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Building and launching Satellites are costly business. Making a satellite can cost from $290 million upwards, while a single satellite launch can range in cost from a low of about $50 million to a high of about $400 million. Any fault could lead to making billion dollar satellite useless and has to be replaced, which is both difficult and extremely expensive. Space has also become another domain of warfare and there is threat of degradation or destruction of satellites through electronic and kinetic attacks by adversaries.
Increasing complexity and costs of satellite missions promote the idea of extending the operational lifetime or improving functionalities/ performance of a satellite in orbit instead of simply replacing it by a new one. Further, satellites in orbit can severely be affected by aging or degradation of their components and systems as well as by consumption of available resources. These problems may be solved by satellite on-orbit servicing (OOS) missions
For on orbit-servicing, a service spacecraft is built with robotic arms. “The actual servicing process changes depending on the design, orbit, and needs of the client spacecraft, but generally include rendezvous and gentle capture of the client, completion of servicing tasks using the servicer’s robotic arms and toolkit, and then release of the client within a few days,” explains Richard White, President, SSL Government Systems. The client continues to operate during most on-orbit servicing procedures.
The US China, and Russia have also reportedly developed so-called “inspection satellites” that can maneuver close to other spacecraft in low orbits and examine them for malfunctions.
Many Countries led by US, China, Russia, UK, Israel and Germany have planned satellite on-orbit servicing (OOS) missions. Orbital ATK almost two years ago struck a groundbreaking deal with Intelsat to add years of service life to an aging communications satellite. The companies on Jan 2018 announced they are solidifying their partnership with a second contract to service another satellite. Orbital’s first “mission extension vehicle” known as MEV-1 is scheduled to launch on a Proton rocket from International Launch Services. Orbital ATK’s main competitor in this sector, Maxar Technologies’ SSL division, is also developing space robotic servicing vehicles for NASA and for the Defense Advanced Research Projects Agency. SSL is involved with another satellite servicing program, called Restore-L, funded by NASA, That program seeks to develop a spacecraft for satellite servicing in low Earth orbit, with an initial goal of refueling the Landsat-7 spacecraft. NASA is developing robotic satellites, known as “service stations in orbit,” that would not only refuel satellites, they could drastically improve their longevity and lifespan. The robots could fix minor maintenance issues, keeping up with current orbiters as they age and sustain damage.
The Space Dynamics Department of Germany’s Institute of Robotics and Mechatronics runs a mission called Deutsche Orbitale Servicing (DEOS) which involves two satellites, a ‘client’ and a ‘servicer’. The servicer will chase and rendezvous with the client, demonstrate refuelling and module exchange, and then safely de-orbit the client. In early 2016, ESA flew the Intermediate Experimental Vehicle (IXV); in 2020 it is expected to fly the Program for a Reusable In-orbit Demonstrator from Europe (PRIDE). IXV demonstrated many key capabilities for on-orbit manoeuverability; PRIDE will provide a platform for the experimentation with and development of on-orbit servicing capabilities.
In-space-assembly is also being advanced by US DOD to enhance space security. DOD is trying to enhance the space security of their assets is developing capability to manipulate, service and assemble satellites on orbit by using highly capable robotics and end effectors. DARPA’s Robotic Servicing of Geosynchronous Satellites vehicle, which a Maxar business unit called Space Infrastructure Services will commercialize for government and commercial satellites, is scheduled to launch in 2021. Maxar has a contract with fleet operator SES to provide on-orbit life extension of a satellite using RSGS. “We are striving to change the paradigm of satellite operations. Our Robotic Servicing of Geosynchronous Satellites (RSGS) program is developing a system to inspect, repair, relocate, and upgrade satellites in geosynchronous orbit to extend their mission lifetimes,” said Dr. Steven Walker, DARPA Deputy Director, at the Transition Ceremony for the Space Surveillance Telescope.
However, this technology is also dual use , the same satellites which are designed to repair owns satellites can also be use to degrade or destroy adversary’s satellites. They could be weaponized with lasers or explosives. The satellites are very vulnerable by their construction. As Secretary Wilson said, our SBIRS satellites are “vulnerable” to “kinetic attacks” including the grapple and crash by robotic arms.
The scope of space warfare therefore now have expanded from ground-to-space warfare, such as attacking satellites from the Earth using anti-satellite missiles or directed energy weapons to space-to-space warfare, such as satellites attacking satellites; and space-to-ground warfare, such as satellites attacking Earth-based targets.
Space warfare using ground launched missiles is increasingly difficult the farther the satellites from earth i.e. from LEO to GEO as is likely to be conducted at far greater distances and speeds than terrestrial combat. The vast distances involved pose difficult challenges for targeting and tracking, as even light requires a few seconds to traverse ranges measured in hundreds of thousands of kilometers. For example, if attempting to fire upon a target at the distance of the Moon from the Earth, the image one sees reflects the position of the target slightly more than a second earlier. Thus even a laser would need approximately 1.28 seconds, meaning a laser-based weapon system would need to lead a target’s apparent position by 1.28×2 = 2.56 seconds. A projectile from a railgun recently tested by the US Navy would take over eighteen hours to cross that distance, assuming that it would travel in a straight line at a constant velocity of 5.8 km/s along its entire trajectory.
Three factors conspire to make engaging targets in space very difficult. First, the vast distances involved mean that an error of even a fraction of a degree in the firing solution could result in a miss by thousands of kilometers. Second, space travel involves tremendous speeds by terrestrial standards—a geostationary satellite moves at a speed of 3.07 km/s whereas objects in low earth orbit can move at up to 8 km/s. Third, though distances are large, targets remain relatively small. The International Space Station, currently the largest artificial object in Earth orbit, measures slightly over 100m at its largest span. Other satellites can be orders of magnitude smaller, e.g. Quickbird measures a mere 3.04m. Therefore countries including Russia are looking for space to space warfare using killer microsatellites.
This is leading to new race among space faring nations to develop similar satellites which could function as killer microsatellites. Space warfare has added a a new dimension of Space to Space warfare using in-space robotic satellites to deorbit adversaries satellites. Orbital or space-based systems are satellites that can deliver temporary or permanent effects against other spacecraft. These systems could include payloads such as kinetic kill vehicles, radiofrequency jammers, lasers, chemical sprayers, high-power microwaves, and robotic mechanisms. Some of these systems, such as robotic technology for satellite servicing and repair and debris removal, have peaceful uses but can also be used for military purposes.
Russia’s sophisticated on-orbit capabilities
Since 2010, Russia has been testing technologies for rendezvous and proximity operations in both low-earth and geosynchronous orbits. These technologies that could lead to or support a co-orbital capability. In this context, research suggests that Russia has prioritized two separate programs: Burevestnik, a co-orbital ASAT program, and Nivelir, a space surveillance/satellite tracking program. A third program that is currently in development called Ekipazh, will be used to develop nuclear-powered space-based electronic warfare capability.
Russia continues to research and develop sophisticated on-orbit capabilities that could serve dual-use purposes. For example, inspection and servicing satellites can be capable of closely approaching satellites to inspect and potentially fix issues causing malfunctions; this same
technology could also be used to approach another country’s satellite and conduct an attack that results in temporary or permanent damage.
In 2017, Russia deployed what it described as an “inspector satellite capable of diagnosing the technical condition of a Russian satellite from the closest possible distance”; however, its behavior is inconsistent with on-orbit inspection activities or space situational awareness capabilities.
In July 2020, The US and Britain accused Russia of carrying out an anti-satellite weapons test in space, firing a projectile from a Russian satellite that could be used to take down other satellites in orbit. “We are concerned by the manner in which Russia tested one of its satellites by launching a projectile with the characteristics of a weapon,” said Air Vice Marshal Harvey Smyth, head of the UK’s Space Directorate, in a statement late Thursday. “Actions of this kind threaten the peaceful use of space and risk causing debris that could pose a threat to satellites and the space systems on which the world depends. We call on Russia to avoid any further such testing,” he said. Russia’s Defense Ministry said of the July 15 test that “During testing of the latest space technology, one of the domestic satellites was examined close up using the specialized equipment of small space craft,” adding that “valuable information about the technical condition of the object under investigation” had been obtained.
US Space Command said that in July 15, 2020 a Russia satellite called Cosmos 2453 “operated in abnormally close proximity to a US government satellite in low-earth orbit before it maneuvered away and over to another Russian satellite, where it released another object in proximity to the Russia target satellite.” This test is inconsistent with the intended purpose of the satellite as an inspector system, as described by Russia.” “This is further evidence of Russia’s continuing efforts to develop and test space-based systems, and consistent with the Kremlin’s published military doctrine to employ weapons that hold US and allied space assets at risk,” he added.
China Designs Spacecraft to Extend Lifespan of Satellites
Chinese scientists are designing a new type of spacecraft that can move a de-orbiting satellite back into its intended orbit, thus extending its period of service, according to the China Daily Monday. Engineers from the China Academy of Space Technology are conducting research and development on the proposed spacecraft, which would help bring satellites that have run short on fuel or experienced technical problems back to their designed trajectories. The new spacecraft is engineered to connect to a target satellite via robotic arms and then provide attitude control assistance and push the satellite back into its proper orbit.
Once it finishes a life-extension task with a satellite, the service spacecraft will undock with the target and autonomously fly toward the next satellite that requires assistance. The spacecraft’s R&D will take about two years to complete. Once the vehicle enters service, it is expected to bring at least 10 years of extra operational time to multiple satellites, the newspaper cited the academy as saying. The vehicle will enjoy great commercial potential in the satellite industry, said Hu Di, chief designer of the spacecraft.
The British and Israeli firm building Space Drones announced in 2018
UK based Effective Space company announced a teaming agreement with Israel Aerospace Industries (IAI) in 2018 , to develop an in-orbit satellite servicing capability. The service will extend the satellites’ lifespan in geostationary orbit.
The Space Drone is a small spacecraft that provides propulsion to a satellite just before it runs out of fuel, thus extending its service far beyond its designated lifespan. Unlike the host satellite that uses chemical propulsion such as hydrazine or bi-propellant, the 400 kg Space Drone is propelled by electric propulsion. These thrusters that use Xenon gas, are 10-15 times more energy efficient than chemical propellants. The spider-shaped drone is equipped with ‘thruster arms’ that are flexibly manipulated to achieve the most efficient maneuver much larger satellites.
At the moment, about two dozen big geosynchronous com-sats (those with orbits exactly 24 hours long, which thus hover continuously over the same spot on Earth) are retired each year, most commonly because of fuel exhaustion. Mr Campbell, the head of Effective Space’s British operation, proposes to do something about that. The purpose of Effective Space’s devices, which it calls space drones, is to prolong the lives of communications satellites (com-sats) that would otherwise be decommissioned for lack of fuel for station-keeping—in other words, for maintaining their proper orbits. The British and Israeli firm which is building them, that is the way to think of the robotic spacecraft his company plans to start launching in 2020.
Once itself in geosynchronous orbit, at an altitude of 36,000km, each drone will slowly approach and clamp onto such an exhausted com-sat, giving it a new set of thrusters with which to manoeuvre—and thus, since the thrusters should last 15 years, a new lease of life. It will support all functions the original propulsion would perform, including station-keeping and attitude-control, relocation, orbit and inclination correction, de-orbiting and ‘bringing into use’ (BIU). In case of the host satellite malfunction, for reasons other than propulsion, the drone will be able to position it on a self-destruct course or move it to a ‘graveyard orbit’ at a higher altitude.
The first-generation Space Drones to be launched in 2020 will be dedicated to a single satellite and maintain it for years, Halsband said. If this works, dozens more drones should follow. According to Mr Campbell, Effective Space already has one contract, worth $100m, for such repositioning work.
US Missions
There are numerous other upcoming initiatives to make satellites work longer in space. To name a few: Made in Space’s Archinaut spacecraft is supposed to maintain satellites and build large structures in orbit, NASA’s Restore-L robotic refueling demonstration is set to launch soon, and the U.S. Defense Advanced Research Projects Agency (DARPA) is developing the Robotic Servicing of Geosynchronous Satellites. In past years, NASA completed several robotic refueling demonstrations on the International Space Station, and DARPA launched two prototype servicing satellites in 2007 under the Orbital Express program.
Northrop Grumman space vehicle successfully docked with a commercial satellite communications satellite in Feb 2020
A Northrop Grumman space vehicle successfully docked with a commercial satellite communications satellite Feb. 25, marking the first time two commercial satellites have docked on orbit, the company announced Feb. 26. SpaceLogistics LLC, a Northrop Grumman subsidiary, plans to use its Mission Extension Vehicle-1 to provide life extension services to Intelsat 901, a communications satellite. The docking is the first iteration of the company’s new satellite life-extension service.
A satellite’s lifespan is limited by the amount of fuel it has. Without fuel, the satellite loses the ability to maneuver, either to stay in its correct orbit or to move to a new one. Even if the on board components remain functional, without fuel the satellite is destined for the graveyard. SpaceLogistics wants to solve this problem by essentially delivering more fuel to the satellite on orbit. Once launched, their mission extension vehicle can sidle up to a low on fuel satellite, dock with it, and then use its own fuel and propulsion systems to transport the client satellite.
MEV-1 will provide life extension services to Intelsat 901 for five years before transporting the communications to its final decommissioning orbit. MEV-1, however, will then move on to another satellite to provide similar services. The company claims their spacecraft can perform multiple docking and undocking maneuvers over its 15-year life span.
The Space and Missile Systems Center awarded SpaceLogistics a contract through the Space Enterprise Consortium in July to study the possibility of servicing four national security satellites on orbit. SpaceLogistics is exploring its next generation of on-orbit servicing products. In the next iteration, a Mission Robotic Vehicle will launch along with a series of Mission Extension Pods. The pods will fan out until they are close to the client satellite in geostationary orbit, and then they will wait. The vehicle will make its way to each pod in turn and go through the process of attaching it to the client satellite, where it will be able to extend each satellite’s service life by augmenting propulsion. Once the pod is attached and working, the vehicle moves on to the next pod/satellite pair that needs to be attached.
In addition to installing the pods, the technology can also be used for basic satellite repairs, inspections and directly docking with on-orbit spacecraft. Once installed, the pods are controlled by the customer. And when the satellite eventually reaches the end of its extended life, the pod will be able to remove the satellite from orbit or take it to the geosynchronous graveyard, preventing it from contributing to the growing threat of space debris. SpaceLogistics’ next generation of satellite-servicing crafts is slated for launch in late 2023 or 2024.
Orbital ATK Begins Assembly of Its On-Orbit Servicing System
Orbital ATK has developed first “mission extension vehicle,” (MEV) that would dock with the similarly-sized Intelsat-901 in 2019, extending its life for five years. “A whole bunch of new robotic capability is coming on line with our next-generation system,” Wilson said.
The first MEV should be up and running in 2019, extending the life of the Intelsat-901 satellite for five years. The MEV-2 is expected to be in service by mid-2020 on a five-year mission. Intelsat spokesperson Shannon Booker declined to say which satellite MEV-2 will service. Orbital ATK will introduce on-orbit commercial satellite servicing with MEV 1, which is based on the company’s GEOStar spacecraft platform. Once the 4,500-pound vehicle reaches orbit, it will dock with the similarly-sized Intelsat-901 in a “graveyard” orbit about 300 miles above the geostationary arc to conduct tests and make sure everything works before the satellite is put back to work in a yet-to-be stated orbital slot. Controlled by the company’s satellite operations team, the MEV 1 uses a docking system that attaches to existing features on a customer’s satellite. The MEV 1 then provides life-extending services by taking over the orbit maintenance and attitude control functions of the client’s spacecraft.
If something were to go wrong with the satellite, the MEV can take it back to graveyard, drop it off, undock from it and go dock with another Intelsat satellite, said Wilson. “That’s part of the benefit of our system. If there’s an issue with one satellite, we can go to another within their fleet of satellites that are running low on fuel.” The vehicle has a 15‑year design life with the ability to perform numerous dockings and repositionings during its life span.
“That will lead to a revolution in the way satellites are manufactured,” he said. “Repair and life extension is going to lead to assembly,” he added. On-orbit assembly could allow for larger satellites than what can fit inside today’s rocket fairings. Orbital ATK’s longer-range plan is to establish a fleet of on-orbit servicing vehicles that can address diverse space logistics needs including repair, assembly, refueling and in-space transportation. In addition to its commercial life extension services, the company is working closely with U.S. government agencies to develop key technologies to support these services, such as advanced robotics and high-power solar-electric propulsion.
NASA’s Restore-L Mission to Refuel Landsat 7, Demonstrate Crosscutting Technologies
Current commercial satellite systems are inflexible assets whose capability is defined during early purchase negotiations and becomes fixed at launch. Launch vehicle constraints on payload launch mass and volume severely limit resulting operational performance. A new deployment paradigm is needed for space operations to separate the operational spacecraft configuration from the constraints of the launch vehicle.
Restore-L is a technology demonstration mission planned by NASA for the in-orbit servicing and refueling of a satellite not designed to be serviced. The project is currently in formulation and planned for launch in 2022. NASA’s Restore-L mission aims to launch a robotic spacecraft in 2020, called Restore-L servicer that shall be able to rendezvous with, grasp, refuel, and relocate a client spacecraft. The current candidate client for this venture is Landsat 7, a government-owned satellite in low-Earth orbit.
Benjamin Reed, deputy project manager for the NASA office, explained: “With robotic servicing on the table, satellite owners can extend the lifespan of satellites that are running low on fuel, reaping additional years of service – and revenue – from their initial investment. If a solar array or a communications antenna fails to deploy, a servicer with inspection cameras and the right repair tools could help recover the asset that otherwise would have been lost. The loss of an anticipated revenue or data stream can be devastating.”
SSL is working with NASA Goddard Space Flight Center’s Satellite Servicing Projects Division (SSPD) to build a spacecraft that will for the first time refuel a satellite in LEO not designed to be serviced. In addition to demonstrating refueling capability, Restore-L will validate the use of tools, technologies and techniques developed to enable future space exploration missions and satellite servicing in LEO.
Future candidate applications for individual Restore-L technologies include on-orbit manufacturing and assembly, propellant depots, observatory servicing, and orbital debris management. Besides servicing other spacecraft, NASA is also directly applying several Restore-L technologies to the Asteroid Redirect Mission. NASA is also using Restore-L to test various technologies for future missions to Mars and farther locations.
“Restore-L effectively breaks the paradigm of one-and-done spacecraft” said Frank Cepollina, associate director of Goddard’s Satellite Servicing Capabilities Office, and former leader of the shuttle servicing missions to Hubble. “It introduces new ways to robotically manage, upgrade and prolong the lifespans of our costly orbiting national assets,” Cepollina said in a NASA press release. “By doing so, Restore-L opens up expanded options for more resilient, efficient and cost-effective operations in space.”
Restore-L’s design is based on the SSL 1300 spacecraft platform, which will provide the structural support, propulsion, attitude control, data and communications interface, and power to support the Restore-L robotic payload for the on-orbit demonstration. The robot arms in development to fly on Restore-L is similar to arms flown on NASA’s Mars rovers — a “combination of in-house NASA expertise and technology, and the best from industry,” said Benjamin Reed, deputy project manager at NASA’s Satellite Servicing Capabilities Office at Goddard.
Restore-L technologies include an autonomous relative navigation system with supporting avionics, and dexterous robotic arms and software. The suite is completed by a tool drive that supports a collection of sophisticated robotic tools for robotic spacecraft refueling, and a propellant transfer system that delivers measured amounts of fuel at the proper temperature, rate, and pressure.
Orbit Logic reports NASA has selected the company’s STK Scheduler software for the Restore-L technology demonstration mission. During its mission, the Restore-L spacecraft will demonstrate the technologies required to rendezvous with, grasp, refuel and relocate a government-owned satellite. Restore-L chose an Orbit Logic solution because STK Scheduler’s timing and event constraint checking, along with its auto-sequencing features, will provide NASA with an adaptable, invaluable tool to perform Restore-L’s highly complex mission timeline and sequencing.
Given that Restore-L is both complex in its rendezvous and servicing tasks, and is being executed in low-Earth orbit, schedule visibility for radio frequency (RF) communications is critical to mission success. Strict rulesets and mission constraints, coupled with RF communications, must be cross-referenced for specific servicing tasks and approach sequences.
The technology demonstration mission – the first of its kind in low-Earth orbit – will demonstrate a carefully curated suite of satellite servicing technologies. These in-orbit solutions for autonomous satellite rendezvous and grasping, with telerobotic-enabled refueling and satellite repositioning, could make spaceflight more sustainable, affordable and resilient.
Missouri University’s professor developing Robotic Inspection microsatellite for Air Force
Dr. Hank Pernicka, associate professor of mechanical and aerospace engineering at Missouri S&T, is developing a microsatellite imager that could be used to check satellites, do small repairs or refuel spacecraft — and keep astronauts from making risky exploratory missions when something goes wrong. Pernicka and his team are working for Delivery to the Air Force is in the spring of 2017.
The spacecraft is composed of two microsatellites, with MRS SAT docked to MR SAT during the launch to the space station. After reaching the orbit the spacecraft is released from the shuttle, which then gets separated into two satellites. MR SAT, then use its 12 micro-thrusters to maintain a 10-meter distance from the MRS SAT and then starts orbiting and taking pictures of “her” with “his” two stereoscopic lenses.
Made of machined aluminum, it weighs less than 100 pounds when fully assembled. Both parts are covered in solar panels to provide power to electrical systems, and MR SAT has a fuel tank filled with R-134a propellant found in car air conditioners or the HVAC system in a home. The tank is about the size of a 2-liter bottle of soda, only slimmer.
“It has applications for many things,” Pernicka says. “It can check for damages, such as those that doomed the space shuttle Columbia.” “It could check on the status of spy satellites, fix components that have gone out of alignment on a spacecraft and check for debris,” he says. An orbital facility staffed entirely by remotely-operated probes could maintain, upgrade and resupply the satellites, boosting the lifespan of commercial communications and military spy satellites while cutting down on space junk.
References and Resources also include:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160011573.pdf
https://motherboard.vice.com/en_us/article/xw4vwk/darpa-repair-satellite-rsgs
https://spaceflightnow.com/2016/12/09/nasa-selects-builder-for-robotic-satellite-servicing-mission/
http://www.xinhuanet.com/english/2018-08/13/c_137386630.htm
