Guest essay by Eric Worrall

NASA Scientists performing experiments on actual Asteroid fragments have presented conclusions about the limits of inbound Asteroid deflection, and the need to plan for multiple “bumps” if the Asteroid is made of an unfavourable material.

Deflecting an Asteroid Before It Hits Earth May Take Multiple Bumps

After years of shooting meteorites with a special gun owned by NASA, researchers highlighted challenges for a preferred method of planetary defense.

By Katherine Kornei
Aug. 25, 2021

There’s probably a large space rock out there, somewhere, that has Earth in its cross hairs. Scientists have in fact spotted one candidate — Bennu, which has a small chance of banging into our planet in the year 2182. But whether it’s Bennu or another asteroid, the question will be how to avoid a very unwelcome cosmic rendezvous.

For almost 20 years, a team of researchers has been preparing for such a scenario. Using a specially designed gun, they’ve repeatedly fired projectiles at meteorites and measured how the space rocks recoiled and, in some cases, shattered. These observations shed light on how an asteroid might respond to a high-velocity impact intended to deflect it away from Earth.

At the 84th annual meeting of the Meteoritical Society held in Chicago this month, researchers presented findings from all of that high-powered marksmanship. Their results suggest that whether we’re able to knock an asteroid away from our planet could depend on what kind of space rock we’re faced with, and how many times we hit it.

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Read more: https://www.nytimes.com/2021/08/25/science/asteroid-deflection-collision.html

The research paper is below (original source here).

It is nice to see NASA scientists getting their hands dirty, performing physical experiments, rather than just spinning up a bunch of models.

Although the risk of an Earth impactor which causes more than localised damage is extremely low, a large impact could have severe consequences, causing widespread disruption to food chains or worse.

I would personally like to see the Project Orion research programme restarted.

Project Orion was one of the most powerful space drives ever conceived, a method of propelling a space ship using nuclear explosions. The most powerful version could have been used to send a 100 year manned mission to Proxima Centauri, at around 3% of the speed of light – a slow journey, but not inconceivable.

For a while Orion was a serious contender for the Apollo missions, until politicians chickened out, and chemical powered Saturn rockets were chosen. An Orion powered Apollo mission would have included a tour of the inner solar system, with landings on the Moon and Mars, and a visit to Venus.

So plenty of power for carrying space cannons or whatever to any corner of the solar system, all buildable using 1950s technology.

Freeman Dyson, one of the principals of the Orion Project, was confident it was worth a try, based on actual physical tests using nuclear explosions, but he had lingering concerns about accelerated erosion of the centre of the pusher plate, due to turbulence in the nuclear bomb blast – a concern which would have required a full scale physical test of a minimum size Orion spaceship to settle.

Obviously nobody wants a return to regular atmospheric nuclear tests. But surely after all the tests in the 1950s, we could stand to have a few atmospheric detonations in some remote part of the Pacific Ocean, just to see if this potential planet saver works, before we have to scramble to try to build it for real. A single Orion launch would release far less radiation into the Pacific Ocean than the Fukushima meltdown, and such a launch would provide inestimable value in terms of developing planetary Asteroid defence capabilities.

Video – meteor striking in Lapland.

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