Smash up in Space
Earth’s contender launches Tuesday 23rd November, 2021
NASA/Johns Hopkins Applied Physics Lab
Did you know that the Planetary Defence Coordination Office (PDCO) even existed? Well it does, which must mean Men In Black was true after all. It is American and part of NASA. They decided to set-up the PDCO in 2016, but not to deal with numerous aliens living on earth. It’s to identify Near-Earth objects (NEO’s) and develop plans in order to deal with any found to be on a collision course with us.
A calm way of saying that the testosterone filled film, Armageddon, 1998, with Bruce Willis, the oil driller and his friends or the more thoughtful Deep Impact, 1998, with Robert Duvall and Morgan Freeman, aren’t entirely fanciful science fiction stories. (If you like the asteroid storyline, then you might like Melancholia, 2011, with Kirsten Dunst, Charlotte Gainsbourg and Kiefer Sutherland. Available to rent on Amazon Prime for 99p).
Near Earth Objects (NEO’s)
An NEO is any solar system object, usually an asteroid, occasionally a comet, whose orbit around the sun brings them into close proximity with Earth at some point. I vaguely remember learning about Halley’s Comet which flies by Earth every 75 years. If you’re lucky, you might see it twice in your lifetime. It’s due back in 2061. A much more personal encounter was the Comet Kohoutek, in 1973, and being told to repent while we still could by the Breakells, our Jehovah-fearing friends who we played with most days during the school holidays.
A more dangerous near miss was 4581 Asclepius, a sub-kilometre sized asteroid in March 1989, which was discovered 9 days after its closest encounter with Earth. It was 425,000 miles away, which is outside the Moon’s orbit but is regarded as a close miss in cosmic terms. A collision would have released energy comparable to the explosion of a 600 megaton atomic bomb. To put that into perspective, the Little Boy atomic bomb dropped on Hiroshima at the end of World War II was 15 kilotons in size and that levelled a city. 66 of those bombs would roughly give you the explosive power of 1 megaton.
To date, scientists are aware of 27,000 NEO’s. The dangerous ones are classified as potentially hazardous objects (PHO’s) and need to be larger than 140 metres in size.
Double Asteroid Redirection test (DART)
NASA Scientists have come up with such a boring name for such an extraordinary event. Hopping a ride on a Space X rocket due to take off as early as Tuesday, 23rd November, is a spacecraft (DART) which is going to deliberately smash into an asteroid.
DART’s target is a two asteroid system. The bigger one is called Didymos, roughly 780 metres across and a much smaller one, 160 metre, Dimorphos, which orbits Didymos every 11 hours and 55 minutes. Astronomers have been watching these asteroids for years. There is absolutely no chance that they are on a collision course with earth. But they are relatively close, which is why they’ve been picked for this head-on collision.
DART will cruise away from earth for the next 10 months, with its two, 28 feet solar arrays unfurled, arriving at its destination conveniently when the asteroids are closest to us. 10 days before the big event, the Italian Space Agency’s miniature satellite LICIACube will exit DART, only to start following from a safe distance. It’s there with the intention of grabbing a ringside seat to capture the impact in all its glory as thousands of tonnes of asteroid explode into space. It’s not going to be a fair fight. DART is planning to smash into Dimorphos at 15,000 mph, but it’s 100 times smaller than the big lump. It will be obliterated.
This technique of smashing into things in space is called asteroid deflection and up until now it’s all been theory. What the scientists plan to measure is how much momentum was transferred into the asteroid which will then be measured by looking at the orbital path. They’re hoping that there might be a path change as small as 1%, which might mean the orbit is a few minutes shorter than it is currently. Because of the relatively close proximity to earth, ground-based telescope observations can be used to measure any changes, before and after impact.
Given that the PDCO is part of NASA which is controlled by the US government, it’s fair to say that its primary interest is to protect American interests. Of course if a big lump of rock, and the scariest discovered so far is Bennu, was to collide with earth, you’d like to think that the Chinese, Russians and Europeans would all play nicely together with the Americans, in order to try and avert disaster.
Ironically, over the weekend, Russia decided to fire an anti-satellite weapon at one of its own satellites. It was successful. One object has now created a cloud of 1,500 trackable fragments which endangered the International Space Station (ISS). The Russian, European and US astronauts onboard had to take refuge in the two spacecraft attached to the ISS as a precautionary measure.
Actions like this would suggest that space is now becoming a potential battlefield because of the super-powers reliance on satellites for intelligence on the ground.
It’s average diameter is 492 metres and it comes close to earth every 6 years. It’s classified as a bad boy and is predicted to pass the earth inside the Moon’s orbit, which is particularly close in 2135. Bennu’s orbit will change slightly as a result of coming so close to earth which may lead to an impact towards the end of the 21st century. The risk according to the Jet Propulsion Laboratory’s Centre for NEO Studies (CNEOS) is still a 99.963% chance that it won’t.
Saving the planet
I love the idea of this amazing space theatre. But it is easier and saner to argue that the US would be better off using the millions of dollars spent on deflecting asteroids to introduce a radical rethink on per capita US consumption, recycling and phasing out fossil fuels faster, to ensure that earth remains inhabitable everywhere for the next 100 years and beyond.