Nuclear weapons, have, let's face it, a rather bad press. But nukes can be thought of as cute, cuddly and useful if they save mankind (and yes womankind) as we know them. Nukes, to their credit may save us by stopping Asteroids, bent on destroying Earth.
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The Leader and Follower detect, engage and destroy or deflect the Aseroid. (Diagram courtesy page 6 of this HAIV Document)
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A Hypervelocity
Asteroid Intercept Vehicle (HAIV)
is
a spacecraft being developed by NASA to deflect
dangerous Near Earth Objects (NEOs) such as comets
and asteroids that threaten colliding with Earth. HAIVs focus on
utilizing powerful explosives, such as nuclear bombs, to achieve deflection by
detonating on the surface of the NEO to change its trajectory away from Earth.
This method of asteroid impact avoidance
is
intended to be used on dangerous NEOs detected within a short time frame (less
than 5 years) before a possible impact event
with
Earth. The idea came about when asteroid detection became accurate and since
then, scientists and engineers have come up with a well thought out design for
an HAIV.
---
---
A Hypervelocity
Asteroid Intercept Vehicle (HAIV)
is
a spacecraft being developed by NASA to deflect
dangerous Near Earth Objects (NEOs) such as comets
and asteroids that threaten colliding with Earth. HAIVs focus on
utilizing powerful explosives, such as nuclear bombs, to achieve deflection by
detonating on the surface of the NEO to change its trajectory away from Earth.
This method of asteroid impact avoidance
is
intended to be used on dangerous NEOs detected within a short time frame (less
than 5 years) before a possible impact event
with
Earth. The idea came about when asteroid detection became accurate and since
then, scientists and engineers have come up with a well thought out design for
an HAIV.
Even a meteor of only 30 meters in diameter (but weighing
an estimated 13,000 tonnes) caused major damage in Chelyabinsk,
Russia .
After detecting many of the asteroids within our solar system
and observing their composition through meteorite remains, NASA has identified
multiple large asteroids that may collide with Earth. To combat these NEOs,
NASA has come up with the following design for an HAIV.
The vehicle is split
into two major parts; the leader craft and the follower craft. These can be boosted into space by a Delta IV M+ "Heavy" booster rocket.
The leader craft is initially attached to the follower craft,
but before impact the two crafts are spread out by an extendable pillar known
as the AstroMast Boom. Furthermore, it contains the primary guidance systems
including normal cameras and Lidar (light based radar). The purpose of this
craft is to make an initial crater in the target NEO where the follower craft
may detonate in. Doing this helps direct the explosive energy of the follower
craft, hopefully applying enough force to change the orbit of the NEO.
The follower craft
contains the following:
· Solar panels and batteries to power both the follower and leader
craft.
· A large antenna and communication electronics to relay
information back to Earth.
· A camera to check on the status of the leader craft.
· The NED (Nuclear
Explosive Device)
which detonate upon impact with the NEO.
· Thrusters and fuel tanks to help the vehicle to travel towards
the target NEO.
· Other support systems and fail safes in the case of a
malfunction.
Once the leader craft impacts the NEO and makes a crater, the
follower craft detonates its NED soon after. It also relays back whether the
detonation was a success or failure which can be confirmed by observation from
the Earth.
There are numerous factors that have slowed the development of
the HAIV. These include but aren't limited to budget, law, and irregular NEOs.
Initial test missions have cost between $600 million to $1.8
billion and these were to test the feasibility of the guidance. A full mission
may cost much more than this amount, especially in the case of a NEO detected
with a short time till collision with Earth. With recent cuts to NASA's
funding, it is unsure whether an HAIV mission will ever occur.
The use of nuclear explosive devices is an international issue
and will need to be addressed by the United
Nations Committee on the Peaceful Uses of Outer Space. The
1996 Comprehensive Nuclear-Test-Ban Treaty technically bans nuclear weapons in space. But saving the Earth looks like a "peaceful" use...more see."
Pete
8 comments:
@Pete:
Tangentially related, it appears that the US specifically kept some nuclear weapons in a disassembled but not disposed/disarmed state specifically with the reason of asteroid defense listed (totally possible this isn't the *real* reason, but interesting regardless). The specific type appears to be the B-53, which would make sense. The B-53 was the last really large multi-megaton weapon (10Mt) in the US inventory that was maintained at deployable status in small numbers (1-2 dozen) for well after more modern weapons replaced it as a bunker buster until the B-61 mod 11 ground penetrating weapon was re-manufactured from mod 7's (this role will soon go to GPS/INS guided mod 12s). I believe it was the largest US deployed warhead (same basic package also used on Titan II) outside the B-41 which was the only three stage fision-fusion-fision weapon in US service and was 25Mt.
The logistics of sending a nearly 5 ton weapon past escape velocity would be rather daunting; for the US at least B-83 would perhaps be the more logical off the shelf physics package.
GAO report mentioning 'planetary' defense about 2/3 of the way down:
http://www.gao.gov/assets/670/662840.pdf#page=46
Cheers,
Josh
One issue with asteroid defence is how little we know about the composition of them. If its a big chunk, fine a big bomb may deflect it. If its a "composite" agglomeration of stuff that is loosely bound then an big bomb turns it into a "shotgun" load heading our way.
Even that may be worthwhile depending on the scenario. Less of the mass reaches the surface.
But underlying ALL of this is the capability to detect and classify threats as far out as possible. That NEEDS to be taken seriously and funded, and really, wouldnt cost that much. Ground or Near Earth orbit telescopes can do a lot nowdays.
Hi Josh
Luckily existing nuclear powers seem to be getting out of the multi-megaton "Doomsday" bomb business. I wonder if Russia has retained some Doomsdays?
I also wonder if North Korea will built large bombs for super sabre-rattling?
Pete
Hi imacca
It is a positive move by space agencies like NASA to do research on passing. The Deep Impact spacecraft was a project in 2005 https://en.wikipedia.org/wiki/Deep_Impact_(spacecraft)
SStardust and Rosetta are other projects https://en.wikipedia.org/wiki/Comet#Spacecraft_missions
Regards
Pete
@Pete:
Russia has always been fairly opaque about its arsenal so I don't have designations or yields for their weapons. But while they stayed in the multi-megaton business longer, it seems likely for practical reasons they've gone <= 1 megaton like the US has. Because of the inverse square law the energy delivered to target(s) goes down at a cubic function of distance from ground zero. Having several RVs or cruise missiles deliver smaller weapons to several points more efficiently delivers energy to an area of effect, even if the total yield is smaller and the targets aren't dispersed. And clearly the advantage of hitting a dozen point targets with a lot of distance of separation vice a couple of 10-20Mt impact points is helpful in terms of number of targets hit and redundancy of targeting. There is also the very real problem of fratricide of weapons - having your second 10Mt warhead disabled by the x-rays given off by the first is an inefficient way to run a nuclear exchange.
Once accuracy improved such that weapons could be expected to be within a couple hundred meters of targets instead of several km, using smaller weapons made more sense (miniaturization tech also had to catch up). The exception was deeply buried targets under rock, and for this the US retained small numbers of B-53 for a long time (and the Russians SS-18 'Satan').
The DPRK doesn't even have thermonuclear* weapons (my personal analysis). It certainly is a fact their largest detonation to date is ~10kt, which means they lag behind both of the first two weapons designs the US used WWII (Mk1 / Mk3). So for North Korea 1Mt, let alone 10Mt, will likely be forever out of their reach.
*as in two stage fission-fusion weapons
Cheers,
Josh
Hi Josh [at 29/9/16 12:40 AM]
My vote on the sharp decline in nuke yields goes to greater accuracy.
Russian Khrushchev threats of "we will bury you" also declined - hence city-country destroying nukes went out of propaganda vogue.
Also increased numbers of nukes available to nuclear powers allowed the spreading out of blast effects that you describe
The https://en.wikipedia.org/wiki/B53_nuclear_bomb at 9 meg was certainly nightmarish.
I can just see one of NKs Kim Dynasty reviving "we will bury you" and backing it with a multi-megaton bomb. Although testing ground for NK may be limited.
Regards
Pete
@Pete:
Its not just testing, its technical capability. The DPRK still hasn't equaled what the US did on its first try with the Trinity Test (Fat Man/Mk3 implosion Pu239 type) or even the first untested operational use of the 'gun' type (Little Boy/Mk1 U235 accelerated target type). Those weapons were 15-20kt, making any of the three (two cities, one test) greater than what the DPRK has yet achieved as a test, let alone a deliverable weapon. None of these weapons is a fusion/H-bomb type weapon; these are all pure fission. Much greater yields for much smaller packages come about when you use fission to compress a light material that can fuse - hydrogen and helium in the sun, I think lithium and deuterium (hydrogen isotope) in fission-fusion weapons. The DPRK is no where near this level of tech; they are still trying to make simple fission scale up to what the US did on its first try. I'm sure they will want a 10MT bomb when they are able, but I don't see the country surviving the decades it will take for them to get there, even assuming none of the surrounding powers decide to step in to stop them.
Cheers,
Josh
A small spaceship with an ion drive would be sufficient to change the asteroids way.
The most important step to avoid a collision with earth is to detect the astroid early enough. That is the problem today not some fancy way to blow the astroid up.
Regards,
MHalblaub
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