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Free-flying Progress spacecraft in process of docking to the International Space Station
SpaceX Dragon spacecraft attached to the Canadarm2 in preparation for berthing to the ISS

Docking and berthing of spacecraft is the joining of two space vehicles. This connection can be temporary, or partially permanent such as for space station modules.

Docking specifically refers to joining of two separate free-flying space vehicles.[1][2][3][4] Berthing refers to mating operations where a passive module/vehicle is placed into the mating interface of another space vehicle by using a robotic arm.[1][3][4] Because the modern process of un-berthing requires more crew labor and is time-consuming, berthing operations are unsuited for rapid crew evacuations in the event of an emergency.[5]

History

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Docking

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The first spacecraft docking was performed between Gemini 8 and an uncrewed Agena Target Vehicle on March 16, 1966.

Spacecraft docking capability depends on space rendezvous, the ability of two spacecraft to find each other and station-keep in the same orbit. This was first developed by the United States for Project Gemini. It was planned for the crew of Gemini 6 to rendezvous and manually dock under the command of Wally Schirra, with an uncrewed Agena Target Vehicle in October 1965, but the Agena vehicle exploded during launch. On the revised mission Gemini 6A, Schirra successfully performed a rendezvous in December 1965 with the crewed Gemini 7, approaching to within 0.3 metres (1 ft), but there was no docking capability between two Gemini spacecraft.[6] The first docking with an Agena was successfully performed under the command of Neil Armstrong on Gemini 8 on March 16, 1966. Manual dockings were performed on three subsequent Gemini missions in 1966.

The Apollo program depended on lunar orbit rendezvous to achieve its objective of landing men on the Moon. This required first a transposition, docking, and extraction maneuver between the Apollo command and service module (CSM) mother spacecraft and the Lunar Module (LM) landing spacecraft, shortly after both craft were sent out of Earth orbit on a path to the Moon. Then after completing the lunar landing mission, two astronauts in the LM had to rendezvous and dock with the CSM in lunar orbit, in order to be able to return to Earth. The spacecraft were designed to permit intra-vehicular crew transfer through a tunnel between the nose of the Command Module and the roof of the Lunar Module. These maneuvers were first demonstrated in low Earth orbit on March 7, 1969, on Apollo 9, then in lunar orbit in May 1969 on Apollo 10, then in six lunar landing missions, as well as on Apollo 13 where the LM was used as a rescue vehicle instead of making a lunar landing.

Unlike the United States, which used manual piloted docking throughout the Apollo, Skylab, and Space Shuttle programs, the Soviet Union employed automated docking systems from the beginning of its docking attempts. The first such system, Igla, was successfully tested on October 30, 1967, when the two uncrewed Soyuz test vehicles Kosmos 186 and Kosmos 188 docked automatically in orbit.[7][8] This was the first successful Soviet docking. Proceeding to crewed docking attempts, the Soviet Union first achieved rendezvous of Soyuz 3 with the uncrewed Soyuz 2 craft on October 25, 1968; docking was unsuccessfully attempted. The first crewed docking was achieved on January 16, 1969, between Soyuz 4 and Soyuz 5.[9] This early version of the Soyuz spacecraft had no internal transfer tunnel, but two cosmonauts performed an extravehicular transfer from Soyuz 5 to Soyuz 4, landing in a different spacecraft than they had launched in.[10]

In the 1970s, the Soviet Union upgraded the Soyuz spacecraft to add an internal transfer tunnel and used it to transport cosmonauts during the Salyut space station program with the first successful space station visit beginning on 7 June 1971, when Soyuz 11 docked to Salyut 1. The United States followed suit, docking its Apollo spacecraft to the Skylab space station in May 1973. In July 1975, the two nations cooperated in the Apollo-Soyuz Test Project, docking an Apollo spacecraft with a Soyuz using a specially designed docking module to accommodate the different docking systems and spacecraft atmospheres.

Beginning with Salyut 6 in 1978, the Soviet Union began using the uncrewed Progress cargo spacecraft to resupply its space stations in low earth orbit, greatly extending the length of crew stays. As an uncrewed spacecraft, Progress rendezvoused and docked with the space stations entirely automatically. In 1986, the Igla docking system was replaced with the updated Kurs system on Soyuz spacecraft. Progress spacecraft received the same upgrade several years later.[7]: 7  The Kurs system is still used to dock to the Russian Orbital Segment of the International Space Station.

Berthing

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Flight Support Structure in Columbia's payload bay under the 180 degree mark on the -V3 plane of the Hubble Space Telescope during STS-109.

Berthing of spacecraft can be traced at least as far back as the berthing of payloads into the Space Shuttle payload bay.[11] Such payloads could be either free-flying spacecraft captured for maintenance/return, or payloads temporarily exposed to the space environment at the end of the Remote Manipulator System. Several different berthing mechanisms were used during the Space Shuttle era. Some of them were features of the Payload Bay (e.g., the Payload Retention Latch Assembly), while others were airborne support equipment (e.g., the Flight Support Structure used for HST servicing missions).

Hardware

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Androgyny

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Look up androgynous in Wiktionary, the free dictionary.

Docking/berthing systems may be either androgynous (ungendered) or non-androgynous (gendered), indicating which parts of the system may mate together.

Early systems for conjoining spacecraft were all non-androgynous docking system designs. Non-androgynous designs are a form of gender mating[2] where each spacecraft to be joined has a unique design (male or female) and a specific role to play in the docking process. The roles cannot be reversed. Furthermore, two spacecraft of the same gender cannot be joined at all.

Androgynous docking (and later androgynous berthing) by contrast has an identical interface on both spacecraft. In an androgynous interface, there is a single design which can connect to a duplicate of itself. This allows system-level redundancy (role reversing) as well as rescue and collaboration between any two spacecraft. It also provides more flexible mission design and reduces unique mission analysis and training.[2]

List of mechanisms/systems

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Image Name Method Internal crew transfer Notes Type
Gemini Docking Mechanism Docking No Allowed the Gemini Spacecraft (active) to dock to the Agena target vehicle (passive). Non-Androgynous
Apollo Docking Mechanism Docking Yes Allowed the Command/Service Module (active) to dock to the Apollo Lunar Module[12] (passive) and the Skylab space station (passive). Was used to dock to the Docking Module adapter (passive) during the Apollo–Soyuz Test Project (ASTP), which enabled the crew to dock with a Soviet Soyuz 7K-TM spacecraft. It had a circular pass through diameter of 810 mm (32 in).[13][14] Non-Androgynous
Original Russian probe and drogue docking system Docking No The original Soyuz probe-and-drogue docking system was used with the first generation Soyuz 7K-OK spacecraft from 1966 until 1970 in order to gather engineering data as a preparation for the Soviet space station program. The gathered data were subsequently used for the conversion of the Soyuz spacecraft – which was initially developed for the Soviet crewed lunar program – into a space station transport craft.[1]

A first docking with two uncrewed Soyuz spacecraft – the first fully automated space docking in the history of space flight – was made with the Kosmos 186 and Kosmos 188 missions on October 30, 1967.

Non-Androgynous
Kontakt docking system Docking No Intended to be used in the Soviet crewed lunar program to allow the Soyuz 7K-LOK ("Lunar Orbital Craft", active) to dock to the LK lunar lander (passive).[15] Non-Androgynous
SSVP-G4000 Docking Yes SSVP-G4000 is also known more vaguely as the Russian probe and drogue or simply the Russian Docking System (RDS).[1][16] In Russian, SSVP stands for Sistema Stykovki i Vnutrennego Perekhoda, literally "System for docking and internal transfer".[17]

It was used for the first docking to a space station in the history of space flight, with the Soyuz 10 and Soyuz 11 missions that docked to the Soviet space station Salyut 1 in 1971.[1][16] The docking system was upgraded in the mid-1980s to allow the docking of 20 ton modules to the Mir space station.[17] It has a circular transfer passage that has a diameter of 800 mm (31 in) and is manufactured by RKK Energiya.[3][4][17]

The probe-and-drogue system allows visiting spacecraft using the probe docking interface, such as Soyuz, Progress and ESA's ATV spacecraft, to dock to space stations that offer a port with a drogue interface, like the former Salyut and Mir or the current ISS space station. There are a total of four such docking ports available on the Russian Orbital Segment of ISS for visiting spacecraft; These are located on the Zvezda, Rassvet, Prichal and Poisk modules.[17] Furthermore, the probe-and-drogue system was used on the ISS to dock Rassvet semipermanently to Zarya.[1]

Non-Androgynous
APAS-75 Docking Yes Used on the Apollo-Soyuz Test Project Docking Module and Soyuz 7K-TM. There were variations in design between the American and Soviet version but they were still mechanically compatible. Androgynous
APAS-89 Docking Yes Used on Mir (Kristall,[15][18] Mir Docking Module), Soyuz TM-16,[15][18] Buran (was planned).[18] It had a circular transfer passage with a diameter of 800 mm (31 in).[1][3][4] Androgynous (Soyuz TM-16), Non-Androgynous (Kristall,[19] Mir Docking Module[20])
APAS-95 Docking Yes It was used for Space Shuttle dockings to Mir and ISS,[18] On the ISS, it was also used on Zarya module, Russian Orbital Segment to interface with PMA-1 on Unity module, US Orbital Segment[21] It has a diameter of 800 mm (31 in).[1][3][4] Described as "essentially the same as" APAS-89.[18] Androgynous (Shuttle, Zarya[citation needed] and PMA-1[1]), Non-Androgynous (PMA-2 and PMA-3)[1]
SSVP-M8000 (Hybrid Docking System) Docking Yes SSVP-M8000 or more commonly known as "hybrid", is a combination of a "probe and drogue" soft-dock mechanism with an APAS-95 hard-dock collar.[17] It began to be manufactured in 1996.[17] It is manufactured by RKK Energiya.[17]

Used on ISS (connects Zvezda to Zarya, Pirs, Poisk[1] Nauka[22] and Nauka to Prichal)

Non-Androgynous
Common Berthing Mechanism Berthing Yes Used on ISS (USOS), MPLMs, HTV, SpaceX Dragon 1,[23] Cygnus. The standard CBM has a pass through in the shape of a square with rounded edges and has a width of 1,300 mm (50 in).[4] The smaller hatch that Cygnus uses results in a transfer passage of the same shape but has a width of 940 mm (37 in).[24] Non-Androgynous
Chinese Docking Mechanism Docking Yes Used by Shenzhou spacecraft, beginning with Shenzhou 8, to dock to Chinese space stations. The Chinese docking mechanism is based on the Russian APAS-89/APAS-95 system; some have called it a "clone".[1] There have been contradicting reports by the Chinese on its compatibility with APAS-89/95.[25] It has a circular transfer passage that has a diameter of 800 mm (31 in).[26][27] The androgynous variant has a mass of 310 kg and the non-androgynous variant has a mass of 200 kg.[28]

Used for the first time on Tiangong 1 space station and will be used on future Chinese space stations and with future Chinese cargo resupply vehicles.

Androgynous (Shenzhou)
Non-Androgynous (Tiangong-1)
Chinese Docking Mechanism Grappling-type No Used for China's uncrewed sample return missions when ascender transfers samples to orbiter for Earth return such as Chang'e 5/6. Non-Androgynous
International Docking System Standard (IDSS) Docking or Berthing Yes Used on the ISS International Docking Adapter, SpaceX Dragon 2, Boeing Starliner and future vehicles. Circular transfer passage diameter is 800 mm (31 in).[29] The International Berthing and Docking Mechanism (IBDM) is an implementation of IDSS to be used on European Space Agency spacecraft.[30] IBDM will also be used on Dream Chaser.[31] Active, Passive, or Androgynous (i.e., both). Active(Commercial Crew Vehicle, Orion);
Passive (IDA)
ASA-G/ASP-G Berthing Yes Used by Nauka Science (or Experiment) Airlock, to berth to nauka forward port. The berthing mechanism is a unique hybrid derivative the Russian APAS-89/APAS-95 system as it has 4 petals instead of 3 along with 12 structural hooks and is a combination of an active "probe and drogue" soft-dock mechanism on port and passive target on airlock. Non-Androgynous
SSPA-GB 1/2 (Hybrid Docking System) Docking Yes It is a modified passive hybrid version of SSVP-M8000.

Used on ISS (Prichal lateral ports for future add-on modules)

Non-Androgynous
Bhartiya Docking System (BDS) Docking or Berthing Yes Modified IDSS. In contrast to the 24 motors used in IDSS, the BDS only uses two. The docking port at SpaDex is 450 mm (18 in) in diameter, whereas the docking port at the Gaganyaan and Bharatiya Antariksha Station will be 800 mm (31 in) as on IDSS.[32][33][34] Androgynous (i.e., both). Used on SpaDeX, Gaganyaan and Bharatiya Antariksha Station.

Adapters

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A docking or berthing adapter is a mechanical or electromechanical device that facilitates the connection of one type of docking or berthing interface to a different interface. Such interfaces may be docking/docking, docking/berthing, or berthing/berthing. Previously launched and planned to be launched adapters are listed below:

  • ASTP Docking Module: An airlock module that converted U.S. Probe and Drogue to APAS-75. Built by Rockwell International for the 1975 Apollo–Soyuz Test Project mission.[35]
  • Pressurized Mating Adapter (PMA): Converts an active Common Berthing Mechanism to APAS-95. Three PMAs are attached to the ISS, PMA-1 and PMA-2 were launched in 1998 on STS-88, PMA-3 in late 2000 on STS-92. PMA-1 is used to connect the Zarya control module with Unity node 1, Space Shuttles used PMA-2 and PMA-3 for docking.
  • International Docking Adapter (IDA):[36] Converts APAS-95 to the International Docking System Standard. IDA-1 was planned to be launched on SpaceX CRS-7 until its launch failure, and attached to Node-2's forward PMA.[36][37] IDA-2 was launched on SpaceX CRS-9 and attached to Node-2's forward PMA.[36][37] IDA-3, the replacement for IDA-1 launched on SpaceX CRS-18 and attached to Node-2's zenith PMA.[38] The adapter is compatible with the International Docking System Standard (IDSS), which is an attempt by the ISS Multilateral Coordination Board to create a docking standard.[39]
  • SSPA-GM: Converts passive SSVP-M8000 (Hybrid Docking System) to passive SSVP-G4000.[40] The docking ring initially used for Soyuz MS-18 and Progress MS-17 docking on Nauka until detached by Progress MS-17 for Prichal module arrived on ISS.[41] It was made for the Nauka nadir and Prichal nadir ports of the International Space Station, where Soyuz and Progress spacecraft had to dock to a port designated for modules. Before removal of SSPA-GM, the docking ring is 80 cm (31 in) in diameter; that becomes 120 cm (47 in) after removal.
  • ASTP Docking Module
    ASTP Docking Module
  • Pressurized Mating Adapter
    Pressurized Mating Adapter
  • International Docking Adapter
    International Docking Adapter
  • APAS to SSVP (SSVPA-GM) Docking Ring
    APAS to SSVP (SSVPA-GM) Docking Ring

Docking of uncrewed spacecraft

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The Soft-Capture Mechanism (SCM) added in 2009 to the Hubble Space Telescope. The SCM allows both crewed and uncrewed spacecraft that utilize the NASA Docking System (NDS) to dock with Hubble.

For the first fifty years of spaceflight, the main objective of most docking and berthing missions was to transfer crew, construct or resupply a space station, or to test for such a mission (e.g. the docking between Kosmos 186 and Kosmos 188). Therefore, commonly at least one of the participating spacecraft was crewed, with a pressurized habitable volume (e.g. a space station or a lunar lander) being the target—the exceptions were a few fully uncrewed Soviet docking missions (e.g. the dockings of Kosmos 1443 and Progress 23 to an uncrewed Salyut 7 or Progress M1-5 to an uncrewed Mir). Another exception were a few missions of the crewed US Space Shuttles, like berthings of the Hubble Space Telescope (HST) during the five HST servicing missions. The Japanese ETS-VII mission (nicknamed Hikoboshi and Orihime) in 1997 was designed to test uncrewed rendezvous and docking, but launched as one spacecraft which separated to join back together.

Changes to the crewed aspect began in 2015, as a number of economically driven commercial dockings of uncrewed spacecraft were planned. In 2011, two commercial spacecraft providers[which?] announced plans to provide autonomous/teleoperated uncrewed resupply spacecraft for servicing other uncrewed spacecraft. Notably, both of these servicing spacecraft were intending to dock with satellites that weren't designed for docking, nor for in-space servicing.

The early business model for these services was primarily in near-geosynchronous orbit, although large delta-v orbital maneuvering services were also envisioned.[42]

Building off of the 2007 Orbital Express mission—a U.S. government-sponsored mission to test in-space satellite servicing with two vehicles designed from the ground up for on-orbit refueling and subsystem replacement—two companies announced plans for commercial satellite servicing missions that would require docking of two uncrewed vehicles.

The SIS and MEV vehicles each planned to use a different docking technique. SIS planned to utilize a ring attachment around the kick motor[46] while the Mission Extension Vehicle would use a somewhat more standard insert-a-probe-into-the-nozzle-of-the-kick-motor approach.[42]

A prominent spacecraft that received a mechanism for uncrewed dockings is the Hubble Space Telescope (HST). In 2009 the STS-125 shuttle mission added the Soft-Capture Mechanism (SCM) at the aft bulkhead of the space telescope. The SCM is meant for unpressurized dockings and will be used at the end of Hubble's service lifetime to dock an uncrewed spacecraft to de-orbit Hubble. The SCM used was designed to be compatible to the NASA Docking System (NDS) interface to reserve the possibility of a servicing mission.[47] The SCM will, compared to the system used during the five HST Servicing Missions to capture and berth the HST to the Space Shuttle,[citation needed] significantly reduce the rendezvous and capture design complexities associated with such missions. The NDS bears some resemblance to the APAS-95 mechanism, but is not compatible with it.[48]

Non-cooperative docking

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Docking with a spacecraft (or other human made space object) that does not have an operable attitude control system might sometimes be desirable, either in order to salvage it, or to initiate a controlled de-orbit. Some theoretical techniques for docking with non-cooperative spacecraft have been proposed so far.[49] Yet, with the sole exception of the Soyuz T-13 mission to salvage the crippled Salyut 7 space station, as of 2006, all spacecraft dockings in the first fifty years of spaceflight had been accomplished with vehicles where both spacecraft involved were under either piloted, autonomous or telerobotic attitude control.[49] In 2007, however, a demonstration mission was flown that included an initial test of a non-cooperative spacecraft captured by a controlled spacecraft with the use of a robotic arm.[50] Research and modeling work continues to support additional autonomous noncooperative capture missions in the coming years.[51][52]

Salyut 7 space station salvage mission

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Main article: Soyuz T-13
Commander Vladimir Dzhanibekov (left) with Oleg Grigoryevich Makarov (right) on a 1978 Soviet postage stamp
Doctor of technical sciences Viktor Savinykh with Vladimir Kovalyonok pictured on a Soviet postage stamp commemorating a Salyut 6 mission

Salyut 7, the tenth space station of any kind launched, and Soyuz T-13 were docked in what author David S. F. Portree describes as "one of the most impressive feats of in-space repairs in history".[15] Solar tracking failed and due to a telemetry fault the station did not report the failure to mission control while flying autonomously. Once the station ran out of electrical energy reserves it ceased communication abruptly in February 1985. Crew scheduling was interrupted to allow Soviet military commander Vladimir Dzhanibekov[53] and technical science flight engineer Viktor Savinykh[54] to make emergency repairs.

All Soviet and Russian space stations were equipped with automatic rendezvous and docking systems, from the first space station Salyut 1 using the IGLA system, to the Russian Orbital Segment of the International Space Station using the Kurs system. The Soyuz crew found the station was not broadcasting radar or telemetry for rendezvous, and after arrival and external inspection of the tumbling station, the crew judged proximity using handheld laser rangefinders.

Dzhanibekov piloted his ship to intercept the forward port of Salyut 7, matched the station's rotation and achieved soft dock with the station. After achieving hard dock they confirmed that the station's electrical system was dead. Prior to opening the hatch, Dzhanibekov and Savinykh sampled the condition of the station's atmosphere and found it satisfactory. Attired in winter fur-lined clothing, they entered the cold station to conduct repairs. Within a week sufficient systems were brought back online to allow robot cargo ships to dock with the station. Nearly two months went by before atmospheric conditions on the space station were normalized.[15]

Uncrewed dockings of non-cooperative space objects

[edit]
Orbital Express: ASTRO (left) and NEXTSat (right), 2007

Non-cooperative rendezvous and capture techniques have been theorized, and one mission has successfully been performed with uncrewed spacecraft in orbit.[50]

A typical approach for solving this problem involves two phases. First, attitude and orbital changes are made to the "chaser" spacecraft until it has zero relative motion with the "target" spacecraft. Second, docking maneuvers commence that are similar to traditional cooperative spacecraft docking. A standardized docking interface on each spacecraft is assumed.[55]

NASA has identified automated and autonomous rendezvous and docking — the ability of two spacecraft to rendezvous and dock "operating independently from human controllers and without other back-up, [and which requires technology] advances in sensors, software, and realtime on-orbit positioning and flight control, among other challenges" — as a critical technology to the "ultimate success of capabilities such as in-orbit propellant storage and refueling," and also for complex operations in assembling mission components for interplanetary destinations.[56]

The Automated/Autonomous Rendezvous & Docking Vehicle (ARDV) is a proposed NASA Flagship Technology Demonstration (FTD) mission, for flight as early as 2014/2015. An important NASA objective on the proposed mission is to advance the technology and demonstrate automated rendezvous and docking. One mission element defined in the 2010 analysis was the development of a laser proximity operations sensor that could be used for non-cooperative vehicles at distances between 1 metre (3 ft 3 in) and 3 kilometers (2 mi). Non-cooperative docking mechanisms were identified as critical mission elements to the success of such autonomous missions.[56]

Grappling and connecting to non-cooperative space objects was identified as a top technical challenge in the 2010 NASA Robotics, tele-robotics and autonomous systems roadmap.[57]

Docking states

[edit]

A docking/berthing connection is referred to as either "soft" or "hard". Typically, a spacecraft first initiates a soft dock by making contact and latching its docking connector with that of the target vehicle. Once the soft connection is secured, if both spacecraft are pressurized, they may proceed to a hard dock where the docking mechanisms form an airtight seal, enabling interior hatches to be safely opened so that crew and cargo can be transferred.

Berthing spacecraft and modules

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Docking and undocking describe spacecraft using a docking port, without assistance and under their own power. Berthing takes place when a spacecraft or unpowered module cannot use a docking port or requires assistance to use one. This assistance may come from a spacecraft, such as when the Space Shuttle used its robotic arm to push ISS modules into their permanent berths. In a similar fashion the Poisk module was permanently berthed to a docking port after it was pushed into place by a modified Progress spacecraft which was then discarded. The Cygnus resupply spacecraft arriving at the ISS does not connect to a docking port, instead it is pulled into a berthing mechanism by the station's robotic arm and the station then closes the connection. The berthing mechanism is used only on the US segment of the ISS, the Russian segment of the ISS uses docking ports for permanent berths.

Mars surface docking

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SEV components
SEV components

Docking has been discussed by NASA in regards to a Crewed Mars rover, such as with Mars habitat or ascent stage.[58] The Martian surface vehicle (and surface habitats) would have a large rectangular docking hatch, approximately 2 by 1 meter (6.6 by 3.3 ft).[58][failed verification]

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Docking and berthing of spacecraft

View on Grokipedia
from Grokipedia
Docking and berthing of spacecraft are critical procedures for joining two space vehicles in , enabling operations such as crew transfer, cargo resupply, module assembly, and extended mission capabilities. Docking occurs when an active "chaser" spacecraft uses its system to autonomously rendezvous, align, and execute a controlled soft collision with a passive "target" vehicle's docking port, achieving capture and a sealed connection without external aid. Berthing, by contrast, involves delivering the chaser to a proximate location at zero , after which a system—such as a —grapples the vehicle, maneuvers it into alignment, and secures it to the target's berthing interface. These methods ensure precise, reliable unions in the microgravity environment, accommodating tolerances for relative motion and structural loads during contact. The history of spacecraft docking began with early demonstrations of rendezvous and attachment technology during the Space Race. The United States achieved the first successful docking on March 16, 1966, when Gemini 8 linked with an Agena target vehicle using a probe-and-drogue mechanism, though the mission was abbreviated due to stability issues. The Soviet Union followed with its inaugural docking on January 16, 1969, involving Soyuz 4 and Soyuz 5 spacecraft, marking the first crew transfer between vehicles. NASA's Apollo program refined docking for lunar missions, with Apollo 9 completing the first test of its probe-and-drogue system on March 3, 1969. A pivotal international milestone came during the Apollo-Soyuz Test Project on July 17, 1975, when the U.S. Apollo command module docked with the Soviet Soyuz 19 using the innovative Androgynous Peripheral Attachment System (APAS), fostering early U.S.-Soviet cooperation in space. The Space Shuttle era advanced docking for station operations, including nine missions to the Soviet Mir space station between 1995 and 1998, where the orbiter used a modified APAS to dock and transfer crews and supplies. With the (ISS), launched in 1998, docking and berthing became routine for multinational assembly and sustainment. Russian Soyuz and Progress vehicles have docked to ISS ports using probe-and-drogue interfaces since November 2000, providing continuous crew access and resupply. The U.S. segment employs the (CBM) for berthing operations, as seen with the first CBM use in 2001 for the Destiny laboratory module, and later for cargo missions like Japan's (HTV), which was berthed via the Canadarm2 robotic arm starting in 2009. Pressurized Mating Adapters (PMAs) on the ISS convert Russian docking ports to NASA standards, enabling compatibility. Europe's Automated Transfer Vehicle (ATV) achieved the first automated docking to the ISS in 2008, while NASA's Space Shuttle performed 37 dockings through 2011, including the installation of PMAs during in 1998. Modern advancements emphasize automation, interoperability, and commercial involvement. SpaceX's Crew Dragon on its Demo-1 mission demonstrated the first U.S. commercial autonomous docking to the ISS on March 3, 2019, followed by the first Cargo Dragon 2 docking in December 2020 and the crewed Crew Dragon's debut docking on May 31, 2020, both using the International Docking Adapter (IDA) installed on the Harmony module. Boeing's Starliner completed its first crewed docking to the ISS on June 6, 2024, as part of NASA's Commercial Crew Program, docking to the forward Harmony port; however, due to propulsion issues, the crew remained on the ISS and returned to Earth aboard SpaceX's Crew-9 in March 2025, while Starliner returned uncrewed in September 2024. These vehicles adhere to the International Docking System Standard (IDSS), a collaborative specification finalized in 2016 by NASA, Roscosmos, ESA, and JAXA, which defines common mechanical, electrical, and data interfaces for androgynous docking ports to support emergency rescues and joint missions. NASA's implementation, the NASA Docking System (NDS) Block 1, qualified in 2017, features electromechanical actuators and soft capture latches for precise alignment and power/data transfer. Looking ahead, docking and berthing technologies are vital for NASA's and beyond, including autonomous operations for the station and potential Mars transit vehicles. The IDSS extends to deep-space applications, promoting for international partners and commercial providers to enable modular habitats, fuel depots, and in-orbit servicing. Ongoing developments focus on enhanced sensors for relative navigation, such as NASA's Navigation and Alignment Aids, to improve safety and efficiency in proximity operations.

Fundamentals

Definitions and distinctions

Docking refers to the process by which one , known as the chaser, autonomously or semi-autonomously aligns with, contacts, and forms a rigid, airtight connection to another or station, the target, using compatible interface mechanisms. This involves precision navigation to achieve closing rates typically of 0.05 to 0.10 m/s at contact, followed by soft capture to absorb impact energy and hard mating for structural integrity. In contrast, berthing is a human-assisted operation where the incoming or module is captured by an external or grapple system on the target, positioned in close proximity to the mating interface, and then secured through mechanical latching, without an autonomous soft-capture phase. This method relies on ground control or onboard operators to guide the robotic manipulator, ensuring near-zero during initial contact to minimize stresses. The key distinctions lie in autonomy and capture mechanisms: docking demands onboard guidance, navigation, and control (GNC) systems for the chaser to execute a controlled approach and soft capture, often using probe-and-drogue systems that allow independent operation. Berthing, however, transfers control to the target's robotic systems, such as the International Space Station's Canadarm2, for grapple and alignment, making it suitable for larger or less maneuverable vehicles but introducing dependencies on oversight and potential handoff delays. For instance, docking interfaces like the (APAS) enable self-alignment, while berthing ports require manipulator intervention. The terminology originated in the with Soviet Kosmos missions, where "docking" described the first automated connections, such as between Kosmos 186 and 188 in 1967, marking a shift from manual to precise orbital joins. "Berthing" emerged in the 1980s during NASA's , applied to robotic payload integrations into the orbiter's bay, evolving into standardized procedures for station assembly. Both processes presuppose mastery of relative , including managing closing rates through phased rendezvous—such as station-keeping and matching—and attitude control via thrusters for or reaction wheels for rotation, ensuring stable alignment within capture envelopes of centimeters and degrees.

Importance and applications

Docking and berthing technologies are essential for enabling in-orbit assembly of large-scale structures, such as the International Space Station (ISS), which was constructed using 16 pressurized modules connected primarily through berthing operations. These mechanisms facilitate crew transfers between vehicles like Soyuz and Crew Dragon, ensuring safe personnel movement and emergency evacuations. Additionally, they support critical propellant resupply, as demonstrated by Progress spacecraft delivering storable propellants to the ISS for attitude control and reboosting, while emerging orbital refueling concepts, such as those planned for SpaceX's Starship, enable deep-space missions by transferring cryogenic fuels in low Earth orbit. In debris mitigation efforts, docking systems allow for active removal of defunct satellites, reducing collision risks through robotic capture and deorbiting, as explored in proximity operations for uncooperative targets. The strategic benefits of these technologies include extending mission durations and operational lifespans, with regular dockings and berthings enabling the ISS to maintain continuous human presence since November 2000, as of 2025 projected to operate through at least 2030 via ongoing resupply and maintenance. By promoting reusable hardware, such as the capsule, docking reduces launch costs and minimizes waste compared to single-use systems. Furthermore, these capabilities foster international , exemplified by contributions from , ESA, , and to the ISS program, where shared docking standards like the (IDSS) allow interoperable access to the station's resources. Numerous successful dockings and berthings to the ISS have sustained this multinational effort, supporting scientific research and technology development across partner agencies. Docking and berthing address key challenges in space operations, including the isolation of individual by enabling resource sharing, such as systems and power distribution between joined vehicles on the ISS. They also enhance scalability for future habitats, providing multiple docking ports on platforms like the to accommodate expanding modules and visiting vehicles for sustained lunar exploration. Emerging applications include in-situ resource utilization (ISRU) for Mars missions, where docking facilitates the transfer of processed propellants from surface-extracted resources to orbiting transfer vehicles, reducing Earth-launch dependencies. In the commercial sector, servicing via docking, as demonstrated by Northrop Grumman's Mission Extension Vehicles and upcoming autonomous operations by Starfish Space, extends lifespans and supports on-orbit repairs without full replacements.

History

Early docking developments

The pioneering efforts in spacecraft docking during the 1960s were driven by the need to enable complex missions such as space stations and lunar explorations, with the achieving the first automated docking on October 30, 1967, when the uncrewed Kosmos 186 successfully rendezvoused and docked with Kosmos 188 using the Igla -based system. This milestone, conducted in , demonstrated fully autonomous operations without ground intervention during the final approach, marking a significant advancement in rendezvous technology. The Igla system relied on line-of-sight for precise alignment, allowing the vehicles to close at controlled velocities to ensure structural integrity. Building on this, the Soviets accomplished the first crewed docking on January 16, 1969, when , commanded by Vladimir Shatalov, linked with Soyuz 5 using the same Igla interface, enabling a crew transfer via and validating human-rated docking procedures. In parallel, the pursued docking through the Gemini program, achieving the first crewed docking on March 16, 1966, when , piloted by and , successfully connected to the uncrewed using a probe-and-drogue mechanism. However, the mission encountered a critical issue when a thruster malfunction induced an uncontrollable spin, forcing an early abort and highlighting the risks of manual control in close proximity operations. The U.S. refined these techniques with , launched on March 3, 1969, where astronauts , , and Russell Schweickart conducted the first successful docking between the command/service module and in Earth orbit, testing the probe-and-drogue system essential for lunar missions. This operation confirmed the ability to separate, maneuver independently, and redock under crew control, with no major anomalies reported. Early docking faced substantial challenges, including the balance between manual piloting and emerging , collision avoidance during high-relative-speed approaches, and achieving airtight seals for equalization in . The incident underscored collision risks from unexpected attitude deviations, while Soviet tests emphasized automated guidance to mitigate . Technological milestones included the widespread adoption of probe-and-drogue interfaces, which guided the active probe into the passive drogue at limited closing speeds of 0.1-0.3 m/s (0.33-1 ft/s) to prevent structural damage or misalignment. These developments were fueled by competition, prompting rapid iterations; by 1971, the superpowers had conducted over 20 uncrewed docking tests collectively, including multiple Soviet Kosmos missions (such as 212/213 in 1968 and 238 in 1969) and U.S. Agena pairings, laying the groundwork for sustained orbital operations.

Berthing evolution and key milestones

The development of berthing techniques began with NASA's , where the Remote Manipulator System (RMS), a 15-meter built by , enabled the first in-orbit handling. During in March 1982, astronauts used the RMS to deploy the OSS-1 from the orbiter's cargo bay, demonstrating robotic manipulation capabilities that laid the groundwork for future berthing of larger structures to other spacecraft. As the (ISS) assembly progressed, berthing evolved into a critical process for integrating modules using the Shuttle's RMS in coordination with spacewalks. In December 1998, during , Endeavour's crew employed the RMS to extract the Unity connecting module from the payload bay, position it near the pre-orbiting Zarya module, and berth it using the (CBM), completing the first structural connection of the ISS core. This milestone highlighted the transition from payload manipulation to station-scale assembly, requiring enhanced coordination between and arm control to achieve alignment within centimeters. Key berthing milestones in the late 2000s underscored international collaboration and technological refinement on the ISS. In February 2008, delivered the European Space Agency's (ESA) Columbus laboratory module aboard ; the Shuttle RMS lifted it from the bay for handover to the ISS's Canadarm2, which then berthed it to the node at a relative speed under 0.1 m/s, enabling Europe's primary contribution to ISS research facilities. Similarly, Japan's Kibo (Japanese Experiment Module) was progressively assembled starting with in March 2008, which berthed the Experiment Logistics Module-Pressurized Section (ELM-PS) to the node using the Shuttle RMS. in May 2008 followed, berthed the main Pressurized Module (PM) to the ELM-PS with assistance from Canadarm2. The Exposed Facility was added during in July 2009, attached to the PM to expand the station's external experiment capabilities. The commercial era marked a shift toward routine, human-supervised berthing with enhanced robotics. In May 2012, SpaceX's Dragon C2+ mission achieved the first private spacecraft berthing to the ISS, where Canadarm2—now a 17-meter arm equipped with the Dextre robotic hand for fine manipulation—grappled the uncrewed capsule at a relative closure rate of approximately 0.01 m/s before soft-capture and hard-berth to Harmony via CBM. This demonstrated the arm's upgraded precision, allowing capture of grapple fixtures with sub-millimeter accuracy and supporting NASA's Commercial Orbital Transportation Services program. Northrop Grumman's Cygnus spacecraft achieved its first berthing to the ISS during the Orb-1 mission on January 12, 2014, when Canadarm2 grappled the uncrewed vehicle and secured it to the Harmony module's nadir port via the CBM, marking the second U.S. commercial cargo berthing capability. International contributions further diversified berthing operations. ESA's Automated Transfer Vehicle (ATV) , launched in March 2008, approached the ISS autonomously but relied on Russian docking systems for attachment to Zvezda, influencing subsequent hybrid techniques for cargo integration. JAXA's (HTV-1, or Kounotori) in September 2009 introduced dedicated berthing for exposed payloads, with Canadarm2 capturing and berthing it to at low relative speeds to accommodate its unpressurized cargo. Roscosmos adapted resupply missions with partial robotic support via the European Robotic Arm (installed in 2021) for post-docking adjustments, though primary attachments remained docking-based. By 2025, berthing advancements focus on deep-space applications. Boeing's Starliner completed docking tests during its 2024 Crew Flight Test to the ISS, paving the way for berthing-compatible adapters on the , where Canadarm3—a next-generation 9-meter arm—will enable module and habitat attachments starting in the late 2020s. These evolutions prioritize human oversight for safety while incorporating AI-assisted trajectory control to handle dynamics.

Hardware and systems

Docking mechanisms

Docking mechanisms are specialized hardware systems designed to enable the precise alignment, capture, and rigid connection of during orbital rendezvous, ensuring structural integrity and a pressurized pathway for crew or cargo transfer. These systems typically involve active and passive components that manage relative velocities up to 0.10 m/s and misalignments while withstanding significant loads. The probe-and-drogue system, exemplified by the Soviet/Russian Sistema Stykovki i Vnutrennego Perekhoda (SSVP), uses an extendable probe on the active spacecraft, such as Soyuz, that inserts into a conical on the passive target, like an ISS module. Upon insertion, soft-capture latches at the drogue's apex engage the probe tip, followed by retraction of the probe via electric motors, which draws the spacecraft together and activates eight peripheral structural latches to form an 800 mm diameter airtight tunnel. This design, first operational in 1969 for Soyuz missions, allows for internal crew transfer and has been used in early docking demonstrations like and 5. The (APAS), developed for international cooperation, features identical "petal-like" guide structures on both , enabling genderless mating without designated active or passive roles. Each APAS ring includes three guide petals for initial alignment, soft-capture latches that engage upon contact, and 12 structural latches for hard capture, with the active side extending its guide ring to initiate connection. Variants like APAS-89 supported Shuttle-Mir dockings from 1995, while APAS-95 integrated with the ISS for Shuttle and Zarya module interfaces starting in 1998. The (IDSS), led by in the 2010s, standardizes a for global , featuring soft-capture latches on guide petals for initial contact and hard-dock mechanisms with dual concentric seals for pressurization, all compatible with 800 mm circular ports. The system includes three active latches per side for soft capture (tension up to 3,900 N) and 12 hook pairs for hard capture, supporting compressive loads up to 300,000 N and tensile loads of 100,000 N, with initial alignment tolerances including lateral misalignment up to 0.10 m and angular misalignments up to 4.0 degrees. Adopted for vehicles like and international partners, IDSS ensures compatibility for diverse missions. Common key components across these mechanisms include tunnel seals, such as inflatable or elastomeric types that achieve pressurization post-latching, structural latches capable of withstanding axial loads exceeding 100,000 N, and alignment guides like petals or pins that accommodate initial positional misalignments up to 0.10 m laterally to enable capture. Performance metrics emphasize rapid soft capture in under 1 second at closing rates of 0.05-0.10 m/s, with full hard-dock sealing completed within 2-5 minutes to enable pressure equalization and leak checks.

Berthing mechanisms

Berthing mechanisms in spacecraft operations rely on robotic systems to capture and secure incoming vehicles or modules to a host station, such as the (ISS), without requiring autonomous alignment by the incoming craft. These systems typically involve a combination of articulated robotic arms, passive capture fixtures, and automated latching hardware to achieve precise attachment under human or semi-autonomous control. Unlike docking, which uses self-guiding interfaces, berthing emphasizes external manipulation to position the spacecraft within millimeters of the target port, ensuring structural integrity and pressure sealing for subsequent operations. The primary robotic arm used for ISS berthing is Canadarm2, a 17-meter-long manipulator with seven , enabling it to mimic human arm movements for reaching and maneuvering payloads. Equipped with force-moment sensors (FMS) at its , Canadarm2 provides tactile feedback during grapple fixture capture, detecting forces and torques to avoid overloads and ensure gentle handling of targets approximately 20 cm in size. These sensors integrate with force-moment accommodation algorithms to simplify alignment and limit contact stresses during operations. Grapple fixtures serve as passive end-effectors mounted on , such as the Flight-Releasable Grapple Fixture on SpaceX's vehicle, designed for secure capture by the . These fixtures feature a central pin with a spherical head that allows the arm's latching to snare it using three wire loops, followed by powered retraction to align and lock the connection. This wire-snare mechanism ensures reliable initial capture without active components on the fixture itself, enabling the arm to tow the to the berthing port while inhibiting its thrusters to maintain free-drift stability. Once positioned, the (CBM) on the ISS facilitates final attachment, featuring an active side with four capture latches and 16 powered bolts driven by motorized actuators to engage the passive side of the incoming vehicle. The latches initially pull the interfaces together from about 11.4 cm apart, while alignment guides and pins achieve high-precision positioning, compressing seals for pressure integrity. Vision systems, including laser scanners like the RVS 3000 , support this process by providing real-time 3D pose estimation of the target, aiding operators in overcoming relative motion uncertainties. These mechanisms are engineered for substantial loads, with Canadarm2 capable of handling up to 116,000 kg for large modules, incorporating redundancies such as dual actuators and backup power paths to mitigate failure modes like joint jams or sensor faults. Such design features ensure operational resilience, allowing safe recovery from anomalies during capture or berthing sequences.

Androgynous designs and adapters

Androgynous docking designs feature identical interfaces on both mating , eliminating the need for distinct active () and passive () roles to enhance flexibility in orbital operations. This genderless approach allows any compatible vehicle to serve as either the chaser or target, simplifying mission planning and increasing interoperability across international programs. The Docking System (NDS), compliant with the (IDSS), exemplifies this concept through its fully androgynous configuration about one axis, enabling two identical NDS units—such as the NDS-301 or NDS-303 variants—to dock without predefined roles. The IDSS further standardizes this androgynous interface to support crew rescue, collaborative missions, and resource transfer, accommodating vehicle masses from 5 to 350 tonnes while maintaining low-impact soft capture via guide petals and magnets. Early implementations of androgynous systems include the (APAS) family, developed by Soviet engineers for compatibility with the Buran orbiter and later adapted for international cooperation. The APAS-89 variant, a ring-shaped mechanism with 12 peripheral latches, was first deployed in passive configuration on the space station's Kristall module in 1990, enabling the to dock during in 1995 for crew exchange and resupply. This system supported Shuttle-Progress dockings and was modified for the Core Module, demonstrating tolerances for initial misalignments in radial and angular positions to ensure reliable capture. The APAS-95, an evolution retaining the 12-latch design but optimized for passive use on the (ISS), was integrated into the Zvezda service module in 2000, facilitating ongoing U.S.-Russian segment connections and Shuttle dockings until 2011. Adapters play a critical role in extending androgynous compatibility to legacy systems, converting berthing ports to standardized docking interfaces. The (PMA), such as PMA-2 installed on the ISS's Unity node during in 1998 and relocated to the Destiny laboratory's forward port in February 2001 via , bridges the U.S. (CBM) to Russian APAS ports, enabling pressurized tunnel access for crew and cargo transfer. Building on this, the (IDA) conforms to IDSS specifications, outfitting PMA-2 and PMA-3 to support docking of diverse vehicles like SpaceX's Crew Dragon and Boeing's Starliner, which feature IDSS-compatible ports for autonomous alignment and hook engagement. The IDSS framework incorporates electrical connectors in its adapters for seamless power and data transfer, including 120 VDC or 28 VDC power lines and protocols like MIL-STD-1553B and Ethernet via the Power/Data Transfer Umbilical (PDTU). This enables compatibility between Soyuz spacecraft—using probe-and-drogue interfaces—and Dragon vehicles through IDA-mediated IDSS ports on the ISS, as demonstrated by Dragon's first crewed docking in 2020. Such standardization reduces the complexity of mission planning by allowing multiple vehicle types to interface with a single port, as seen with the Harmony node's adapters supporting both Russian and commercial U.S. operations. Overall, these designs and adapters enhance safety and efficiency by minimizing custom hardware needs and supporting up to 50 docking cycles per mission with single-fault tolerance.

Docking procedures

Crewed docking processes

Crewed docking processes involve a structured sequence of maneuvers where a human-piloted , such as the Soyuz, approaches and connects to a target like the (ISS) under partial or full crew control, emphasizing safety and precision to enable crew transfer. These operations typically follow an automated rendezvous initiated shortly after launch, transitioning to crew-monitored phases as the vehicles draw closer, with the crew ready to intervene using manual controls if needed. The process prioritizes maintaining low relative velocities and alignments to avoid structural damage, drawing on heritage systems from Soviet-era missions refined for ISS compatibility. The docking sequence begins with the approach phase, conducted at ranges of 10-20 km where the incoming achieves a below 1 m/s relative to the target, using ground-commanded burns to establish a co-orbital . This phase relies on long-range to position the vehicle for finer adjustments, ensuring the crew can monitor progress via . Proximity operations follow at approximately 500 m, involving station-keeping maneuvers where the holds position or performs slow drifts to align axes, allowing visual confirmation through onboard cameras. Contact and capture occur in the final moments, with closure rates of 0.1-0.3 m/s to softly engage the docking probe with the target's cone, retracting the probe to secure latches. Crew members play a central role in piloting, particularly during proximity and contact phases, using joystick-based manual systems like the Russian TORU (Telerobotically Operated Rendezvous Unit) for fine attitude and translation control, supplemented by ranging lasers and video feeds from the docking port. In the Soyuz, the commander typically handles TORU inputs while the monitors displays, with the option to handover to automation like the Kurs system if conditions allow. This approach provides redundancy, as crews train extensively in simulators to respond to anomalies without disrupting the timeline. Navigation aids are essential for precision, with the Russian Kurs radio system providing ranging and velocity data up to 200 km, enabling automated guidance of the Soyuz's SOUD thrusters toward the ISS port. For U.S. vehicles like the , relative GPS receivers offered differential positioning accurate to within meters during approach, integrating with inertial systems for crewed verification. Modern U.S. commercial crew vehicles, such as SpaceX's Crew Dragon and Boeing's Starliner, rely on fully autonomous docking systems using relative GPS, , and thermal cameras for , with crews monitoring via onboard displays and able to intervene manually if required. Crew Dragon first demonstrated this in 2020, while Starliner achieved its inaugural crewed docking in June 2024. These aids ensure the spacecraft maintains alignment within tolerances, feeding data to displays for real-time crew adjustments. Contingencies emphasize abort options to protect both vehicles, such as initiating an abort-to-orbit maneuver if misalignment exceeds 5 degrees or if sensors detect excessive rates, involving immediate thruster firings to back away and reattempt or return to a safe . Crew protocols include predefined "no-go" criteria during proximity, like thresholds or communication loss, triggering manual overrides or full aborts to prevent collision. A notable example of crew intervention occurred during the Soyuz TMA-14 docking to the ISS on March 28, 2009, when an automated sensor glitch prompted commander Padalka to switch to TORU manual control for the , successfully aligning and capturing the vehicle despite the failure. This backup demonstrated the robustness of Soyuz-ISS operations, with the crew completing the docking two days after launch and proceeding to crew rotation.

Uncrewed docking processes

Uncrewed docking processes rely on fully automated systems to achieve precise rendezvous, approach, and capture without human intervention, enabling reliable resupply and assembly missions in orbit. These processes typically begin with autonomous rendezvous, where the pursuing uses integrated GPS and inertial systems (INS) to close from distances up to approximately 200 km, providing relative position accuracies on the order of 5 cm through Kalman-filtered state estimation. As the chaser nears the target, typically within 10-20 km, infrared cameras transition to short-range guidance, followed by activation for the final approach phase starting around 10 m, where closure rates are controlled to 0.1 m/s or less to ensure safe alignment. Soft capture occurs via mechanical latches that engage upon contact, attenuating loads before transitioning to hard docking, as implemented in systems like the Docking System. Sensor suites form the backbone of uncrewed docking , fusing data for real-time relative . and provide range measurements with accuracies of 1-3 cm at close proximity (e.g., 2 m), enabling hazard detection and precise trajectory corrections during the final meters. Star trackers complement these by delivering attitude determination with precisions around 0.005 degrees, essential for aligning docking ports within tolerances of a few centimeters. These sensors operate in a multi-layered : long-range absolute positioning via GPS/INS gives way to relative sensing as the vehicles enter the target's keep-out zone, typically below 1 km. Control algorithms drive the process through predictive estimation and safety protocols. Extended Kalman filters integrate sensor inputs to estimate the chaser's six-degree-of-freedom state relative to the target, enabling trajectory optimization and collision avoidance maneuvers, as demonstrated in 1990s Progress-M missions where automated holds prevented unsafe contacts. Modern implementations, such as Russia's Kurs-NA system on Progress vehicles, achieve success rates exceeding 95% in the 2020s, with over 90 automated dockings to the as of November 2025, underscoring the maturity of these algorithms in operational environments. Key challenges in uncrewed docking include operations in GPS-denied environments, such as lunar orbits or shadowed regions, where absolute positioning fails due to signal unavailability. These are addressed through relative navigation techniques, fusing , cameras, and INS data via onboard filters to maintain centimeter-level accuracy without external references, as validated in simulations for deep-space missions.

Berthing procedures

Orbital berthing operations

Orbital berthing operations enable the attachment of free-flying spacecraft to the (ISS) using robotic arms, distinguishing this process from direct docking by requiring manual capture and positioning. The workflow begins with the spacecraft's autonomous approach along the R-bar relative motion vector, halting at a safe distance of approximately 1 km to allow ground and crew monitoring for any anomalies. At this stage, the visiting vehicle holds position while proximity sensors and cameras provide real-time data to ensure clearance from station appendages. Crew operators, positioned in the Cupola module, oversee the capture using its seven windows for direct visual observation of external activities, including vehicle approaches and robotic maneuvers. The robotic workstation in the Cupola integrates multiple camera feeds and 3D graphical overlays for enhanced , allowing precise control of the Canadarm2 or similar systems during the grapple phase. This phase involves the arm snaring the spacecraft's grapple fixture, typically completing the initial capture within 5-10 minutes under nominal conditions, after which the vehicle is held in a stable "free-flyer" configuration. Following capture, the robotic arm translates and orients the spacecraft to the designated Common Berthing Mechanism (CBM) port on modules like Harmony or Unity, achieving alignment tolerances as fine as 1 mm in lateral and angular positioning to enable secure latching. For instance, NASA's Commercial Resupply Services (CRS) missions using Northrop Grumman's Cygnus spacecraft employ the CBM, where the spacecraft's passive common berthing mechanism interfaces with the active port, allowing 16 hooks and latches to secure the connection and establish power, data, and thermal links. Cygnus completed its debut demonstration berthing to the ISS in September 2013. Its first operational CRS mission berthed in January 2014, marking the second U.S. commercial cargo provider under CRS after SpaceX's Dragon. As of 2025, Cygnus continues to perform regular berthing operations, such as the NG-23 mission in September 2025. The entire berthing sequence—from arm grapple to full hard mate and hatch opening—typically spans 1-2 hours, depending on vehicle mass and port location, with unberthing reversing the steps to release the for departure. During the 2013 Cygnus demonstration mission, berthing was delayed by a GPS navigation discrepancy that required repositioning and software adjustments, ultimately resolved without aborting the operation. These operations prioritize through redundant monitoring, ensuring minimal risk to the station and during the mediated attachment of uncrewed cargo vehicles.

Module and payload berthing

Module and payload berthing involves the attachment of substantial structural elements, such as laboratory modules or expandable habitats, to an orbital platform like the (ISS), often requiring specialized adaptations to the standard orbital berthing process for handling their size and complexity. These operations typically employ robotic manipulators to pre-position the near the target port, followed by precise alignment and securement using the (CBM). The CBM consists of an active half with capture latches, fine alignment pins, and 16 powered bolts, paired with a passive half featuring sockets and nuts, enabling structural linkage and the establishment of pressurized seals. Once aligned by coarse guides, the mechanism draws the components together, advances the bolts in stages for preload, and facilitates umbilical connections for power, , and environmental control transfer. A key example of this process occurred during in February 2001, when the delivered the Destiny laboratory module. The shuttle's grappled Destiny from the payload bay, rotated it 180 degrees, and maneuvered the 14.5-metric-ton structure to the forward of the Unity node, where it was secured via the CBM. During subsequent spacewalks, crew members disconnected shuttle-side cables and connected umbilicals, expanding the ISS's habitable volume by 41% and integrating the module for scientific operations. Similarly, the Zarya module, launched via Proton rocket in November 1998 as the ISS's foundational element, provided the initial berthing target for subsequent payloads, including Unity during , demonstrating early adaptations for module-to-module integration without independent propulsion for final positioning. Berthing large modules presents unique challenges, particularly in mass handling and dynamic control. Payloads exceeding 10 metric tons, such as segments or labs approaching 20 tons in assembly configurations, demand precise robotic maneuvering to maintain stability within the ISS's microgravity environment, often relying on the Remote Manipulator (SSRMS) for capture and alignment. To mitigate risks from inertial forces, operations incorporate large capture envelopes and coordinated arm control, though dual-arm handoffs—using both the shuttle arm (SRMS) and SSRMS—have been employed for heavier lifts to distribute loads and enhance precision. Vibration damping is critical during installation; the CBM's spring-loaded standoff plungers absorb shocks from contact, preventing damage to seals or structures while ensuring smooth transition to rigid attachment. Post-berth integration emphasizes rapid verification to enable operational use. After securement, crews conduct power-up sequences to initialize and , followed by comprehensive leak tests using pressure differentials to confirm integrity before hatch opening. For instance, the (BEAM), berthed to the Tranquility node in April 2016 via the Canadarm2, underwent expansion and tests over several weeks, powering up sensors to monitor and performance, paving the way for future habitats. Looking ahead, commercial payloads are set to expand this domain. Axiom Space's habitat modules, selected by in 2020 for attachment to the ISS's Node 2 forward port via CBM, target berthing starting in 2026 or later as of 2025, to support extended crew stays and research, transitioning toward independent free-flying stations by the late 2020s. These operations will leverage enhanced robotic capabilities for heavier commercial elements, building on CBM standards to integrate diverse payloads seamlessly.

Advanced and special cases

Non-cooperative docking

Non-cooperative docking refers to the rendezvous and attachment procedures where a chaser spacecraft engages with an inactive, tumbling, or unresponsive target lacking operational attitude control, power, or communication capabilities. This capability is critical for on-orbit servicing, active removal, and salvage missions targeting defunct satellites or upper stages. Unlike scenarios, the chaser must perform all , guidance, and capture autonomously, relying on onboard sensors to estimate the target's relative pose without assistance from the target itself. Key techniques for non-cooperative docking emphasize robust relative and capture mechanisms. Vision-based pose estimation, often using flash sensors, generates 3D point clouds to track the target's motion and orientation in real time, enabling precise approach even for irregularly shaped or tumbling objects. For instance, systems like those tested in NASA's FlashPose provide high-accuracy pose data for autonomous rendezvous with non-cooperative targets. Additionally, s facilitate initial stabilization of the target before final docking; the European Space Agency's e.deorbit mission concept (2013–2017) proposed a chaser equipped with a to grasp and detumble debris, such as the , prior to deorbiting. This approach integrates cameras and grippers to handle unknown target geometries. Modern efforts focus on scalable solutions for debris mitigation. In the 2010s, the U.S. pursued the , which envisioned a servicing using robotic manipulators, nets, or grippers to capture and repurpose components from retired geosynchronous satellites, bypassing traditional docking interfaces for non-cooperative targets. These alternatives address the limitations of rigid docking ports on defunct objects, prioritizing flexible capture methods tested in ground simulations. Recent advancements include Astroscale's ELSA-M mission, launched in 2024, which demonstrated uncooperative rendezvous and capture technologies for active debris removal. Non-cooperative docking presents significant challenges, including unpredictable target attitudes and rotational rates up to 5 degrees per second due to residual or perturbations, compounded by the absence of or cooperative beacons from the target. These factors demand advanced autonomous (GNC) systems on the chaser to ensure safe proximity operations and collision avoidance. Recent developments in China's Tianzhou cargo series have advanced these capabilities by solving quasi-static hovering and safe rendezvous issues for non-cooperative targets through enhanced attitude determination and control systems (ADCS), supporting broader on-orbit servicing goals.

Planetary surface docking

Planetary surface docking refers to the specialized adaptations required for spacecraft attachment or rendezvous operations in the gravitational environments of celestial bodies like the Moon and Mars, where low gravity, regolith, and surface irregularities impose unique constraints compared to orbital scenarios. Unlike zero-gravity docking, surface operations must account for partial gravity fields—approximately 1/6 g on the Moon and 0.38 g on Mars—that affect stability and thrust control during approach and capture. These adaptations are critical for missions involving sample return, habitat assembly, or ascent vehicle integration, enabling precise alignment on uneven terrain without atmospheric assistance. Key surface constraints include dust mitigation, low-gravity anchoring, and terrain-relative . Lunar and Martian can be ejected by thruster plumes during or docking maneuvers, potentially obscuring sensors and abrading interfaces; mitigation strategies employ in-situ resource utilization (ISRU) structures like vented pads that redirect exhaust flow outward through grates and deflectors to minimize . Anchoring in low prevents slippage during attachment, using to create stable footings that embed or robotic arms into the surface material, enhancing hold in environments where traditional bolts may fail due to reduced weight. Terrain-relative (TRN) systems use onboard cameras to match real-time imagery against pre-mapped orbital data, achieving positional accuracy within tens of meters to guide landers or rovers to docking ports amid craters and slopes. For lunar applications, the emphasizes surface operations through (CLPS) landers, which deploy payloads using mechanical latches to secure instruments or habitats directly on the , facilitating modular assembly in the Moon's 1/6 g environment. While the station in (NRHO) handles primary docking, surface CLPS missions like those from and incorporate latch-based berthing for rover or equipment attachment, tested for reliability in vacuum conditions. Technical hurdles encompass thermal extremes ranging from -150°C in shadowed regions to 120°C in sunlit areas, which stress seals and actuators during extended surface exposure; regolith particles cause abrasion on docking interfaces, eroding rubberized seals and requiring hardened materials like metallic composites. The absence of atmosphere further complicates thruster efficiency, as plumes expand uncontrollably in , generating high-velocity that can destabilize approaching vehicles or contaminate ports. Recent simulations, including 2024-2025 rover analog tests at facilities mimicking Perseverance's Jezero Crater terrain, have validated low-velocity closure rates around 0.05 m/s in vacuum chambers to replicate surface docking dynamics, confirming sensor fusion for alignment under dust and low-gravity conditions.

Safety and states

Docking alignment and capture states

The docking alignment and capture states represent the critical transitional phases in spacecraft docking, where the approaching vehicle (chaser) transitions from relative free-flight to secure mechanical attachment with the target vehicle. These states ensure precise alignment to prevent damage and enable subsequent hard capture for structural integrity and sealing. In systems adhering to the (IDSS), the process begins in free-flight, where the chaser maintains a controlled approach using aids to position within the capture envelope, typically at relative velocities below 0.15 m/s. Upon reaching the contact state, the chaser's soft capture system (SCS), often featuring a or extended ring with guide petals, initiates physical interface with the target's or receptacle. This probe insertion absorbs initial impact energies, with contact velocities limited to 0.03–0.06 m/s axially and up to 0.04 m/s laterally to minimize structural loads. Soft capture follows immediately, where mechanical latches or magnets engage to arrest relative motion, achieving residual velocities below 0.01 m/s through compliant mechanisms that dampen oscillations. In this state, the vehicles are structurally linked but not fully sealed, allowing for initial load sharing. Retraction then occurs, wherein actuators pull the probe or ring to refine alignment, transitioning to hard capture . Alignment tolerances during these states are stringent to ensure seal integrity and prevent binding. For soft capture under IDSS, lateral misalignment must not exceed 10 cm, with angular deviations limited to 4 degrees in pitch, yaw, and roll; axial tolerances are managed via retraction to under 2 cm for hard capture initiation. These parameters accommodate minor errors from systems while guide pins and petals correct finer offsets, achieving sub-centimeter precision in final alignment. Roll alignment below 1 degree is particularly critical to avoid torsional stresses on seals. Sensors play a vital role in monitoring these states for safety and performance. Strain gauges embedded in the SCS and hard capture system (HCS) components measure axial and shear loads in real-time, detecting excessive forces that could indicate misalignment or impact anomalies. Pressure transducers at the interface seals assess initial pressurization and detect micro-leaks during soft capture, ensuring no premature venting before full retraction. These sensors feed into the guidance, navigation, and control system to validate state transitions. Failure modes in alignment and capture primarily stem from misalignment exceeding tolerances, which can trigger automatic abort sequences to separate the vehicles and prevent collision. In IDSS-compliant systems, such as the Docking System, testing has demonstrated near-100% success in the capture phase within specified envelopes, with recovery from single-latch failures or minor drifts. Unlike berthing, which relies on robotic arms for positioning, docking employs direct mechanical interfaces without external manipulation, emphasizing autonomous precision in these states.

Post-docking verification and undocking

After hard capture in spacecraft docking, post-docking verification ensures the integrity of the connection before crew transfer or resource sharing can proceed. This process begins with pressure integrity checks to confirm a secure seal between the vehicles, typically involving leak rate assessments to verify that the delta-pressure remains below stringent thresholds, such as a maximum leak rate of 0.0040 lbm/day (approximately 0.0018 kg/day) at 14.7 psia for certain Docking System (NDS) configurations. Structural integrity tests follow, including confirmation of hook engagement and load-bearing capacity, where the Hard Capture System (HCS) latches provide up to 300,000 N of compressive axial load tolerance under the International Docking System Standard (IDSS). analysis may be incorporated via sensors to monitor docking-induced oscillations and ensure no compromises to the joint structure, as explored in techniques using piezoelectric wafers. Once seals are verified, pressure equalization occurs across the interface, followed by a waiting period of typically 1 to 2 hours post-seal confirmation to allow stabilization before hatch opening. This step confirms the vestibule is safe for intra-vehicular activity (IVA), with redundant seals (primary and backup) maintaining a pressure-tight environment up to 1100 hPa. Hatch opening then enables crew passage through a corridor typically 27 inches in diameter. The undocking sequence reverses these steps to safely separate the vehicles. It starts with closing and sealing the hatches, followed by depressurizing the interconnecting tunnel to isolate the environments. The docking mechanism then retracts, with the HCS disengaging its 12 active hooks and push-off springs providing an initial separation velocity of approximately 0.04 m/s for vehicles up to 25 metric tons. A small separation , imparting about 0.1 m/s delta-V, ensures clear departure from the host vehicle. Safety protocols emphasize redundancy and rapid response capabilities. Dual concentric pressure seals limit adhesion forces to ≤900 N, preventing unintended retention during separation, while backup systems like resettable push-off springs (1778–2670 N force) mitigate failures. For emergency undocking, Soyuz vehicles use thrusters to achieve rapid separation if hooks fail, fired via host controls. A notable incident highlighting the importance of post-docking checks occurred with in 2018, when a 2 mm hole was detected in the orbital module approximately two months after docking to the ISS on June 8, causing a slow air leak that prompted immediate patching with sealant and extended integrity verifications before undocking. A more recent example is the Crew Flight Test docking to the ISS on June 6, 2024, where multiple thruster failures required manual piloting by the crew to complete alignment and capture, avoiding an abort and demonstrating the value of redundant control systems in verification processes. For berthing operations, the verification and undocking processes are analogous but involve robotic arm release instead of mechanical probe retraction, with the arm ungrappling the payload after seal confirmation and tunnel depressurization.

References

  1. https://www.nasa.gov/reference/jsc-rendezvous-prox-ops-docking-subsystems/
  2. https://ntrs.nasa.gov/api/citations/20180004167/downloads/20180004167.pdf
  3. https://ntrs.nasa.gov/api/citations/20110010964/downloads/20110010964.pdf
  4. https://ntrs.nasa.gov/api/citations/20110023479/downloads/20110023479.pdf
  5. https://www.nasa.gov/international-space-station/space-station-visiting-vehicles/
  6. https://www.nasa.gov/blogs/spacestation/2020/05/31/crew-dragon-docks-to-space-station/
  7. https://www.nasa.gov/blogs/spacestation/2024/06/06/boeings-crew-flight-test-on-starliner-docks-to-station/
  8. https://ntrs.nasa.gov/api/citations/20170001546/downloads/20170001546.pdf
  9. https://ntrs.nasa.gov/api/citations/20170001548/downloads/20170001548.pdf
  10. https://www.nasa.gov/history/50-years-ago-the-first-automatic-docking-in-space/
  11. https://www.nasa.gov/international-space-station/international-space-station-assembly-elements/
  12. https://ntrs.nasa.gov/api/citations/20000121212/downloads/20000121212.pdf
  13. https://dspace.mit.edu/handle/1721.1/112364
  14. https://www.nasa.gov/faqs-the-international-space-station-transition-plan/
  15. https://www.nasa.gov/international-space-station/space-station-international-cooperation/
  16. https://www.nasa.gov/international-space-station/space-station-facts-and-figures/
  17. https://newspaceeconomy.ca/2025/09/20/human-spacecraft-docking-and-rescue-capabilities/
  18. https://www.researchgate.net/publication/338768867_Integrated_In-Situ_Resource_Utilization_System_Design_and_Logistics_for_Mars_Exploration
  19. https://www.northropgrumman.com/what-we-do/space/space-logistics-services
  20. https://ntrs.nasa.gov/api/citations/20230010521/downloads/Barbour_Bruce_AAS23_155_Conference_Finalized2.pdf
  21. https://ntrs.nasa.gov/api/citations/19930013076/downloads/19930013076.pdf
  22. https://www.nasa.gov/mission/gemini-viii/
  23. https://www.nasa.gov/mission/apollo-9/
  24. https://www.nasa.gov/history/50-years-ago-apollo-9-launched-to-test-the-lunar-module/
  25. https://www.nasa.gov/history/40-years-ago-sts-3-columbias-third-mission-to-space/
  26. https://www.nasa.gov/international-space-station/unity-module/
  27. https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/Columbus/Columbus_installed_in_new_home_on_ISS
  28. https://www.nasa.gov/wp-content/uploads/2015/06/649910main_cots2_presskit_051412.pdf?emrc=55fba3
  29. https://www.nasa.gov/history/10-years-ago-orbital-sciences-cygnus-arrives-at-station/
  30. https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/ATV/Jules_Verne_ATV_given_go_for_docking
  31. https://global.jaxa.jp/article/special/transportation/torano01_e.html
  32. https://www.eoportal.org/satellite-missions/iss-era
  33. https://www.nasa.gov/mission/boeing-crewflighttest/
  34. https://internationaldeepspacestandards.com/wp-content/uploads/2024/02/IDSS-IDD-Rev-F-07262022.pdf
  35. https://www.russianspaceweb.com/docking.html
  36. https://spacecraft.ssl.umd.edu/design_lib/42120.ISS.APAS.ICD.pdf
  37. https://ntrs.nasa.gov/api/citations/20110011626/downloads/20110011626.pdf
  38. https://apps.dtic.mil/sti/tr/pdf/ADA443198.pdf
  39. https://www.asc-csa.gc.ca/eng/iss/canadarm2/about.asp
  40. https://www.asc-csa.gc.ca/eng/iss/canadarm2/data-sheet.asp
  41. https://goodvibrationsengineering.com/web4FMS.pdf
  42. https://www.nasa.gov/podcasts/houston-we-have-a-podcast/robotic-arms-in-space/
  43. https://arc.aiaa.org/doi/pdf/10.2514/6.2012-1272635
  44. https://www.nasa.gov/image-article/canadarm2-reaches-out-grapple-spacex-dragon/
  45. https://www.gocivilairpatrol.com/media/cms/1_End_Effectors_A02D7770CCD51.pdf
  46. https://ntrs.nasa.gov/api/citations/20130013168/downloads/20130013168.pdf
  47. https://ntrs.nasa.gov/api/citations/19920015843/downloads/19920015843.pdf
  48. https://esmats.eu/amspapers/pastpapers/pdfs/2004/foster.pdf
  49. https://ntrs.nasa.gov/api/citations/20250000863/downloads/AAS-25-092_RVS3000XLIDAR_FINAL.pdf
  50. https://ntrs.nasa.gov/api/citations/20070021628/downloads/20070021628.pdf
  51. https://www.nasa.gov/history/space-station-20th-sts-71-first-shuttle-mir-docking/
  52. https://www.internationaldockingstandard.com/
  53. https://ntrs.nasa.gov/api/citations/20140003570/downloads/20140003570.pdf
  54. https://ntrs.nasa.gov/api/citations/20140004821/downloads/20140004821.pdf
  55. https://ntrs.nasa.gov/api/citations/20070025134/downloads/20070025134.pdf
  56. https://ntrs.nasa.gov/api/citations/20110008220/downloads/20110008220.pdf
  57. https://www.russianspaceweb.com/soyuz_tech.html
  58. https://sma.nasa.gov/SignificantIncidents/assets/nasa-astronauts-on-soyuz.pdf
  59. https://www.spacesafetymagazine.com/spaceflight/rendezvous-docking/malfunction-kurs-na-resulted-manual-dock-iss/
  60. https://www.nasa.gov/missions/commercial-crew-program/
  61. https://www.nasa.gov/missions/boeing/starliner/
  62. https://ntrs.nasa.gov/api/citations/19760014158/downloads/19760014158.pdf
  63. https://www.sandiegouniontribune.com/2009/03/28/soyuz-sensor-malfunction-prompts-manual-docking/
  64. https://www.researchgate.net/publication/253911187_Integrated_GPSINS_navigation_system_design_for_autonomous_spacecraft_rendezvous
  65. https://ntrs.nasa.gov/api/citations/20180004168/downloads/20180004168.pdf
  66. https://engineering.usu.edu/ece/faculty-sites/cail/software
  67. https://amostech.com/TechnicalPapers/2021/Poster/Plotke.pdf
  68. https://ntrs.nasa.gov/api/citations/20150019634/downloads/20150019634.pdf
  69. https://ntrs.nasa.gov/api/citations/20160001403/downloads/20160001403.pdf
  70. https://www.russianspaceweb.com/progress_m_0m.html
  71. https://ntrs.nasa.gov/api/citations/20080013593/downloads/20080013593.pdf
  72. https://www.nasa.gov/international-space-station/cupola/
  73. https://www.nasaspaceflight.com/2017/04/crew-replace-cupola-window-iss/
  74. https://www.nasaspaceflight.com/2013/09/cygnus-second-attempt-berth-iss/
  75. https://www.nasa.gov/missions/commercial/cygnus/ng-23-northrop-grumman-mission/
  76. https://www.planetary.org/articles/dragon-makes-history-berths
  77. https://www.nasaspaceflight.com/2013/09/cygnus-cots-graduation-iss-berthing/
  78. https://www.nasa.gov/history/space-station-20th-sts-98-delivers-destiny-to-the-international-space-station/
  79. https://www.nasa.gov/international-space-station/zarya-module/
  80. https://www.nasa.gov/international-space-station/bigelow-expandable-activity-module-beam/
  81. https://www.nasa.gov/news-release/nasa-selects-first-commercial-destination-module-for-international-space-station/
  82. https://www.sciencedirect.com/science/article/abs/pii/S0376042117300428
  83. https://pmc.ncbi.nlm.nih.gov/articles/PMC6209945/
  84. https://technology.nasa.gov/patent/GSC-TOPS-102
  85. https://www.frontiersin.org/journals/robotics-and-ai/articles/10.3389/frobt.2018.00100/full
  86. https://spacenews.com/darpa-project-aims-turn-space-junk-satellites/
  87. https://www.astroscale.com/en/news/from-docking-plates-to-debris-removal-astroscale-uks-year-in-review
  88. https://www.sciencedirect.com/science/article/abs/pii/S0273117722002034
  89. https://www.researchgate.net/publication/343800854_Rendezvous_Approach_Guidance_for_Uncooperative_Tumbling_Satellites
  90. https://spj.science.org/doi/10.34133/space.0006
  91. https://www.globalspaceexploration.org/wp-content/uploads/2019/12/2019_GER_Technologies_Portfolio_ver.IR-2019.12.13.pdf
  92. https://www.researchgate.net/publication/348256800_Lunar_PAD_-_On_the_Development_of_a_Unique_ISRU-Based_Planetary_Landing_Pad_for_Cratering_and_Dust_Mitigation
  93. https://techport.nasa.gov/projects/146020
  94. https://science.nasa.gov/science-research/science-enabling-technology/technology-highlights/terrain-relative-navigation-landing-between-the-hazards/
  95. https://www.nasa.gov/missions/artemis/clps/six-nasa-instruments-will-fly-to-moon-on-intuitive-machines-lander/
  96. https://www.nasaspaceflight.com/2025/01/lunar-missions-roundup/
  97. https://ntrs.nasa.gov/api/citations/20110008483/downloads/20110008483.pdf
  98. https://www.mdpi.com/2075-4442/11/8/334
  99. https://www.sciencedirect.com/science/article/pii/S0094576524006672
  100. https://www.kiss.caltech.edu/papers/xterramechanics/papers/simulations.pdf
  101. https://modernsciences.org/nasa-mars-rover-testing-august-2025/
  102. https://www.researchgate.net/publication/387969700_Structural_Health_Monitoring_of_Spacecraft_Docking_Using_Piezoelectric_Wafer_Sensors
  103. https://www.nasa.gov/news-release/nasa-astronauts-launch-from-america-in-historic-test-flight-of-spacex-crew-dragon/
  104. https://www.nasa.gov/mission/soyuz/
  105. https://www.nasa.gov/blogs/spacestation/2018/08/30/international-space-station-status-3/
  106. https://www.foxnews.com/us/nasa-astronaut-reveals-nearly-failed-dock-boeing-starliner-international-space-station
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