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Space logistics is the science of planning and carrying out the movement of humans and materiel to, from and within space combined with the ability to maintain human and robotics operations within space. In its most comprehensive sense, space logistics addresses the aspects of space operations both on the earth and in space that deal with: (a) design and development, acquisition, storage, movement, distribution, maintenance, evacuation, and disposition of space materiel; (b) movement, evacuation, and hospitalization of people in space; (c) acquisition or construction, maintenance, operation, and disposition of facilities on the earth and in space to support human and robotics space operations; and (d) acquisition or furnishing of services to support human and robotics space operations.
Note that while any object in orbit is generically referred to as a satellite, the term spacecraft refers to an object which has been engineered to be controlled and deliberately employed in order to perform a useful purpose while traveling in, from, and to the space domain. Debris refers to any spacecraft or artificial satellite (e.g., a rocket body) in orbit that no longer serves a useful purpose.
Payload is defined as modules carried on spacecraft with the ability to perform certain functionalities. The spacecraft provides services to the payload including: power, communications, attitude and orbital management. Payload includes equipment such as transponders, repeaters, antennas, radar, multi-spectral sensors, cameras, technology demonstrators, and scientific experiments.
Categories of Space Logistic Services
There are currently 5 categories of space logistics services:
- access to space;
- space logistics for crewed space stations;
- space logistics for payloads;
- space logistics for spacecraft; and
- space situational awareness.
Access to Space
Access to space is an established category that includes the following services:
- mission planning, management, and spacecraft operations;
- space insurance;
- launch broker;
- launch integrator;
- launch aggregator;
- ground station infrastructure supporting Earth to spacecraft communications;
- spaceport infrastructure; and
- Earth to space transportation (rideshare and dedicated) for spacecraft.
This topic is covered in detail by the following articles: Space Insurance – A Quick Overview, Launch Operations Processes – A Quick Overview, After Artemis Has Successfully Launched… What Happens Next?, Insights into Global Orbital Spaceports, Spaceports – A Quick Overview, Insights into US Spaceports, Insights into Operational Orbital Launch Vehicle Types, Industry Disruptor: SpaceX Falcon 9 LEO Launch Pricing 2010 to 2022, and New Orbital Rockets on the Horizon.
Space Logistics for Crewed Space Stations
Space logistics for crewed space stations (e.g. International Space Station) is an established category, which includes the following services:
- delivery of cargo, e.g. food, water, scientific experiments, equipment;
- propellants replenishment for space station propulsion units;
- disposal of refuse;
- delivery and return of crew;
- return of scientific experiments and equipment to earth;
- exterior inspection of the space station; and
- adjusting the altitude and/or orbit of the space station.
This topic is covered in detail by the following articles: Space Logistics Lessons Learned from NASA Space Flights, New Space Stations on the Horizon, Space Stations Current and Future, Cargo Spacecraft from the Past to the Future, Crewed Spacecraft from the Past to the Future and Insights into Space Station Logistics Spacecraft – Past, Present, and Future.
Space Logistics for Payloads
Space logistics for payloads is currently a nascent category, which includes the following services:
Space Factory: An autonomous platform which transports payloads into Earth orbit and returns them to Earth. Pressurized and unpressurized payloads may be supported. The platform provides payloads with power, communications, attitude control, and orbital maintenance. The purpose of this service is to support experiments and/or manufacturing activities by the payloads in a microgravity environment. Space Cargo Unlimited‘s REV1 is an example of a proposed Space Factory.
Orbital Outpost, Orbital Depot or Orbital Hub: An autonomous platform which is in permanent Earth orbit or cislunar space, and receives payloads from Earth. The platform provides payloads with power, communications, attitude control, and orbit maintenance. Payloads may also be provided access to shared resources such as sensors, computing and data storage. Payloads may remain permanently attached to the platform, or they may be returned to Earth by another specialized spacecraft. The platform may also provide: asset inspection, maintenance repair, and propellant refueling services to visiting spacecrafts. Arkisys’s Port is example of a proposed Orbital Hub.
Satellite as a Service or Hosted Payloads: An autonomous platform which transports payloads into Earth orbit, cislunar space, or deep space. The platform provides shared services to payloads which promises to reduce costs and development time for payload operators. The shared services include: power, communications, attitude control, and orbit maintenance. The payloads remain permanently attached to the platform and remain in space for as long as the platform remains in space. This topic is covered by Satellite as a Service / Hosted Payloads – A Quick Overview.
Space Logistics for Spacecraft
Space logistics for spacecraft is an emerging category with a wide range of names being used by organizations to define subcategories. Current subcategories naming includes: On-Orbit Servicing Assembly and Manufacturing (OSAM), On-Orbit Servicing (OOS), On-Orbit Assembly and Manufacturing (OOAM), Orbital Support Services (OSS), Mission Extension (ME), Life Extension (LE), In-Orbit Servicing Assembly and Manufacturing (ISAM), Orbital Transfer (OT), Last Mile Logistics (LML), Space Transportation (ST), In-Orbit Inspection (IOI), Last Mile In-Space Delivery (LMD), Debris Mitigation (DM), End of Life Management (EOLM), and others.
Services are provided by autonomous robotic vehicles which are able to: change their orbit and altitude; and perform rendezvous, proximity operations, and docking with customer spacecraft. These vehicles provide one or more of the following services:
- Maintenance Repair (also known as OSAM, OOS. OSS, ME, LE, and ISAM): repairing or replacing parts of a spacecraft in orbit in order to extend or maintain the spacecraft in operational conditions.
- Reconfiguration (also known as OSAM, OOS. OSS, ME, LE, and ISAM) modifying the spacecraft’s payloads or modules in order to repurpose the mission of a spacecraft.
- Refuelling (also known as OSAM, OOS. OSS, ME, LE, and ISAM): providing and transferring propellant, fuel pressurants or coolants from the servicer spacecraft to the target one, in order to keep the system operational.
- Recharging (also known as OSAM, OOS. OSS, ME, LE, and ISAM): providing electric power to a spacecraft in orbit through power beaming or docking.
- Upgrade (also known as OSAM, OOS. OSS, ME, LE, and ISAM): replacing or adding components to a spacecraft to improve its capabilities.
- Manufacturing (also known as OOAM, OSAM and ISAM): assembling or manufacturing components for a spacecraft.
- Station-keeping (also known as OSAM, OOS. OSS, ME, LE, and ISAM) docking of the servicer spacecraft with a target spacecraft in order to keep the target in a particular orbit or attitude.
- Relocation (also known as OT, LML, LMD, ST, OSAM, OOS. OSS, ME, LE, and ISAM): modifying the position of the spacecraft to a different altitude or orbit.
- Active Debris Removal (also known as DM and EOLM): capturing a spacecraft to relocate it to a graveyard orbit or to accelerate its atmospheric re-entry.
- Recycling (also known as OOAM, OSAM, and ISAM): retrieving the raw materials of orbiting rocket bodies to transform them into other space components or products.
- Asset Inspection (also known as IOI, OSAM, OOS. OSS, and ISAM): assessing the physical status and conditions of a spacecraft and potentially detecting anomalies or examining the consequences of an attack or collision.
A comprehensive timeline of space logistics for spacecraft advances is provided in Timeline of In-Orbit Servicing, Assembly, and Manufacturing (ISAM) Advances – Past, Present and Future.
Potential Applications and Benefits
Space logistics for spacecraft can provide benefits to various space activities such as science, exploration, national security, and commercial missions. Some specific use-cases include:
- rideshare spacecraft relocation;
- in-space robotic manufacturing and assembly;
- space sustainability management; and
- spacecraft life extension.
Rideshare Spacecraft Relocation
Rideshare spacecraft relocation services can:
- Increase the number of orbits available to rideshare spacecraft than would otherwise be possible based on the initial deployment from the rideshare launch vehicle. This can eliminate the need for customers to purchase expensive dedicated launches.
- Reduce the amount of time required for the spacecraft to transition into their target orbit and begin operations.
- Save spacecraft propellant that would otherwise be used to transition into the operational orbit. The propellant savings can contribute to longer lifespan in orbit for the spacecraft.
Vehicles providing rideshare relocation services are commonly referred to as Orbital Transfer Vehicles (OTVs). OTVs can generally carry multiple spacecraft, from one, or more, customer, and deploy each spacecraft to different orbits. D-Orbit is an example of a company currently providing this type of service.
In-Space Robotic Manufacturing and Assembly
In-space manufacturing and assembly can enable the creation of large infrastructure in space that cannot be assembled before launch due to their weight, volume, size or structure.
Potential benefits include:
- enabling remote, in-space construction of communications antennae, large-scale space telescopes, power generation, and other complex structures;
- enabling small spacecraft to deploy large surface area power systems and reflectors that currently are reserved for larger spacecraft;
- eliminating spacecraft volume limits imposed by rockets; and
- avoiding the inherent risk of spacewalks by performing some tasks currently completed by astronauts.
Space Sustainability Management
Asset Inspections can improve SSA capabilities by providing additional data about space objects.
Active Debris Removal can enable governments and/or operators to de-orbit debris that threatens human spaceflight and/or commercial spacecraft operations.
Spacecraft Life Extension
Spacecraft life extension offers the following benefits to (primarily GEO) spacecraft operators:
- prolongs revenues by extending spacecraft life;
- improves financial performance;
- defers capital expenses;
- redeploys spacecraft to start new orbital roles;
- protects current revenue streams by creating on-orbit backup;
- protects spacecraft revenues from procurement delays and launch failures;
- manages risk of transition to new technologies; and
- provides recovery option from on-orbit anomalies.
Spacecraft life extension services can:
- Extend the life of satellites by: refueling satellites when they run out of propellant; adjusting their orbit in case they are drifting; or take over orbital maintenance and attitude adjustment.
- Allow operators to wait until their spacecraft are out of propellant and/or out of service to relocate them to the graveyard orbit for GEO spacecraft, or through re-entry into the Earth’s atmosphere for LEO spacecraft. Currently operators have to reserve propellant to conduct this activity.
- Restore or repair parts that get damaged, or did not deploy correctly after launch such as solar panels. Solar panel failures can significantly reduce the lifetime of the satellite or render it inoperable from the start of their mission. Also, a servicer could directly connect to the customer spacecraft and act as a supplementary power source.
- Provides operators with the means to modify payloads and repurpose the mission of a spacecraft instead of launching a new one.
Northrop Grumman is an example of a company currently offering spacecraft life extension services using their Mission Extension Vehicle (MEV).
Space Situational Awareness
Space Situational Awareness (SSA) is the understanding, knowledge, characterization, and maintained awareness of the space environment: artificial space objects, including spacecraft, rocket bodies, mission-related objects and fragments; natural objects such as asteroids (including Near Earth Objects or NEOs), comets and meteoroids, effects from space weather, including solar activity and radiation; and potential risks to persons and property in space, on the ground and in air space, due to accidental or intentional re-entries, on-orbit explosions and release events, on-orbit collisions, radio frequency interference, and occurrences that could disrupt missions and services.
Civil SSA combines positional information on the trajectory of objects in orbit (mainly using optical telescopes and radars) with information on space weather. Military and national security SSA applications also include characterizing objects in space, their capabilities and limitations, and potential threats.
SSA is an inherently international and cooperative venture. It requires a network of globally distributed sensors as well as data sharing between satellite owner-operators and sensor networks. SSA also forms the foundation of space sustainability as it enables safe and efficient space operations and promotes stability by reducing mishaps, misperceptions, and mistrust.
Space Traffic Management (STM) Terms Definition provides an overview of the various terminologies associated with Space Situational Awareness.
Types of SSA Sensors
Ground-based radars have historically been the backbone of SSA. Radar consists of at least one transmitter and receiver. The transmitter emits radio waves at a specific frequency, some of which reflect off the target and are measured by the receiver, which can then calculate the location of the target in relation to the radar. The primary advantages of radars are that they can actively measure the distance to a target and some types of radars can accurately track many objects at once. Some radars can also detect the motion of an object and construct a representation of its shape. The main disadvantages of radars are their cost, size, and complexity.
Optical telescopes are also widely used for SSA. Telescopes collect light or other electromagnetic (EM) radiation emitted or reflected by an object and focused into an image using lenses, mirrors, or a combination of the two.
The main advantages of using optical telescopes for SSA is their ability to cover large areas quickly and, in particular, to track objects above 5,000 km (3,100 mi) altitude. Some telescopes can create high resolution images of space objects. The main disadvantage of optical telescopes is that they require specific lighting conditions and clear skies to see an object, although space-based optical telescopes eliminate some of these limitations.
Other types of sensors can be used for SSA, including sensors that detect radio frequency (RF) or other types of signals from satellites, lasers that measure the distance or range to a satellite very accurately, and infrared sensors that detect heat. Combining data from many different types of sensors, both ground- and space-based, that are also distributed around the globe provides a much more complete picture of the space environment and of activities in space.
Who does SSA?
Although historically done by the U.S. and Russian militaries, today there are a growing number of countries, academic and scientific institutions, commercial companies, satellite operators, and even private citizens who are providing various types of SSA data.
Over the last few years, there has been increased activity from the private sector on SSA. Multiple companies are now developing or providing data and analysis services to governments and satellites operators. LEO Labs is an example of a company offering SSA services.
Why is SSA Important?
SSA is critical to the long-term sustainability of outer space. It provides knowledge that allows everyone who uses space to evaluate the impact of their activities and make informed decisions. SSA makes using space safer and more efficient and enables protection of valuable satellites and space-based services.
SSA also provides a level of transparency to reduce tensions, help verify agreements between countries, and prevent accidents or misperceptions from triggering or escalating conflict.
What Does The Future Hold for Space Logistics?
In general, the space logistics market is nascent and very early days. The ability to have spacecraft serviced on-orbit and structures produced in space may eventually affect the design of spacecraft themselves and the launch vehicles that place them into space.
The concept of in-orbit services raises a growing number of questions regarding the technical feasibility, business profitability, competitiveness as well as legal issues for activities that currently do not have a regulatory framework or standards.