Friday, October 25, 2019

Asteroid arriving today?

What is the chance of an asteroid hitting earth today?


The weekend starting Friday 25 October 2019, the 700m diameter asteroid 1998 HL1 zooms past Earth at over 40,000kph - there was never a doubt that it would miss this time round, passing 16 times further away than the moon.

HL1 actually visits regularly and has been seen 408 times since it was discovered 21 years ago and orbits the sun every 508 days. It will come even closer in 2140.

Another little number the size of a school bus zooms past on 22 September 2020.


But asteroids don't always travel alone - could a pack of asteroids ravish earth?


Just a week ago, Friday 18 October 2019, five asteroids approached earth, all on close approach trajectories, the fastest traveling at over 85,000kph. This pack was first spotted just a month ago. That's the scary part of this story... 

00:53 UTC, 2019 TE2 is about 25-50m diameter but passed by at a mere 36,000kph - that would still cause quite a splash if it hit, but is at the very small end of what we need to worry about. Small meteoroids are likely break up and/or burn up before reaching the ground, with mostly only small fragmental meteorites or meteroic dust being found.  Most so-called shooting stars are small meteors that don't reach the ground intact. Many of them actually are shed by comets.

06:25 UTC, 2019 TW6 (discovered October 6) was slightly smaller and slower than TE2...

07:37 UTC, 2019 TP5 (discovered October 7) was slightly larger and considerably faster, and made the closet approach at arund 3 million kms - almost 8 times further away than the moon.

12:53 UTC, 2019 TA1 (discovered October 3) was around the same diameter as TE2 but slower...

14:44 UTC, 2019 TM5 (discovered October 6) was around twice the apparent size as TE2 and by far the fastest!

But the the warning we had for these was around a month - later for the smaller ones or faster ones. These are all Apollo type asteroids whose strongly elliptic orbits take them near the sun at perihelion and pass through or near earth's orbit on the way to their aphelion.

Unfortunately for smaller asteroids still, including ones that hit earth  or explode in the atmosphere, we may have less than a day's notice.  It is rare to detect an asteroid like this, but Richard Kowalski has detected three - but only about 20 hours ahead of time, once it is not much further away than the moon.

But many asteroids have hit the earth, including some with catastrophic results - even extinction events. And smaller asteroids can have significant regional and climatic effects - and even near misses can be very disruptive - and we are expecting some biggies in the next 60 years.

There are many near misses, as well as as apparent past and likely future non-misses. NASA predicts Apophis will pass by in 2029 only 31,200km away (noting that geosynchronous orbit is at an altitude of 35,786km). 2019 SU3 is scheduled to revisit in 2084 and approaching within 10,000km (noting that GPS satellites operate at 20,000km). These can be expected to cause some disruption.

On the other hand, it is pretty certain that one of these significant asteroids will eventually hit Earth. And there are a lot out there.

JPL/NASA have a great animation showing all the asteroids discovered, images showing the particles emitted by asteroid Bennu, as well as a page on 243 Ida(and much much more):
Here is NASA's animation of a segment of the known asteroids in the main band (orange) between Mars (red) and Jupiter (green) as well as the known Near Earth Objects (cyan) - around 40 are discovered every day, but the animation is a little out-of-date (shows the state of play, 18000 NEOs as of early 2018 – over 20000 now).
Animation depicts a mapping of the positions of known near-Earth objects






















My Paradisi Lost stories

Encounters with asteroids, exploited, benign and catastrophically dangerous feature in the Paradisi Chronicles stories, including my Casindra Lost subseries, which also feature genetic engineering, an emergent AI 'Al' and a captain who is reluctantly crewed with him on a rather long journey to another galaxy - just the two of them, and some cats... There's another AI, 'Alice' that emerges more gradually in the Moraturi arc. The Paradisi colonization aims to preserve the pristine ecosystems of New Eden, restrict mining to the other planets and asteroids of the system, and genetically modify people to suit the ecosystem rather than overwhelm it with introduced species: https://paradisichronicles.wordpress.com/

Casindra Lost
Kindle ebook (mobi) edition ASIN: B07ZB3VCW9 — tiny.cc/AmazonCL
Kindle paperback edition ISBN-13: 978-1696380911 justified Iowan OS
Kindle enlarged print edn ISBN-13: 978-1708810108 justified Times NR 16
Kindle large print edition ISBN-13: 978-1708299453 ragged Trebuchet 18

Moraturi Lost
Kindle ebook (mobi) edition ASIN: B0834Z8PP8 – tiny.cc/AmazonML
Kindle paperback edition ISBN-13: 978-1679850080 justified Iowan OS 

Moraturi Ring
Kindle ebook (mobi) edition ASIN: B087PJY7G3 – tiny.cc/AmazonMR
Kindle paperback edition ISBN-13: 979-8640426106 justified Iowan OS 

Author/Series pages and Awards

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