Hardened veteran readers will know that last year when Asteroid (2012 DA14) made a close approach to the Earth, and on the same day a fireball exploded over Chelyabinsk in Russia, I set out to discover – using my home-made orbital simulation model – whether a companion rock of DA14 might have been the one that fell on Chelyabinsk.
To cut a long story short, I couldn’t find one, although I got pretty near.
So I was very interested today when Rose directed me to this Telegraph report:
A meteorite landed “like a bomb” just missing Nicaragua’s main airport and raising concerns over scientists’ ability to track space objects on potential collision courses with Earth.
Officials said they “thanked God” there were no injuries as the rock landed in Managua, a sprawling city of 1.2 million people where it left a crater 12 metres (40ft) wide and five metres (16ft) deep.
The object was believed to have been a small part of the asteroid 2014 RC, nicknamed “Pitbull,” which astronomers had been monitoring as it passed the planet.
So I immediately got hold of the barycentric state vectors – which are the x,y,z locations and velocities of a body in the solar system – of (2014 RC) from NASA (amazing that they were available, because it’s only been a week since (2014 RC) was first discovered), and plugged them into my simulation model, and found that (2014 RC) passed 39,400 km below the Earth at about 18:00 UTC on 7 Sep 2014.
And I then started adding small clouds of rocks near (2014 RC), travelling at the same speed and direction as it, to see if I could get them to land on Nicaragua at about 6:00 UTC. This proved pretty easy to do. Here’s my best attempt so far:
The thick blue line is the approach path of a cloud of about 350 rocks spaced a hundred km apart, and the red blob is the impact site. It’s actually a bit north of Nicaragua, but it’s at about the right time. The x displacement of the centre of the rock cloud was -320,000 km from (2014 RC), and the y displacement was +140,000 km, and the z displacement was +93,000 km on Julian date 2456869.5. The asteroid that struck Managua would have approached from the west, but might well have been descending near-vertically at impact.
The faded black line below the blue line is the path of another rock which is passing over the Atlantic ocean and swooping 250 km over north Africa. And this is my current best shot at another fireball that was seen over much of Spain (6:55 am in Barcelona) early on 7 Sep 2014. Here’s a slightly better image, in which it’s possible to see the trajectory looping over the Earth:
If the Spanish fireball was travelling from SW to NE, then it’s perfectly possible that it was a second companion rock of (2014 RC), because Spain seems to have been at about the limit that such rocks could have landed on the Earth.
Here’s another composite image looking down the z axis on all three asteroids. The green line is asteroid (2014 RC) passing about 37,000 km below the Earth.
It should be possible to get an accurate position for both the Managua meteor and the Spanish fireball relative to (2014 RC). If so, it should be a strong argument for what I suspected last year with DA14: that these rocks very often have a cluster of companion rocks around them. I spent a lot of last year looking at rock clouds that formed when asteroids broke up, and their component rocks gradually drifted apart.
And these companion rocks are the ones to worry about whenever you hear that some big rock (like DA14 and 2014 RC) is going to miss the Earth by a few thousand km. Because if the headline asteroid is surrounded by companions, some of these may strike the Earth. It should be possible to find regions where companion rocks are most likely to land, and where they’ll be skimming through the high atmosphere as fireballs.
P.S. Thanks, Rose!