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Scientists feel it's past time to reconsider how space firms dispose satellites to decrease "casualty risk."

The phrase "casualty risk" does not imply that people would be killed by falling satellites, but there is a growing danger of satellite collisions, which might obstruct or even destroy future orbital operations. Satellites that deorbit without permission might endanger property or endanger the lives of those on the ground.

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Current Satellite Casualty Risk Now Crucial Level

A team of academics performed an examination of how satellites re-enter the Earth's atmosphere and burn up, including situations when pieces of them survive to strike the Earth. The study, "Re-Entry Prediction and Demisability Analysis for the Atmospheric Disposal of Geosynchronous Satellites," concluded that the "casualty risk" surpasses the critical level.

The scientists used the casualty area (the region where the satellite breaks apart and its component pieces disperse or scatter), landing (or impact) sites, and a dataset representing population centers called the Gridded Population of the World (GPW) to compute the on-ground fatality risk. In addition to material characteristics, the Phoenix program takes into consideration finer variables like as break-up circumstances and height at which solar panels are destroyed.

The scientists' findings revealed that the casualty risks in none of the GSO trajectories studied met the 10-4 figure required by risk regulations, implying that "design-for-death techniques, or controlled and semi-controlled re-entries would be required to allow GSO satellites to be disposed [of] via re-entry." Higher temperatures during the early phases of re-entry can break apart satellites or spacecraft, altering the region of probable touchdown. More research is needed. However, as major satellite networks continue to grow at unprecedented rates, more space stations enter orbit, and a new space tourism industry emerges, the need to responsibly design satellites to reduce the risk of collisions will become critical for a long-term human and technological presence in space.

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Higher-Orbiting Satellites May Use Lunar, Solar Gravity for Re-Entry

According to the study (per Interesting Engineering), the amount of human-made satellites launched from federal and private entities has increased at exponential rates since the early 1990s, and the continued developing space activities from Blue Origin, NASA, SpaceX, and others. They have created "systematic congestion of specific orbital regions around the planet." European Space Agency said there are several types of orbits.

Geosynchronous orbit (GSO) and low-Earth orbit (LEO) are the two most inhabited orbital zones. The latter is critical since it allows for relatively low-cost satellite activities such as remote sensing, Earth observation, and telecommunications.

The GSO area, on the other hand, provides weather forecasts, television broadcasts, and global communications (since no single LEO satellite will be in the same relative position above the Earth at all times). However, due to the fast development of space activities, the number of dormant satellites in orbit has increased. Those in LEO are often destroyed by natural re-entry into the atmosphere, since atmospheric drag is sufficient to slow them down onto a terminal trajectory in very short durations without the need for further boost.

Satellites in GSO, medium Earth orbit (MEO), or highly elliptical orbit (HEO) require more complex deorbiting techniques. According to the report, the European Space Agency's GSO missions conclude by adding additional 235 kilometers (46 miles) to its perigee (farthest point in orbit), putting the dormant satellite into a "graveyard orbit." These higher-orbiting satellites in the MEO and HEO sectors, however, should be transferred to a location where "lunisolar gravitational disturbances" can produce a long-term trajectory that will eventually lead them into a natural re-entry vector, according to the researchers. But destructive re-entry necessitates a determination of each spacecraft's "casualty risk," which the researchers studied using a software package named "Phoenix."

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