User:Tony Mach/Spacecraft docking

< Spacecraft docking and berthing mechanisms

< User:Tony Mach/Docking

The free-flying Progress in the process of docking to the ISS

Dragon prior to being berthed to the ISS by the Canadarm2 robotic arm

Spacecraft docking and berthing mechanisms are mechanisms which are used to connect a spacecraft or a "space station module" to either another spacecraft or an space station. This connection is either temporary for visiting spacecraft or semipermanently for space station modules.

A docking mechanism is used when one spacecraft actively maneuvers under its own propulsion to connect to another spacecraft.

A berthing mechanism is used when space station modules or spacecraft are attached to one another by using a robotic arm instead of their own propulsion – berthing typically involves connection to a space station.

Docking and berthing are so far mutually exclusive in the deployed mechanisms – the NASA Docking System (NDS) currently under design will be the first system to support both berthing and docking operations.

The terms docking and berthing are derived from the maritime terms for the useage of a dock or a berth, and it is said that one spacecraft actively "docks" to another spacecraft or that it "was berthed" passively to another.

History of spacecraft docking

Early concepts

Inflatable tunnel: A one-man space station proposed by McDonnell. In this version, access to the laboratory was through an inflated tunnel connecting the Mercury-type capsule (in which the astronaut rode into orbit) with the laboratory.

Gemini

Spacewalks

• Kontak: Soviet LK lander
• Early Soyuz (Soyuz 4 & Soyuz 5)

Apollo

ASTP

Docking and berthing today

Docking and berthing mechanisms are part of a system needed to join two spacecraft. For both, a space rendezvous maneuver is necessary so that both spacecraft arrive at the same orbit, and then approach each other at very close distance. This rendezvous maneuver can be either controlled by the crew or the ground, or it can be automated with a docking system such as the Russian Kurs system used for the Soyuz and Progress spacecraft.

The steps that follow a successful rendezvous differ for docking and berthing.

Docking maneuver

For a docking maneuver, one spacecraft is using its maneuver systems as the active spacecraft, and the target of the docking is designated the passive spacecraft. After the rendezvous maneuver, the maneuvering thrusters are used on the active spacecraft to align both spacecraft so that the docking interfaces of both face each other. When the alignment is confirmed, a controlled collision trajectory is then initiated by the active spacecraft. This docking maneuver can be flown manually or controlled by an automated docking system mentioned above. No manned United States spacecraft have ever been equipped with non-experimental automated rendezvous and docking equipment.

Contemporary examples of spacecraft that use docking mechanisms are the Soyuz, Progress and ATV spacecraft, which dock to the ISS.

Soft dock and hard dock (soft capture and hard capture)

The spacecraft docking mechanisms typically enter what is called soft capture, followed by a load attenuation phase, and then the hard docked position which establishes an air-tight structural connection between spacecraft.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090014038_2009013104.pdf :

• Alignment system
• Latch system
• Tunnel housing
• Seals

Berthing

Berthing, by contrast, is when an incoming spacecraft is grappled by a robotic arm and its interface mechanism is placed in close proximity of the stationary interface mechanism. Then typically there is a capture process, coarse alignment and fine alignment and then structural attachment.

This will be discussed in more detail in later chapters. A family tree of docking and berthing mechanisms is shown in Figure 1. It shows the chronological development of mating mechanisms from the world’s space faring nations.

Typical examples of berthing are

Capture

E.g. HST Servicing Missions.

Androgyny

Early systems for conjoining spacecraft were all non-androgynous docking system designs. Non-androgynous designs are a form of "gender mating" where each spacecraft to be joined has a unique design 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, on the other hand has an identical interface design on both spacecraft, allowing system-level redundancy (role reversing) as well as rescue and collaboration between any two spacecraft vehicles. In an androgynous interface, there is a single design which can connect to a duplicate of itself. This results in more flexible mission design and reduces unique mission analysis and training.

Future

Docking of unmanned spacecraft

A graphic depicting the Soft-Capture Mechanism (SCM) added in 2009 to the Hubble Space Telescope. The SCM allows both manned and unmanned spacecraft to dock with Hubble.

During the first fifty years of spaceflight, the main objective of most docking and all berthing missions was to transfer crew, construct or resupply a space station, or to test for such a mission. Therefore commonly at least one the participating spacecraft was "manned", with a pressurized habitable volume (e.g. a space station or a lunar lander) being the target. The exception were a few unmanned Soviet flights, which targeted space stations while they were unmanned (e.g. Cosmos 1443 or Progress 23 with Salyut 7).

This is changing, as a number of economically driven commercial dockings of unmanned spacecraft are planned starting as soon as 2015. In early 2011, two commercial spacecraft providers have announced plans to provide new autonomous/teleoperated unmanned resupply spacecraft for servicing other unmanned spacecraft. Notably, both of these servicing spacecraft will be intending to dock with satellites that were not designed for docking, nor in-space servicing.

The early business model for these services is primarily in near-geosynchronous orbit, although large delta-v orbital maneuvering services are also envisioned.

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 have announced new commercial satellite servicing missions that will require docking of two unmanned vehicles.

• Space Infrastructure Servicing (SIS) is a spacecraft being developed by Canadian aerospace firm MacDonald, Dettwiler and Associates (MDA)—maker of Canadarm—to operate as a small-scale in-space refueling depot for communication satellites in geosynchronous orbit. Intelsat is a requirements and funding partner for the initial demonstration satellite, aimed to be launched in approximately 2015.

• Mission Extension Vehicle (MEV) is a spacecraft being developed by the U.S. firm ViviSat, a 50/50 joint venture of aerospace firms U.S. Space and ATK, to operate as a small-scale in-space satellite-refueling spacecraft. MEV will dock but will not transfer fuel. It will rather use "its own thrusters to supply attitude control for the target."

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

A prominent spacecraft that received a mechanism for unmanned dockings is the Hubble Space Telescope. 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 unmanned 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 an Multi-Purpose Crew Vehicle docked mission. The NDS bears some resemblance to the APAS-95 mechanism, but is not compatible with it.

Non-cooperative docking

With the single exception of the emergency docking of Salyut 7 and Soyuz T-13, as of 2006, all spacecraft dockings have been accomplished with vehicles where both spacecraft involved were under either piloted, autonomous or telerobotic attitude control. However, it might be desirable to dock with a spacecraft that does not have an operable attitude control system, for purposes of repair or disposal. Theoretical techniques for docking with non-cooperative spacecraft have been proposed, and the emergency USSR crewed docking with an uncontrolled spacecraft is described below.

Crewed missions

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". 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 Russian military commander Vladimir Dzhanibekov and technical science flight engineer Viktor Savinykh 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 and matched the station's rotation. After hard docking to the station and confirming the station's electrical system was dead, Dzhanibekov and Savinykh sampled the station atmosphere prior to opening the hatch. Attired in winter fur-lined clothing, they entered the station to conduct repairs. Within a week sufficient systems were brought back online to allow robot cargo ships to dock with the station.

No manned United States spacecraft have ever been equipped with non-experimental automated rendezvous and docking equipment.

Uncrewed spacecraft

Non-cooperative rendezvous and capture techniques have been theorized and, in a few instances, put to practice with uncrewed spacecraft in orbit.

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.

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.

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 kilometres (2 mi). Non-cooperative docking mechanisms were identified as critical mission elements to the success of such autonomous missions.

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.

List of types of spacecraft docking and berthing mechanisms

Manned

Name and image	Type	Usage
Gemini Docking Mechanism The passive interface of the target (left) and active of the Gemini spacecraft.	Docking mechanism (Fixed active/passive role) Note: No internal crew transfer	Allowed the Gemini Spacecraft to dock to the Agena target vehicle as a preparation for the Apollo project.
Apollo Docking Mechanism On the left the active "probe" interface used on the CSM, which docks to the passive "drogue" on the right.	Docking mechanism (Fixed active/passive role)	Allowed the Command/Service Module (CSM) to dock to the Apollo Lunar Module and the Skylab space station. Was used to dock to the Docking Module adapter during the Apollo–Soyuz Test Project (ASTP), which allowed to dock with an Soviet Soyuz 7K-TM spacecraft .
Kontakt docking system Left the passive side designed for the lunar lander and right the active side.	Docking mechanism (Fixed active/passive role) Note: No internal crew transfer	Intended to be used in the Soviet manned lunar program to allow the Soyuz 7K-LOK ("Lunar Orbital Craft") to dock to the LK lunar lander.
Soyuz "probe and drogue" (original type) Left the passive and right the active side.	Docking mechanism (Fixed active/passive role) Note: No internal crew transfer, only used to gather engineering data.	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 an preparation for the Soviet space station program. The gathered data was subsequently used for the conversion of the Soyuz spacecraft – which was initially developed for the Soviet Moon program – into a space station transport craft. An first docking with two unmanned 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.
Soyuz "probe and drogue" (Salyut-1 type) On the left an active probe interface, as used to dock to an passive drogue on the right.	Docking mechanism (Fixed active/passive role)	The contemporary Russian docking mechanism, the Soyuz "probe and drogue" docking system of Salyut-1 type, is in use since 1971. 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. The "probe and drogue" system allows visiting spacecraft using the "probe" docking interface, such as Soyuz, Progress and ATV spacecraft, to dock to space stations that offer an port with an "drogue" interface, like the former Salyut and Mir or the current ISS space station. In total four "drogue" interfaces are available for visiting spacecraft on the ISS; These are located on the Zvezda, Rassvet, Pirs and Poisk modules. Furthermore the "probe and drogue" system was used on the ISS to dock Rassvet semipermanently to Zarya.
APAS-75 Two US-build APAS-75 docking mechanisms prior to testing.	Docking mechanism (Androgynous)	Used on the Docking Module (ASTP) to dock an Apollo Spacecraft with an Soyuz 7K-TM during the Apollo–Soyuz Test Project (ASTP).
APAS-89 On the left an APAS-89 in active, on the left in passive configuration.	Docking mechanism (Androgynous) Note: Was fixed in passive role for Kristall and Mir Docking Module	The APAS-89 was, besides the Soyuz "probe and drogue" system, used on Mir to allow visiting spacecraft to dock to the space station – initially intended for the Soviet Buran space shuttle which never flew to the station, it was actually used with an APAS-95 adapter by the Space Shuttle fleet after a test with Soyuz TM-16. APAS-89 ports on Mir were installed on the modules Kristall and the Mir Docking Module.
APAS-95 On the left an APAS-95 can be seen in active configuration, its soft dock ring with the three petals extended; On the left an APAS-95 in passive configuration.	Docking mechanism (Androgynous) Note: Is fixed in passive role for PMA-2 and PMA-3.	APAS-95 was used to dock the Shuttle to the Mir space station during the Shuttle–Mir Program and then later to the ISS. APAS-95 ports, which are compatible with APAS-89, were installed on the Space Shuttles Discovery, Atlantis and Endeavour, but not on the oldest shuttle Columbia. Three Pressurized Mating Adapters (PMA) with an APAS-95 docking port are installed on the ISS, with PMA-1 semi-permanently connected to the APAS interface of Functional Cargo Block (Zarya), connecting the US Orbital Segment (USOS) and the Russian Orbital Segment (ROS); The other two PMAs are free, possibly available for visiting spacecraft.
Hybrid Docking System On the left an active Hybrid Docking System with its probe, on the right an passive version with its drouge.	Docking mechanism (Fixed active/passive role)	Used by some modules on the Russian Orbital Segment (ROS) of the ISS. The name "hybrid" derives from the combination of a "probe and drogue" soft-dock mechanism with a APAS-95 hard-dock collar. Connects Zvezda to Zarya, and Pirs & Poisk to Zvezda.
Common Berthing Mechanism (CBM) On the left an "active" CBM (with its micrometeorite shield still attached), on the right a "passive" CBM.	Berthing mechanism (Fixed active/passive role)	Used for berthing of all pressurized modules on the US Orbital Segment (USOS) on the ISS. Is used by visiting cargo supply craft and modules such as MPLMs, HTV, Dragon Cargo, and Cygnus. Has as of 2012 not been used to berth a manned spacecraft to the ISS.
Chinese Docking Mechanism Left the passive and right the active configuration.	Docking mechanism (Androgynous) Note: Is fixed in passive role for Tiangong-1	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 and would according to the Chinese allow for dockings with the ISS. Used for the first time on Tiangong 1 space station and will be used on future Chinese space stations.
NASA Docking System (NDS) Left the passive and right the active configuration.	Dual role: Docking mechanism (Androgynous) and Berthing mechanism (Androgynous) Note: Will be fixed in passive role for the IDAs to be installed on PMA-2 and PMA-3.	The NASA Docking System (NDS) is intended to be used for future US spacecraft. Also known as (international) Low Impact Docking System (iLIDS or LIDS). The NDS bears some resemblance to the APAS-95 mechanism, but is not compatible with it. Can be used both for docking and berthing. An NDS interface will be available on the two International Docking Adapters (IDA), which are intended to be installed on two of the three Pressurized Mating Adapters (PMA) on the ISS. The Soft Capture Mechanism (SCM) on the Hubble Space Telescope is compatible with the NDS.

Adapters

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. While such interfaces may theoretically be docking/docking, docking/berthing, or berthing/berthing, only the first two types have been deployed in space to date. Previously launched and planned to be launched adapters are listed below.

The backup Docking Module of the Apollo–Soyuz Test Project mission using the APAS-75.

One of the Pressurized Mating Adapters (PMA) that provide APAS-95 ports on the ISS, pictured here with the docked Shuttle Discovery.

A graphic showing an International Docking Adapter to be added to the Pressurized Mating Adapters PMA-2 and PMA-3.

Docking Module

The Docking Module converted NASA's "Probe and Drogue" docking system used for Apollo spacecraft to the APAS-75 system used for the 1975 Apollo–Soyuz Test Project mission.

Pressurized Mating Adapter (PMA)

The Pressurized Mating Adapter (PMA) allows spacecraft utilizing the Androgynous Peripheral Attach System (APAS-95) to dock to the ISS and is semi-permanently attached to an "active" CBM berthing port. There are three PMAs attached to the ISS, with PMA-2 and PMA-3 being available to visiting spacecraft and the PMA-1 adapter being semi-permanently attached to the Functional Cargo Block (Zarya) and Node 1 (Unity), in order to connect the Russian Orbital Segment to the rest of the station.

International Docking Adapter (IDA)

International Docking Adapters (IDA) will be attached to the Pressurized Mating Adapters PMA-2 and PMA-3 and convert their APAS-95 docking interface to the NASA Docking System (NDS). PMA-2 and PMA-3 will be outfitted with IDAs, one in late 2014 and the other in either 2015 or 2016, and with one being attached to Node-2's (Harmony) forward CBM port and the other to its zenith CBM port. The adapter was slated to be compatible with the International Docking System Standard (IDSS), which was an attempt by the ISS Multilateral Coordination Board to create a docking standard, a standard now known as NASA's NDS.

See also

• Space rendezvous