Bad Astronomy | The THOR program accelerates the search for nearby asteroids

Note: This article is written in part to promote June 30 is Asteroid Day, a global effort to raise awareness of the dangers and scientific significance of asteroids. Every year on June 30, 1908 Anniversary of the Great Tunguska Influenceand the B612 Foundation mentioned below is one of the founding partners. I should have been in Luxembourg – Asteroid Day HQ – manage some panels and talk about asteroids, but a health problem (now solved!) Discouraged me from traveling. still, I hope you will take a look at the wonderful events planned, including live broadcasts with scientists, astronauts and other experts.. Learn everything and have fun!

Thanks to THOR, the discovery of asteroids near Earth made a huge leap.

Yes, different THOR. This means Tracket-less Heliocentric Orbit Recovery, and it’s a way to speed up the detection of asteroids, but also to search them using old, archived images, regardless of when they were taken. It’s faster and Can use a wide database of observations on the Internet. Yes, this is a great thing.

In general, finding asteroids is not difficult, it just takes time. They move slowly in the sky as they revolve around the sun. So you use a telescope to take a picture of a single point, wait a while – you usually go to other points in the sky to observe them – and then observe that point again. Do it again and you now have three images of the same sky patch.

The stars do not move, so if you straighten the three images, all the stars will appear in the same place, but the asteroid will move, creating a line consisting of three points. This is a trace of his movement during that time, so this short line is called a treklet. It is sufficient to use centuries-old equations of motion to create a predictable orbit for an object, and the equation describing that orbit can then be projected into the future or past to see where it will be or whether it is in the sky; You can search to see if future observations or previously archived are there, and the orbit can be cleared.

In practice, this is certainly more complicated, but more or less how it was done. One of the problems is that this method is very time consuming and inefficient. Other asteroids do not always appear to move in straight lines; The Earth’s motion around the Sun – or the orbit of an observatory in orbit around the Earth – can shake these lines and make it difficult to detect asteroids. Also, over the next few years, as giant queries turn to the Internet, they will find millions of asteroids (!!), and this method will sink in, trying to track them all.

Enter THOR [link to paper]is a project developed by Asteroid Institutea project B612 Foundation. The idea here is not to track the asteroids themselves, but to create theoretical test orbits for the asteroid, which is a kind of backwardness from ordinary work. The test orbit is actually the equation of an imaginary orbit, say, a circular orbit 300 million km from the Sun with a certain inclination and orientation. This creates a set of numbers called orbital parametersand they, in turn, determine a solvable equation for the location of the asteroid at a given time.

This test orbit is then projected forward or backward until the time of other observations, and then objects close to that path are searched. Algorithms for this type of search are general and are extremely fast.

This method has a number of advantages – The Asteroid Institute has a good FAQ to explain all of this – but what is really remarkable is that in order to work, there is no need for close observations in time and in a certain cadence. The location of a potential asteroid in test orbit can be calculated for the time of any observation from any observatory. Because we know when the observation was made and where it was taken in the sky, it is possible to see whether a potential asteroid was observed at that time, even if it was taken weeks or more ago.

It is extremely powerful. There are many, many many – Astronomical observations stored in databases and, in fact, the team that created the algorithm tested it on real data. They used two weeks of observations Zwicky Temporary Enterprise, conducted a large celestial survey to search for potential asteroids and was able to recover more than 97% of the previously known asteroids seen in the data! Impressive.

They also used the information NOIRLab Source catalog, researched a large database of astronomical observations and monthly observations. According to the report, 104 new asteroids were discovered by them Small Planet Center. Thus, it can find both known asteroids and new ones. This is important because new observations could trigger thousands of warnings about potential asteroids; If they can be destroyed quickly for known asteroids, it will save a lot of time.

THOR can hit asteroids quickly and through different observations, and can also use old images to destroy orbits. As these new giant queries become available on the Internet, it seems that THOR will be incredibly useful in finding the many asteroids expected to be discovered. 6 million in the next decade.

This is a lot of stones. Knowing where they are and, more importantly, where they will be, obviously very importantso I bathe for it.

Note: If you are a coder, THOR is on GitHub.