Not sure if this a GQ question so feel free to move if necessary. Part of my question is factual but speculation may also be also necessary…
Had astronomers spotted the Russian meteorite, and predicted it would be an Earth impactor, what steps would they take? How would government react? How easily would they be able to pinpoint its ultimate destination? And to what accuracy would they be able to predict its effects? For instance, might this have looked like something that could have caused significant loss of life?
You are asking a set of questions with overlapping social, political and technical answers. The set of responses would have to be based on a complex infrastructure involving those same overlapping social, political and technical issues, with all parties involved making and acting upon time-sensitive decisions. An existing military structure would be well suited to the task, but motivating civilian political and social structures would be akin to herding cats.
Three real world scenarios right now are fire drills, tornado warnings and hurricane warnings. Two require almost instantaneous decision-making and action by civilians, while the latter has the luxury of time. All cases are somewhat effective with constant training, but we’re talking ordinary people living their lives. Having experienced all three scenarios, in training and practice, I place my bets with grade school children in school during fire drills. They are the only group with regular Pavlov’s Dog training and response that really works.
In other words, there would be significant human and infrastructure losses and not a damn thing could be done about it.
A number of years back, there was some sattelite (or something similar) that was expected to crash back into the earth at the end of its useful life. I think it mostly landed in the ocean. But about all that was done at the time was comedians made a lot of jokes about it.
Okay, I’ll be a little bit more specific then. Ive been looking at the Torino Scale that deals with classification of threat from space objects: Torino scale - Wikipedia
Looking at that scale it would rank as level 2 or 3 (if spotted early enough), then 5, then 8 but that final level is with the benefit of hindsight. An earlier Wikipedia entry about the event claimed the astroid would have ranked it at 9 (all reference to it now removed). How accurately could we have assessed the danger of this astroid? Would the Torino Scale have given us an accurate prediction BEFORE the event?
Everything below 1MT energy release are considered to be level 0, and the typical diameter for that energy release at typical speeds is 20m.
Nasa estimates it’s diameter to have been 17m and energy release to have been 500kT. Presumably the asteroid would have been Torino scale 0 even if it was 100% confirmed to hit us.
If we’d been able to accurately predict where it would land and the damage it would do, we’d have gone: “Phew! We’re going to be all right. But you people stay away from glass, just in case.”
If we’d only have a guesstimate of impact point and magnitude, we’d have gone: “Cross your fingers and follow the news closely, preferably from a basement if you’re near the predicted impact point.”
My understanding is there’s not much we can do, in any case – movies to the contrary notwithstanding.
Most measures that might be feasible would be more likely to change the impact location than avoid it completely, which raises serious liability issues. It’s not likely that with the present state of the technology (i.e., zero real experience) we’d be able to predict the result of any mediation measures with enough accuracy to guarantee hitting the ocean. Furthermore, the ocean is the most likely site anyway.
I’ve read suggestions that we should be working on a solution. However, if my understanding of the odds is correct, it’s probably not cost-justified.
Well, if the trajectory were known well enough to accurately predict the impact zone, people could have taped or boarded windows which might have prevented many of the flying glass injuries, minor though most were. Also, run outside to view the spectacle instead of looking through a window!
When satellites deorbit, we usually have at least some degree of control over them, such that we can steer them to land someplace harmless. And if a satellite is getting old and losing most of its control mechanisms, what control it has left is going to be used to deliberately deorbit it in this way, while we still can. This obviously isn’t the case for any spacerock.
Fiendish Astronaut, you may be getting confused between two different objects. Friday saw a close pass by a largeish asteroid that we knew about well in advance and which we knew wouldn’t hit us (but which would have been pretty bad news if it did). Friday also saw an actual impact in Russia of an apparently-unrelated object, smaller than the first but still larger than most meteors, which caused some damage and injuries but did not (so far as I’ve heard) kill anyone.
Since most of the injuries from the one that actually hit seem to have been caused by broken glass, the obvious preparation, had we known about it, would have been to warn people to stay away from windows at the appropriate time, and possibly to cover windows with plywood or the like.
The Torino scale, like all simple tabular presentations of risk estimates, fails to fully capture all of the nuances of evaluating how much hazard a potential impactor might pose. For one, although kinetic energy is a significant measure of damage you also need to assess the composition of the object; is it a light and fluffy ball of snow, likely to fragment in the upper atmosphere and disperse, or a dense stony bolide that will impact? Are there any large population centers, critical industrial zones, or terrestrial hazards such as nuclear power plants or hazardous chemical storage sites within the impact hazard lines? If a water impact is predicted, could it initiate a tsunami that could do widespread coastal damage? I’m not sure what the rationale is for a 1 MT cutoff, but at that level it certainly poses some non-infinitesmial hazard at high probabilities (P>0.01) of impact.
For a modest outlay (~US$8B) we could easily deploy a constellation of observatories (based upon existing spacecraft bus and optical scanning technology) that would orbit the Sun between Venus and Earth which would be capable of seeing and cataloguing with high precision the orbits of the vast majority of potentially hazardous objects (PHO) e.g. nearly all asteroids, the larger centaurs and loose trojans, et cetera. Currently, the only dedicated observation of PHO is from terrestrial observatories, and because of the relatively narrow field of view between the Sun and such objects throughout most of their trajectories as observed from the Earth’s surface, we can only see such objects for small fractions of their orbits.
As for stopping or deflecting such threats, while it is true that there is no existing system which has this capability or can be readily adapted to deflect a PHO, there are a number of schemes which may be used to effect such a change given a couple of years of lead time. The main problem is that you can’t just blow up a PHO or mount a rocket to it to push it to the side; many PHOs are actually multiple objects loosely cemented together and if they break up while attempting to deflect they just become multiple fragments on essentially the same trajectory that now pose a more spread out hazard. You have to be able to redirect the entire mass–solid or loose–into a new orbit that does not affect the Earth or its surroundings. Deflecting to an ocean impact is not necessarily any better than a land impact, and depending on where it lands may ultimately do even more damage due to tsunamis and disruption of delicate littoral ecosystems.
My own proposal is to use a nuclear fission device to heat a puck of polystyrene material to plasma temperatures, which would be directed at the object in order to apply a relatively gentle distributed impulse to shove the entire mass into a new orbit. The basic concept is similar to how a fission Primary is used to compress the Secondary in a thermonuclear weapon. This is obviously a novel application that would require considerable engineering effort to develop and delivery, but it is in no way beyond the state of the art to develop this. Based upon some preliminary studies I’ve done, it would be possible to launch a maneuvering spacecraft carrying a fair number of these devices (10-20) on an existing launch vehicle like a Delta IV Heavy, Ariane 5, or the forthcoming Falcon Heavy. The total impulse of all of the devices (assuming a 10% efficiency factor, derived from some of the calculations on the Project ORION vehicle) would be capable of redirecting a PHO of up to 500 m in diameter without significantly dispersing the PHO field. Such a capability could be developed for ~US$10B using largely off-the-shelf technology, and deployed for ~$2-3B per single mission.
Note that this isn’t just crucial for protecting the surface of the Earth and its inhabitants, but may also provide protection to orbiting satellites and facilities that are even more vulnerable to impacts, especially from large dispersed fields of objects. Given that the loss of a single high value satellite is on the order of US$1B (including end-to-end replacement costs) and damage to any densely inhabited area on the Earth’s surface by a large (>50 m diameter) bolide would likely be on the order of tens of billions of dollars, it is clearly worthwhile to develop and deploy both a solar orbiting constellation of observatories and at least have an interception system ready in the wings (and obviously under international control to allay concerns about any one country possessing a space-based weapon system).
No confusion here Chronos, I was talking about the Russian impactor. And I wonder how accurately we’d have been able to predict what actually happened. Had it been seen, would the experts have known this would produce a roughly 500kt explosion or would they have said something else? Or would they have had to admit to a large range of possibilities?
That brings up another element: whether we would be in any way able to estimate reasonably if the object would cross the atmosphere substantially intact until surface impact or lower tropospheric airburst, or disintegrate in the stratosphere like this one did (the lower the altitude at disintegration, the smaller the radius of damage but far greater the intensity thereof – imagine if it had exploded over an inhabited zone at 2 km instead of 20 km altitude, and any community at the point where trajectory intercepts ground surface would still rather have that), and depending on angle and speed of atmospheric entry, prediction uncertainty could mean a few hundred miles’ swath of surface locations on duck-and-cover mode.
(BTW, evac would have to be done laterally away from the predicted flightpath)
From this morning’s AIAA Daily Launch news bulletin:
*Officials Tell Congress US Is Not Prepared For Meteor Threat.
NBC Nightly News (3/19, story 7, 2:15, Williams) broadcast on today’s Congressional hearing where “leading space scientists told lawmakers the US is not prepared to defend itself against meteors” the size of the one that exploded over Russia, which the article characterized as “city killers.” When asked by Rep. Bill Posey what the US could do if one was headed for New York City, NASA Administrator Charles Bolden said, “The answer to you is if it’s coming in three weeks - pray.” Reporter Stephanie Gosk said while the risk from these objects is low, “at present funding levels NASA believes it will take almost 20 years to identify them all. What would help is an infrared telescope” that it cannot afford alone. Gosk also said NASA said it needs more money in order to mitigate the threat.
The CBS Evening News (3/19, story 9, 1:00, Schieffer), in its broadcast, had the same comment from Bolden. Schieffer said, "John Holden, the President's Assistant for Space and Technology said there are 10,000 asteroids in space that could wipe out a city and that we can only detect about 10% of them. Still the odds of one hitting us any time soon are remote."
USA Today (3/19, King) notes Holdren "said meeting Congress' directive to detect 90% of such asteroids by 2020 is proving 'much more challenging' than locating larger objects." At the hearing, according to the article, Bolden described the way NASA is teaming up with "universities, other federal agencies and international partners to beef up tracking efforts," but when it came to diverting an object "most of those options would require slightly changing the object's trajectory years or even decades in advance, Holdren said."
The Houston Chronicle (3/20, Sullivan) "Texas On The Potomac" blog notes Bolden said NASA would reach Congress' directive by 2030, 10 years later than mandated. Rep. Lamar Smith "said he'd look into possible budgetary assistance" to help in this effort. Bolden, who also discussed the partnership with the private B612 Foundation to launch an infrared telescope to detect objects, said, "Ground-based systems are great…but if you really want to find and detect asteroids and near earth objects early enough that we can do something, you want that vehicle to be in space." *
I like your proposal. I’d enjoy seeing a cost/benefit analysis based on best estimates of the probabilities of incidents. My wild-ass guess is that any plan that comes up with a solution by 2050 is probably good enough.
The problem with doing a probabilistic cost-benefit analysis is evaluation of hazard/causalty probability. It is an inherently “swan tail” part of whatever distribution you select, and because of the limited data set and associated errors, the resulting pertubation makes any optimization problem highly indeterminate. Assuming that a workable solution only requires conventional technology and infrastructure (EELV launcher, existing spacecraft bus design, Deep Space Network for telemetry and communications) and that ORION and similar research can be leveraged to minimize development testing, there is really no benefit to defer initiating development, i.e. we don’t expect it to cost less if we push it down the road, and it isn’t as if we will save or use the money for some other purpose that will mitigate the threat. There is certainly no advantage to pushing off deployment of a constellation of space surveillance satellites other than just not having to spend the money. Again, this is a “pay no or pay later” proposition with no material benefit for deferring deployment.
We would have had even more (and better) videos of the event. Religious nut cases would have flocked to the area to “predict” the doom of man/coming of Revelations and such. We may have launched a quick satellite to study the event or even if possible use it as a test for missile defense in the guise of “doing something” just in case.
And if it was a city destroyer governments probably wouldn’t have mentioned that aspect; perhaps just telling a few key people and family to come visit them somewhere far away that day.
