Scientists have calculated the probability of trash falling into space and killing someone – ScienceAlert

The chance of someone being killed by space junk falling from the sky might seem very small. After all, no one has yet died from such an accident, although there have been cases of injury and property damage.

But given that we’re launching an ever-increasing number of satellites, rockets, and probes into space, do we need to start taking the risks more seriously?

New study Posted in natural astronomyover the next ten years, estimate the probability of casualties from falling parts of the missiles.

Every minute of every day, debris rains down on us from space – a danger we almost don’t realize. Microscopic particles from asteroids and comets travel through the atmosphere to settle unnoticed on Earth’s surface – adding up to about 40,000 tons of dust each year.

While this is not a problem for us, such debris can damage the spacecraft – as has been the case recently. Reported to the James Webb Space Telescope. Occasionally, a larger sample arrives as a file meteorAnd, maybe once every 100 years or so, an object across tens of meters manages to drive through the atmosphere to dig a hole.

And – fortunately very rarely – Kilometer-sized creatures It can reach the surface, causing death and destruction – as evidenced by the lack of dinosaurs roaming the earth today. These are examples of natural space debris, whose uncontrolled arrival is unpredictable and more or less evenly spread throughout the world.

However, the new study looked at the uncontrolled access to artificial space debris, such as spent rocket stages, associated with launching rockets and satellites.

Using mathematical modeling of the inclinations and orbits of rocket parts in space and the population density beneath them, as well as past 30 years of satellite data, the authors estimated where rocket debris and other unwanted pieces of Earth would be in space when they fell to Earth.

And they find there is a small, but significant, risk that parts will re-enter in the next decade. But this is more likely to occur at southern latitudes than at northern latitudes.

In fact, the study estimated that the probability of landing missile objects at the latitudes of Jakarta in Indonesia, Dhaka in Bangladesh or Lagos in Nigeria is almost three times greater than those in New York in the United States, Beijing in China or Moscow in Russia. .

The authors also calculated the “expectation of losses” – the risk to human life – over the next decade as a result of the uncontrolled re-entry of missiles. Assuming each return spreads deadly debris over a ten-square-meter area, they found that there was a 10 percent chance of one or more casualties over the next decade, on average.

Until now, the potential for debris from satellites and missiles to cause damage to the Earth’s surface (or to air traffic) has been neglected.

Most studies From this space debris She focused on the risks posed by defunct satellites in orbit that might impede the safe operation of operating satellites. Unused fuel and batteries also lead to explosions in orbit that generate additional waste.

But as the number of entries into the missile launch business increases – and the move from government to private enterprise – it is very likely that the number of accidents, both in space and on Earth, such as those that followed the launch Chinese Long March 5Bwill also increase.

The new study cautions that the 10 percent is therefore a conservative estimate.

what can he do

There are a range of techniques that make it entirely possible to control debris re-entry, but their implementation is prohibitively expensive. For example, a spacecraft can be “passivated”, where unused energy (such as fuel or batteries) is spent rather than stored once the spacecraft’s life is over.

Choosing a satellite’s orbit can also reduce the chance of debris production. A defunct satellite can be programmed to move into low Earth orbit, where it will burn up.

There are also attempts to launch reusable missiles which, for example, SpaceX show and blue origin This is a development. These create a lot of debris, although there will be some paint and metal shavings, as they return to the ground in a controlled manner.

Many agencies take the risks very seriously. The European Space Agency is planning a mission Attempt to capture and remove space debris with Four-armed robot. The United Nations, through its Office for Outer Space Affairs, has issued a set of Space debris mitigation guidelines In 2010, which was reinforced in 2018.

However, as the authors of the new study point out, these are guidelines rather than international law, and do not provide details on how mitigation activities should be implemented or controlled.

The study argues that developing technologies and more thoughtful mission design would reduce the rate of uncontrolled re-entry of spacecraft debris, reducing the risk of danger worldwide. It states that “uncontrolled missile body re-entries are a problem of collective action; solutions exist, but every launching country must embrace them.”

Requiring governments to work together is not unprecedented, as evidenced by the ban agreement ozone Chlorofluorochemicals destroying the layer.

But, somewhat unfortunately, this type of action usually requires a major event with disastrous consequences for the Northern Hemisphere before any action can be taken. Changes to international protocols and agreements take time.

In five years, it will be 70 years since The launch of the first satellite in the space. It would be a fitting celebration of this event if it could be distinguished by a strong and binding international treaty on space debris, ratified by all the nations of the United Nations. Ultimately, all nations will benefit from such an agreement.

Monica GradyProfessor of Planetary and Space Sciences, The Open University.

This article has been republished from Conversation Under a Creative Commons License. Read the original article.

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