Timeline of In-Orbit Servicing, Assembly, and Manufacturing (ISAM) Advances – Past, Present and Future

The history of satellite servicing, refueling, assembly, and upgrade spans from crewed servicing of telescopes, to in-space construction and maintenance of large structures, and to autonomous robotic servicing missions. Recent commercial operations have extended the lifespan of satellites that are low on fuel. This article provides a timeline of ISAM major advances and milestones from 1961 into the future.


๐Ÿ‡บ๐Ÿ‡ธ Gemini

Gemini demonstrated rendezvous, proximity operations, and docking (RPOD).


๐Ÿ‡บ๐Ÿ‡ธ NASA Space Tug Concept

The Space Tug concept was intended to be a reusable multipurpose space vehicle designed to transport payloads to different orbital inclinations. Utilizing mission-specific combinations of its three primary modules (crew, propulsion, and cargo) and a variety of supplementary kits, the Space Tug would have been capable of numerous space applications. The Space Tug program was cancelled.


๐Ÿ‡บ๐Ÿ‡ธ Skylab

Skylab demonstrated on-orbit repairs to fix critical components.


๐Ÿ‡บ๐Ÿ‡ธ Solar Maximum Mission

Solar Maximum Mission took advantage of a modular design using Orbital Replacement Units (ORUs) to streamline the on-orbit repair process.


๐Ÿ‡บ๐Ÿ‡ธ Hubble Space Telescope

Hubble Space Telescope “Hubble” was serviced five times, which included replacement of circuit boards, the addition of hardware to correct a mirror flaw, regular upgrades of the scientific instruments, and the installation of a device to facilitate deorbit at the end of mission lifetime. NASA is currently exploring options to reboost Hubble to a higher orbital altitude.


๐Ÿ‡ฏ๐Ÿ‡ต Engineering Test Satellite VII

The Engineering Test Satellite VII (ETS-VII) successfully made the first remotely-controlled unmanned rendezvous docking between two spacecraft in history.


๐Ÿ‡บ๐Ÿ‡ธ International Space Station (ISS)

The International Space Station (ISS) was assembled on-orbit and is continually replenished with propellant, supplies, and new modules to enhance its capabilities and provide new science opportunities. Commercial resupply missions to the ISS continuously promote technological growth of RPOD activities due to the consistent need to dock.

For information on space logistics vehicles related to space stations: Insights into Space Station Logistics Spacecraft โ€“ Past, Present, and Future and Cargo Spacecraft from the Past to the Future.



DART proved the technologies required for spacecraft to locate and rendezvous with another spacecraft without direct human guidance. While NASA has performed rendezvous and docking missions in the past, astronauts have always piloted the spacecraft. The autonomous rendezvous technologies demonstrated by DART represented a critical step for establishing an autonomous rendezvous capability for the United States and will lay the groundwork for future reusable crewed and uncrewed launch vehicle operations. Future applications of this technology include cargo delivery, space operations for the International Space Station (ISS) and other on-orbit activities such as satellite retrieval and servicing missions.


๐Ÿ‡บ๐Ÿ‡ธ DARPA Orbital Express

The Defense Advanced Research Projects Agency’s Orbital Express demonstrated a full end-to-end robotic satellite servicing mission, the first of its kind. The mission included autonomous docking, fuel transfer, and ORU change-out essentially removing humans from the equation.

2011 to 2013

๐Ÿ‡บ๐Ÿ‡ธ NASA Robotic Refueling Mission (RRM)

The Robotic Refueling Mission (RRM) investigation uses the International Space Station’s two-armed robotic handyman, Dextre, to show how future robots could service and refuel satellites in space. RRM tests NASA-developed technologies, tools and procedures to refuel and repair satellites that were not originally designed to be serviced.

2014 to 2016

๐Ÿ‡บ๐Ÿ‡ธ NASA RRM Phase 2

RRM-P2 is demonstrating technologies and capabilities related to satellite servicing including: testing a new inspection tool, practicing intermediary steps leading up to cryogen replenishment, testing electrical connections for “plug and play” space instruments, and working with decals that could help operations guided by machine vision go more smoothly. RRM-P2 is the continuation of the satellite-servicing demonstrations that began in the first phase of RRM operations.

2017 to 2023

๐Ÿ‡บ๐Ÿ‡ธ NASA RRM 3

Robotic Refueling Mission 3 (RRM3) demonstrates the first transfer and long term storage of liquid methane, a cryogenic fluid, in microgravity. The ability to replenish and store cryogenic fluids, which can function as a fuel or coolant, can help enable long duration journeys to destinations like the Moon and Mars.


๐Ÿ‡ฌ๐Ÿ‡ง University of Surrey’s RemoveDEBRIS

University-led mission launched in 2018 to test technologies for debris removal: net, harpoon, dragsail, and LiDAR vision. These demonstrations concluded in early 2019.


๐Ÿ‡บ๐Ÿ‡ธ SpaceLogisticsโ€™ MEV

SpaceLogistics’ Mission ExtensionVehicle-1 (MEV-1) became the first commercial servicer spacecraft to perform a docked life extension procedure upon an out-of-operation commercial satellite, Intelsat IS-901. This was followed by the MEV-2’s docking to Intelsat IS-1002 on April 12,


๐Ÿ‡บ๐Ÿ‡ธ Moog OMV

Large family of Orbital Maneuvering Vehicles (OMVs) designed to serve as a modular platform for payload hosting and deployment. They are able to serve as space tugs to conduct orbit raising maneuvers for deployed payloads.


๐Ÿ‡บ๐Ÿ‡ธ DIU Orbital Outpost

Defense Innovation Unit (DIU) has selected Sierra Nevada Corporation (SNC), NanoRacks, and Arkisys for Phase I contracts for the Orbital Outpost. It will be a self-contained, free-flying spacecraft capable of supporting assembly, microgravity experiments, logistics, manufacturing, training, and hosted payloads. Currently no schedule for orbital deployment.


๐Ÿ‡ฎ๐Ÿ‡น D-Orbit ION Satellite Carrier

An OTV designed for the last-mile delivery of CubeSats and microsats of mass up to 150 kg and to perform in-orbit experiments of hosted payloads. Four successful missions as of 2022, with over 70 payloads delivered to orbit.


๐Ÿ‡บ๐Ÿ‡ธ Rocket Lab Photon

Photon supports hosted payloads and lastโ€“mile satellite deployment ranging from LEO to deep space.


๐Ÿ‡บ๐Ÿ‡ธ Spaceflight Sherpa

The Sherpa line of five OTVs are designed to provide final delivery to rideshare customers’ desired orbits. Includes delivery to LEO, GEO, and Lunar orbits.


๐Ÿ‡ฏ๐Ÿ‡ต Astroscale’s ELSA-d

Astroscale’s End-of-Life-Service by Astroscale-demonstration (ELSA-d) demonstrated key rendezvous and proximity operations technologies necessary for orbital servicing, and space debris removal.


๐Ÿ‡บ๐Ÿ‡ธ Orbit Fab’s Tanker-001 Tenzing

Tanker-001 Tenzing was launched June 30, 2021 and is the world’s first operational fuel depot. Tenzing stores High-Test Peroxide (HTP) propellant in a sun-synchronous orbit to refuel other spacecraft.


๐Ÿ‡บ๐Ÿ‡ธ Momentus Vigoride

Vigorride is an OTV capable of transporting 200 to 750 kg of payload to LEO. Future plans include support for hosted payloads, refueling, repairing, inspecting, relocation, etc.


๐Ÿ‡บ๐Ÿ‡ธ White House ISAM National Strategy

This National Strategy outlines how the United States will support and stimulate the United States Government (US), academic, and commercial ISAM capability development. It provides strategic goals to advance ISAM capability development discussed in the United States Space Priorities Framework. The next step following the strategy is to develop US implementation action plans to fulfill the goals.


๐Ÿ‡บ๐Ÿ‡ธ Launcher Orbiter

Orbiter can transport up to 400 kg of payload to LEO. It can also support hosted payloads.


๐Ÿ‡ซ๐Ÿ‡ท Infinite Orbits OrbitGuard

OrbitGuard, is a small satellite that can autonomously carry out far and near range rendezvous and provides SSA and inspection services to satellite operators. OrbitGuard 1 & 2 are slated to launch Q4 2022 onwards and provide services from 2023.



This small satellite provides one-on-one asset inspection capabilities for high-value satellites. It is forecast to be launched in 2023.


๐Ÿ‡บ๐Ÿ‡ธ Rogue Laura

Laura will provide asset inspection and monitoring using high definition cameras and sensors.


๐Ÿ‡บ๐Ÿ‡ธ Rogue Fred

Fred will provide payload transportation and orbital adjustment for satellites to GEO and LEO.


๐Ÿ‡ฏ๐Ÿ‡ต JAXA CRD2

Astroscale’s Active Debris Removal by Astroscale-Japan (ADRAS-J) has been contracted for the initial phase of JAXA’s Commercial Removal of Debris Demonstration (CRD2) program. A public-private collaboration, Phase 1 of this program is expected to launch in 2023. Once Phase 1 displays non-cooperative RPO capabilities, Phase 2 plans to demonstrate the removal of a launch vehicle’s second stage in fiscal year 2025.


๐Ÿ‡บ๐Ÿ‡ธ Atomos Quark

Atomos is developing Quark Orbital Transfer Vehicle (OTV) to deliver satellites to their desired orbits utilizing high-power electric propulsion and advanced RPO techniques. Expected launch in 2023.


๐Ÿ‡ฉ๐Ÿ‡ช Exolaunch Reliant

The Reliant OTV comes in a Standard and Pro model to transfer satellites to different orbital altitudes. Reliant Pro will also have modular satellite upgrade and debris collection abilities.


๐Ÿ‡ช๐Ÿ‡ธ UARX Space OSSIE

Orbit Solutions to Simplify Injection and Exploration (OSSIE) is a modular and scalable orbital transfer vehicle designed to provide precise orbital injection and inclination changes for CubeSats and small spacecraft. Can deliver to Earth orbits, the moon, and beyond.


๐Ÿ‡ซ๐Ÿ‡ท Exotrail Space Van

The Space Van is capable of transporting up to 400 kg of payload to LEO and GEO.


๐Ÿ‡ฆ๐Ÿ‡บ Space Machines Company Optimus Transport

Optimus is capable of payload transport to LEO, GEO, and deep space. Future support for active debris removal, life extension, and in-space manufacturing.


๐Ÿ‡ฏ๐Ÿ‡ต Astroscale ELSAโ€“M

ELSAโ€“M will be the worldโ€™s first mission to de-orbit multiple small satellites.


๐Ÿ‡ฌ๐Ÿ‡ง Lunasa VIA

VIA plans to offer last-mile transportation, AOCS takeover, and hosted payloads.


๐Ÿ‡บ๐Ÿ‡ธ Redwire Space Archinaut / OSAM-2

OSAM-2 will demonstrate the feasibility of using additive manufacturing technology (3D printing) and advanced robotics to build two beams on a free-flying satellite. The first beam will unfurl a surrogate solar array, and the second beam will be used to characterize additively manufactured structures in LEO.


๐Ÿ‡บ๐Ÿ‡ธ Turion DROID

DROID is planned to support asset inspection, orbital adjustment, and debris mitigation functionalities in LEO.



DARPA has partnered with SpaceLogistics to develop and deploy a robotic servicer or MRV. The program is called Robotic Servicing of GEO Satellites (RSGS). Naval Research Laboratory (NRL) will integrate robotic payload elements including manipulator arms. Launch planned for 2024.


๐Ÿ‡บ๐Ÿ‡ธ SpaceLogistics MRV and MEP

The Mission Robotic Vehicle (MRV) will be a commercial servicing spacecraft with advanced robotics technology. The primary purpose will be the installation of Mission Extension Pods (MEPs) to provide propulsion augmentation. The MRV is also designed to address inspection and repair, relocations, propulsion augmentation, and replacement of parts and systems. Planned launch in 2024. This is part of the DARPA RSGS program.


๐Ÿ‡บ๐Ÿ‡ธ Arkisys Port

Arkisys is building one of the first Business Platforms in Space for new Technology Hosting, Satellite Integration, Assembly and Resupply. The Arkisys Port supports scaleable rapid prototyping, new payload and technology testing, assembly and integration of new free-flying space platforms and destinations for orbital transfer vehicles and on-orbit assembly and manufacturing.


๐Ÿ‡บ๐Ÿ‡ธ Nanoracks Mission Extension Kit (MEK)

The MEK aims to repurpose the upper stage of launch vehicles for use as platforms for robotic manufacturing, servicing, etc. These platforms are intended to be controllable and function across multiple orbits.


๐Ÿ‡ซ๐Ÿ‡ท Ariane Group ATRIS

The ATRIS is an optional stage positioned on top of Ariane 6’s upper stage, which will allow the rocket to place several satellites into different orbits in a single launch, or to inject a satellite directly into its final orbit, optimizing a wide scope of missions.


๐Ÿ‡บ๐Ÿ‡ธ Maxar SPIDER / OSAM-1

Space Infrastructure Dexterous Robot (SPIDER) / OSAM-1 will robotically assemble seven individual components into one large antenna reflector.


๐Ÿ‡บ๐Ÿ‡ธ Axiom Station

Axiom Space’s commercial space station is under construction. The first Axiom module is expected to dock with the International Space Station in 2024. Additional modules will launch each year. Axiom Station will become an independent commercial space station prior to the end of life of the ISS.

Other commercial space stations planned and proposed are described here Space Stations Current and Future.


๐Ÿ‡ซ๐Ÿ‡ท Infinite Orbits Endurance

Endurance performs autonomous rendezvous & docking and provides full AOCS capability for 5 years to an end of life GEO satellite. Life Extension Services will be available from 2025 onwards.


๐Ÿ‡บ๐Ÿ‡ธ Orbital Fab HTP Orbital Gas Station

Orbital Fab plans to offer HTP propellant to GEO satellites starting in 2025. $20 million per 100 kg.


๐Ÿ‡ช๐Ÿ‡บ ESA ClearSpace-1

ESA selected ClearSpace for first ever debris removal of an ESA-owned item. ClearSpace-1 will use an experimental, four-armed robot to capture a Vega Secondary Payload Adapter (Vespa) left behind by ESA’s Vega launcher in 2013. Expected launch in 2026.


๐Ÿ‡ช๐Ÿ‡บ European Commission EROSS+

European Robotic Orbital Support Services (EROSS) is a technology demonstration led by Thales Alenia Space intended to provide: life extension, refueling, inspection, controlled debris reentry, and other operations. On-orbit demonstration expected by 2026.

No Forecast

๐Ÿ‡ช๐Ÿ‡ธ UARX Space LUCAS

Upgraded version of OSSIE vehicle, planned to transport 1000 kg of payloads to lunar orbit.

No Forecast

๐Ÿ‡ฏ๐Ÿ‡ต Astroscale LEXI

The Life Extension In-orbit servicer is intended to provide life extension by acting as the propulsion system for client satellites. By using four robotic arms, LEXI can position itself to provide stationkeeping, attitude control, and other orbital relocation services. LEXI can dock/undock with clients, allowing it to service multiple clients per mission.

No Forecast

๐Ÿ‡ธ๐Ÿ‡ช porkchop porkchopโ€“M

porkchop is planning to build a reusable orbital transfer vehicle.

No Forecast

๐Ÿ‡ฌ๐Ÿ‡ง Skyrora Space Tug

Skyrora’s Space Tug is planned to transport 350 kg into a 500 km SSO. Future scope may include the potential to: remove space debris, conduct inspections, and fix faulty satellites.

No Forecast

๐Ÿ‡บ๐Ÿ‡ธ Starfish Space Otter Space Tug

The Otter is a small space tug expected to support: satellite life extension, active debris removal, and autonomous transportation services.