Monday, June 12, 2023

4048 - SPACE GARBAGE - should we worry about it?

 

-    4048  -  SPACE  GARBAGE  -  should we worry about it?  -    Robot operation in space itself might solve this last problem by creating a large enough infrastructure in space to allow for the design and assembly of robots themselves in space. That is still a long way off, but numerous teams worldwide are working on making it a reality. Someday it will be, and overcoming these technical challenges will help it become so.

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-----   4048   -     SPACE  GARBAGE  -  should we worry about it?

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-    Space junk orbiting around Earth.   A Russian KOSMOS 2499 satellite broke up for a second time according to the Space Force’s 18th Space Defense Squadron.   The Space Force said they are currently tracking 85 individual pieces of debris at an altitude of 726 miles. The breakup occurred on January 4, 2023, but the reason for the disintegration remains unknown.

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-    At this high altitude, it will take decades for the debris to deorbit and burn up in the Earth’s atmosphere, and presence of this debris in an increasingly busy region in Earth orbit.  But this is actually the second breakup event of Kosmos 2499. The first fragmentation occurred on October 23, 2021.   That event created 22 pieces of trackable debris.

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-    This satellite has had a curious history. Russia quietly launched KOSMOS 2499 on May 23, 2014. But tracking indicated the satellite performed unusual maneuvers, leading some to speculate that it may be an experimental anti-satellite weapon, satellite maintenance vehicle, or collector of space debris.

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-    Both the first and now second breakup event was thought to be caused by an explosion of that propulsion system. LeoLabs, Inc., a commercial provider of low Earth orbit mapping and tracking also tweeted about the current situation, saying that their analysis points toward a low intensity explosion, due to the asymmetry of the debris cloud, magnitude of the velocity imparted to the fragments, and a known energetic source on board, the propulsion system.

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-   LeoLabs said another identical spacecraft, Kosmos 2491, exploded in 2020, and that event has been attributed to an explosion of the propulsion system.

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-    This event follows a recent close call where two pieces of leftover Soviet-era space junk passed within feet of each other on January 27, 2023. A piece of a rocket stage came as close as 19.7 feet from a defunct satellite at an altitude of 611 miles  above Earth’s surface.

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-    A mysterious black object was photographed orbiting the Earth in 1998, during the first Space Shuttle mission to the International Space Station (ISS).  The space agency refers to the strange entity as item STS088-724-66 in its catalogue of space junk floating in low-Earth orbit (within 1,200 miles).

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-    Jerry Ross, an astronaut who took part in that mission, says that the object is a wayward thermal blanket that broke loose while his team tried to attach an American module to a Russian module on the ISS. But for a small, devoted following, it’s a 13,000-year-old, artificially made satellite known as the Black Knight satellite. So, could this peculiar object really have come from ancient aliens? Or is it just an innocuous piece of space debris?

 

-    While NASA and other space organizations keep catalogs of the space debris that they encounter, these lists are still incomplete and dependent on nations sharing sometimes sensitive data.

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-    Space robots have been around since 1981 when the Shuttle Remote Manipulator System (SRMS) was launched with the space shuttle, whose astronauts then operated them. They have expanded far beyond that original use case in the last forty years, playing an increasingly important role in everything from assembling the International Space Station (ISS) to more recently proof-of-concept missions to service a failing satellite in Earth’s orbit.

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-    Rtobot's vision systems are consistently being improved here on Earth, especially those tied to the operation of autonomous cars. However, while the visual surrounding might not be near as chaotic in space, it can be challenging to have a robot visually understand what it is looking at, especially if a satellite is tumbling uncontrollably.

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-    Pattern recognition, such as circles placed around the docking ports of a satellite expecting to be serviced is still difficult.  Partly that is because the computational load of doing the recognition algorithm must be done on the robot itself. That requires increased computational power, directly related to increased power consumption and heat that must be dealt with. Recognizing an “un-cooperative” satellite that isn’t designed to accept help from a robot is even more difficult, especially in real-time.

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-    Once a robot sees where it’s going and what it’s trying to interact with, the next step is to get there and effectively interact with the thing.   Motion and control technologies. present solutions to several unique control problems, including how to deal with the forces of a robot when there is very little gravity affecting it.  Dynamic control algorithms can help dampen some of the more dangerous vibrations, potentially shaking the robot apart if left uncontrolled.

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-   But even if there was a control system to dampen vibrations, other coordination factors can still be complex, including coordinating multiple arms to interact with an object. While that has been done before, it still proves difficult to do the coordination simultaneously, as it does with robots on Earth.

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-    When a robot (or its manipulator) reaches its intended target, another technology has to interact with it – its end-effector. In robotics, end-effectors are how the robot interacts with objects. They’re the equivalent of human hands but can be much more functional, as they can both be made out of things that human hands are not made out of (screwdrivers) and can be switched out to something else entirely, such as by switching from a screwdriver to a soft-gel gripper.

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-    The possibilities of end-effectors and a robot’s efficiency at switching between end-effectors are endless, and plenty of technical work still needs to be done to make robots as capable as they can be in space.

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-       One method to help effectively operate a robot’s end-effector is to allow a human to teleoperate it. This has been relatively common practice for most of the existence of robots in space, with astronauts operating the SRMS from inside the shuttle or the Canadarm2 from inside the ISS. However, teleoperation takes time, and an astronaut’s time is extremely precious. So efforts are underway to teleoperate robots in space from the ground.

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-   We’ve recently reported on some efforts for the reverse, where an astronaut controlled a robot back on Earth. Those experiments aimed to prove the concept of operating robots down on the surface of other worlds like the Moon or Mars. This form of teleoperation would still suffer from the same delay difficulty – and what’s more, the delay might change depending on where a robot is in its orbital path.

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-    Various solutions have been posed to this problem, including a virtual reality control setup that predicts where the robot will be at the end of the time delay so the operator can plan ahead without waiting for feedback. Force feedback is also a popular option, though it still suffers from the same time delay issues. Numerous technical solutions exist to this hurdle, but nothing can eliminate the fact that signals don’t transmit instantaneously over long distances.

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-   Even back on Earth, there are still challenges.   High-fidelity ground verification is difficult. Verification in engineering means proving that something works as expected in the environment, it’s intended to work in. That is almost impossible for a robot meant to operate in microgravity since it would be prohibitively expensive to launch a verification prototype into microgravity and deal with all the issues that inevitably crop up during verification testing.

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-   Several technical solutions to the problem have been in use for a while, including suspending the robot in pockets of forced air to simulate floating, using either freefall or a parabolic flight on an airplane to test how it would operate in those conditions, or even dunking it in a pool and seeing how it would operate underwater.

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-     Hardware-in-the-loop is the most promising new technology used in other industries. This models the expected behavior of the robotic system and mimics specific environments via software that the robot might experience in space.   Creating the models for this system is complex and can lead to inaccuracies in the verification test itself. So far, there is no optimal solution for ensuring a robot will operate in space while it is still being developed on the ground.

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-  June 10,  2023       SPACE  GARBAGE  -  should we worry about it?       4048

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