Announcment edit
In May 2016, NASA officially moved forward with plans to execute the ambitious, technology-rich OSAM-1 (formerly Restore-L) mission, an endeavor to launch a robotic spacecraft to refuel a live satellite.
Objectives edit
The mission – the first of its kind in low-Earth orbit - will demonstrate that a carefully curated suite of satellite-servicing technologies are fully operational. The current candidate client for this venture is Landsat 7, a government-owned satellite in low-Earth orbit.
Beyond refueling, the OSAM-1 mission also carries another objective: to test other crosscutting technologies that have applications for several critical upcoming NASA missions. As the OSAM-1 servicer rendezvous with, grasps, refuels, and relocates a client spacecraft, NASA will be checking important items off of its technology checklist that puts humans closer to Mars exploration.
OSAM-1 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.
Future candidate applications for individual OSAM-1 technologies include on-orbit manufacturing and assembly, propellant depots, observatory servicing, and orbital debris management. NASA is also directly applying several OSAM-1 technologies to the Asteroid Redirect Mission.
The robotic vehicle of NASA’s Asteroid Redirect Mission directly leverages OSAM-1’s autonomous rendezvous system, avionics, dexterous robotics and software, and tool drive and other systems. This mission, along with the Wide-Field Infrared Survey Telescope (WFIRST) observatory, is being designed to be refuelable.
NASA's second, equally important objective for OSAM-1 is to infuse its technologies to domestic commercial entities to help jumpstart a new, competitive industry in robotic satellite servicing, an area ripe with possibility.
Possibilities edit
Currently, spacecraft launch to space with a finite amount of fuel, their lifespans restricted by the amount of propellant within their metal spacecraft buses at launch. A refueling capability in space, offered by future propellant-delivery spacecraft similar to OSAM-1, could provide satellite owners the ability to manage, maintain, and save their most valuable assets in space.
American industry appears eager to offer such services and has expressed strong interest in this burgeoning field. NASA's transfer of OSAM-1 technologies to interested domestic entities could help spur the arrival of such commercial life extension and repair offerings. The OSAM-1 mission could also help decrease the risk for future servicing ventures and establish a global precedence for safe rendezvous operations in orbit.
OSAM-1’s technologies are foundational for other ambitious objectives beyond refueling. “You cannot entirely forecast how the aerospace community will run with new, capability-building servicing technologies, but we can predict likely short-term innovations,” says Benjamin Reed, deputy project manager for SSCO.
"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,” Benjamin Reed, deputy project manager for Satellite Servicing Capabilities Office.
Servicing capabilities could help satellite owners better manage their space assets in innovative ways. This could include launching a spacecraft with a half-empty fuel tank and allotting the saved weight to mission-specific instruments. “Dependable robotic satellite servicing unlocks countless opportunities,” Reed says.
“NASA’s Space Technology Mission Directorate rapidly develops, demonstrates, and infuses revolutionary, high-payoff technologies – OSAM-1 embodies these goals and we look forward to realizing its potential,” says Jim Reuter, deputy associate administrator for programs in STMD.
Instruments edit
Space Infrastructure Dexterous Robot (SPIDER) edit
The OSAM-1 spacecraft will include an attached payload called Space Infrastructure Dexterous Robot (SPIDER).
SPIDER includes a lightweight 16-foot (5-meter) robotic arm, bringing the total number of robotic arms flying on OSAM-1 to three. Previously known as Dragonfly during the ground demonstration phase of the NASA Tipping Point partnership, SPIDER will assemble seven elements to form a functional 9-foot (3-meter) communications antenna. The robotically assembled antenna will demonstrate Ka-band transmission with a ground station.
The payload also will manufacture a 32-foot (10-meter) lightweight composite beam using technology developed by Tethers Unlimited of Bothell, Washington. The assembly and manufacturing element of the demonstration will verify the capability to construct large spacecraft structures in orbit.
SPIDER will help mature space technologies with many potential cross-cutting applications, including:
Enabling new architectures and capabilities for a wide range of government and commercial missions Enabling In-space construction of large communications antennae and telescopes Eliminating volume limits imposed by rockets Replacing some astronaut extravehicular activity tasks with precision robotics Introducing the potential for longer mission durations enabled by planned or unplanned maintenance
Servicing Technologies edit
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To succeed, OSAM-1 needs an relative navigation system — a collection of cameras, sensors, computers, algorithms and avionics that join forces to independently track the client satellite at different ranges — all in real time.
Once this system visually locks into the client, it can safely "guide and drive" OSAM-1 through precise rendezvous maneuvers with its client satellite.
NExIS is working to advance the technologies for such an autonomous relative navigation system. This same system could be adapted and applied to support missions involving rendezvous with other objects, including planetary bodies and spacecraft.
Dexterous Robotic Arms edit
The Robotic Servicing Arm has extensive heritage from arms used in past Mars rover missions. The system design heavily leverages the flight-qualified robotic arm developed for Defense Advanced Research Projects Agency (DARPA)'s Spacecraft for the Universal Modification of Orbits and Front-end Robotics Enabling Near-term Demonstration (FREND) programs in the mid-2000s. In particular, it builds off of previous NASA and DARPA investments in motion control, robotic software frameworks, flex harnesses, force-torque sensor, joint design, and flight operations experience.
Range of Motion Opening a door, grabbing a pencil, pouring a glass of water; these are all are examples of simple, everyday tasks that use your arm. Like your arm, the NASA servicing robot has "seven degrees of freedom"— a three-axis shoulder, a pitch actuator at the elbow, and a three-axis spherical wrist. Other features include a six-axis force/torque sensor at the end of the arm, and a flex harness that routes data, power, and video.
With such a high level of maneuverability, this arm is ideally suited for missions requiring autonomous capture and dexterous operations — from grabbing a satellite for on-orbit servicing, to extracting a boulder from an spinning asteroid, to assembling and servicing a large telescope in orbit, or setting up worksites on Mars for astronauts.
Propellant Transfer System edit
Millions of cars are refueled each day. How difficult could it be for a robot to fill up a satellite? The truth is, it's extremely hard. The challenges are stacked as the robot has to deal with uncooperative, triple sealed fuel caps, floating hoses, and extremely corrosive satellite fuel contained under intense pressures—all handled in the weightlessness of space. Not to mention that the robot servicer and the client are both 22,000 miles above our heads—far away from their human operators.
The solution? A comprehensive suite of new robotic technologies and procedures to overcome each obstacle. The team at Goddard is working with Kennedy Space Center as an integrated team to develop, test and build a flexible hose, new fueling tools, and propellant transfer system that meet mission requirements.
The Robotic Refueling Mission, RRM showed in January 2013 that remotely controlled robots can work through the caps and wires on a satellite fuel valve and transfer fluid into existent, orbiting spacecraft that were not designed to be serviced. RRM was the important first step—but doing more was always part of the long-term plan.
Propellant Transfer System (PTS) edit
Consisting of oxidizer tanks, seal-less pumps, flow-metering devices, and a maze of tubing , the PTS contains the technologies a servicer satellite would need to replenish the propellant of orbiting spacecraft for many years and many missions. It also contains an adjustable, deployable-length hose delivery system. Roughly the size of a roll of quarters, the PTS pump is designed to deliver the oxidizer at high pressure and at flow rates required for bubble-free formation in the individual client tank — an extremely important factor for client propulsion system performance. The system uses very little power, a precious commodity in space flight. An innovative metering system ensures that the PTS dispenses hypergolic propellants in accurate and precise amounts.
Flexible Fuel Hose edit
The hose is the essential link between the Propellant Transfer System and the Oxidizer Nozzle Tool during transfer. Developed by Kennedy Space Center, the device is flexible enough to be robotically maneuvered, yet tough enough to handle corrosive satellite propellant at flight pressures. It has a multi-layered wrapping and a suite of heaters to ensure that the propellant and Hose components work properly in the harsh environment of space.
Oxidizer Nozzle Tool (ONT) edit
Designed by the same team that built the tools for the Hubble Space Telescope Servicing Missions and the Robotic Refueling Mission, the Oxidizer Nozzle Tool is built to connect to - and seal against - a satellite valve that wasn't originally designed to be accessed on orbit. The ONT uses a Quick Disconnect adapter to seal to the satellite valve and operate the valve to permit propellant transfer. Once the Tool is in place and the satellite valve is open, the Propellant Transfer system kicks into gear to transfer the oxidizer through the valve. The ONT draws from lessons the team learned building and testing the Robotic Refueling Mission Nozzle Tool.
What makes oxidizer so dangerous? Oxidizer -- namely nitrogen tetroxide -- is a chemical that, when mixed with satellite fuel, causes instant combustion that provides thrust (motion) for a satellite. Oxidizer is contained within a satellite tank at intense pressures, up to 300 pounds per square inch (about 20 times atmospheric pressure). Toxic, extremely corrosive and compressed, it requires special handling and a unique set of technologies to transfer it.
Mission Facts edit
ORBIT: Polar low Earth orbit (LEO)
CLIENT: A satellite in LEO owned by the U.S. government
OPERATIONS: Autonomous rendezvous and grasping with telerobotic refueling and relocation
MANAGEMENT: The Space Technology Mission Directorate at NASA Headquarters and the Satellite Servicing Projects Division at NASA's Goddard Space Flight Center