Space has become another domain of warfare and there is threat of degradation or destruction of satellites through electronic and kinetic attacks by adversaries. One of the measures DOD is taking to enhance space security is In-space-assembly. 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 (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. According to DARPA, GEO orbit contains the largest concentration of unserviced high-value satellites, 1,300 satellites worth over $300B and many of them perform critical economic and defense roles. Even fully functional satellites sometimes find their working lives cut short simply because they carry obsolete payloads—a frustrating situation for owners of assets worth hundreds of millions of dollars. The goal of the RSGS program is to cooperatively inspect, capture, reposition, repair, and upgrade GEO spacecraft.
“The ability to safely and cooperatively service satellites in GEO would expand public and private opportunities in space. It could enable entirely new spacecraft designs and operations, including on-orbit assembly and maintenance, which could lower construction and deployment costs while extending satellite utility, resilience and reliability,” said Al Tadros, vice president, Civil and DOD Business at SSL.
DARPA initiated the RSGS program in 2016 and chose Space Systems Loral, part of Maxar Technologies, as its commercial partner in 2017. Space Logistics, then a subsidiary of Orbital ATK, unsuccessfully protested the award on the basis that it constituted unfair government competition since it was developing its own satellite servicing technologies. Orbital ATK and Space Logistics were later acquired by Northrop Grumman.
After successfully docking its Mission Extension Vehicle-1 (MEV-1) with the Intelsat 901 communication satellite, Northrop Grumman’s Space Logistics subsidiary scored a contract with DARPA in March 2020 to take satellite servicing to the next level. They will partner on the Robotic Servicing of Geosynchronous Satellites (RSGS) program, with Space Logistics replacing Maxar Technologies, which withdrew last year.
In announcing the MEV-1/Intelsat 901 docking last week, Space Logistics President Tom Wilson, who is also Northrop Grumman’s Vice President for Space Systems, mentioned the company’s future plans to build a Mission Robotic Vehicle (MRV) with robotic arms that would be used to install Mission Extension Pods — fuel pods — on satellites already in orbit to extend their lifetimes. That apparently was a reference to this agreement with DARPA, though the RSGS system has broader applications.
The Defense Advanced Research Projects Agency plans to have a spacecraft in orbit in 2022.
DARPA is having even more ambitious plan to design , assemble and build satellites in space to replace satellites due to space weapons.These automated agents shall enhance operational performance as they shall be capable of integrating new technologies into satellites like improved sensors or countermeasures against adversaries space weapons. They could also expand or reconfigure capability to meet user or mission needs. Assets can be refuelled to extend operational life and repairing or refurbishing systems in response to system degradation.
But these efforts all face a major roadblock: the lack of clear, widely accepted technical and safety standards for responsible performance of on-orbit activities involving commercial satellites, including rendezvous and proximity operations (RPO) that don’t involve physical contact with satellites and robotic servicing operations that would. Without these standards, the long-term sustainability of outer space operations is potentially at risk, says DARPA.
DARPA’s Consortium for Execution of Rendezvous and Servicing Operations (CONFERS) program aims to help overcome these challenges and provide the foundation for a new commercial repertoire of robust space-based capabilities. CONFERS envisions a permanent, self-sustaining, and independent forum where industry could collaborate and engage with the U.S. Government about on-orbit servicing. This industry/government forum would be composed of experts from throughout the space community. DARPA, primarily in partnership with NASA, will bring decades of operational experience from government missions to the consortium.
DARPA’s Robotic Servicing of Geosynchronous Satellites (RSGS) program
RSGS is intended to deliver a GEO spacecraft with a payload consisting of two large 2 meter arms and a number of tools that will allow it to perform maintenance and other work on satellites in GEO. The spacecraft will perform four main functions in space: inspection, orbital adjustments, anomaly resolution and installation of self-contained payloads.
Under the RSGS vision, a DARPA-developed modular toolkit, including hardware and software, would be joined to a privately developed spacecraft to create a commercially owned and operated robotic servicing vehicle (RSV) that could make house calls in space. DARPA would contribute the robotics technology, expertise, and a Government-provided launch. The commercial partner would contribute the satellite to carry the robotic payload, integration of the payload onto it, and the mission operations center and staff. If successful, the joint effort could radically lower the risk and cost of operating in GEO.
DARPA had issued a Request for Information (RFI) , calling on commercial and private space groups to partner with them to accomplish a robotic servicing mission anywhere in Geostationary Earth Orbit, within the next five years. The RFI addressed the critical technologies for assembling in orbit, including the development of space robotics, to be able to inspect spacecraft that had operational problems, fix mechanical problems like antenna issues, or even might be able to move satellites into other orbits.
The RSGS payload was developed by the Naval Research Laboratory and consists of two dexterous robotic manipulator arms plus tools and sensors. The robotic payload consists of a pair of 2 meter, 7-Degree of Freedom (DoF) robotic arms with tool changers, a suite of tools, control systems (including electronics, software, machine vision and control algorithms), cameras and lights, a payload power distribution system, high resolution imaging sensors, rendezvous and proximity operations sensors, and a single 3-4 meter robotic inspection arm with up to 9-DoF.
While DARPA is developing the payload with robotic arms, according to Parrish, DARPA needs a commercial partner to build the spacecraft that will house the payload and carry it around in orbit. “We’re looking for the partner to provide the spacecraft bus — so using a heritage GEO bus that may have had some tailoring for RSGS requirements, integrating the payload and the spacecraft bus together, procuring and launching that integrated spacecraft to GEO, and then providing mission control center for operations for a long period of time,” explained Parrish.
The new agreement is a public-private partnership. DARPA provides the NRL-developed payload, while Space Logistics provides the spacecraft, launch, and mission operations. In return, Space Logistics will be able to offer services to government and private sector customers. The program will be implemented in two phases: a six-month period to assess joint program interfaces and business case, followed by execution of the flight program.
In a statement, Wilson said the “new robotics technology on this mission advances our vision to build a fleet of vehicles that provide customers with a variety of options to select the type of life-extension or in-orbit repairs they need.” Michael Leahy, Director of DARPA’s Tactical Technology Office, added it will pave the way for routine “inspection, repair, life extension and improvement” of satellites in geosynchronous orbit.
A key element will a dexterous robotic arm DARPA has developed called FREND, which has multiple joints and is designed to connect with vessels that aren’t built for docking. DARPA said it plans to add advanced machine-vision algorithms that will allow for supervised robotic operations.”(DARPA’s arm has) interesting characteristics, like robot reflexes and compliance control to greatly minimize the risk of debris from inadvertent collisions,” said Melroy, now deputy director of the agency’s Tactical Technology Office. The first of two flight robotic manipulator arms is in final assembly and will be shipped to the Naval Research Lab, where it will be integrated into the payload. The second arm is currently in assembly. A third FREND arm might replace the robotic inspection arm.
Space Systems Loral (SSL), announced it has received $20.7 million from the Defense Advanced Research Projects Agency (DARPA) to design and build robotic arm flight hardware for the agency’s Robotic Servicing of Geosynchronous Satellites (RSGS) program. The contract is for two complete robotic arm systems, which would be able to carefully capture and berth with satellites that were not previously designed for docking. The robotic arms would each have multiple joints enabling dexterous movement and could carry and use multiple generic and mission-specific tools.
After a successful on-orbit demonstration of the robotic servicing vehicle, U.S. Government and commercial satellite operators would have ready access to diverse capabilities including high-resolution inspection; correction of some mission-ending mechanical anomalies, such as solar array and antenna deployment malfunctions; assistance with relocation and other orbital maneuvers; and installation of attachable payloads, enabling upgrades to existing assets.
DARPA’s RSGS program manager Joseph Parrish said the NRL payload passed its Critical Design Review in 2019 and launch is targeted for 2023. “RSGS would be the first concrete step toward a transformed space architecture with revolutionary capabilities.” “Right now, we don’t build satellites to be serviced, but once we have that capability, then you can start seeing things like modular, serviceable satellites that become routine,” said Melroy, deputy director of DARPA’s Tactical Technology Office. The robotic platform is one of three concepts that comprise the DARPA Phoenix program.
DARPA Phoenix program
DARPA is enhancing space security by devising new ways to design satellites via cellularization, faster tempo to get the “cells” and/or low mass material to orbit, and assembling using the cell based modules or satlets. DARPA is also looking into means of outfitting launch vehicles with pods that could deliver the satlets, satellites, and robotic repair probes into GEO. The first orbital tests for the satlet and pod technology are expected in the next year or two. This robotic on-orbit servicing technologies, combined with on-orbit assembling technologies shall allow shaping future space system architectures.
DARPA through its Phoenix program has set out to develop and demonstrate the technologies that make it possible to inspect and robotically service cooperative space systems in GEO and to validate new satellite assembly architectures, according to DARPA’s website. It had endeavored to develop a new architecture of space systems where full satellite functionality is achieved by aggregating multiple satlets or ‘miniature satellites’ to enhance modularity and enable high volume low cost manufacturing. The primary objective was to demonstrate the ability to upgrade or create new space systems at greatly reduced cost, and support DoD mission needs in a new way that increases tempo, allowing a much faster response to new challenges.
The three pillars of developing this capability are devising a new way to design satellites via cellularization, faster tempo to get the “cells” and/or low mass material to orbit, and ways to manipulate and assemble satellites on orbit by using highly capable robotics and end effectors handling and assembling using the cell based modules or satlets. “Satlets idea in which production-line-possible satellite components weighing about 15 pounds (7 kilograms) each could be assembled in space. Looking much like Legos, the components encapsulate such satellite aspects as power, sensors and thermal management capacity. They could be assembled in different ways to accommodate different missions,” said Melroy, who as a NASA astronaut.
DARPA Phoenix Program Releases Payload Orbital Delivery (POD) Interface Requirements
Another Phoenix approach is a Payload Orbital Delivery (POD) system that would standardize satellites and/or their components to take advantage of hosted payload opportunities offered by commercial satellites. The payloads would be about 1.3 feet by 1.6 feet by 2.2 feet and weigh between approximately 150 and 220 pounds, and would use a standard interface to attach the POD to the host satellite and release it at the proper orbit.
Launches of satellites for the Department of Defense (DoD) or other government agencies often cost hundreds of millions of dollars each and require scheduling years in advance for one of the handful of available slots at the nation’s limited number of launch locations. This slow, expensive process is causing a bottleneck in placing essential space assets in orbit, especially in geosynchronous Earth orbit (GEO) approximately 22,000 miles (36,000 kilometers) above the Earth.
Launches of commercial communications satellites, on the other hand, are relatively frequent and inexpensive. Commercial launch vehicles also often have unused carrying capacity that their operators can offer to other satellite owners through “hosted payload” services. Unfortunately, no technology currently exists to enable government and military satellites to share rides and separate themselves from commercial communications satellites headed to GEO.
PODs are designed to help take advantage of the frequency of commercial satellite launches and associated hosted payload service opportunities to enable faster and lower-cost delivery of payloads to GEO.