2, the largest robotic arm on the ISS, has a mass of 1,800 kilograms (4,000 lb) and is used to: dock and manipulate spacecraft and modules on the USOS; hold crew members and equipment in place during EVAs; and move Dextre to perform tasks. Other by-products of human metabolism, such as methane from the intestines and ammonia from sweat, are removed by activated charcoal filters. Part of the ROS atmosphere control system is the oxygen supply. Triple-redundancy is provided by the Elektron unit, solid fuel generators, and stored oxygen. The primary supply of oxygen is the Elektron unit which produces O2 and H2 by electrolysis of water and vents H2 overboard. The 1 kW (1.3 hp) system uses approximately one litre of water per crew member per day. This This is much more than the 14 kW of the Early External Active Thermal Control System (EEATCS) via the Early Ammonia Servicer (EAS), which was launched on STS-105 and installed onto the P6 Truss. === Communications and computers === The ISS relies on various radio communication systems to provide telemetry and scientific data links between the station and mission control centers. Radio links are also used during rendezvous and docking procedures and for audio and video communication between crew members, flight controllers and family members. As a result, the ISS is equipped with internal and external communication systems used for different purposes. As it closes in, more accurate transceivers align the craft with the docking port and control the final approach. The crew supervises the procedure and can intervene using the TORU (Tele-robotically Operated Rendezvous Unit) system if required. Automated docking has been used by the Soviet program since 1967, with Kurs introduced on Mir in 1986 and refined since. Though costly to develop, its reliability and standardised components have delivered significant long-term savings. The American SpaceX Dragon 2 cargo and crewed spacecraft can autonomously rendezvous and dock with the station without human intervention. However, on crewed Dragon missions, the astronauts have the capability to intervene and fly the vehicle manually. Other automated cargo spacecraft typically use a semi-automated process when arriving and departing from the station. These spacecraft are instructed to approach and park near the station. Once the crew on board the station is ready, the spacecraft is commanded to come close to the station, so that it can be grappled by an astronaut using the Mobile Servicing System robotic arm. The final mating of the spacecraft to the station is achieved using the robotic arm (a process known as berthing). Other, more frequent supply spacecraft do not require this adjustment as they are substantially higher performance vehicles. Atmospheric drag reduces the altitude by about 2 km a month on average. To reduce drag the ISS puts its solar arrays while in the dark of Earth's night side edge on toward the flight direction into Night Glider mode. For station keeping, to bring the station back to a higher altitude, a so-called reboost is performed, which takes approximately two orbits (three hours) to be completed. Maintaining ISS altitude uses about 7.5 tonnes of chemical fuel per annum at an annual cost of about $210 million. Orbital boosting can be performed by the station's two main engines on the Zvezda service module, or Russian or European spacecraft docked to Zvezda's aft port. The Automated Transfer Vehicle is constructed with the possibility of adding a second docking port to its aft end, allowing other craft to dock and boost the station. The Russian Orbital Segment contains the Data Management System, which handles Guidance, Navigation and Control (ROS GNC) for the entire station. Initially, Zarya, the first module of the station, controlled the station until a short time after the Russian service module Zvezda docked and was transferred control. Visiting crew members use tethered sleeping bags attached to available wall space or inside their spacecraft. While it is possible to sleep floating freely, this is generally avoided to prevent collisions with sensitive equipment. Proper ventilation is critical, as astronauts risk oxygen deprivation if exhaled carbon dioxide accumulates in a bubble around their heads. The station's lighting system is adjustable, allowing for dimming, switching off, and color temperature changes to support crew activities and rest. === Crew activities === The ISS operates on Coordinated Universal Time (UTC).

Apollo 9 was launched aboard a Saturn V on March 3, 1969 from Kennedy Space Center. The crewmembers, Commander James McDivitt, Command Module Pilot David Scott, and Lunar Module Pilot Russel Schweickart spent 10 days in Earth orbit. The primary purpose of the Apollo 9 mission was to test the systems, rendezvous procedures, and docking procedures of the Lunar Module (nicknamed "Spider"). In addition, an extra-vehicular activity (EVA) was performed to test the new Lunar EVA spacesuits. Both "Gumdrop", the Command and Service Modules (CSM 104), and "Spider" (LM-3) functioned without problems, thu

crewed by Wilmore and Williams; Fincke trained as the backup. Williams is the first woman to fly on a maiden crewed flight of an orbital spacecraft type Boeing Crew Flight Test (Boe-CFT) was the first crewed mission of the Boeing Starliner capsule. Launched on June 5, 2024, the mission flew a crew of two NASA astronauts, Barry E. Wilmore and Sunita Williams, from Cape Canaveral Space Force Station to the International Space Station. The mission was meant to last eight days, ending on June 14 with a landing in the American Southwest. However, Starl In the hours after getting into orbit, the crew performed several manual maneuvering exercises, including pointing the antenna towards the Tracking and Data Relay Satellite System (TDRSS) communications satellites, pointing the solar panels towards the sun, manually using the star tracker, manually braking and accelerating the spacecraft to perform orbital maneuvers, and manually orienting the spacecraft for reentry. Although the Starliner spacecraft is designed to operate autonomously and these capabilities are not required in a nominal mission, these tests showed that the crew can take over many functions of the craft during an emergency. Wilmore said that Starliner performed exceptionally well during these initial tests, approaching that of a perfect handling qualities rating. Following these tests, the crew attempted to sleep for several hours, but reported that the cabin of the spacecraft was uncomfortably cold, with temperatures about 50 °F (10 °C), which forced them to put on their heavy spacesuits, including their boots and gloves. Late on June 5, just before the crew's sleep time, flight controllers on the ground detected two more helium leaks in different parts of Starliner's propulsion system. To manage these leaks, flight controllers temporarily closed the two helium manifolds associated with the new leaks, which disabled six of the spacecraft's 28 reaction control system thrusters. The leaks were described a NASA announced that Boeing prepared to reassemble the vehicle for flight, following multiple checkouts, for the CFT mission in August 2020, and that new parachutes and airbags would be fitted. The Boe-CFT capsule's docking system was modified to accommodate the new re-entry cover, which debuted on the Boe-OFT‐2 test flight. == Crew == Because of the delays, crew assignments were changed several times after the initial assignments in 2018. Matthew Dominick replaced him on the backup crew. On April 18, 2022, NASA said that it had not finalized which of the cadre of Starliner astronauts, including Barry E. Wilmore, Michael Fincke, and Sunita Williams, would fly on this mission or the first operational Starliner mission. On June 16, 2022, NASA confirmed that this CFT (Crewed Flight Test) mission would be a two-person flight test crewed by Wilmore and Williams; Fincke trained as the backup. Williams is the first woman to fly on a maiden crewed flight of an orbital spacecraft type. == Mission == === Overview === The third launch of the Atlas V N22 variant launched Starliner with a crew of two. Although the Starliner spacecraft is designed to operate autonomously and these capabilities are not required in a nominal mission, these tests showed that the crew can take over many functions of the craft during an emergency. Wilmore said that Starliner performed exceptionally well during these initial tests, approaching that of a perfect handling qualities rating. Following these tests, the crew attempted to sleep for several hours, but reported that the cabin of the spacecraft was uncomfortably cold, with temperatures about 50 °F (10 °C), which forced them to put on their heavy spacesuits, including their boots and gloves. Late on June 5, just before the crew's sleep time, flight controllers on the ground detected two more helium leaks in different parts of Starliner's propulsion system. To manage these leaks, flight controllers temporarily closed the two helium manifolds associated with the new leaks, which disabled six of the spacecraft's 28 reaction control system thrusters. The leaks were described as small and the spacecraft still had plenty of helium to complete its mission, so managers gave permission to dock. The helium manifolds were reopened during rendezvous and docking and were subsequently closed once the spacecraft docked, as is standard procedure. On June 13, the CFT crew worked to support a planned spacewalk by astronauts Matt Dominick and Tracy Dyson; they helped the pair during the suit-up process, and, once the spacewalk was canceled, helped them get out of their spacesuits. Later in the day, they took an inventory of the personal consumables they had used up to that point and worked with flight controllers to update their tablets with emergency procedures. On June 14, after their undocking date was pushed back to June 22, the CFT astronauts had a call with Boeing mission managers to discuss the end of the mission and then entered Starliner to review the spacecraft's flight operations and procedures. Because each crew member must have a "lifeboat" to use if the station suffers an emergency, SpaceX developed and NASA approved an emergency evacuation configuration of the Dragon spacecraft in which up to three crew members would strap themselves to the floor of the Dragon spacecraft, where cargo is normally stored, which would be covered with foam padding. Starliner's problems and the consequent extension of the astronauts' stay received much media attention. Boeing Administrator Jared Isaacman said that while the spacecraft has design and engineering deficiencies requiring correction, he was most troubled by the failures in decision-making and leadership at both NASA and Boeing. == See also == Media related to Boeing Crew Flight Test at Wikimedia Commons Development of the Commercial Crew Program SpaceX Dragon 2 Crew Dragon Demo-2, SpaceX's first crewed mission of their capsule == Notes == == References ==