Posted on 01/25/2010 9:58:55 AM PST by Yollopoliuhqui
http://www.theregister.co.uk/2010/01/25/only_nukes_can_stop_asteroids/
Only nukes can stop planetsmash asteroids, say US boffins
Nix on the 'world free of nuclear weapons', Mr President
By Lewis Page
Posted in Space, 25th January 2010 14:22 GMT
Top American boffins have warned that the US government's efforts to prevent global apocalypse caused by meteor strike are inadequate. The scientists add that nuclear weapons are the only practical means of defence against large, planet-wrecker sized asteroids.
In a new report, the US National Research Council says that so-called Near Earth Objects (NEOs) fall broadly speaking into three classes.
First and most terrible are large NEOs bigger than 1km (eg roughly Vatican sized and up) which would release energies in the hundred-thousand-megaton range - more than a global nuclear war, and with similarly catastrophic consequences for human civilisation or even survival. NASA has got most of these NEOs logged in its databanks, but not all - there are likely to be a few on orbits which only bring them within observation at very long intervals.
Apart from planet-busting big jobs like these, however, there are also a lot of quite hefty space boulders, snowballs etc in the 140m+/cathedral size range. These, owing to their terrific speed, would tend to cause destruction in the hundred-megaton range on impact - equivalent to a limited nuclear bombardment.
NASA was ordered by the US Congress to log 90 per cent of these medium-sized NEOs by 2020, and according to the National Research Council analysts this simply isn't going to happen as things stand - in large part because the politicians didn't assign any extra funds and the administration has asked for none. The $4m per annum the US currently spends on sky-search activities is seen as inadequate.
That said, the NRC's new report offers some alternative ways ahead which could see most of the threatening space objects spotted - either on time by 2020 using an expensive space-based telescope system, or taking a bit longer using cheaper ground instruments. The boffins also say that NASA should start scanning for smaller, 30-50m (ordinary church) sized objects, as these would still be very nasty if they hit in a populated area.
This much had already been mostly stated in a preliminary report released last year, but the NRC boffins have now gone further and taken a look at the various tactics humanity might use in the event of a dangerous NEO being detected. There are many of these, some of them quite delicate and refined - using the gravitational pull of a spacecraft's own mass to minutely drag an asteroid off course, for instance.
But "slow push/pull" methods like these are practical, according to the NRC, only for smaller NEOs and "would likely require decades of warning". Even "kinetic" plans where a spacecraft crashes into an asteroid would only work on less potent sub-Vatican threats, and again "may require decades of warning".
In the current state of human technology, the NRC warns, the only way to be sure is to nuke 'em from orbit:
Nuclear explosions are the only current, practical means for dealing with large NEOs (diameters greater than 1 kilometer) or as a backup for smaller ones if other methods were to fail.
It would seem that current plans by President Obama to strive for "a world free of nuclear weapons" would in the end - sooner or later - be a death warrant for humanity, rather than its salvation.
The full NRC report can be read here. http://www.nap.edu/catalog.php?record_id=12842
There is some evidence of periodicity to the major bombardments that suggests that a large body perturbs the orbits of objects in the Oort Cloud thus causing them to head sunward.
The greatest danger may lie in objects that suddenly appear from the outer reaches of the Solar System closing at over 100 Km/sec. We will be hard pressed to mount a mission in time to divert or break up such objects since we will have little warning. I don’t think there are launch vehicles readily available to send a nuke out at over 10 Km/sec. so the engagement will be relatively near the Earth.
We would still need timely warning. The nuke would have to be buried to have any affect at all on a solid rock or metal asteroid. Dozens of nukes would be needed to vaporize a comet ice ball type and/or flashed very close or impact the comet. They’ll need to drag out the TESLA weapons that everyone has been trying to keep secret and direct earths considerable electrical/ magnetic energy at them.
For large 1 mile diameter and above asteroids,I like the notion of massively constructed (100 meter to 1 km size diameter or 300 to 3000 meter circumference) “nuclear grenades” that have a core of intensely powerful thermo-nuclear bombs surrounded by duterium slush all encased in a thick constructed metal/rock sphere. It would be slowly accelerated out to a predetirmined impact point using ION engines. Even gentle acceleration over 2 or 3 months would cause the object to build up speeds of 20 to 30 miles a second over time. The timing would have to be perfect so that the explosion occurs just before impact so that the combined effects of kinetic force and intense nuclear flash/plasma expansion would push (if not obliterate) the object out of its killing path.
We have the technology to construct them now...we just need the will and the threat to do it. They could be kept in the Earth moon Lagrange points or at various lagrange points in the solar system. They could serve as space labs when not needed for their primary purpose and artificial magnetic fields could be generated on them by small nuke plants to keep harmful cosmic and solar radiation away from them. The living areas could be constructed on the inner surfaces of these shells(with “up” being oriented toward the center of the spheres and the floor plans slightly angled to derive the best benefit of the angular momentum of the station) and these stations “spun” to provide artificial gravity.
Why are the objects traveling so fast when they get here...Sol’s acceleration constant ?
Do you live at Cape Canaveral or Vandenburg AFB? Asteroid/comet intercepts would be launched from one of those sites.
NASA (using contractors) has launched a number of of RTGs (Radio-Thermal Generators) on lunar and deep space missions over the years. There was only one mishap called Apollo 13. When the LEM reentered over the Pacific at 25,000 MPH, the RTG survived the crash as it was designed to do. It now rests with its load of plutonium under 7 miles of water in the Marianas Trench. Bet you never heard that before!
They accelerate for up to 100 years as they come from the Oort Cloud. Look at the velocities that comets attain.
I know! We’ll sign a UN treaty with the asteroids and that will take care of everything!
Let's practice.
Right now they are called Master Sergeants (USAF) and Chief Petty Officers (USN.)
Leftists are often driven by size envy. In the mind of a journalist, is the Vatican a unit of measure? Could size be the root cause of leftist Catholic resentment?
You don't want to blow them up, you want to move them. That is, you want to shift their orbit so that they miss the earth. Nukes can do that, but you set them off near, but not on, the object. You want to push it.
Given more warning, you could also build what is called a "mass driver", to effectively throw material off the object, causing it to move a bit in the opposite direction. A sort of fairly low exhaust velocity rocket is what you'd have.
OTOH, with nukes you can make a Project Orion type vehicle (aka "Old Bang Bang") , and go anywhere in the solar system you might want to go, and fairly quickly.
Another conceptual drawing
They load them alright, but it's Lieutenants and Captains (USAF) and Lieutenant Commanders and Commanders (maybe even Captains) (USN) that launch them.
But if the military didn't do it for the asteroid movers, then it would likely be contractors, from Boeing, Lockheed-Martin, etc, etc, that would do both.
Sure. And a parsec is a measure of speed.
:^)
That’s my idea concerning large NEO’s and large scale nuclear grenades...if they didn’t completely destroy the object, the resultant push of superheated plasma,gas, and molten particles at 10 miles a second should knock the object off course.
The nuclear grenades would also have a fairly heavy iron stony base relative to the upper portions which would fracture quickly with the “blast”, spewing out plasma/gas/ and molten metal/stone fragments from the bomb enhanced with deuterium slush just within several hundred meters of the asteroid, with the heavy base of the grenade slamming in immediately afterward.
Perhaps a large heavy nickle iron asteroid wouldn’t be completely destroyed. Yet,a large area would be super heated and molten enough that gases spewing from the heated areas would effect trajectories and spin enough to deflect the object off course (in a addition to the kinetic and super heated walloping it just got).
The scientists are right to point out that nucs would just be “flashes” that wouldn’t necessarily destroy large stony/metal asteroids unless buried. Even then, a large part of what causes a nuc’s bang on earth are the atmospheric shock waves. Even when buried on earth, there is air trapped in the various sand grains/ air pockets as well as the surrounding soils themselves melting rapidly with a flash to cause sufficient ‘bang’ that can be measured with seismometers.
There is no air in space, and even if you could land on a rapidly spinning asteroid(in three dimensions no less), and bury the nuke, there is no atmosphere or trapped air in the asteroid to carry the shock wave through the asteroid.
My concept would have us take heavy hydrogen laden fluids and atmosphere to the nuke (using concepts found in Boyle’s laws) in addition to just the flash of a thermo nuke! The idea is to concentrate and direct a super heated plasma gas mixture at just the right point to give that object a push. Think of it as a giant thermonuclear shot gun shell, pushing molten fragments first then the heat/plasma following, only the heavier “shell” base comes crashing in last a super heated molten state.
Comet ice and snow type objects should be easier to do away with...flash a couple of nukes with in meters of the surface and the initial heat breaks the methane/ water compounds to simpler elements especially hydrogen. At a hundred million degrees centigrade...some of that hydrogen should start fusing creating a whole chain reaction until the ice comet is consumed.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.