Mitigating Impact Risks
Posted by Jeriaska on December 26th, 2008
Bruce Damer is the CEO of DigitalSpace, an international corporation with a leading practice in virtual worlds for industrial design engineering, education and public outreach. He is also the director of Contact Consortium, a California 501c(3) non-profit organization catalyzing the development of multi-user virtual worlds and virtual communities in cyberspace. For the 2008 Global Catastrophic Risks conference in Mountain View, he presented on the subjects of mitigating impact risks from Near-Earth objects, and the long-term potential for utilizing the source of these possible threats as stepping stones to a sustainable space program.
The following transcript of Bruce Damer’s GCR08 presentation “Asteroids and Comets: Mitigating Impact Risks and Stepping Stones to a Sustainable Space Program” has not been approved by the speaker. Video and audio are also available.
Mitigating Impact Risks
Hello, my name is Bruce Damer. I’m grateful to the organization for inviting me here to talk about NEOs, or Near-Earth objects, as they are called. I have a small company here in Silicon Valley that does a lot of research for NASA on visualizing and doing physics-based simulations of a lot of space missions. In the last couple years we have been picking up projects on Near-Earth objects.
There are going to be two parts to the talk. Mitigating the risks of Near-Earth objects impacting the earth—what are they, where are they? Also, looking at them as an opportunity for creating an actual, sustainable space program.
Where did NEOs come from? The very birth of the solar system—they have been around since the accretion of the disc of material around the sun. The lower image is a visualization of the accretion of the moon after an impact with the Earth. The upper is a vision of this whole solar accretion disk.
These are just leftovers—where are they today? Well, they’re everywhere. This is a chart from the Association of Space Explorers showing the detection of NEOs. In red are the bigger ones and in blue are the littler ones. This is the century of the Tunguska event in Cyberia, where several hundred square miles of forest were flattened by an air burst. They think it was probably about a 20-40 foot-wide comet exploding at about five miles, and the shockwave flattened this area. That was a century ago.
There are slightly around 300,000 Tunguska-or-larger objects that have been tracked. What does this look like from a perspective of being above the solar system? The Earth’s orbit is the one in light blue, while the red and yellow specks are potentially threatening objects. This is from 2005, and as the space detection systems get better and better, they are going to find more—there are just so many of them out there.
How have NEOs shaped life on Earth? They have uniquely impacted our evolution. Here are some artists’ conceptions on the top. Probably impacts would not really look like this. This is the Meteor Crater near Flagstaff, Arizona. It’s a really cool thing to go and experience. Here is our NEO vacuum cleaner, the moon. It has taken a lot of hits on our behalf, and what credit do we give?
Could this happen again? Yes, indeed. This is from a planetarium show that has been running for the last two years. Robert Redford is explaining about the K-T dinosaur killer. You see all this material that was thrown up—that lava wall was about two kilometers in height. The rock was about five miles. You will watch the materials striking the atmosphere and it creates a superheated condition where the atmosphere actually burns, everything burns. The surface temperature reaches about 500 degrees, and is a minor component in the wave.
This is just like the San Francisco earthquake, where the damage was caused by fire, not by the actual seismic event. North America was directly in the path of the ejecta. It would have reached the highest temperatures. Things that were underground or in the oceans survived. The models show 60 minutes after the impact that was the temperature, but then for months and months there would have been fire.
The next piece of this film shows a gravity tractor solution that we have been working on visualizing for the B612 Foundation with Rusty Schweickart. The idea of a gravity tractor is you have a spacecraft flying alongside the NEO, and even if you don’t have any contact with the NEO, the tiny gravitational attraction to the spacecraft will gradually change the orbit of the NEO. You have to find it early enough and have to have many, many years to make this effective. This is very conceptual, but we did some real research work this summer on this. This is showing the NEO passing by the Earth, which has now got city lights… This looks much better on the dome of the Hayden Planetarium.
One particular asteroid is called Apophis, which got in the news a couple years ago as a potential impactor. It is 400 meters long, and most of these things are potato-shaped and rotating. They recently reduced its hazard to a 1 in 450,000 chance of passing in 2029 through something called a gravitational keyhole; it has a chance of returning and impacting the Earth in 2036. The chances are extremely low, but it will raise awareness.
These are risk corridors of other NEOs of concern. This does not mean that they are going to impact, but this is a typical scatter pattern.
Have we visited NEOs? Yes, we have—with robotics. This is the NEAR-Shoemaker Mission from five or ten years ago. Hayabusa visited Itokawa, and actually made a soft touch-down. You can see the NEO is actually sort of a rock pile—this is why you don’t want to blow them up. You go from a rifle shot to a shotgun effect coming at you. Deep Impact, which sent a slug of copper into Tempel 1, got a good sample of what Tempel 1 is made out of.
Could humans visit NEOs? “Yes, we can!” to quote our incoming president. Here is a way it could work. Two years ago, NASA asked us to produce a design visualization of how to land a human spacecraft on one of these objects. The real challenge is the low gravity. I came up with this design—this ring of airbags. You are coming in, and this rock is really low gravity, and the real challenge is finding a secure place to set down. You have to tie yourself to the surface.
I came up with this concept of a ring of airbags that would push into the surface to see if it is crumbling or not. You can get a reading and determine whether it is a solid surface. You throw out these rock climbers’ pitons to attempt to tie yourself down. The EVA activity would be more like scuba diving, so you need all these handholds. This is part of a study that went to headquarters a couple of years ago for Congress. Here we have an Earth flag flying on the NEO… still got to salute it, though. It’s got to be military guys in there somewhere.
This was on the cover of Popular Science a year ago this month. They declare it’s NASA’s new target, but it was not. We kept saying this was a study. This is their vision of the constellation hardware on a NEO.
Can we mitigate the threat posed by NEOs? Yes, we can. It wouldn’t work this way. You wouldn’t have South African miners going in there to blow things up, or what they did in Deep Impact or in Armageddon. The tricky thing about NEOs is they are really hard to track. They don’t have a little radio transponder on them. You have to go up there and figure out if they are threats. If you don’t go out there to figure out if they’re a threat, and there may be several, then you’ll never know until it’s too late. You have to go years and years in advance to track a bunch of them.
This would make a good Google X-Prize—come up with a low-cost mission for a fly-by of these things to determine where they are actually going. You have an orbit determination phase with a small spacecraft, very low cost. If you did determine that it was a threat, you could use a combination of a gravity tractor solution and little kinetic impactors like Tempel 1. Here is our orbit determination craft and a little image of what a kinetic impactor might do. This is a visualization we produced with data from JPL, and this was handed to the Secretary General of the UN a couple months ago on DVD.
The critical questions from a political standpoint: Who issues the warnings, based on what information? How does the public react, especially if you are posting statistical probabilities? It’s almost like if you didn’t really know hurricane history, you just have to hand-wave. “It could be a threat, but we just don’t know, and we need to invest money to find out.”
Who approves the technologies? Who accepts the liability if it doesn’t work? Who decides if it acceptable to temporarily increase the risks to one part of the Earth and reduce it to the other part? You might say, “We don’t have any cities on the oceans, so we don’t mind a mid-ocean impact.” What is the biggest one we can safely decide to ignore? If the Tunguska had happened over Europe, the force of the downward airburst would have blown the roofs in of a major city, like a nuclear airburst without any nuclear material. That is though virtually no material reached the surface, it would have been very serious.
Who pays for it? Should there be two space programs competing to do the job? What Rusty was proposing to the UN was establishing a couple million dollar a year agency to think about this as a go-to location for this issue.
There is a little bit of side benefit to studying NEOs and worrying about them. Can we use them to support exploration and settlement of the solar system? Perhaps. These are fanciful visions of doing this kind of thing—kind of a NEO as a cosmic seed.
What benefits do you get? It turns out the Moon is so dry and the temperature swings so much, it’s a tough place to operate. It’s a long way away, down at the bottom of a gravity well. If you could actually learn how to move an asteroid around, they are fairly rich in resources. Apologies to Carl Sagan, we are made of NEO stuff, not of star stuff. If you could get one to miss the Earth, it might come in and be captured by the Earth. You might wind up with a Phobos/ Deimos-type little moon. You could then circularize the orbit, bring it in lower and lower, and mine it.
What would you mine it for? Initially, consumables: hydrogen, oxygen, methane, etc. You could mine that for consumables, especially as a source for propulsion. If you can get to orbit, find a fueling station, you can launch a lighter-weight spacecraft. The whole solar system could open up to us if we had one of these things in orbit. You could use it as a space elevator. In fact, one of my dear friends who is a mining engineer is big on mining the moon, and I always bring up these problems of operating in a lunar environment. I posed a question to him one night: If you looked up into the night sky and the Earth had captured a comet blowing off its material… his eyes lit up and he said that would be the most valuable real estate in the solar system. Everyone would be after that.
Now, of course, who can stake a claim? Could it be a threat to drop one of these? You might get one of these little ones that wouldn’t pose a threat to anybody, because they would just burn up in the atmosphere. Ultimately, if we are going to be a spacefaring civilization we could do all kinds of things, like evolving life forms that are better suited in environments outside the Earth.
The ultimate thing is that NEOs could become biospheres. You could use it for a great big space station. It’s huge, there are tons of resources and it is radiation shielded. It’s a happenin’ place. I would expect that if you found an ET civilization, you would find that their whole planet is completely surrounded by these things and they have built huge infrastructures around them. They have brought in all the goodies, and then have used those as stepping stones to expand out. Then you explain to them why we can’t do this because we have all these tribes, and one would worry that another one would drop it on them. And they would say, “Are you crazy? You’ve got to get over that.”
There are tons of resources on this on these sites: the B612 Foundation, NASA’s Near-Earth Object Program. On our site you can see all these simulations—some of them are drivable 3D simulations, some of them are movies. Thank you for your attention.
