Asteroid Threat Double Header in Congress
19 Mar: House Hearing: Threats from Space: A Review of U.S. Government Efforts to Track and Mitigate Asteroids and Meteors, Part 1
– Prepared Statement By Air Force Space Command Commander Shelton
– Prepared Statement By OSTP Director Holdren
– Prepared Statement By NASA Administrator Bolden
20 Mar: Senate Hearing: Assessing the Risks, Impacts, and Solutions for Space Threats
– Prepared Statement by Ed Lu
– Prepared Statement by James Green
– Prepared Statement by Richard DalBello
– Prepared Statement by Joan Johnson-Freese
White House will appoint Merlen Olson to combat any future asteroid threats. (by taking cover in a sleeping bag.)
Merlen Olson died 2 years ago this month. God bless his soul
I was refering to his idea of hiding in a sleeping bag in the movie Fire in the Sky. (great actor and person, Mr. Olson.)
Bolden was unfortunately incorrect in his response to the question ‘what do we do if an object just like the one that exploded over Russia is found to be on a collision course with New York City in three weeks?’. The answer is that we can prepare, similar to we do with hurricanes. That is, we can work a combination of evacuation and sheltering in place. Sheltering includes staying out of questionable buildings (including wood structures, which might collapse or catch fire) and staying away from glass windows (to avoid injuries from flying glass).
Small objects can be deflected if we have enough lead time. We just need to find them first. In this regard, Bolden is right in stating that a robotic spacecraft in a Venus-like orbit is needed to find these NEOs.
We need eyes looking in toward the Sun for space weather and looking outward at Earth with a front-lit view of near-Earth space.
There is no amount of preparation that is going save you from a EOL event.
There is no amount of preparation that is going to save NYC in three weeks.
Our law makers need to suck it up and fund planetary defense. It isn’t lunacy. Its the reality.
One lesson from the Chelyabinsk bolide is that this is not the sort of impact that we need to be greatly concerned about.This was not a replay of the 1908 Tunguska explosion, which released an order of magnitude more energy. Most important, this 0.5 megaton stratospheric explosion did not trigger military or civilian fear of a nuclear attack. For this we should all breathe a sign of relief. Second, in spite of the fact that this happened very close to a major city, no one was killed. It would of course be better to have had a few hours of warning, but the significant impact hazard concerns larger asteroids, and quite properly that has been the emphasis of both asteroid surveys such as Spaceguard and thinking about possible future defense systems. And that is why many of us support the B612 Sentinel proposal for a space-based detection system. The first priority has to be to find potentially hazardous asteroids.
What if the Chelyabinsk bolide had hit the atmosphere perpendicular to the ground rather than tangentially?
One minute or so earlier(or later), and it may have impacted the ground instead of exploding in the atmosphere…. That doesnt give me much confidence that the next one will be so “Low-Key” even if it is the same size.
If the Chelyabinsk bolide had been moving more nearly perpendicular to the ground, the deceleration stresses would have built up more quickly, and it might have exploded higher. However, the downward momentum of the resulting fireball might have penetrated deeper. In any case, the asteroid would not have impacted the ground. If you are worried about asteroid impacts, please focus on the most dangerous size range, which peaks between 100 and 300 m diameter.
That “threat” was moving at 18 km/s.
The Earth’s stratosphere is about 51 km.
So the Meteor would have had about 2.8 seconds to heat up to the point of exploding.
Sorry, dont think so, Ground Impact!
Heating of the object has nothing to do with its explosion. The physics is entirely different. Sorry, no ground impact.
To elaborate a little on what David is saying; you have the physics bass ackwards. When a natural bolide enters the atmosphere, the strong shock front out in front compresses the air in the path of the bolide to the point where it is incandescent (in fact brighter and hotter than the surface of the Sun). That incandescent shock front transfers heat onto the exposed surface of the bolide primarily via radiation (as opposed to convection) and starts boiling the surface away.
Also, the pressure on the front of the bolide acts to decelerate it, while the inertial force of the bolide acts to keep it moving. When the internal stress in the body of the bolide caused by these opposing forces exceeds the bearing strength of whatever the bolide is made of, it starts breaking apart. Because each piece of the original body is now smaller than the original, all the pieces immediately experience even higher internal stress (because of the square-cube law of scaling) and break apart, forming even smaller pieces, and so on. It is not really an “explosion” at all, but an exponentially increasing disintegration–both the rate at which pieces of the original body are subdividing and the rate at which the atmospheric density is increasing with depth into the atmosphere increase exponentially.
Each piece, of course, is still travellng at the cosmic velocity with which it entered the atmosphere and so forms its own incandescent shock front, etc. But now, the total surface area of all the pieces and therefore the total power being radiated into the atmosphere is many orders of magnitude greater than when the bolide was a single piece.
In summary, the disintegration of the bolide causes the almost instantaneous release of heat, not the other way around.
There is only one reasonable approach; One reasonable start in getting a handle on all of this: OBSERVE-TOUCH-EARLY-OFTEN.
Also, when witnesses where asked about groups working in the NEO/NEA area, the response included the UN, NASA, & B612. We also have the SBAG (Small Bodies Assessment Group), TargetNEO, IPEWG (International Primitive Body Exploration Working Group), the new SSERVI (Solar System Exploration & Research Virtual Institute), and so on…