Chinese, Ukrainian scientists develop new asteroid imaging technique - study

Near-Earth asteroids (NEAs) tend to move very fast, which makes it hard to take precise images of them with telescopes. Researchers from China and Ukraine got around this with time delay integration.

By AARON REICH, Jerusalem Post, MAY 29, 2024

https://www.jpost.com/science/space/article-804226

An illustrative image of an asteroid passing Earth. (photo credit: INGIMAGE)

Scientists from China and Ukraine have developed a new technique for studying near-Earth asteroids (NEAs) that could help identify and prevent catastrophic asteroid impacts, according to a recent study.

The findings of this study were published in the peer-reviewed academic periodical The Astronomical Journal.

The results of this research, by scientists from the Shanghai Astronomical Observatory in China and the Mykolaiv Astronomical Observatory in Ukraine, are a new technique known as a rotating-drift scan, which could potentially help mitigate asteroid impacts in the future.

Detecting the asteroids flying past the Earth

There are over a million known asteroids in the Solar System, and many of them have orbits that take them near the Earth, sometimes even crossing over Earth's own orbit around the Sun.

These asteroids near the Earth are known as near-Earth asteroids (NEAs) or sometimes near-Earth objects (NEOs). Of them, a select group has been the subject of considerable scientific interest—and worry. These are known as potentially hazardous asteroids (PHAs), which must have diameters of over 140 meters and be close enough to Earth.

An asteroid is seen flying near Earth in this artistic illustration. (credit: PIXABAY)

While small asteroid impacts do happen and are usually relatively harmless, an impact from an asteroid over 140 meters in diameter can be devastating; according to the Davidson Institute of Science, the educational arm of Israel's Weizmann Institute, such an asteroid would release an amount of energy at least a thousand times greater than that released by the first atomic bomb.

Scientists in the field of planetary defense have been hard at work finding countermeasures against potential dangers from space. The most famous of these so far is kinetic deflection, as exemplified by NASA's Double Asteroid Redirection Test (DART) mission, which slammed into an asteroid to alter its orbit.

But that's just one side of the coin. The other side is monitoring – trying to build a full net of telescope observations to watch out for NEAs. While methods such as DART could be said to be our last hope against asteroids, these wide-range telescope networks are our first line of defense. That's why there are already so many such telescope systems out there for this purpose, such as the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) and the Asteroid Terrestrial-impact Last Alert System (ATLAS).

However, there are some issues with these systems, namely speed. When NEAs pass the Earth, they can be observed for quite a long period of time, relatively speaking. They also tend to have very high velocities due to both their existing momentum and external gravitational influences. This high speed and long observation time can cause streaks to form in their images, which could make astronomical measurements less precise.

The solution the researchers behind this study devised was the rotating-drift-scan (RDS) charge-coupled device (CCD) method. It means using a CCD camera that can use time delay integration imaging, typically used to capture images in low lighting and fast-moving objects. In other words, it is designed to avoid the streaking in images that happens when something moves too fast.

Telescope operators can use this camera on a rotation platform attached to the telescope. Next, the scientists have to synchronize the telescope's movement and the asteroid's trajectory. By controlling the camera's angle and adjusting the CCD based on how fast the NEA is moving, the end result is effectively real-time photos of the asteroid taken by keeping up with its speed. This way, scientists should be able to capture more accurate images of fast-moving asteroids.

This isn't entirely new. Scientists have been using a technique like this to study asteroids for at least five years. Using the RDS CCD method, the researchers built on observations made in China from 2019-2023 and in Ukraine from 2011-2022.

The researchers attempted to prove its viability by looking at a relatively recently discovered asteroid, 2023 BJ7. This asteroid passed the Earth on January 30, 2023, and was tracked by telescopes over three days. Overall, the researchers say their observations achieved a high rate of precision. This solution isn't perfect, as the possibility for error is still present—something the researchers acknowledged. However, they argue it does have potential, and further studies could help support that.

If it is successful, the greater picture of the cosmos and its dangers can become a bit clearer for us on Earth.