Mark Boslough (ADXP chair), Rusty Schweickart (Apollo 9 astronaut and Asteroid Day co-founder), and Pol Felten (Asteroid Day Communications Manager) continue a conversation about about Salvation.
Mark: The latest plot twists give us plenty to talk about after week 4. Since we’re not Siskel and Ebert, let’s leave it to others to critique the writing, characters, acting, and so forth. I want us stay in our comfort zone and just talk about the science and technology of planetary defense as we did last time. What parts of the storyline struck you as realistic and unrealistic from that perspective?
Pol: I only really saw one aspect worth elaborating on, when they were talking about breaking the asteroid apart into smaller fragments using the kinetic impactor. You already mentioned in our previous post that the Io probe probably wouldn’t have the mass to actually break a massive asteroid apart. But assuming it would manage to do so, are there any legal considerations following such a break up?
Mark: That’s a good question. There are as many legal systems as there are countries, and there are both civil and criminal laws. Most of us understand the concept of “if you break it, you buy it”. But there are also “Good Samaritan” laws on the books that limit liability to parties that are acting in good faith. In this case, who has jurisdiction? If you get smacked by an asteroid fragment because of an action taken by the US government, can you sue for damages? Who is the arbiter or judge?
Pol: In the case of the series, the smaller asteroid fragments would miss the Western hemisphere and instead rain down as a meteor shower on Russia, China, Mongolia, etc. – basically all over Asia, with an estimated total death rate of 1,146,342,214. Yes, I’m screengrabbing the show now!
Salvation‘s Io Probe – Again
Rusty: I’ve got two points regarding the the kinetic impactor resulting in fragmentation and shifting the impact zone (now a distributed zone vs. point) to the East and wiping out billions of people. One is technical the other geopolitical.
Mark: Just to catch up on the story first, the “Io Probe” is apparently a small interplanetary NASA mission to study Io, a moon of Jupiter. The Pentagon tried to repurpose it and crash it into the asteroid to break it up and have the main fragments miss the US at the expense of other parts of the world. But the uplink communications were hacked by a saboteur who sent a different command and the mission failed. All this action takes place over a few minutes in the vicinity of Jupiter, which is inconsistent with orbital dynamics (the asteroid would have been plunging into the inner solar system since it was discovered, and a probe in orbit around the gas giant would not have the fuel or performance to leave the enormous gravitational well and chase the asteroid down, let alone on such a compressed time scale). Again, artistic license trumps physics in favour of a dramatic story line.
Rusty: Here’s my technical point about the kinetic impactor (going beyond the earlier point that fragmentation would not be likely and accepting the premise of it breaking up for our discussion’s sake). In a fragmentation scenario the resulting debris cloud, likely comprised of lots of small and some big chunks, would end up distributed along a line across the Earth due to orbital mechanics. We call this line the risk corridor, representing the uncertainty in precisely where the asteroid would impact as long as it isn’t entirely diverted. The Planetary Defense Conference actually runs exercises based on hypothetical asteroid impact scenarios where a risk corridor like the one picture below come into play.
The Risk Corridor and Geopolitics
Rusty: The distribution of debris along a line is important since evacuation would be done perpendicular to that line, i.e. to the North and South (assuming that the line is East/West). Now if one assumes, logically, that there would be some pretty big chunks remaining, say hundreds of metres in diameter, that would really fatten the line and influence how far North or South one would have to go to be safe. Likely hundreds of miles, maybe thousands. So to make that clear: The impact zone might well be a line, 20 km x 2,000 km resulting in an evacuation zone 2,000 km x 3,000 km. That’s a lot of people to evacuate but not likely billions.
But if any of the fragments that impact Earth after a fragmentation (whether by kinetic impact or nuclear explosion) are larger than 2 km in diameter (and there could hypothetically be over 40 of these in a 7 km diameter asteroid!), then on impact we’re talking about the end of civilisation on Earth, not just problems in “the Eastern hemisphere”! Fragmentation is problematic, to understate it.
Mark: This reminds me of the scenarios that Paul Chodas of JPL developed for our last two Planetary Defense Conferences. Our 2015 conference in Italy had a risk corridor representing uncertainty of impact location that extended from Turkey at the western end across southern and southeast Asia and on to the eastern Pacific. In this year’s scenario it crossed Europe, Russian and the far east and into the mid-Pacific. Those playing the decision makers in the exercise had to decide whether to push the asteroid to the east or west in each scenario, but that shifts the risk from one part of the world to another.
Rusty: That brings me to the geopolitical issue, where reality breaks away from the Salvation plot most dramatically. We earlier stated that the discovery of an asteroid impact within 6 months could not be kept secret. Not only would the entire scientific community know about it, but other nations besides the US would also get wind of the discovery through their own space agencies and the aforementioned channels. So the only acceptable action would be to shove the impact point not from the Western hemisphere to the Eastern Hemisphere, as in the story, but entirely off the planet, which would mean about double or more than what they attempt to do.
But all deflections essentially mean dragging the original impact point across the Earth’s surface either East or West following the storyline until it’s off the Earth. But in reality the world will have to decide which way. It’s going to be one way or the other. And in all likelihood the probability of success will be high. But the possibility of a partial deflection will always be there and that means that those who live along the line of the risk corridor in the direction of deflection will have, temporarily, an increased risk of ending up in the impact zone. That’s the real either-or. And it’s real. But it’s not going to be a secret, one nation’s military or government saying “them or us”.
Pol: Let’s see where they go next, and if the planetary defense aspect will remain relevant. I predict it’s all going towards Tanz evacuating his 160 attractive young artists, philosophers and scientists towards Mars, moving away from an asteroid impact story to one about birthing a new civilisation on another planet. A non-deviated asteroid would obviously help push the funding for this project of his. Or maybe he plans on letting it crash into Mars, using it to terraform the planet in the same way that asteroids or comets might have brought water and life to Earth billions of years ago. Let’s wait and see what happens.
Rusty already dedicated an entire blog post to the geopolitical issues of putting a nation or region’s citizens temporarily at risk while deflecting an asteroid, with quite some interesting insights, as part of his planetary defense blog series.
Further information on asteroid detection can be found here.
To learn more about asteroids in general, click on this link.
We will keep revisiting Salvation in the coming weeks whenever interesting concepts pop up that our Expert Panel feels need further explanation or insight. Therefore keep coming back here to find out more! In the meantime, you will already find plenty of information about several other topics the series touches on throughout the Asteroid Day website: For more information on various asteroid deflection methods, please visit our page dedicated to these efforts. Rusty Schweickart also wrote an entire blog series about planetary defense that will help to clarify some issues!