The National Aeronautics and Space Administration (NASA) has developed an advanced propulsion technology that will facilitate the use of small spacecraft for future planetary exploration missions. Not only will this technology enable new types of planetary science missions, one of NASA's commercial partners is already preparing to use it for another purpose – to extend the life of spacecraft already in orbit. Finding opportunities for industry to use this new technology not only advances NASA's goal of commercializing the technology, but also has the potential to open a path for NASA to acquire this important technology from industry for future planetary missions.
NASA's new propulsion technology enhances the ability of small spacecraft to carry out future planetary missions and extends the operational life of existing satellites. By partnering with commercial entities, NASA not only advances its technology commercialization goals, but also supports the global leadership of the U.S. space industry. Source: Northrop Grumman
Planetary science missions using small spacecraft will require challenging propulsion maneuvers such as achieving planetary escape velocities, orbital capture, etc., which require velocity change (delta-V) capabilities that far exceed typical commercial requirements and current state of the art. Therefore, the first enabling technology for these small spacecraft missions is an electric propulsion system capable of performing these high-delta-V maneuvering missions. This propulsion system must operate at low power (below kilowatts) and have a high propellant throughput (i.e., the ability to use a high total mass of propellant over its lifetime) to gain the impulse needed to perform these maneuvers.
After years of research and development, researchers at NASA's Glenn Research Center (GRC) have created a small spacecraft electric propulsion system that meets these needs—the NASA-H71M sub-kilowatt Hall effect thruster. In addition, the successful commercialization of this new type of thruster will soon provide at least one such solution to achieve delta-V of up to 8 km/s required for scientific missions in the next generation of small spacecraft. This technological initiative is made possible by the miniaturization of many of the advanced high-power, solar-electric propulsion technologies developed over the past decade, including the power and propulsion elements of the Gateway, the first space station to orbit the Moon.
Left: NASA-H8M Hall-effect thrusters on a thrust frame at the Glenn Research Center's Vacuum Facility. Pictured right: Dr. Jonathan Mackey commissions the thrust frame before shutting down the test facility and pumping it out. Source: NASA
Small spacecraft using NASA-H71M electric propulsion technology will be able to independently maneuver from low Earth orbit (LEO) to the Moon and even from geosynchronous transfer orbit (GTO) to Mars. This capability is particularly salient as commercial launch opportunities for the transfer of orbits to low-Earth orbit and geosynchronous orbit have become routine, and excess launch capacity from these missions is often sold at low prices for the deployment of secondary spacecraft. The ability to carry out missions from these near-Earth orbits could significantly increase the frequency and reduce the cost of scientific missions to the Moon and Mars.
This propulsion capability will also expand the coverage of the second stage of spacecraft, which has historically been limited to scientific targets consistent with the launch trajectory of the main mission. This new technology will enable secondary missions to deviate significantly from the orbit of the main mission, contributing to the exploration of a wider range of scientific targets.
In addition, these secondary spacecraft science missions often have only a short time to collect data as they fly by distant objects at high speeds. Greater propulsion capacity will allow deceleration and entry into planetary orbit for long-term scientific research.
In addition, smaller spacecraft equipped with this powerful propulsion capability will be able to better manage late changes in the launch trajectory of major missions. This change is often the greatest risk for science missions of small spacecraft with limited on-board propulsion capabilities, as they rely on the initial launch trajectory to reach the scientific target.
The giant constellation of small spacecraft currently forming in low-Earth orbit has made low-power Hall-effect thrusters the most widely used electric propulsion system in space today. These systems are very efficient at using propellant and can be used for orbit insertion, deorbiting, and years of collision avoidance and rephasing. However, due to the cost-focused design of these commercial electric propulsion systems, they inevitably limit their lifespan, often operating for less than a few thousand hours, and these systems can only handle 10% or less of the initial mass of a small spacecraft.
By comparison, planetary science missions benefiting from NASA-H71M electric propulsion system technology can operate for 15,000 hours and process more than 30 percent of the initial mass of small spacecraft. This game-changing capability far exceeds the needs of most commercial low-Earth orbit missions, and its cost premium makes commercialization of such applications unlikely. As a result, NASA has sought and continues to seek partnerships with companies developing innovative commercial small spacecraft mission concepts that place exceptionally high demands on propellant throughput.
Northrop Grumman's NGHT-1X engineering model Hall Effect Thruster operates in the Glenn Research Center's Vacuum Facility 8. The design of the NGHT-1X is based on the NASA-H71M Hall-effect thruster. Source: Northrop Grumman
SpaceLogistics, a wholly owned subsidiary of Northrop Grumman, is one of the partners that will soon use NASA-licensed electric propulsion technology in commercial small spacecraft applications. The Mission Expansion Module (MEP) satellite service vehicle is equipped with a pair of Northrop Grumman's NGHT-1X Hall-effect thrusters, based on the NASA-H71M. The propulsion capabilities of this small spacecraft will allow it to reach geosynchronous orbit (GEO) and be mounted on a much larger satellite. Once installed, the MEP will act as a "propulsion jet pack," extending the life of its main spacecraft by at least six years.
Northrop Grumman is currently conducting a Long Term Abrasion Test (LDWT) on the NGHT-1X at GRC's Vacuum Facility 11 to demonstrate its lifetime operation. LDWT is funded by Northrop Grumman through a fully reimbursable Space Law Agreement. The first MEP spacecraft are expected to launch in 2025, and they will extend the lives of three communications satellites in geosynchronous orbit.
Partnering with U.S. industry to find small spacecraft applications with similar propulsion requirements to NASA's future planetary science missions not only supports U.S. industry in maintaining global leadership in commercial space systems, but also creates new commercial opportunities for NASA to acquire these important technologies when needed by planetary missions.
NASA continues to mature H71M electric propulsion technology to expand the range of data and documentation available to U.S. industry to develop similarly advanced and high-capability, low-power electric propulsion units.
编译来源：ScitechDaily