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Earth’s lasers can now detect space debris in daylight



ESA optical ground station

A visible green laser is projected from the ESA Optical Ground Station (OGS). Part of the Teide Observatory, OGS is located at an altitude of 2400 m above the volcanic island of Tenerife, used to develop optical communication systems for space as well as space debris and orbital surveys near Earth and quantum communication experiments. Credit: IAC – Daniel López

Earth lasers are used to measure the positions of space debris overhead, providing important information on how to avoid collisions in space. So far, this technique is still a fatal flaw.

At some point, the laser could only be used to measure the distance to space debris during twilight hours, during which the Earth ‘laser’ station was engulfed in darkness, but objects debris overhead is still bathed in the last rays of the Sun.

Similar to how the Moon is brightest when it glitters in the sunlight while it is night on Earth, space debris are easier to spot when reflecting sunlight when viewed from a vantage point. dark.

However, since debris objects are much closer to Earth, there is only one small window in which they light up but not on Earth observers.

Now, a recent study has demonstrated that it is indeed possible, in daylight, to use lasers to determine the distance to the debris. This new method of laser scoping will help improve orbital prediction for debris objects, significantly increase the time available to make observations and keep valuable spacecraft safe.


Distribution of space debris in orbit around the Earth.

By using a special combination of telescopes, detectors, and light filters at specific wavelengths, the researchers have discovered that, in fact, it is possible to increase the contrast of objects. compared to the daytime sky, revealing previously hidden objects in clear view.

“We are used to the idea that you can only see the stars at night, and the same is true when observing debris with telescopes, except with a much smaller time window for Observe objects in low orbit, ”explains Tim Flohrer, Head of ESA, the Office of Space Debris.

Using this new technique, it will be possible to track ‘invisible’ objects that previously were lurking in the blue sky, which means we can work all day with laser ranges to support them. avoid collision.

Debris space

The growing problem of space debris. Credit: Spacejunk3D, LLC

Fragments dancing in the dark

Our planet is covered with a curtain of debris – millions of small, but dangerous debris left over from previous space launches as well as explosions and collisions in orbit.

They are joined by hundreds of spacecraft and the entire, but defunct, broken or abandoned spacecraft orbiting space.

Even millimeter debris, traveling around 7 km / sec, could damage a satellite on impact, but colliding with a dead spacecraft or large debris could completely destroy the wares. par is active.

Network monitoring space debris in the future

The concept for a future space debris surveillance system using optical technology, ground-based radar and lasers as well as orbital survey equipment. Photo Vendor: ESA / Alan Baker, CC BY-SA 3.0 IGO

So it’s important to understand the location of the fragments so we can avoid them – but retrieving this information is not easy.

Laser range is a very well established technology that uses Earth lasers to send pulses of light to a satellite carrying a reflector.

By measuring the time it takes for the signal to return to the telescope on Earth, known as a ‘bidirectional travel time’, it is possible to accurately determine the distance to the satellite.

Unfortunately, some satellites carry ‘reflector’ that allow light to easily reflect and return to Earth. Determination of distances to such objects was only demonstrated a few years ago, and development of related technologies is progressing rapidly.

Laser from optical ground station on Tenerife

ESA’s optical ground station (OGS) at 2400 m above sea level on the volcanic island of Tenerife. The visible green laser beams were used to stabilize the sending and receiving of telescopes on two islands. Image provider: IQOQI Vienna, Austrian Academy of Sciences

Detect debris in daylight

In recent tests, 40 different debris objects (and the stars about 10 times fainter than what is visible to the naked eye) were observed using the new technology, which stands out against the sky. green, was observed for the first time in the middle of the day – which was not possible before.

“We expect that these results will significantly increase debris observation time in the near future,” explained Michael Steindorfer from the Austrian Academy of Sciences.

Ultimately, that means we will better understand the fragment population, allowing us to better protect Europe’s spatial infrastructure.

Further development of such technologies is a core goal of ESA’s Space Safety program, including the establishment of a network of space debris laser stations.

A new laser station next to ESA’s famous Optical Ground Station in the Canary Islands is awaiting implementation, which will serve as a ‘test bed’ for various laser technologies, as well as developing concepts. die.




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