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Lucifer's Hammer

Wednesday, February 19, 2003

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2002 NT7

The official designation is 2002 NT7; it is an asteroid that is on an impact course with Earth on 1 February 2019. Naturally there are a number of uncertainties. 


Begin with the first posting in mail:


And if we didn't have enough to worry about, I have more than a dozen letters on this:

Potential Lucifer's Hammer alert! 

An asteroid discovered just weeks ago has become the most threatening object yet detected in space.

A preliminary orbit suggests that 2002 NT7 is on an impact course with Earth on 1 February 2019, although the uncertainties are large.

Astronomers have given the object a rating on the so-called Palermo technical scale of threat of 0.06, making NT7 the first object to be given a positive value.

From its brightness astronomers estimate it is about 2km wide, large enough to cause continent-wide devastation on Earth.

More at the link.

Lessee, 16+ years off, with NASA's current bureausclerosis, we're all goners if it's on a collision course.


Jim Riticher


Thanks to Jim Riticher, Ed Hume, and many others. Don't Panic. But indeed expecting NASA to Do Something is a pretty futile bet. 

Then came:

And From Henry Vanderbilt on the Hammer:

Interesting. On February 1st, 2019, we come within the error band of a 2 kilometer asteroid's orbit, as best it's currently known. 2002 NT7 is the name of the recently spotted rock.

The stories on this emphasize that as orbital projections for 2002 NT7 are refined - and they will be, quickly, now that astronomers know where to look on old photos - the path will almost certainly be pinned down as missing Earth by a comfortable margin.

"Almost" certainly. Interesting times indeed were we to stay inside the area of uncertainty as it narrows down. Not that there's any mystery about what we can and should do at that point, of course - start building the ships and technology it'd take to go out and move it.

But would we do so in any effective way? Suppose the usual suspects get funded and start doing what they do best, cranking out studies and viewgraphs, all aimed at defining the absolute optimum method of dealing with the problem by the end of, say, FY 2015... Oops! We've fallen a bit behind schedule, but not to worry, our top people are studying the problem!

Cynical? Moi?

Henry Vanderbilt

In fact we could mobilize to Do Something, but we probably won't. Max Hunter used to say that if you could just get a herd of American dinosaurs running together in the right direction, it was a tremendous sight to see. We did go to the Moon in that decade, you know. 

But it would take Presidential priority, appointment of the right managers, and no Congressional interference. And no lawyers. And the lawyers would mostly rather be what they are than get out of the way even if the cost was Hammerfall. And the odds are changing...


Hammer of God, it's gonna fall, Hammer of God come to punish us all,

Dr Dr. Pournelle I've been trolling through various sites covering asteroid 2002 NT7 and had the unnerving experience of seeing the odds of impact dropping from 1 in 10,000,000 (at,1282,54081,00.html ) to something less than 1 in 100,000 (at the New Scientist website: ). Even in Lucifer's Hammer the odds didn't fall that fast (-: At least it's not landing on a Thrusday.

Cheers James Evans

Hot Fudge Sundae... And see below.

The Hammer:

I have a proposal about what to do about what I think of as LH19. Not specifically what to do but how to get things going. The President should borrow a cue from JFK and redo the 'we do these things because they are hard' speech and set forth a deadline for America to produce a package that can rendezvous with this object and alter its orbit.

It doesn't matter if a few years from now the orbit proves to be non-threatening in 2019. It will eventually match up with Earth's passage again so why wait? Also, there are bound to be other threats that make this a prime opportunity to learn how to not only keep bad rocks away but also put them where we want them for exploitation.

The Cold War is over. This time the big space effort should be about realizing a profit.

Eric Pobirs

I can certainly agree with that. I even know how to do it.

Lucifer's Hammer continues on course. As of now I do not intend to be on the side of the planet that it may hit (assuming it's still on course and I'm still around). And the odds keep changing...

I know how to deal with the Hammer. It is apparently of some interest to the high tech community: the site where the beast's orbit could be seen was taken down due to too much traffic.

I'll have some in the column. I know precisely how we can deal with that thing and make a little money in the bargain. After all, the Council I chaired considered all this many years ago...

There will be more on this.



Dear Dr. Pournelle:

Asteroid 2002 NT7 should be classified as a resource and an opportunity (not to be missed). If there be any Caretakers of Planet Earth and The People, they are at present unskilled and unproven and even untested in bringing to reality the ancient philosopher's lever.

It is not too soon to begin the trials and errors (let us hope for none or few errors), and begin to think about collecting all those idle, rusting stockpiles of the world's nuclear warheads, not to dismantle or decommission, but to transform them into those space levers that will be required to change the orbits of certain asteroids of interest or notoriety.

There will be room for lots more years and eons of hope, if practice is begun in prudent time, before Lucifer's cruel Hammer makes all hope futile. Could we be witness to the hand of Providence reaching toward The Children of The Stars, sighing a silent breath of hope, "Wake, Little Ones, Here's a piece of a star. This is your childhood's end. Wait and watch and die, your fossil bones will last awhile. Or reach for stars and bend a planet's tail, your species might live on."

The orbit of Asteroid 2002 NT7 should not be nudged or bent willy-nilly lest future cycles repeat the peril. Instead, consider a landfall on Earth's Moon, or Mars. Someone may want to dig the crash site in 200 years. If energy resources, time, and economics were of no concern, a safe parking orbit might be dreamed of, even a dream of solar wind sail navigation after an initial use of a nuclear nudge.

Belay the dreams. Assemble the corps. Begin the practice. Attain the skills. Earth must be prepared.

Respectfully yours, James Ehman

I would myself think this a better investment of American resources than anything we can do in the Middle East; but I am an old republican, not one of the neoconservative imperialists.

And Roland has found this: 

Which is more relevant than it might at first appear. You will all recall that I was keynote speaker at the last Directed Energy convocation as USAF Phillips Lab...

Then came some reactions. Is this all hysteria?

Over in the SFWA conference I mentioned that the Hammer is coming. I got the res0nse that

> 2002 NT7 has about a 1 in 250,000 chance of impact as of the last time I
> looked at the JPL asteroid risks page last night. See
> As usual, the more sensational press is going nuts about the end of the
> world. All the hooplah is based on 15 days of observations. The asteroid
> will remain in view for some 300 days.
> The real threat to a comfortable retirement these days is the stock
> market.

Which caused me to write this, and I thought it worth repeating here:

1 in 250,000 is pretty thin odds: that is, the expected value (given 4 billion people on earth) is 16,000 dead. If we assume that if 16,000 people were trapped in a mine we would spend at least $1,000,000 on each one of them, (easily what is being spent on the 9 miners in Pennsylvania) that is $16 billion we would spend to prevent a disaster of this magnitude.

In fact we are spending a great deal more to avenge 911, but of course those were New Yorkers and much higher value (for insurance calculations) people than 16,000 random people of Earth.

Or, 1/250000 times 4 trillion dollars loss (surely it is that high) by no great coincidence comes out at $16 billion dollars. Since the expenditure of that $16 billion is not itself a negative thing -- surely we would get SOME return on the investment to build space infrastrucure -- it seems that there is a positive return from spending the money to prevent the disaster even if it turns out it would not have happened.

As with any Bayesian analysis we can also calculate the value of finding out more and narrowing the uncertainties: that is

Preventing the disaster will in fact cost more than $16 billion. Depending on the amount it would cost -- probably more like $160 billion -- we can calculate how much we should spend to find out what the odds really are. Since the most economical path to discovering the true odds would be to spend the money on things that would also be useful in preventing the disaster if it turns out to be more probable than we thought, it's pretty clear what we should do:

fund projects that reduce the cost of access to space.

Which will also aid in the Strategic Defense of the United States. I've already pointed out that the first step to that would be a couple of $2 billion X projects, one Air Force and the other Navy, to develop single-stage to supersonic pure rocket ships with at least 12 (I prefer 16) engines. These should be ships, not ammunition. Reusable with short turnaround times. Vertical takeoff and landing, recoverable, savable, reusable, operations driven: the goal is multiple flights on the same day, with routine operations.

In other words, here is the work statement for the contract:

  1.  Massively Multiple rocket engines
    1. Massive means at least 12; rockets rather than jets
    2. We don't specify the fuel.
    3. Strongly suggest that the fuel not be hydrogen because of operational considerations.
  2. Savable
    1. Able to survive an engine out at takeoff
  3. Routinely reusable with short turn around times
    1. Fly twice in a day and 6 times in a week and do that more than once
  4. Higher and Faster
    1. Performance is secondary to the other three points.
    2. Supersonic flight is the minimum goal. Anything better than that is good.

Given those goals, build the best flying hardware you can build for $2 billion in 3 years.


Once we can do that, we can develop one or two stage to orbit savable reusable ships. And from that we can discover the true odds -- space observations are a lot easier to do than atmospheric -- and develop means to shunt this thing away from us if it is in fact aimed at us. Or even maneuver it into Earth orbit to exploit it.

Jerry Pournelle

Jerry, you should look on JPL's site here

to see the current estimates. The really frightening numbers are for 2060-02-01. According to JPL we are in for a direct hit on that date with a miss of .56 earth radii as against 4.47 for 2019. Of course, the likelihood is, that if it near misses in 2019, then its orbit will be modified by the Earth's gravity and anything possible.

Edward Chambers

Well. .56 radii. Well. So if it misses us in 2019, here it comes again...

I was thinking about the problem of stopping a Hammer-like object and remembered some information about the Deep Space 1 probe mission.

What is to stop us from sending a small network of ion drives to NT7 2002 and using them to do a slow burn orbital insertion of the asteroid into a stable orbit and then mine it for materials? An ion drive is ideal for this kind of application I would think, some information about ion drives just to serve as a refresher:

"The ion propulsion system on Deep Space 1 carries about 81.5 kilograms of xenon propellant, and it takes about 20 months of thrusting to use it all. It increases the speed of the spacecraft by about 4.5 kilometers per second, or about 10,000 miles per hour. If we had the same amount of chemical propellant, it would provide only one tenth as much velocity increment. If DS1 carried a larger solar array, it certainly would have a slightly higher acceleration, and if it carried more Xe propellant it could reach a much higher final velocity by simply thrusting longer. But DS1 is testing ion propulsion solely to find out if it works as well as predicted. Future missions that use it likely will carry more propellant to achieve still higher speeds."

Deep Space 4 is slated to use an array of ion drives for propulsion to test higher speeds among other new tech in 2004.

I don't have the numbers on hand but I would be curious to see if it is feasible to use a small network of ion drives on NT7 2002 with a prolonged burn of a 1-2 year duration would be sufficient enough to put it into a stable orbit around the Earth that would lend to having it get mined easily. We have the technology to do all of this now I think, if not would someone please correct me? What have I missed here? I would be greatly interested to work out the math on this with everyone.

-Dan S.

P.S. Last I heard we had a 1 in 100,000 chance between now and 2060 of being hit by NT7 2002. After 2060 data becomes dicey due to the close passes NT7 2002 will make.

If we have access to space we will have little problem diverting this thing. The risk is real, the expected value of doing something about it is probably positive; the only real question is the will.

A Presidential Priority on X concepts by USAF and USN would do it. Whether they'll get it is another matter.

Above is an estimate of the energy in Lucifer.  6.6 x 10^5 Megatons of HE (this was done in Mathcad)

No small amount...

On the Hammer (I collect this material on its own page, so you can begin there if you like)

I read with interest the cost/benefit analysis you presented in the Hammer page. The trouble is, I don't think it's a 1/250,000 problem - it's a binary problem.

If it hits *at all*, even in the most uninhabited and uninhabitable wasteland on Earth, it will very likely kill far more than 16,000. If it doesn't hit, it won't kill anyone.

None of which should change the basic conclusion, that it can't hurt and will almost certainly help tremendously to have low-cost access to space, even if we do determine it's not going to hit. If not NT7, there will always be something Out There that might need to be investigated or deflected. Imagine trying to execute a "Rendevous with Rama"-like mission today with the resources we have available - it just wouldn't happen.

The last odds I saw were 1 in 100,000, in one of the links to the New Scientist - but the scariest statement I saw in that article was that this was pretty close to the average odds of an asteroid hitting us anyway in that timeframe anyway.

William Harris

Actually, if it hits the casualties will CERTAINLY be far greater than any paltry 16,000, which has been known to happen with earthquakes and tsunamis. The conditional probability given that it hits of 1 million or more casualties is essentially 1.0 (.9 with at many 9999 as you like).

Expected value models are a rough cut. They aren't intended to be exact and they often reflect impossible outcomes (ONLY 16,000 given that it hits is very nearly impossible). On the other hand, an expected value model is easy to compute (as opposed to a weighted average of all possible outcomes) and in fact is pretty good for decision purposes.

Your average probability of  being killed by a meteoric event is about the same as your lifetime probability of being killed in an aircraft accident. It's also an expected value model calculation.

The other point is precisely the case: something will happen, and we don't have the means to do much about it. It's about time we did.

In case you haven't seen this one, the lead-in says it all.

........Karl Lembke

* Asteroid will miss Earth in 2019 * New observations confirm that asteroid 2002 NT7 will not strike the Earth in 2019 - but the possibility cannot yet be ruled out for 2060. Full story:

The chances of one of these hitting us is small for any given century. The chance over a longer time is much larger.  We can if we like DO something.

And for calculating orbits:

Here are some asteroid impact calculators for the Hammer Page

quick and dirty

very detailed

Finally, a Neat Java Applet with a display of the orbit can be seen here. You can Zoom in, spin the solar system around, and animate the display. The data they are using does not currently jive with projected impact date.

NOTE: as seen here

the possible impact in 2019 has been ruled out.

and of course all the basic information on asteroids can be found here, for those who are interested.

Michael Zawistowski

Please visit

Thank You