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Laboratory. “Many robotic systems, like the arms on the shuttle, are oper- ated by an astronaut at the controls. We’ve been looking at what you can do with robots operating on their own or with limited human involvement.” Hudson works with a team that used an experimental set of small, free- flying robots called Astrobees that operate inside the ISS as crew assis- tants. In the zero-gravity environment, they move around using electric fans but also could use an arm to move between grip holds. In the NPS ex- periments, the Astrobee robots trans- ported objects and demonstrated ro- botic hopping using the gripper arm. Outside of the atmosphere con- tained by the ISS, propellers don’t work in space. To meet the constraints of motion in a vacuum, the Space- craft Robotics Laboratory develops robots that move and function like spacecraft themselves. By experimenting on a large fric- tionless platform, robotics research-
ers simulate repair and refueling mis- sions under the conditions of space by testing how robots maneuver around and connect with a satellite that’s also in motion. Saving Rocket Fuel With Optimal Trajectories Rocket science isn’t always about designing and building a bigger and better rocket engine. NPS Distin- guished Professor Mike Ross and Re- search Professor Mark Karpenko of the Department of Mechanical and Aerospace Engineering understand that this won’t help a spacecraft that’s already in space. Instead, they’re mak- ing the best use of a spacecraft’s lim- ited resources, such as thruster fuel, which cannot be replenished. Their team investigates the math- ematics and physics of how a space- craft moves in three dimensions by considering the shapes, sizes, and masses of all the parts that make up the spacecraft and additional factors, such as gravity, solar radiation pres- sure, and other constraints such as obstacle avoidance to keep sensitive instruments away from bright objects. The team developed fast attitude maneuvering by using numerical al- gorithms based on Birkhoff’s theorem to determine the most fuel-efficient trajectory for the spacecraft to travel whenever it’s tasked to maneuver into a new orientation. Surprisingly, the optimal path is not necessarily a straight line from Point A to Point B, but one that appears circuitous. Originally tested on the Transition Region and Coronal Explorer solar ob- servatory, fast attitude maneuvering has recently breathed new life into the Lunar Reconnaissance Orbiter (LRO). A version of the idea applied for mo- mentum dumping has also saved millions of dollars in fuel for the ISS and has supported a similar approach to help extend the life of the LRO by several years. In addition to being able to stretch more missions from LRO, Navy Lt. Cmdr. Timothy Musmanno, a Decem- ber 2023 Space Systems Engineering
Fast attitude maneuvering is applicable across a variety of DoD spacecraft, and other NASA spacecraft, such as the Webb Space Telescope, can also benefit.
graduate, came up with an idea to image Earth utilizing a fast attitude maneuver. Using this operational ma- neuver to efficiently re-task LRO al- lowed the spacecraft to momentarily shift its gaze from the moon and to take stunning images of Earth. “We asked NASA, and they said, ‘Yes.’ So, Musmanno designed a ma- neuver that allowed the spacecraft to be quickly repointed to scan Earth’s surface,” said Karpenko. “We’ve been able to take ideas from the drawing board and the classroom all the way up to practical and operational imple- mentation on NASA systems. And, obviously, there’s all kinds of other applications and implications for DoD space systems.” Fast attitude maneuvering is appli- cable across a variety of DoD space- craft, and other NASA spacecraft, such as the Webb Space Telescope, can also benefit. The Big Blue Picture and Returning to the Moon
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