What would we do if we discovered a large asteroid on course to impact Earth? While highly unlikely, that was the high-consequence scenario discussed by attendees at an Oct. 25 NASA-FEMA tabletop exercise in El Segundo, California.The third in a series of exercises hosted jointly by NASA and FEMA -- the Federal Emergency Management Agency -- the simulation was designed to strengthen the collaboration between the two agencies, which have Administration direction to lead the U.S. response. "It's not a matter of if -- but when -- we will deal with such a situation," s
One would hope that ~ 2 years would be enough to launch a nuclear warhead to deep space, but the question will be how much of a deflection that will give. Several warheads may be needed, or the deflection may not be enough to avoid an impact, just change the impact's location.
That's kind of the point of Mikelepage's chart... he runs some calculations that I would call conservative (but others may differ) for various sized items showing how much lead time is needed to move the thing by 1 earth diameter (and thus a near miss)... arguably 1 earth diameter may not be enough, dunno about you but I'd rather go for 10 diameters if we're talking about anything with any mass (and possible fragments in similar trajectories)
In a reasonable best case scenario, by the time you factor in approvals/preparing the rocket, we would need 3 years or so lead time before the deflection date, which in turn would be 477 days before impact. => we need at least 5 years lead time all up to have a realistic chance at deflecting a dinosaur killer (12km) comet.
Really? 3 years is too little time?
One would hope that ~ 2 years would be enough to launch a nuclear warhead to deep space...
Quote from: whitelancer64 on 12/21/2016 04:25 pmOne would hope that ~ 2 years would be enough to launch a nuclear warhead to deep space...Looking at the launch logs .. No. Only with completely unprecedented and prompt global collaboration maybe, but this is launching nukes to space, so even that would be doubtful.
Quote from: mikelepage on 12/21/2016 02:42 pmReally? 3 years is too little time? You're missing the point of the exercise: it's an evacuation exercise. In other words, assuming that much warning time, what kind of evacuation is realistic?
Quote from: Blackstar on 12/24/2016 12:45 amQuote from: mikelepage on 12/21/2016 02:42 pmReally? 3 years is too little time? You're missing the point of the exercise: it's an evacuation exercise. In other words, assuming that much warning time, what kind of evacuation is realistic?I understand that. My point is, if 3 years is enough time to launch a nuclear deflection mission, then your evacuation planning is completely upended by the fact that the majority of people will be thinking: "let's wait and see how the deflection mission goes before we really get serious about evacuation".
Quote from: mikelepage on 12/26/2016 05:44 amI understand that. My point is, if 3 years is enough time to launch a nuclear deflection mission, then your evacuation planning is completely upended by the fact that the majority of people will be thinking: "let's wait and see how the deflection mission goes before we really get serious about evacuation".Perhaps you should contact the people at NASA and FEMA and tell them that they are doing their work wrong. You can do that through an email or a letter.
I understand that. My point is, if 3 years is enough time to launch a nuclear deflection mission, then your evacuation planning is completely upended by the fact that the majority of people will be thinking: "let's wait and see how the deflection mission goes before we really get serious about evacuation".
(assuming 1% of the warhead's energy is converted to kinetic energy)
Quote from: mikelepage on 12/21/2016 02:42 pm(assuming 1% of the warhead's energy is converted to kinetic energy)That is a SWAG. It could be a lot more - or a lot less.The delta V is given by vaporising one side of the asteroid with gamma rays and x-rays. But this can only be done to a certain depth - probably a couple of metres.To cover the right surface area, the warhead will need to explode above the surface, so more than half the energy will be lost. Or could the gamma rays be channelled?For a metallic asteroid, might a neutron bomb be more effective?In any event, it's likely that several small bombs will be more effective than one large bomb. Using a penetrating nuclear warhead - Hollywood style - might then be left as a last resort.
http://neo.jpl.nasa.gov/pdc17/The 2017 PDC Hypothetical Asteroid Impact Scenario(snip) The date of the most likely potential impact is July 21, 2027 - over ten years away - but the probability of impact is very low, about 1 chance in 40,000.
On August 16, 2022 an approximately 70-meter asteroid entered Earth’s atmosphere. At 2:02:10 P.M. EDT, the space rock exploded eight miles over Winston-Salem, N.C., with the energy of 10 megatons of TNT. The airburst virtually leveled the city and surrounding area. Casualties were in the thousands.Well, not really. The destruction of Winston-Salem was the story line of the fourth Planetary Defense Tabletop Exercise, run by NASA’s Planetary Defense Coordination Office. The exercise was a simulation where academics, scientists and government officials gathered to practice how the United States would respond to a real planet-threatening asteroid. Held February 23–24, participants were both virtual and in-person, hailing from Washington D.C., the Johns Hopkins Applied Physics Lab (APL) campus in Laurel, Md., Raleigh and Winston-Salem, N.C. The exercise included more than 200 participants from 16 different federal, state and local organizations. On August 5, the final report came out, and the message was stark: humanity is not yet ready to meet this threat.